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Background: Flusulfinam, a novel chiral herbicide, effectively controls Echinochloa crusgalli and Digitaria sanguinalis in paddy fields, indicating significant potential for practical agricultural applications. However, limited information is available on flusulfinam from a chiral perspective. A comprehensive evaluation of the enantiomeric levels of flusulfinam was performed., Results: Two enantiomers, R-(+)- and S-(-)-flusulfinam, were separately eluted using a Chiralcel OX-RH column. The bioactivity of R-flusulfinam against the two was 1.4-3.1 fold that of Rac-flusulfinam against two weed species. R-flusulfinam toxicity to Danio rerio larvae and Selenastrum capricornutumwere was 0.8- and 3.0-fold higher than Rac-flusulfinam, respectively. Degradation experiments were conducted using soil samples from four Chinese provinces. The findings indicated that S-flusulfinam (half-life T 1/2  = 40.8 days) exhibits preferential degradation than R-flusulfinam (T 1/2  = 46.2-57.8 days) in the soils of three provinces. Under anaerobic conditions, soil from Anhui exhibited preferential degradation of R-flusulfinam (T 1/2  = 46.2 days) over S-flusulfinam (T 1/2  = 63 days). Furthermore, two hydrolysis products of flusulfinam (M299 and M100) are proposed for the first time., Conclusion: The enantioselective bioactivity, toxicity and degradation of flusulfinam were investigated. Our findings indicate that R-flusulfinam is an extremely effective and low-toxicity enantiomer for the tested species. The soil degradation test indicated that the degradation of flusulfinam was accelerated by higher organic matter content and lower soil pH. Furthermore, microbial communities may play a crucial role in driving the enantioselective degradation processes. This study lays the groundwork for the systematic evaluation of flusulfinam from an enantiomeric perspective. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Chlorinated pollutants may follow distinct degradation pathways in anaerobic environments compared to aerobic settings. However, the understanding of the behaviors and fate of dichlorodiphenyltrichloroethanes (DDTs) under anaerobic conditions remains limited. To address this knowledge gap, we conducted a study on flooded soil samples collected from three typical paddy fields in China using an integrated approach of enantiomer-specific analysis and compound-specific stable carbon isotope analysis. It is unexpected that the dichlorodiphenyldichloroethane /dichlorodiphenyldichloroethylene ratios (DDD/DDE=(o,p'-DDD+p,p'-DDD)/(o,p'-DDE+p,p'-DDE)) were below 1 in over 90 % of the samples. This might be attributed to the higher recalcitrance of p,p'-DDE, which concentrations were found to be 36 times higher than p,p'-DDD on average. There were 71.7 % of the samples showing enantiomeric fractions (EFs) of o,p'-DDT below 0.5, indicating a preferential accumulation of the (-)-enantiomer. The δ 13 C values of the anaerobic metabolite o,p'-DDD (-24.76 ± 1.35 ‰ to -34.39 ± 0.20 ‰) all deviated negatively from the initial product, while those of the aerobic metabolite o,p'-DDE (-23.61 ± 0.48 ‰ to -38.95 ± 0.81 ‰) displayed either negative or positive deviations. This demonstrates that o,p'-DDD is the primary metabolite of o,p'-DDT under anaerobic conditions. However, no clear correlations were observed between the δ 13 C and EF of o,p'-DDT. This study underscores the importance of such an integrated methodology in unraveling the fate and behaviors of DDTs in complex environmental systems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Four pairs of undescribed enantiomeric guaiane sesquiterpenoids, (±)-alismaenols A-D (1a/1b, 3a/3b-5a/5b), together with a pair of known ones (2a/2b) were isolated from the rhizomes of Alisma plantago-aquatica. The structures and relative configurations of the isolates were established by analysis of their 1D, 2D-NMR and HRESIMS data. Their absolute configurations were determined by comparison of their experimental CD spectra and calculated electronic circular dichroism (ECD) spectra or by single-crystal X-ray diffraction analysis. All compounds (1a/1b-5a/5b) were evaluated for their inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 cells, and compound 1a exhibited stronger activity (IC 50  = 12.89 μM) than indomethacin (IC 50  = 14.03 μM)., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier B.V.)

Seven pairs of undescribed monoterpenoid polyprenylated acylphloroglucinol enantiomers [(±)-hypermonanones A-G (1-7)], together with three known analogues, were identified from the whole plant of Hypericum monanthemum Hook. The structures of these compounds were determined by analyses of their UV, HRESIMS, 1D/2D NMR spectroscopic data, and NMR calculations. The absolute configurations of these compounds were assigned by ECD calculations after chiral HPLC separation. Diverse monoterpene moieties were fused at C-3/C-4 of the dearomatized acylphloroglucinol core, which led to 3,4-dihydro-2H-pyran-integrated angular or linear type 6/6/6 tricyclic skeletons in 1-7. Compounds (-)-2 and (+)-2 exhibited significant NO inhibitory activity against LPS induced RAW264.7 cells with the IC 50 values of 7.07 ± 1.02 μM and 11.39 ± 0.24 μM, respectively., Competing Interests: Declaration of competing interest All authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

( S )-Atenolol (( S )-2-(4-(2-Hydroxy-3-(isopropylamino)propoxy)phenyl)acetamide) has been synthesized in >99% enantiomeric excess ( ee ) with the use of Candida antarctica lipase B from Syncozymes (Shanghai, China), in a kinetic resolution of the corresponding racemic chlorohydrin. A catalytic amount of base was used in deprotonation of the phenol building block. The enantiopurity of the chlorohydrin building block remained unchanged upon subsequent amination to yield the final drug. All four steps in the synthesis protocol have been optimized compared to previously reported methods, which makes this new protocol more sustainable and in accordance with green chemistry principles. The overall yield of ( S )-atenolol was 9.9%, which will be further optimized.

