Search

A versatile terpene synthase (LcTPS2) producing unconventional macrocyclic terpenoids was characterized from Leucosceptrum canum. Engineered E. coli and Nicotiana benthamiana expressing LcTPS2 produced six 18-/14-membered sesterterpenoids including five new ones and two 14-membered diterpenoids, representing the first macrocyclic sesterterpenoids from plants and the largest sesterterpenoid ring system identified to date. Surprisingly, none of these macrocyclic terpenoids were detected in L. canum. Two variants F516A and F516G producing approximately 3.3- and 2.5- folds respectively more sesterterpenoids than the wild type enzyme was engineered. Both 18- and 14-membered ring sesterterpenoids displayed significant inhibitory activity on the IL-2 and IFN-I³ production of T cells via inhibition of MAPK pathway. The findings will contribute to the development of efficient biocatalysts to create bioactive macrocyclic sesterterpenoids, and also herald a new potential in the well-trodden territory of plant terpenoid biosynthesis.

Liver fibrosis has accounted for liver diseases and overall mortality, but no relevant drug has been developed. Filamentous fungi are important resources of natural products for pharmaceutical development. Calcarisporium arbuscula is a mushroom endophytic fungus, which primarily produces aurovertins. Here, in an aurovertin null-production mutant, one silent gene cluster (mca17) was activated by overexpression of a pathway-specific zinc finger transcriptional regulator, and a tetramic acid-type compound (1, MCA17-1) was identified. Along with detailed structural characterization, its biosynthesis was proposed to be produced from the core PKS-NRPS hybrid enzyme. Moreover, 1 suppressed the activation of LX-2 upon transforming growth factor-β (TGF-β) challenge and had stronger bioactivity than the positive control obeticholic acid (OCA) against liver fibrosis. Our work suggested that this engineered fungus could be a producer of 1 for promising pharmaceutical development, and alternatively, it would be developed as a mushroom ingredient in dietary therapy to prevent liver fibrosis.

6-Formylisoophiopogonone B (7a) and 8-formylophiopogonone B (7b), two natural products isolated from Ophiopogon japonicus, represent a subgroup of rare 6/8-formyl/methyl-homoisoflavonoid skeletons. Herein we report an efficient method for the synthesis of these formyl/methyl-homoisoflavonoids. The synthesized compounds were evaluated for their neuroprotective effects on the MPP+-induced SH-SY5Y cell injury model and showed marked activity. Exploration of the neuroprotective mechanisms of compound 7b led to an increased expression of autophagy marker LC3-II and down-regulation of autophagy substrate p62/SQSTM1. Molecular docking studies showed that 7b may prevent the inhibition of the classic PI3K-AKT-mTOR signaling pathway by interfering with the human HSP90AA1.

Fungal natural products are rich sources of clinical drugs. Particularly, the fungicolous fungi have a large number of biosynthetic gene clusters (BGCs) to produce numerous bioactive natural products, but most BGCs are silent in the laboratory. We have shown that a fungicolous fungus Calcarisporium arbuscula NRRL 3705 predominantly produces the highly reduced polyketide-type mycotoxins aurovertins. Here after evaluation of the aurovertin-null mutant ΔaurA as an efficient host, we further screened two strong promoters aurBp and A07068p based on RNA-Seq, and successfully activated an endogenous gene cluster from C. arbuscula as well as three additional exogenous BGCs from other fungi to produce polyketide-type natural products. Thus, we showed an efficient expression system from the fungicolous fungus C. arbuscula, which will be highly beneficial and complementary to the conventional Aspergillus and Penicillium fungal cell factories, and provides a useful toolkit for genome-wide mining of bioactive natural products from fungicolous fungi.

Clinacanthus nutans Lindau (Family: Acanthaceae) is a medicinal herb widely distributed in the tropic and subtropic areas of Asia. C. nutans is traditionally consumed as vegetable or herbal tea, as well as a folk medicine for anticancer and antifungal activities. However, to date, chemical constituent responsible for observed health beneficial effects of this medicinal plant is not clear. In the current study, 32 compounds (1−32), including three new megastigmanes (1–3) were isolated from the aerial parts of C. nutans. Their structures were elucidated on the basis of comprehensive NMR, MS, and CD spectroscopic data analysis, as well as chemical hydrolysis. Among the isolates, cycloartane triterpenoids (9, 10, and 12) displayed moderate anti-proliferative effects against HepG2 cell growth with IC50 values ranging from 9.12 to 19.89 μM. Data obtained from flow cytometry analysis and western blotting assays revealed that compounds 9 and 12 induced apoptosis of HepG2 cells by modulating the expression of proteins associated to mitochondrial-mediated apoptotic pathway. Furthermore, megastigmanes 1, 2, 7, and 8 enhanced the anti-Candida albicans activity of amphotericin B (AmB), supporting the synergistic effects between megastigmanes and AmB. This is the first report of anticancer and antifungal potential of cycloartane triterpenoids and megastigmanes in C. nutans, which shed useful insights on the relationship between C. nutans's chemical constituent and its beneficial effects to health. Findings from this study support further development of this medicinal plant for potential pharmaceutical applications.

Two highly rearranged daphniphyllum alkaloids, daphnillonins A (1) and B (2), were isolated from Daphniphyllum longeracemosum and structurally characterized by a combination of diverse methods, including the calculation of electronic circular dichroism. Compound 1 possesses an unprecedented carbon architecture with a very unique 8-methyl-6-azabicyclo[3.2.1]octane moiety, and compound 2 represents a new carbon skeleton with an uncommon 7/6/5/7/5/5-fused ring system. The biosynthetic pathways for the two alkaloids were proposed with the concurrent major alkaloids as the precursors.

Novel antilipid peroxidative carbazole alkaloids, antiostatin A5 (1), antiostatin A6 (2), and (±)-morindolestatin (3), were isolated from a new soil-derived Streptomyces sp. Compound 2 possesses an unusual cyclohexene side chain. Compound 3 was a pair of enantiomers featuring an unprecedented [1,4]oxazino[2,3-c]carbazole ring system. The absolute configuration of 3 was determined by online HPLC-ECD and ECD calculation. A racemization mechanism and putative biosynthetic pathway are discussed.

Over 20 million Americans are affected by allergies such as asthma and allergic rhinitis, which can be caused by common allergens like house dust mites (HDM) or their associated components. The exacerbation of allergies can be fatal in patients with pre-existing chronic lung inflammation. Until now, there is no cure for asthma and type 2 allergies and the only available treatments aim to reduce the disease symptoms. Thus, there is an urgent need to understand the pathogenic mechanism of HDM-induced allergic responses. Since HDM play a major role in triggering allergic reactions, several studies focused on identifying their constituents. Although it is important to study HDM protein components that elicit adaptive type 2 inflammation (e.g. Der p 1), the role of innate sensors such as Toll-like receptors (TLRs) is unknown. A number of studies investigated presence of common adjuvants that may activate host immune receptors and modulate allergic diseases, for example, lipopolysaccharide (LPS) contaminating HDM triggered asthma in mice through acting on TLR4. In addition, single and double-stranded nucleic acids from bacteria or viruses can also act as adjuvants that stimulate innate immune receptors. Clearly, diverse allergen-associated components play an essential role in modulating type 2 lung inflammation in allergic patients. Recently, we have shown that HDM contain immunogenic RNA capable of modulating type 2 lung inflammation by inducing protective interferon responses. Using RNA-seq analysis, we show that HDM contain previously uncharacterized double stranded RNA sequences derived from novel RNA-viruses. Our findings suggest that other allergens may also have immunostimulatory RNA that can regulate type 2 lung inflammation.

Euphorkanlide A (1), a highly modified ingenane diterpenoid with a C24 appendage forming an additional hexahydroisobenzofuran-fused 19-membered macrocyclic bis-lactone ring system was isolated from...