Hexachlorocyclohexanes (HCHs) are a group of highly persistent pesticides. The concentrations of HCHs and the enantiomeric fractions of α-HCH in the O- and A-horizons from 30 mountains across China were analyzed in this study. The concentrations of total HCHs ranged from 0.061 to 46.9 ng/g (mean 2.12 ng/g) and 0.046 to 16.1 ng/g (mean 0.792 ng/g) in the O- and A-horizons, respectively. The HCH residues were mainly derived from the historical applications of technical HCH and lindane. Higher concentrations of HCHs were typically found in northern China, and no significant correlations were found between historical technical HCH usage and HCH isomer concentrations in either the O- or A-horizons (p > 0.05). Conversely, the concentrations of HCH isomers were significantly correlated with the environmental parameters (temperature and precipitation), thus indicating a typical secondary distribution pattern. Some HCH isomers tended to be transported northward under the long-term effect of monsoon. Chiral α-HCH was non-racemic in soils and showed preferential degradation of (-) α-HCH in both the O- and A-horizons. The transformation from γ-HCH to α-HCH might alter the enantiomeric signatures of α-HCH in soils. Moreover, the deviation from racemic of α-HCH was positively correlated with the C/N ratio in the A-horizon (p < 0.01), thus suggesting that the C/N ratio could alter the microbial activity and significantly affect the enantioselective degradation extent of α-HCH in soils., Competing Interests: Declaration of competing interest The authors state that they have no known competitive financial interests or personal relationships, which may affect the work reported in this article. All authors were directly involved in the execution and/or analysis of this study. The contents of this manuscript have not been previously copyrighted or published. We declare that we have no commercial or affiliated interests that represent a conflict of interest in connection with the submitted work., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The study aimed to investigate RRR- α -Tocopherol and synthetic α -Tocopherol stereoisomers in maternal plasma, cord plasma and breast milk from different regions of China, providing a reference for further guidance on maternal diet and the potential need to supplement mothers with vitamin E. Two hundred and twenty-one sample sets from maternal plasma, cord plasma and three stages of milk (colostrum: 1-5 d after delivery; transitional milk: 10-15 d; mature milk: 40-45 d) were collected longitudinally in six regions of Shanghai, Guangzhou, Tianjin, Chengdu, Lanzhou and Changchun. α -Tocopherol and the stereoisomers were determined by HPLC with a fluorescence detector. The RRR configuration accounted for more than 80 % of α -Tocopherol in maternal plasma, cord plasma and breast milk. Overall, there were regional differences both in α -Tocopherol and RRR. There were significant correlations between α -Tocopherol and RRR in maternal plasma, cord plasma and milk ( P < 0.001). As well as negative correlations among α -Tocopherol, RRR and weight-related indicators, which refer to pre-gestation weight and BMI, pre-delivery weight and BMI and pregnancy weight gain, in almost all of samples. This study suggested that RRR- α -Tocopherol was the dominant configuration of α -Tocopherol and the main active form of vitamin E in the early life, guiding the rational supplement of pregnant women and the addition of α -Tocopherol in infant formula milk powder.

This study investigated the occurrence of hexabromocyclododecanes (HBCDs) in soil-maize system around Baiyangdian Lake. The total concentration of ΣHBCDs was in the order of industrial area > residential area > marginal area > Fuhe River estuary in soil. γ-HBCD was predominated in soils, roots and stems, while α-HBCD was the main diastereoisomer in leaves and kernels. Concentration of ΣHBCDs and three diastereoisomer concentrations in soils were significantly reduced and remained low level from 2018 to 2019. Selectivity enrichment of (+)α- and (-)γ-HBCD was found in soils, roots, stems and leaves, whereas only (+)β-HBCD dominated in stems. Most of the total root bioaccumulation factors (ΣRCFs) were less than 1.0, but no significant correlation was showed between translocation factors (TFs) and log K ow . RCFs and TFs of enantiomers suggested (-)β- and (-)γ-HBCD were easily translocated from soil to roots, while (+)α-, (-)β- and (-)γ-HBCD tended to translocate from stems to leaves. Estimated daily intake (EDI) and of ΣHBCDs, diastereoisomers and enantiomers were all lower than the threshold value, while the Calculated margins of exposure (MOE) were well above the threshold value, which demonstrate the safe consumption of Maize around Baiyangdian Lake., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Gossypol acetate (GA), as the product of racemic gossypol and acetic acid conjugated by hydrogen bond, is hydrolyzed into gossypol to exert its effect on treating uterine leiomyoma (UL), which has been listed in China. But hypokalemia and mild changes of liver function limit its clinical application. It had been reported that the biological activities of gossypol optical isomers were different. In this study, we aimed to clarify whether there were differences in the efficacy of gossypol enantiomers and whether a single gossypol optical isomer could alleviate adverse reactions in the treatment of UL. The results indicated that (-)-GA and (+)-GA had significant therapeutic effect on rats with UL. Interestingly, (-)-GA could better significantly ameliorate the pathological structure, inhibit the secretion of estrogen, and downregulate the expression of estrogen receptor-alpha (ER-α) and progesterone receptor (PR) than (+)-GA. Additionally, (-)-GA could better evidently decrease the symptoms of abnormally elevated inflammatory factors caused by UL. In contrast, (-)-GA and (+)-GA had certain effects on potassium ion concentration in serum, liver and kidney function, and the effects of (+)-GA on liver function were more obvious than (-)-GA. These findings will be of great significance to the drug development of gossypol optical isomers., (© 2022. The Author(s) under exclusive licence to The Japanese Society of Pharmacognosy.)

A chiral analytical method was developed and validated for the determination of mandipropamid enantiomers in tomato, cucumber, Chinese cabbage and cowpea. The linearity (R 2 > 0.99), accuracy (recovery: 73.8-106%) and precision (relative standard deviation: < 11%) were adequate for the detection of mandipropamid enantiomers in four vegetables. Field trials were further conducted to investigate the dissipation and residue distribution of mandipropamid and the possible enantioselectivity in different vegetables. Due to the shorter half-lives, mandipropamid dissipated more rapidly in Chinese cabbage (1.8-2.0 d) and cowpea (1.6-2.4 d) than in tomato (5.0-8.4 d) and cucumber (2.4-5.5 d). The residues of mandipropamid were 45-179 µg/kg in tomato 14 d at low dose, 48-98 µg/kg in cucumber 7 d after spraying twice at low dose, and < 2.5-1942 µg/kg in Chinese cabbage and cowpea in all treatments, which were below the maximum residue limits of mandipropamid set by the European Union and Codex Alimentarius Commission. Enantioselectivity was observed during the mandipropamid dissipation process in four vegetables. The S-(+)-enantiomer dissipated more rapidly than the R-(-)-enantiomer in tomato and Chinese cabbage (enantiomeric fractions > 0.5). For cucumber and cowpea, the dissipation of the R-enantiomer was preferential (enantiomeric fractions < 0.5). According to the risk quotient data (<< 100%), the residues of mandipropamid in four vegetables were safe for Chinese consumers. This study could provide useful information for the dissipation fate and residue distribution of mandipropamid in vegetables at the enantiomer level and offer some guidance for the dietary intake risk evaluation of mandipropamid in vegetables., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: The study aimed to investigate the contents and isomer composition of vitamin E in mature milk in different regions of China., Methods: Simultaneously recruited 604 lactating mothers aged(29.58±3.43) from Shanghai, Guangzhou, Tianjin, Chengdu, Lanzhou and Changchun cities. They were mainly primiparas with good education background. A total number of 604 mature milk samples was collected. The contents of α-, γ-, δ-tocopherols and the stereoisomers of α-tocopherol were determined by high performance liquid chromatography(HPLC)., Results: The M(P25, P75) concentrations of α-tocopherol, RRR-α-tocopherol, γ-tocopherol and δ-tocopherol in Chinese mature milk were 3.16(2.29, 4.16)mg/L, 2.57(1.77, 3.48)mg/L, 0.89(0.58, 1.27)mg/L and 0.17(0.09, 0.27)mg/L, respectively. The total α-TE level was 3.09(2.22, 4.10)mg/L with statistically regional differences(P&lt;0.001). RRR-α-tocopherol was the predominated stereoisomers of α-tocopherol, accounting for 83.17%(76.36%, 88.43%). The proportion of RRR in Tianjin mature milk was significantly lower than that in Lanzhou(77.11% vs. 86.16%, P&lt;0.001) while breast milk samples from other regions had similar RRR-α-tocopherol proportions(82.82%-85.39%)., Conclusion: Vitamin E content in mature milk was mainly composed of α-tocopherol. Even though the contents of tocopherols have large regional differences, RRR-α-tocopherol was predominated form in all breast milk samples. It is suggested that RRR-α-tocopherol was the main active form of vitamin E in the early stage of life.