Five undescribed cycloartane triterpenoids, including two cycloartane trinor-triterpenoids, were isolated from a 70% ethanol extract of the whole plant of Actaea vaginata (Ranunculaceae), together with thirteen known cycloartane triterpenoids. Their structures were determined by spectroscopic techniques and quantum chemical calculations for intramolecular noncovalent interactions with reduced density gradient method. All compounds were evaluated for their anti-inflammatory effects by a lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production model in RAW264.7 macrophage cells, and some showed potent inhibitory effects with IC 50 values ranging from 5.0 to 24.4 μ M. Further mechanism studies showed that one compound dose-dependently suppressed LPS-induced NO production and pro-inflammatory cytokines secretion, and decreased the expression of iNOS, through inhibiting NF- κ B activation.

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl2-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A–C (1–3), three new alkaloids with a 1-ethyl-3-formyl-β-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a β-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

Five new racemic alkyl-benzofuran dimers, (±)-dieupachinins I–M (1–5), were isolated from the root tubers of Eupatorium chinense, a well-known traditional Chinese medicine for the treatment of diphtheria in Guangdong province. The structures of these compounds, especially the first examples of 12,10′-epoxy dimer dieupachinin I (1), 12-nor-dimer dieupachinin J (2), and 12,12′-dinor-dimer dieupachinin K (3), were elucidated by spectroscopic data analysis. Chiral resolution were further carried out on a cellulose column by HPLC, and compounds 2–5 were successfully separated into two enantiomers, respectively. The absolute configurations of (+)-(2–5) and (−)-(2–5) were established by theoretical ECD calculation. All the compounds were evaluated for insulin-stimulated glucose uptake in C2C12 myotubes and (±)-dieupachinin I (1) exhibited the best activity. Compound 1 enhanced insulin-stimulated glucose uptake via activating the insulin receptor substrate 1/protein kinase B/glycogen synthase kinase-3β signaling pathway. Moreover, all the isolates were tested for their nitric oxygen (NO) inhibitory effects in lipopolysaccharide-treated RAW264.7 macrophages, and compounds (±)-1, (±)-2, and (±)-4 showed promising inhibitory effects with IC50 values of 6.42 ± 1.85, 6.29 ± 1.94, and 16.03 ± 2.07 μM, respectively. (±)-Dieupachinin I (1) again dose-dependently suppressed LPS-induced expression of inducible NO synthase and nuclear translocation of p65.

Euphorhelipanes A (1) and B (2), two Euphorbia diterpenoids with a new 4-(5,5-dimethylheptan-2-yl)-2,7-dimethylbicyclo[4.3.0]nonane skeleton, were isolated from a 95% ethanol extract of the whole plants of Euphorbia helioscopia. Their structures were elucidated by spectroscopic data analysis, quantum chemical calculations, and single-crystal X-ray diffraction data. Compounds 1 and 2 represent the first examples of Euphorbia diterpenoids with a 5/6 fused carbon ring system, and their plausible biosynthetic pathways originating from jatrophanes are proposed. Compounds 1 and 2 showed a triglyceride-lowering effect in oleic-acid-stimulated HuH7 cells at concentrations of 1-50 μM.

Phytochemical investigation on the twigs and leaves of Trichilia sinensis led to the isolation of two previously undescribed limonoids (i.e., trichiliasinenoids D and E, 1 and 2), two previously undescribed phenolic acids (3 and 4), and one previously undescribed natural phenolic acid dimer (5), together with 11 known compounds (6-16). Their structures were elucidated by extensive spectroscopic analysis (IR, UV, HRESIMS, 1D and 2D NMR) and chemical techniques. The potential anti-inflammatory activities of all the compounds were evaluated in lipopolysaccharide-stimulated RAW 264.7 cells. Among these isolates, compounds 1, 2, 6, and 11-13 expressed weak NO inhibition. The antibacterial activities of all the compounds against bacteria were also tested in vitro. Compound 16 exhibited moderate antibacterial activities against Escherichia Coli.

Podolactones are a class of structural diverse diterpenoid lactones, mainly isolated from the Podocarpus species. Several bioactivities have been disclosed for podolactones, including cytotoxicity and anti-atherosclerosis. In this study, the seeds of P. nagi were isolated by comprehensive chromatographic methods to obtain three new podolatones, named nagilactone B 1-O-β-d-glucoside (1), nagilactone N3 3-O-β-d-glucoside (2), and 2-epinagilactone B (3), as well as a known compound, nagilactone B (4). Their structures were determined by analyses of NMR and HRESIMS data. Compounds 1 and 2 significantly inhibited nitric oxide (NO) production on LPS-stimulated RAW264.7 macrophages, with IC50 values of 0.18 ± 0.04 and 0.53 ± 0.03 μM, respectively. Indomethacin (IC50 4.21 ± 0.32 μM) was used as a positive control. Compound 1 suppressed the expression of inducible NO synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents.

Four novel stemphol derivatives, pleosporols A–D (1, 2 and mixture of 3 and 4) together with known compounds stemfolones (mixture of 5 and 6), stemphol (7) were isolated from a marine fungus Pleospora sp. (PO4) derived from the gut of marine isopod Ligia oceanica. The planar structures of novel compounds were elucidated on the basis of mass and NMR spectral analysis. The stereo-chemistries of 1–2 were determined by CD spectra, NOESY data, coupling constants analysis and modified Mosher’s method while the absolute configurations of 3–6 were not clear. Novel compounds contained α, β-unsaturated cyclohexanone ring and possibly derived from the oxidation of stemphol. All novel ones showed strong antimicrobial activity against Staphylococcus epidermidis CMCC26069 with MIC values less than 10 μg/mL.

Three new 3,4-seco-cycloartane triterpenoids (1-3), including an unusual C-1 oxygenated 3,4-seco-cycloartane triterpenoid lactone (3), along with six known triterpenoids, were isolated from 95% ethanol extract of the flower of Gardenia jasminoides. Their structures were determined by spectroscopic methods, especially 2D NMR and HRESIMS techniques. Compounds 3, 4 (dikamaliartane D), and 7 (ursolic acid) showed promising cytotoxic activity against HepG2 human hepatocellular carcinoma cell line with IC50 values of 9.3, 27.7, and 39.3 μM, respectively.

Two novel pyrrolo[2,3-b]indole alkaloids, named robustanoids A (1) and B (2), featuring an unprecedented 1,2,3,4,8b,8c-hexahydro-2a,4a-diazapentaleno[1,6-ab]indene moiety, were isolated from Coffea canephora beans. Their structures were determined by extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation. The total synthesis of compounds 1 and 2 was successfully conducted to give a decent total yield (∼29%) in 8 steps, which also confirmed the structures determined by spectroscopic data. Compound 2 showed α-glucosidase inhibitory activity comparable to that of the positive control, acarbose.

Ten new cephalotane-type diterpenoids, cephanolides A-J (1-10), and two known analogues were isolated and characterized from Cephalotaxus sinensis. Compounds 1-3 represent the first examples of A-ring-contracted cephalotane-type dinorditerpenoids, and compound 4 is an A-ring-contracted norditerpenoid. The biosynthetic pathways for compounds 1-4 are postulated with the coexisting cephalotane-type troponoids as the precursors. Compounds 11 and 12 showed significant cytotoxicities against a panel of tumor cell lines (A549, KB, HL-60, and HT-29) with IC50 values ranging from 0.464 to 6.093 μM.

Two new gephyromycins ( 1 – 2 ), belonging to angucyclinones, were identified from Streptomyces sp. SS13I. Their structures were elucidated by analysis of HRESIMS, 1D and 2D NMR spectroscopic data, and the structure of 1 was further elucidated by X-ray diffraction data. The absolute configurations of compounds 1 – 2 were evidenced by ECD calculations. To our best knowledge, Compounds 1 – 2 were the second reported gephyromycin-type angucyclinones. Compound 2 exhibited significant cytotoxicity against PC3 cell lines with IC 50 values of 1.38 ± 0.47 μM.