Chemical investigation of the marine sponge Dysidea avara, collected from the South China Sea, yielded 13 steroids, including nine new (1-9) and four known (10-13) ones. The new structures were elucidated as (3S,14R)-3,14-dihydroxycholesta-5,8-dien-7-one (1), (22E,24R)-7α-ethoxy-5α,6α-epoxyergosta-8(14),22-dien-3β-ol (2), 3β-hydroxy-7α-ethoxy-5α,6α-epoxy-8(14)-cholestene (3), 3β,5α-dihydroxy-6α-ethoxychofesta-7,9(11)-diene (4), 3β,5α-dihydroxy-6β-ethoxycholest-7-ene (5), (22E,24R)-24-ethoxy-3β,5α-dihydroxy-6β-ethoxyergosta-7,22-diene (6), (22E)-3β,5α-dihydroxy-6β-ethoxycholesta-7,22-diene (7), 24-ethoxy-3β,5α-dihydroxy-6β-ethoxycholest-7-ene (8 and 9), by extensive spectroscopic analyses, such as HR-ESI-MS, 1D and 2D NMR data. The absolute configuration of 1 was assigned by comparison the experimental ECD spectra with the calculated ones. Among the 13 metabolites, compounds 1, 4, 11, 12, and 13 showed NF-κB inhibitory activities in human HER-293 cells with IC 50 values of 6.4, 18.7, 8.1, 9.6, and 7.5 μM, respectively. Preliminary structure-activity relationship analysis unveiled that the conjugated ketones or unsaturated double bonds might be the functional groups for the five active steroids., (© 2021 Wiley-VHCA AG, Zurich, Switzerland.)

Elucidating the enantiomeric chemistry and enantioselective fate of the novel chiral triazole fungicide mefentrifluconazole is of vital importance for agroecosystem safety and human health. The absolute configuration of mefentrifluconazole was identified firstly as S-(+)-mefentrifluconazole and R-(-)-mefentrifluconazole on a cellulose tris(3-chloro-4-methylphenylcarbamate) chiral phase. A baseline resolution (Rs, 2.51), favorable retention (RT ≤ 2.24 min), and high sensitivity (LOQ, 0.5 μg/kg) of enantiomer pair were achieved by reversed-phase liquid chromatography tandem mass spectrometry combined with a 3D response surface strategy. Nationwide field trials were undertaken to clarify the enantiomer occurrence, enantioselective dissipation, terminal concentrations, and storage stability of S-mefentrifluconazole and R-mefentrifluconazole in watermelon across China. The original deposition of the sum of enantiomer pair was estimated to be 14.4-163.7 μg/kg, and terminally decreased to < LOQ-59.3 μg/kg 10 days after foliage application. S-mefentrifluconazole preferentially degraded (T 1/2 , 3.3-6.0 days), resulting in the relative enrichment of R-mefentrifluconazole (T 1/2 , 3.9-6.6 days) in watermelon. A probabilistic model is recommended for the dietary risk assessment, although both acute (%ARfD, 0.435-22.188%) and chronic (%ADI, 1.697-9.658%) risks are acceptable for associated population. The long-term exposures should be continuously emphasized given the increasing applications and persistent fate of mefentrifluconazole, especially for urban children., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Four pairs of undescribed racemic bi(9,10-dihydro) phenanthrene and phenanthrene/bibenzyl atropisomers, bletistriatins A-D (1-4), along with 22 known compounds were isolated from the rhizomes of Bletilla striata. These dimeric derivatives were constructed through direct C-C connection or an oxygen bridge. The structures of new compounds were fully established by extensive analysis of MS, and 1D and 2D NMR spectroscopic data. Owing to sterically hindered rotation around the biaryl axis, these dimeric 9,10-dihydrophenanthrene derivatives can exist as a pair of enantiomers, but were isolated as racemates. Their racemates were separated to yield enantiomerically pure compounds by HPLC on an optically active stationary phase, and were stereochemically characterized on-line by circular dichroism (CD) spectroscopy (LC-CD coupling). Some isolates were evaluated for cytotoxicity against human cancer cell lines HL-60 and A549. Compounds 13, 17, and 20 showed cytotoxicity against HL-60 and A-549 cell lines with IC 50 values ranging from 2.56 to 8.67 μM., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Ligustici Radix (Chinese name: maoqianhu) consists of the dried roots of Ligusticum brachylobum Franch., which is mainly distributed in the Yunnan and Sichuan provinces. This herbal medicine has been primarily used for the treatment of cough in traditional Chinese medicine. Ligustici Radix is rich in coumarin derivatives. Interestingly, enantiomers and diastereomers are widely used for these coumarins, thus posing a great challenge for in-depth chemical profile characterization. In the present study, a new analytical platform, achiral-chiral liquid chromatography-tandem mass spectrometry (achiral-chiral LC-MS/MS) was configured to profile the chemical composition of Ligustici Radix. Because achiral and chiral columns were serially coupled, especially enantiomers, both chemically and enantiomerically selective separations could be accomplished simultaneously. The newly configured achiral-chiral LC-MS/MS platform did not require any electronic valve; hence, it could overcome the drawbacks of heart-cutting achiral-chiral two-dimensional LC, i. e., sophisticated instrumentation and limited reproducibility due to the use of electronic valve(s) and the undesired retention time shift across different analytical runs. Some available candidates for chemically selective or enantiomerically selective separation were assayed; then, Capcell core RP-C 18 column that was packed with core-shell type particles, and AD-RH column embedding amylose coated particles were employed the achiral and the chiral columns, respectively. The narrow-bore core-shell RP-C 18 column served as the front tool to achieve efficient chemoselective separation of coumarin analogs, and enantioselective enantiomers were obtained by using a wide-bore AD-RH chiral column. The predictive multiple reaction monitoring (predictive MRM) mode allowed for the sensitive detection of potential components, and an enhanced product ion (EPI) scan, which was a unique function of Qtrap-MS, was programmed to record the MS 2 spectra for all captured signals and thus aid structural annotation. Online energy-resolved mass spectrometry (online ER-MS) was introduced to pursue the suitable collision energy for each compound; in particular, inferior collision energy instead of the optimal one was utilized to suppress the response of the primary components such as praeruptorin A, B and pteryxin. The criteria to judge enantiomers or not included identical quantitative and qualitative precursor-to-product ion transitions, identical quantitative versus qualitative responses, and longer retention times from achiral-chiral LC over single-column achiral LC. As a result, a total of sixty components were observed and structurally identified. In particular, enantiomerically selective separations were achieved for eight enantiomers, cis -khellactone (CKL), qianhucoumarin G (QC-G), pteryxin (Pte), praeruptorin A (PA), cis -3'-isovaleryl-4'-acetylkhellactone (IAK), praeruptorin B (PB), praeruptorin E (PE), and cis -3',4'-diisovalerylkhellactone (DIK). Notably, none of the enantiomers were present as racemates; instead, the proportion of one enantiomer in each pair was greater than the other. Achiral-chiral LC-predictive MRM is a feasible choice for the quantitative and qualitative analyses of Ligustici Radix as well as other herbal medicines characterized by enantiomers and diastereomers.