Five previously undescribed lycodine-type alkaloids, named huperzine Y (1), 8,15-epoxy-N-demethylhuperzinine (2), 7-hydroxyl-huperzinine (3), huperzine Z (4), and huperzine D N-oxide (5), were isolated from the aerial parts and roots of Lycopodiastrum casuarinoides (Lycopodiaceae), along with ten known analogues. The structures of the new compounds were elucidated by means of spectroscopic technique (IR, UV, MS and NMR). The absolute configurations of the new compounds were established on the basis of comparison of their experimental and TD-DFT (time-dependent density functional theory) calculated ECD spectra. Moreover, all the isolates were evaluated for acetylcholinesterase (AChE) inhibitory activity. Only huperzine C showed moderate activity, with an IC50 value of 0.525 ± 0.140 μM, which was comparable with the positive control, huperzine A (IC50 = 0.143 ± 0.029 μM).

A novel alkaloid, clausoxamine (1), which possesses an unprecedented 1,3-oxazinan-4-one ring, was isolated from the seeds of Clausena lansium, along with six known analogues. The structure and absolute configuration of 1 were established on the basis of detailed NMR and HRESIMS analysis, as well as comparison of its experimental and TD-DFT calculated ECD spectra. A proposed biosynthetic pathway was predicted for compound 1. The major alkaloid, lansiumamide B, was found to reduce fat mass gain and improve insulin sensitivity on high fat diet treated mice, which might be a potential anti-obesity and insulin sensitizing agent.

Four polycyclic norditerpenoids, cephalotanins A-D (1-4) representing three unprecedented carbon skeletons with highly rigid ring systems, were isolated from Cephalotaxus sinensis and structurally characterized by a combination of various methods. Compounds 1 and 2 are new skeletal norditerpenoid trilactones, while 3 and 4 are two norditerpenoids featuring different new carbon skeletons. Biosynthetic pathways for 1-4 were proposed by involving diverse and very fascinating chemical events with the coexisting cephalotane troponoids as the precursors. Compound 1 exhibited good NF-κB inhibition with an IC50 value of 4.12±0.61 μΜ.

Three new ring B-seco limonoids, ciliatonoids A-C (1-3), were isolated from Toona ciliate and structurally characterized by spectroscopic data, X-ray crystallography, and electronic circular dichroism analysis. Ciliatonoids A and B feature an unprecedented limonoid architecture, while ciliatonoid C belongs to a rare class of limonoids. Biological evaluation showed that compound 3 exhibited modest activities against the tested tumor cell lines.

Five new compounds, namely fimbricalyxoids A–D (1–4) and 13-O-methylfimbricalyx B (5), together with five known compounds (6–10) were isolated from the leaves and stems of Strophioblachia fimbricalyx. Fimbricalyxoid A (1), a cleistanthane diterpenoid, possesses a rare 3,20-oxybridge, while fimbricalyxoids C–D (3–4) are the first seco-ring-A pentanorditerpenoids. Their structures and absolute configuration were established based on NMR and MS data and ECD calculation (1). Compounds 1, 6, and 7 exhibited cytotoxicity against five human tumor cell lines with IC50 values in the range of 1.4–8.2 μM.

Trigochinins A–C (1–3) are three highly oxygenated daphnane-type diterpenes isolated from Trigonostemon chinensis. Their structures with the absolute configurations were initially assigned by a combination of spectroscopic data, X-ray crystallography (Mo Kα radiation) study and CD analysis. In the current study, the absolute configurations of trigochinins A–C were confirmed by single crystal X-ray diffraction (Cu Kα radiation) study, CD spectral analogy, and theoretical ECD study by using quantum chemical TDDFT calculations.

Fourteen acetylbenzofuran derivatives, including three undescribed carbon skeletons with a newly formed hexane or benzene ring on the other side of the benzofuran ring, (±)-eupatonin A (1), (±)-eupatonin B (2), and eupatonin C (3), two new benzofurans (-)-12β-hydroxygynunone (4) and (+)-12-hydroxyl-13-noreuparin (5), as well as 9 known ones (6-14), were isolated from 95% ethanol extract of the roots of Eupatorium chinense. Their structures were determined by spectroscopic methods and quantum chemical DFT and TDDFT calculations of the NMR chemical shifts and ECD spectra, which helped in the determination of the relative configurations of 1 and 2 and the absolute configurations of 4 and 5, respectively. 1 and 2 were further identified to be racemic mixtures by chiral HPLC analysis. All compounds were evaluated for insulin-stimulated glucose uptake in differentiated C2C12 myotubes. Compounds 1, 3, 4, 5, 11, 12, and 13 markedly enhanced insulin-mediated glucose uptake. (±)-Eupatonin A (1) activated the IRS-1/Akt/GSK-3β signaling pathway and enhanced insulin stimulated GLUT4 membrane translocation in C2C12 myotubes. On LPS stimulated RAW264.7 macrophages, several compounds exhibited significant inhibitory effect on NO production with IC50 values ranging from 4.94 to 9.70 μΜ. (±)-Eupatonin A (1) again dose-dependently suppressed LPS-induced NO production and decreased the expression of inducible NO synthase (iNOS), through inhibiting NF-κB activity.