An EtOH extract of the Chinese liverwort Radula apiculata showed cytotoxic activity against the A549 lung cancer cell line. Bioassay-guided fractionation led to the isolation of 19 prenylated bibenzyls, including eight previously unknown dimeric prenylated bibenzyls [radulapins A-H ( 1 - 8 )], four new prenylated bibenzyls ( 9 - 12 ), and seven known compounds ( 13 - 19 ). Compounds 1 - 11 were analyzed as racemates by chiral-phase separation. Their structures were determined by detailed analysis of their spectroscopic data and by single-crystal X-ray diffraction, chiral resolutions, and electronic circular dichroism measurements. Using an MTT assay, these dimers ( 1 - 8 ) showed significant cytotoxic activity against a panel of human cancer cell lines. Further investigation revealed that compound 4 induces PC-3 cell death via mitochondrial-derived apoptosis.

Under the guidance of MS/MS-based molecular networking and HPLC-UV, two new alkaloid racemates, (±)-17-hydroxybrevianamide N ( 1 ) and (±)-N1-methyl-17-hydroxybrevianamide N ( 2 ), featuring a rare o -hydroxyphenylalanine residue and an imide subunit, were isolated from a soft-coral-derived Aspergillus sp. fungus. The true natural products (+)- 1 and (+)- 2 were further monitored and obtained from the freshly prepared EtOAc extracts, while (-)- 1 and (-)- 2 are artifacts generated during extraction and purification processes. Simultaneously, the structures including absolute configurations of (+)-13 S - 1 , (-)-13 R - 1 , (+)-13 S - 2 , and (-)-13 R - 2 were elucidated on the basis of comprehensive spectroscopic analysis, ECD calculations, and X-ray diffraction data. Interestingly, basic solution promotes the racemization of (+)- 1 and (-)- 1 , whereas acidic solution suppresses the transformation. The current research was concerned with the true natural products and their artifacts, providing critical insight into the isolation and identification of natural products.

Eight new lignans, dracomolphin A-E (1-8), together with eight known lignans (9-16) were isolated from the aerial part of Dracocephalum moldavica. The structures of the isolated compounds were established based on NMR and HRESIMS data. Dracomolphin A (1-4) was elucidated as a lignan possessed a 5-membered ketal ring formed between C-8' and C-3, C-4. The two stereogenic centers rendered dracomolphin A as a mixture of two diastereomeric pairs of enantiomers (1-4). All of the four isomers were separated successfully by using chiral HPLC and their stereochemical features were determined by CD spectra. Bioactivity screening revealed that compounds 1-4, 6, 7, 12, 15 and 16 were potential Nrf2 transcriptional activators. Dracomolphin E (8) reduced cell viability of lung cancer NCI-H292 cells associated with apoptosis., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Dufulin is a new type of chiral antiplant virus agent independently developed in China. The present study was conducted to determine the effects of different concentrations of rac-dufulin and dufulin enantiomers (1, 5, and 10 mg/L) on oxidative stress in Tubifex after exposure for 3, 7, and 14 d. Results showed that rac-dufulin and individual enantiomers had no significant effects on total protein content and glutathione reductase activities. Increased superoxide dismutase demonstrated the generation of superoxide anion radical. The increase in glutathione S-transferase may be due to detoxification mechanisms. The different changes in catalase activities could be due to oxidative stress. The increase in malondialdehyde may be due to the accumulation and toxicity of contaminations. The degradation behavior of dufulin enantiomers was studied through spiked-water and spiked-soil tests. The degradation rate of S-(+)-dufulin was faster than that of R-(-)-dufulin. The present study demonstrated the occurrence of enantioselectivity in the degradation and oxidative stress of dufulin to Tubifex. In spiked soil, the concentrations of dufulin enantiomers in underlying soil were significantly higher than those in overlying water; but after 5 d of degradation, the bioturbation of Tubifex could facilitate part of dufulin diffusing from the underlying soil into the overlying water and altered the partitioning of dufulin. The present study provided a basis for conducting environmental safety risk assessments and rationally using dufulin as a chiral pesticide. Environ Toxicol Chem 2020;39:2136-2146. © 2020 SETAC., (© 2020 SETAC.)

Eight bisindole alkaloids including six undescribed ones (1a/1b-5) were isolated from an alcohol extract of the Isatis indigotica roots. Their structures and absolute configurations were supported by extensive spectroscopic data analysis, including 1D, 2D NMR, HRESIMS data, specific rotation data, and comparison of the experimental and calculated ECD data. Compounds 1a and 1b were determined to be a pair of enantiomers with a ratio of approximately 1:1 by chiral-phase chromatography analysis while compound 4 was elucidated as a new type of bisindole alkaloid with the aglycone categorized as bis(indole-1'/3″-yl)methane. All the isolated compounds were tested for their nitric oxide (NO) inhibitory effects and 1-4 and 6 exhibited inhibitory effects with IC 50 values ranging from 11.0 to 37.6 μM., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2020. Published by Elsevier B.V.)