Four previously undescribed compounds, including three rarely occurring seco-dammarane triterpenoid glycosides and a pentacyclic triterpenic acid, were isolated from a 70% ethanol extract of the leaves of Cyclocarya paliurus (Juglandaceae), along with eleven known triterpenoids. Their structures were determined by spectroscopic techniques, including 2D NMR and HRESIMS, as well as chemical methods. Among them, several triterpenoids enhanced insulin stimulated glucose uptake in both 3T3-L1 adipocytes and C2C12 myotubes. Furthermore, compound 1 dose-dependently increased glucose uptake through activating AMP-activated protein kinase (AMPK)-p38 pathway. Collectively, triterpenoids from C. paliurus could be developed as insulin sensitizers, which might have therapeutic potential for insulin resistance and hyperglycemia.

Chemical investigation into the minor constituents of Aphanamixis grandifolia yielded three new diterpenoid dimers, aphadilactones E-G (1-3) featuring a new carbon skeleton. Their structures and absolute configurations were fully established by comprehensive spectroscopic data analysis and ECD calculation. Discovery of another two new dimers (4 and 5) suggested the structure of recently reported aphanamene A to be re-investigated. Compounds 1-5 showed moderate antimalarial activities with low micromolar IC50 values.

Marine life forms are an important source of structurally diverse and biologically active natural products. As a unique case of both enantiomeric and atropisomeric isomers being present in one marine natural product structure, two new dichlorinated diphenylmethanes containing both point and axial chirality, (±)-pestalachlorides E (1) and F (2), were isolated from a marine-derived Pestalotiopsis (ZJ-2009-7-6) fungus. Both of them showed potent antifouling activities against the larval settlement of the barnacle Balanus amphitrite at nontoxic concentrations with EC50 values of 1.65 and 0.55 μg mL−1, respectively, and antifouling activity was detected for the first time for this class of metabolites.

Fourteen 20,24-epoxy-cycloartane triterpenoids, including eight new ones (1-8), were isolated from 95% ethanol extract of the rhizomes of Beesia calthifolia. Their structures were determined by spectroscopic and chemical methods, especially 2D NMR and HRMS techniques. Among them, four new compounds (1-4) possess carbonyl groups at C-16, which were rarely found in cycloartane triterpenoids from this genus. Relative configuration at C-12 in beesioside III (9) and its aglycone (10) was revised to be 12α-OH rather than the reported 12β-OH. Some of the compounds showed potential hepatoprotective activities against human hepatic L02 cell damage induced by d-galactosamine.

Two novel diterpenoids, jatrocurcadiones A (1) and B (2), possessing an unusual 10,11-seco-premyrsinane skeleton were isolated from the twigs of Jatropha curcas. Their structures were determined by combined spectroscopic and chemical methods, and the absolute configurations were elucidated by quantum chemical calculations and Rh2(OCOCF3)4-induced CD analysis. Jatrocurcadione A exhibited more potent inhibitory activity (IC50 = 10.0 μM) than the positive control (curcumin, IC50 = 25.0 μM) against thioredoxin reductase (TrxR), a potential target for cancer chemotherapy with redox balance and antioxidant functions.

Phainanolide A (1), a highly modified triterpenoid incorporating an unprecedented 6/9/6 heterotricyclic system and a highly oxygenated 5,5-spirocyclic ketal lactone, along with three new triterpenoids 2–4 were isolated from Phyllanthus hainanensis. Their structures were completely elucidated by a combination of diverse methods including 2D NMR, quantum chemical NMR and ECD calculations, and NMR data analogy with model compounds. Compounds 1–4 exhibited both remarkable cytotoxic and immunosuppressive activities.