We investigated the levels and distributions of organochlorine pesticides (OCPs) in 159 background soil samples collected from 30 forested mountain sites across China. The sum of DDT was the most abundant OCP, with the concentrations of 0.197-207 ng/g and 0.033-122 ng/g in the O-horizon and A-horizon, respectively. High concentrations of OCPs usually occur near agricultural regions or high consumption areas. The spatial distribution was mainly influenced by the emission sources and soil total organic contents (TOC). The chiral compounds were generally nonracemic in the soils and showed preferential degradation of (-) o,p'- dichlorodiphenyltrichloroethane, (+) trans-chlordane, and (-) cis-chlordane in both the O- and A-horizons. The enantiomeric fraction (EF) distributions of chiral OCPs displayed no differences across the forest sites in the O-horizon or the A-horizon. Comparing the deviation of EFs from racemic (DEVrac = absolute value of 0.500 - EF) with environmental parameters, we found that DEVrac of cis-chlordane demonstrated a strong positive correlation with TOC (p < 0.05) and the C/N ratio (p < 0.01). This relationship suggests that these factors could affect the microbial activity and significantly impact the extent of enantioselective degradation of chiral compounds in the soils. Fresh and historical applications of DDT and historical chlordane and endosulfan uses may be prominent sources of OCP accumulation in Chinese forest soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All authors have directly participated in the execution and/or analysis of this study. The contents of this manuscript have not been copyrighted or published previously. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted. The manuscript will not be copyrighted, submitted, or published elsewhere while acceptance by Environmental Pollution is under consideration., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Perfluorooctane sulfonates (PFOS) are one of the most prominent perfluoroalkyl contaminants in humans and wildlife. Currently, information regarding enantiomer-specific exposure to PFOS in humans through transplacental transfer is lacking. This study examined 32 matched maternal serum, cord serum and placenta samples collected from mother-infant pairs in Wuhan, China. The enantiomer fraction (EF) value of perfluoro-1-methylhptanesulfonate (1m-PFOS) was lower in cord sera (0.362 ± 0.062, n = 23) compared to maternal sera (0.422 ± 0.048, n = 21) and placenta (0.410 ± 0.060, n = 16). Evaluations of the difference between EF 1m-PFOS suggested enantioselective transplacental transfer of 1m-PFOS. In silico evaluation of the binding affinity of 1m-PFOS to human serum albumin (HSA) showed that the two 1m-PFOS enantiomers enantioselectively interacted with the HSA. This result hints the enantioselective carrier protein affinity may be a key factor for stereoselective 1m-PFOS transplacental transfer. The percentage of branched PFOS (%br-PFOS) and EF 1m-PFOS was correlated in maternal sera, but not in cord sera and placentas. These data indicated that %br-PFOS and EF 1m-PFOS may be less reliable in identifying PreFOS exposure when it comes to complex biological processes, such as transplacental transport. This study could expand our understanding of stereoselective placental contaminant transfer in humans., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The chiral pesticide bromothalonil is widely used to control anthracnose disease on fruits and vegetables in China. The pesticidal activity, ecotoxicological effects and environmental behavior of bromothalonil and its enantiomers are still unclear., Results: Bromothalonil presented effective biocidal activities against the tested fungi, its enantiomers showed distinct inhibitory activities against different fungal species. The bioactivities of (+)-bromothalonil was 1.29-10.77 times higher than (-)-bromothalonil toward Rhizoctonia solani, Botrytis cinerea, Curvularia lunata, Corynespora cassiicola, Colletotrichum siamense, and Colletotrichum musae, while the effect pattern was opposite for Colletotrichum cliviicola. Based on the acute toxicity test, bromothalonil was very toxic to Eisenia foetida (E. foetida). Bromothalonil also damaged the lysosomal membrane and exhibited potential genotoxicity toward E. foetida. Moreover, (+)-bromothalonil presented lower toxicity than (-)-bromothalonil. Stereoselective degradation was investigated in tomato, cucumber, chieh-qua, and soil. The half-life values of bromothalonil degradation ranged from 7.14 to 24.75 days, indicating that bromothalonil was easily degraded. Additionally, (+)-bromothalonil degraded 1.2-1.75 times faster than (-)-bromothalonil in the four matrices., Conclusion: This is the first systemic assessment of the stereoselectivity of bromothalonil. Based on the obtained half-life, EC 50 and LC 50 values, bromothalonil is an easily degraded, broad-spectrum biocidal but very toxic pesticide. (+)-Bromothalonil was more degradable in vegetables and soil and showed clearly higher bioactivity toward target organisms and lower toxicity to E. foetida than (-)-bromothalonil. Therefore, the stereoselectivity of bromothalonil enantiomers should be fully considered in comprehensive environmental and ecological risk assessments in future work. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Two new hydroperoxy steroids, namely, xidaosteroids A and B (1 and 2), along with five known related compounds 3-7, were isolated from the South China Sea gorgonian Rumphella sp.. Their structures were established by extensive spectroscopic analyses and comparison of the spectral data with those reported in the literature. In bioassay, compound 3 showed weak cytotoxicities against SNU-398 and Capan-1 cells., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Thallactones A (1) and B (2), enantiomeric aporphine alkaloids with rare cleaved rings A and B, as well as thaliglucine N-oxide (3) and their biosynthetically related precursor, northalphenine (4), were isolated from the whole plant of Thalictrum wangii. Their structures with absolute configurations were elucidated by spectral techniques and electronic circular dichroism (ECD). Moreover, compounds 1, 3, and northalphenine inhibited concanavalin A (Con A)-stimulated proliferation of mice splenocyte significantly in a dose-dependent manner., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Ailanthus altissima Swingle is a deciduous tree, belonging to the Simaroubaceae family. Phytochemical investigation of the root barks of A. altissima showed the presence of eight pairs of enantiomeric 8,4'-type oxyneolignans (1a/1b-8a/8b) including nine undescribed compounds (1b, 2a, 3a/3b, 4a/4b, 5b, 7b, 8a). Their structures were elucidated by comprehensive spectroscopic analyses, and their absolute configurations were determined by comparison of the experimental and quantum chemical calculations of electronic circular dichroism (ECD) curves. In addition, their neuroprotective effects against H 2 O 2 -induced oxidative stress in human neuroblastoma SH-SY5Y cells were investigated. Among them, 4a, 4b, and 8b exhibited moderate neuroprotective activity., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Five new phthalide dimers, chaxiongnolides C-G (1-5), the two enantiomers of riligustilide (6a and 6b) and tokinolide B (7) were isolated from the aerial parts of Ligusticum sinense Oliv cv. Chaxiong. The structures of 1-5 were elucidated through extensive spectroscopic analysis, and the relative configurations of compounds 2 and 3 were further confirmed by an X-ray diffraction experiment. The absolute configurations of 1-3 were assigned by comparing calculated and experimental ECD spectra. The ECD exciton chirality method was used to confirm the absolute configurations of compounds 4, 5, 6a and 6b. Compounds 1-3 are the first dimeric phthalides to be reported that are comprising a sedanolide unit. The compounds were evaluated in vitro for their cytotoxic activity against select human cell lines., (Copyright © 2019. Published by Elsevier B.V.)

Phytochemical investigation of the fruit of Crataegus pinnatifida led to the isolation of four pairs of dihydrobenzofuran neolignan enantiomers (1a/1b-4a/4b) including six new compounds (1a/1b, 2a/2b, 3a and 4a). The enantioseparations of the racemates were achieved successfully by chiral chromatographic column. Their structures were established by comprehensive spectroscopic analyses and the absolute configurations were determined by quantum mechanical calculation of electronic circular dichroism (ECD) spectra. All compounds were evaluated in vitro for their cytotoxicity using human hepatocellular carcinoma Hep3B and HepG2 cells. Among them, it was found that 2a had a selective cytotoxicity against Hep3B cells with IC 50 value of 25.47 μM, while the IC 50 value of its enantiomer 2b on Hep3B cells was 59.37 μM. These results implied that the absolute configurations of 2a and 2b possessed remarkable influences on their cytotoxicity. Further flow cytometry analysis indicated that 2a performed more significant effect on cell apoptosis compared with its enantiomer 2b., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Hexabromocyclododecane (HBCD) is an effective brominated flame-retardant additive, which is mainly produced in the coastal area of China. This study collected soil samples from a HBCD production plant and its surrounding area in Weifang, Shandong Province, China, and analyzed the temporal-spatial distribution of HBCD and its diastereoisomers in soil. The analysis results showed that the concentration of HBCD in soil near the plant was much higher than normal values, with an annual average concentration reaching 5405 ng/g. Soils 1, 2 and 4 km away from the plant were also analyzed, showing that the concentration of HBCD in soil decreased accordingly with the distance from the pollution sources. In order to investigate the effect of the season on HBCD content, the soil samples were collected in all four seasons of the year 2017-2018. According to variations in the wind direction, the concentration of HBCD in soil was also changed. The distribution trend showed that the concentration of HBCD in soil in the downwind direction of the prevailing wind was higher than that in the upwind direction. In addition, this work analyzed the distribution of HBCD in vertical soil sections. It was found that the concentration of HBCD decreased with depth in the soil vertical profile. Finally, the various diastereoisomer patterns in the soil compartments were examined, finding that α-HBCD and γ-HBCD were the predominant diastereoisomers in the soil of the study area., (Copyright © 2019. Published by Elsevier B.V.)

Seven compounds including four undescribed fusaric acid derivatives, namely fusaricates H-K, and two undescribed γ-pyrone derivatives, named fusolanones A-B, as well as a known compound fusaric acid, were isolated from a mangrove endophytic fungus Fusarium solani. Fusaricates H-K represent the first cases of fusaric acid butanediol esters and are diastereoisomers. Their structures including absolute configurations were elucidated based on NMR, MS, chemical synthesis, chiral HPLC analysis and ECD calculations. The antibacterial activity of all undescribed compounds were tested and fusolanone B showed the best activity with MIC value 6.25 μg/mL on Vibrio parahaemolyticus., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The chiral herbicide imazethapyr (IM) is frequently used to control weeds in soybean fields in northeast China. However, the impact of IM enantiomers on microbial communities in soil is still unknown. Genetic markers (16S rRNA V3-V4 regions) were used to characterize and evaluate the variation of the bacterial communities potentially effected by IM enantiomers. Globally, the bacterial community structure based on the OTU profiles in (-)-R-IM-treated soils was significantly different from those in (+)-S-IM-treated soils, and the differences were enlarged with the treatment dose increasing. Interestingly, the Rhizobiaceae family and several other beneficial bacteria, including Bradyrhizobium, Methylobacterium, and Paenibacillus, were strongly enriched in (-)-R-IM treatment compared to (+)-S-IM treatment. In contrast, the pathogenic bacteria, including Erwinia, Pseudomonas, Burkholderia, Streptomyces, and Agrobacterium, were suppressed in the presence of (-)-R-IM compared to (+)-S-IM. Furthermore, we also observed that the bacterial community structure in (-)-R-IM-treated soils was more quickly restored to its original state compared with those in (+)-S-IM-treated soils. These findings unveil a new role of chiral herbicide in the development of soil microbial ecology and provide theoretical support for the application of low-persistence, high-efficiency, and eco-friendly optical rotatory (-)-R-IM.

Stereoisomers of 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH) were determined in sediments and 30 marine species in a marine food web to investigate their trophic transfer. Lipid content was found to affect the bioaccumulation of ΣHBCD and ΣTBECH in these species. Elevated biomagnification of each diastereomer from prey species to marine mammals was observed. For HBCD, biota samples showed a shift from γ- to α-HBCD when compared with sediments and technical mixtures; trophic magnification potential of (-)-α- and (+)-α-HBCD were observed in the food web, with trophic magnification factors (TMFs) of 11.8 and 8.7, respectively. For TBECH, the relative abundance of γ- and δ-TBECH exhibited an increasing trend from abiotic matrices to biota samples; trophic magnification was observed for each diastereomer, with TMFs ranging from 1.9 to 3.5. The enantioselective bioaccumulation of the first eluting enantiomer of δ-TBECH in organisms at higher TLs was consistently observed across samples. This is the first report on the trophic transfer of TBECH in the food web. The estimated daily intake of HBCD for Hong Kong residents was approximately 16-times higher than that for the general population in China, and the health risk to local children was high, based on the relevant available reference dose.

One novel protease sin3406-1 was identified from Streptomyces niveus SCSIO 3406, which was isolated from the deep sea of the South China Sea, and heterologously expressed in E. coli BL21(DE3). Protease sin3406-1 was further used as a green biocatalyst in the kinetic resolution of racemic ethyl-3-hydroxybutyrate. After careful process optimization, chiral product ethyl (S)-3-hydroxybutyrate was generated with an enantiomeric excess of over 99% and a conversion rate of up to 50% through direct hydrolysis of inexpensive racemic ethyl-3-hydroxybutyrate catalyzed by sin3406-1. Interestingly, protease sin3406-1 exhibited the same enantio-preference as that of esterase PHE21 during the asymmetric hydrolysis of the ester bonds of racemic ethyl-3-hydroxybutyrate. Through mutation studies and molecular docking, we also demonstrated that the four residues close to the catalytic center, S85, A86, Q87 and Y254, played key roles in both the hydrolytic activity and the enantioselectivity of protease sin3406-1, possibly through forming hydrogen bonds between the enzyme and the substrates. Deep-sea microbial proteases represented by sin3406-1 are new contributions to the biocatalyst library for the preparation of valuable chiral drug intermediates and chemicals through enzymatic kinetic resolution.