Sheath blight, which is caused by Rhizoctonia solani, is a disease that majorly impacts rice production. A biocontrol agent used for control rice sheath blight must be sprayed on the stem at specific times during rice growth, a process that is labour-intensive and renders the antagonist vulnerable to environmental factors. In this study, Trichoderma asperellum T12 was used to produce preparation by solid-state fermentation using a surface-response method. Rice hull was selected as a carrier based on its ability to sustain the T12 floating in the water and protect T12 from ultraviolet irradiation. The production of a T12-based preparation required 32% wheat bran, 7% inoculum, 2.3 g kg−1 (NH4)2SO4 and 65% water content, with fermentation at 27.5°C for 30 days and agitation every six days. The preparation demonstrated 90% biocontrol efficacy and significantly (P > 0.05) increased the seed-set rate and 1000-grain weight as compared with the pathogen treatment. The population of Trichoderma on the surface of r...

Two pairs of new neolignan enantiomers, (±)-torreyayunan A (1a/1b) and (±)-torreyayunan B (2a/2b), featuring a rare C-8 − C-9′ linked skeleton, were isolated from leaves and twigs of Torreya yunnanensis. Their absolute configuration involving two chiral centers was determined by combined spectral and Density Functional Theory (DFT) calculation. This is the first report of the absolute configuration of this group of neolignans. Chirality 26:825–828, 2014. © 2014 Wiley Periodicals, Inc.

Two new cycloartane triterpenoids, (23R)-21,23:23,27-diepoxycycloarta-1,24-diene-3,27-dione (1) and (3α)-(α-L-arabinopyranosyloxy)-1α-hydroxy-23-oxocycloartan-28-oic acid (2), together with six known pentacyclic triterpenoids, 3–8, and five known C29 steroids, 9–13, were isolated from Kleinhovia hospita. The structures of these compounds were determined by analysis of their spectroscopic data. Moreover, the absolute configuration of 1 was confirmed by quantum-chemical TDDFT calculation of its ECD spectrum. All compounds were evaluated for their cytotoxic activities against human colon carcinoma (HCT116) and gastric carcinoma (SGC7901) cell lines, and compounds 6, 7, 8, 11, and 12 exhibited antiproliferative activities with IC50 values ranging from 23.0 to 91.8 μM.

α-Tocospiro C ( 1 ), the first example of nor-α-tocopheroid possessing unusual 7,8-dimethyl-1-oxaspiro[4.4]non-7-ene-6,9-dione carbon skeleton, was isolated and characterized from Cirsium setosum . Its structure and absolute configuration were determined by extensive spectroscopic methods, especially 2D NMR and ECD data analysis. The biosynthetic pathway was postulated. α-Tocospiro C ( 1 ) exhibited significant selective cytotoxic activities against human colon cancer (HCT8) cells, with IC 50 values of 0.03 μM.

Two new guaiazulene-based analogues, ochracenoids A (1) and B (2), along with four known analogues (3–6), were isolated from the gorgonian Anthogorgia ochracea collected from the South China Sea. The planar structures of the new compounds were elucidated by comprehensive spectroscopic data. The absolute configuration of 1 was determined as 3R by the comparison of TDDFT calculated electronic circular dichroism with its experimental spectrum. Compound 1 is a rare guaiazulene-based analogue possessing a unique C16 skeleton. The possible generation process of 1 through an intermolecular one-carbon-transfer reaction was also discussed. Compound 2 was previously described as a presumed intermediate involved in the biogenesis of anthogorgienes A and I. Compound 3 exhibited antiproliferative effects on the embryo development of zebrafish Danio rerio.