Hexabromocyclododecanes (HBCDs) are a class of widely used brominated flame retardants (BFRs) that exhibit strong hydrophobicity. The ubiquity and persistence of HBCDs in sediment have attracted significant attention because of public health concerns. The environmental fate and ecological risks of HBCDs closely depend on their phase distribution in sediments. However, little information is available regarding the freely dissolved concentrations (C free ) of HBCDs in sediment porewater. In this study, we developed a method to measure C free of HBCDs in sediment porewater using triolein-embedded cellulose acetate membranes (TECAM). The TECAM-to-water partitioning coefficient (log K TECAM ) was 4.69, 4.77, and 4.63 for α-HBCD, β-HBCD, and γ-HBCD, respectively. In sediments, HBCDs sorbed to the sediment solid phase accounted for more than 99% of the total chemical mass. The dissolved organic carbon (DOC)-water partition coefficient (K DOC ) values were derived from TECAM measurements, and the log K DOC values ranged from 5.77 to 6.23 for the three HBCD diastereomers, suggesting a strong tendency for HBCDs to sorb to DOC. The high sorption of HBDCs for DOC implies a potential for DOC-facilitated transport which may enhance the environmental mobility of HBCDs.

Vibrational circular dichroism (VCD) method has become robust and reliable alternative for the stereochemical characterization of natural products. In this paper, three new serrulatane-type diterpenoids, euplexaurenes A-C (1-3), and a known metabolite, anthogorgiene P (4), were obtained from the South China Sea gorgonian Euplexaura sp. GXWZ-05. The absolute configuration of C-11 in 1-4, which was difficult to be determined by common means due to the high conformational flexibility of the eight-carbon aliphatic chain attached at C-4, was determined by VCD method, suggesting a new horizon to define the absolute configurations of natural products possessing chains. Compounds 1-4 were found to show selective cytotoxic activities against human laryngeal carcinoma (Hep-2) cell line with the IC 50 values of 1.95, 7.80, 13.6 and 5.85 μM, respectively.

A rapid and sensitive liquid chromatography-tandem mass spectrometric method was developed for the first time and validated for the determination of cefprozil diastereomers in human plasma. The plasma samples were prepared by protein precipitation using acetonitrile. Detection was performed using an electronic spray ion source in the negative ion mode, operating in the multiple reaction monitoring of the transitions m/z 388.0 to m/z 205.0 for cefprozil diastereomers and m/z 346.1 to m/z 268.1 for cephalexin (the internal standard). The calibration curves of cis-cefprozil and trans-cefprozil were linear in the ranges 0.125-16.0 µg/mL and 0.0403-1.72 µg/mL, respectively. The lower limits of quantification of cis- and trans-cefprozil were 0.125 and 0.0403 µg/mL in human plasma, respectively. The intra- and inter-day precisions of cis- and trans-cefprozil were all <9.7%, and the accuracy ranged from 99.2 to 104.7% and from 100.6 to 102.2%, respectively. The validated method was successfully applied to a bioequivalence study of two cefprozil formulations in 24 healthy Chinese volunteers. The two cefprozil tablets were bioequivalent by measurement of cis-, trans- and total cefprozil. We suggest that the bioequivalence of cefprozil formulations can be evaluated only using cis-cefprozil as the analyte in future studies., (Copyright © 2015 John Wiley & Sons, Ltd.)

Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsible nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I. shangrila and I. nitidus, are typical in this regard. Six synthetic candidate pheromone components that we earlier identified from hindguts of unmated males of these two Ips species were tested for field activity in Qinghai province, P. R. China. For I. nitidus, racemic ipsdienol ((±)-Id) could replace the naturally-produced blend of enantiomers containing 74% (-)-(S)-Id (74:26 S:R), in attractive ternary or binary blends. In contrast, sympatric I. shangrila were attracted mainly to blends including Id of opposite chirality, 97%-(+)-(R)-Id. Of the verbenols, (-)-trans-verbenol was inactive for I. nitidus or inhibitory for I. shangrila, but (-)-cis-verbenol (cV) was a key component of the pheromone in both species. Two fully factorial experiments demonstrated that (±)-Id, cV, and 2-methyl-3-buten-2-ol (MB) are components of the aggregation pheromone of I. nitidus, whereas only (+)-Id and cV are essential components of the aggregation pheromone of I. shangrila. While MB is not necessary for attraction of I. shangrila, it is an active antagonist and likely functions in species isolation. A review of the pheromone production and responses in Palearctic Ips and Pseudoips showed that cV is more common than methylbutenols, and both elicit qualitatively variable responses. Ipsdienol is the most common component with variable chirality, and is a necessary, but often not sufficient, factor for determining pheromone specificity.

The sesquiterpenoid curdione is one of the main bioactive components in the essential oil of Rhizoma Curcumae (Curcuma wenyujin, Curcuma phaeocaulis, and Curcuma kwangsiensis), which has been clinically used for the treatment of cancer in mainland China. Recently it was reported that natural curdione could be hydroxylated by Aspergillus niger and transferred to its corresponding curcumalactones under acidic conditions. Based on this study, the development of a sesquiterpenoid library through the "mirror-image" manipulation of bioactive (non)natural curdione scaffolds by chemical and biological approaches is presented herein. A. niger induced the hydroxylation of two pairs of curdione enantiomers, yielding the corresponding mirror-image hydroxylated curdiones. Simultaneously, the acid-mediated intramolecular "ene" rearrangements of these curdiones and hydroxylated curdione enantiomers yielded the corresponding mirror-image curcumalactones and hydroxylated curcumalactones. Among the 16 pairs of enantiomers obtained in this study, 23 compounds are new sesquiterpenoids. These curdione and curcumalactone derivatives are of particular interest, as they have the potential to be used as lead compounds and scaffolds in drug discovery.

Two pairs of new enantiomers, lucidulactones A and B (1 and 2), and two known compounds were isolated from Ganoderma lucidum. Their structures were determined by means of spectroscopic methods. The chiral HPLC was used to separate the ( - )- and (+)-antipodes of the new compounds.

Three new polyunsaturated lipids, (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraen-3-one (1), (6Z,9Z,12Z,15Z)-1-bromooctadeca-6,9,12,15-tetraen-3-one (2), and (Z)-ethyl docos-5-enoate (3), together with two known polyunsaturated lipids, 4(Z),7(Z),10(Z)-tridecatrienoic acid (4) and (6Z,9Z,12Z,15Z)-octadeca-1,6,9,12,15-pentaen-3-one (5), were isolated from the marine sponge Haliclona sp., which was collected from Guangxi, using HSCCC and HPLC methods. Chemical structures of the five compounds were elucidated by spectroscopic techniques.

One new ergostane-type steroid, (12β,15β,22R,23S,24S)-22,25-epoxy-12,15,23-trihydroxyergost-4,6,8(14)-trien-3-one (1), three new phthalide derivatives, 5-(2',3'-epoxy-3',3'-dimethylpropoxy)-7-methoxy-6-methylphthalide (2), (2')-(Z)-5-(3'-hydroxymethyl-3'-methylallyloxy)-7-methoxy-6-methylphthalide (3), and 5-(3',3'-dimethylallyloxy)-7-hydroxy-6-methylphthalide (4), along with one known phthalide derivative, 5-(3',3'-dimethylallyloxy)-7-methoxy-6-methylphthalide (5), were isolated from cultures of the basidiomycete Albatrellus confluens. The structures of the new compounds were established on the basis of extensive spectroscopic data (IR, MS, 1D, and 2D NMR) analyses. All compounds were evaluated for their cytotoxic activities on five tumor cell lines.

Two new laurane-type sesquiterpenoids, debromo-3α-hydroperoxy-3-epiaplysin (1) and debromo-3β-hydroperoxyaplysin (2), together with seven known related compounds (3-9), were isolated from the Chinese red alga Laurencia okamurai. Their structures were elucidated by detailed analysis of spectroscopic data and by comparison with the literature. In bioassay, compounds 2, 4, 8, and 9 exhibited significant PTP1B inhibitory activity with IC50 values ranging from 4.9 to 14.9 μg/ml.

Two new dopamine derivatives divesamides A (1) and B (2), along with six known N-containing compounds were isolated from the Chinese black ant (Polyrhachis dives). Their structures were determined on the basis of spectroscopic methods. Compound 1 is a racemate, and chiral HPLC separation yielded a pair of antipodes. The absolute configuration of (+)-1 was assigned by a computational method. The double signals in the (1)H and (13)C NMR spectra of 2 that resulted from the presence of a formamide group were discussed. The T- and B-lymphocytes proliferation assay showed that 2 has moderate immunosuppressive activity toward T- and B-lymphocytes proliferation at a concentration of 20 μM.

(+)- and (-)-cochlearols A (1) and B (2), two meroterpenoids with novel polycyclic skeletons, were isolated from the fruiting bodies of the fungus Ganoderma cochlear. Their structures and stereochemistry were determined by using spectroscopic, computational and single-crystal X-ray diffraction methods. Cochlearol A is a new normeroterpenoid containing a naturally unusual dioxaspiro[4.5]decane motif. Biological studies showed that (-)-2 is a strong inhibitor of p-Smads, exhibiting renoprotective activities in TGF-β1 induced rat renal proximal tubular cells.

A new pentacyclic indole alkaloid, kopsiyunnanine E, was isolated from Yunnan Kopsia arborea, and its structure, which was inferred from spectroscopic data, was established by a 16-step asymmetric total synthesis that proved that the natural alkaloid was not enantiomerically pure.

Five new norditerpene endoperoxides, named diacarperoxides H-L (1-5), and a new norditerpene diol, called diacardiol B (6), were isolated from the South China Sea sponge, Diacarnus megaspinorhabdosa. Their structures, including conformations and absolute configurations, were determined by using spectroscopic analyses, computational approaches and chemical degradation. Diacarperoxides H-J (1-3) showed some interesting stereochemical issues, as well as antimalarial activity.

Four new steroids with an acetoxy linked at the end of the side chain, echrebsteroids A-D (1-4) were obtained from the South China Sea gorgonian Echinogorgia rebekka. The absolute configurations of 1-3 were determined using the modified Mosher's method on the hydrolysis products. The isolation of the pair of epimers (2 and 3) represents the first reported separation of C-25 epimers of 26-acetoxy steroids. The (25R)-epimer (3) exhibited promising antiviral activity against respiratory syncytial virus with an IC50 value of 0.19 μM and a comparatively higher therapeutic ratio (TC50/IC50 = 128).

A pair of unusual benzannulated 6,6-spiroketal enantiomers [(-)-1 and (+)-1] and three new biogenetically related compounds (2-4), together with two known related analogues (5 and 6), have been isolated from a mangrove fungus, Penicillium dipodomyicola HN4-3A. Their structures were elucidated on the basis of spectroscopic analysis (1D and 2D NMR data) and X-ray crystallography. The absolute configurations of enantiomers (-)-1 and (+)-1 were determined using quantum chemical calculations of the electronic circular dichroic (ECD) spectra. Compounds 2 and 3 exhibited strong inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC50 values of 0.16±0.02 and 1.37±0.05 μM, respectively.

Cercosporenes A-F (1-6, respectively), six new guanacastane diterpenes, including a homodimer (5) and a heterodimer (6), were isolated from the crude extract of the fungus Cercospora sp., endophytic to the medicinal plant Fallopia japonica. The structures of 1-6 were elucidated by nuclear magnetic resonance experiments, and 4 and 5 were further confirmed by X-ray crystallography. The absolute configuration of 1 and 3 was assigned by electronic circular dichroism calculations, whereas that of 6 was deduced by the application of the circular dichroism exciton chirality method. In addition to its cytotoxicity against a panel of five human tumor cell lines, HeLa, A549, MCF-7, HCT116, and T24, heterodimer 6 also induced autophagy in HCT116 cells.

Background: Aroma-active compounds, together with sugars, amino acids, fat and nucleotides, are the main chemical species determining the characteristic aroma and taste of food. For selecting yeast extract pastes products with a less undesirable aroma, the aroma-active compounds that affect the overall consumer acceptance of yeast extract pastes products were analysed in this work., Results: The aroma-active compounds of yeast extract pastes were extracted by using dynamic headspace extraction or simultaneous distillation extraction, and were detected by gas chromatography-olfactrometry-mass spectrometry in conjunction with dynamic headspace dilution analysis or aroma extract dilution analysis. Sensory results revealed that a meaty, roasted aroma was the dominant of overall aroma. The important aroma-active compounds referred in this work were mainly aldehydes, acids, ketones, furan derivatives, pyrazines, and sulfur-containing compounds. Of these, six volatile compounds such as 3-methylbutanal, 2,3-butanedione, 2,3,5-trimethyl-pyrazin, acetic acid ethenyl ester, 2-acetyl-1-pyrroline and (E,E)-2,4-decadienal had never been reported before as key aroma-active compounds of yeast extract pastes., Conclusions: The key aroma-active compounds were identified in basic and characteristic meaty flavour yeast extract pastes, and their characterisation was determined., (© 2013 Society of Chemical Industry.)