Six 3,3″-biflavanones, including a new compound isochamaejasmenin C (1), were isolated from EtOH extracts of the roots of Stellera chamaejasme L. Their structures were elucidated on the basis of spectroscopic methods, including HR-ESI-MS and 2D NMR techniques. The absolute configurations on 2, 3, 3″, and 2″ of compounds 1, 3, and 6, which represent three geometry types of these compounds, were determined by TDDFT quantum chemical calculations of their ECD spectra. All compounds were evaluated for their cytotoxicities against eight human solid tumor cell lines and compounds 2, 4, and 6 showed strong anti-proliferative effects against all these cell lines with IC50 values ranging from 1.08 to 15.97 μM, which were in the same range as the positive control paclitaxel.

Aphadilactones A-D (1-4), four diastereoisomers possessing an unprecedented carbon skeleton, were isolated from the Meliaceae plant Aphanamixis grandifolia. Their challenging structures and absolute configurations were determined by a combination of spectroscopic data, chemical degradation, fragment synthesis, experimental CD spectra, and ECD calculations. Aphadilactone C (3) with the 5S,11S,5'S,11'S configuration showed potent and selective inhibition against the diacylglycerol O-acyltransferase-1 (DGAT-1) enzyme (IC50 = 0.46 ± 0.09 μM, selectivity index > 217) and is the strongest natural DGAT-1 inhibitor discovered to date. In addition, compounds 1-4 showed significant antimalarial activities with IC50 values of 190 ± 60, 1350 ± 150, 170 ± 10, and 120 ± 50 nM, respectively.

Two novel cyclodepsipeptides containing an unusual anthranilic acid dimer and a d-phenyllactic acid residues, clavatustides A (1) and B (2), were identified from cultured mycelia and broth of Aspergillus clavatus C2WU isolated from Xenograpsus testudinatus, which lives at extreme, toxic habitat around the sulphur-rich hydrothermal vents in Taiwan Kueishantao. This is the first example of cyclopeptides containing an anthranilic acid dimer in natural products, and the first report of microbial secondary metabolites from the hydrothermal vent crab. Clavatustides A (1) and B (2) suppressed the proliferation of hepatocellular carcinoma (HCC) cell lines (HepG2, SMMC-7721 and Bel-7402) in a dose-dependent manner, and induced an accumulation of HepG2 cells in G1 phase and reduction of cells in S phase.

Phytochemical study on the root tubers of Ophiopogon japonicus resulted in the isolation and identification of 13 homoisoflavonoids, including three new compounds, 8-formyl-7-hydroxy-5,4′-dimethoxy-6-methylhomoisoflavone (1), 6-formylisoophiopogonone B (2), and 8-formylophiopogonanone B (4), and the ten known homoisoflavonoids 3, and 5–13. The absolute configurations of 8-formylophiopogonanone B (4) and 8-formyl-7-hydroxy-5,4′-dimethoxy-6-methylhomoisoflavanone (5) were confirmed by time-dependent density-functional-theory (TD DFT) calculations of their theoretical electronic circular dichroism (ECD) spectra. The structure of the formerly reported ‘6-aldehydoisoophiopogonone B’ was revised to 8-formylophiopogonone B (3). All compounds were evaluated for their cytotoxic activities against the human-lung-tumor A549 cell line, and compounds 3, 9, 10, and 13 exhibited promising antiproliferative activities with IC50 values of 10.01, 6.40, 0.84, and 1.66 μM, respectively.

Kleinhospitines A-D, four unprecedented cycloartane triterpenoid alkaloids possessing a spiro α,β-unsaturated γ-lactamlactone side chain, were isolated as two mixtures of C-23 epimers from Kleinhovia hospita. Kleinhospitines C and D represent the first examples of naturally occurring cycloartane triterpenoids with a 9α,10α-cyclopropyl ring. The structures and absolute configurations were determined on the basis of spectroscopic analyses and comprehensive quantum chemical calculations. The two mixtures showed hepatoprotective activity against H2O2-induced oxidative damages on primary cultured rat hepatocytes with EC50 values of 167.0 and 126.5 μM.

Two new polyketide derivatives, huaspenones C and D (1 and 2, resp.), were isolated from the cultures of an endophytic fungus Peyronellaea sp. HS-12, derived from the stems of Huperzia serrata. They share N-bearing furan-3(2H)-one backbone, and 2 has an unprecedented furo[3,2-c]pyridine skeleton. Their structures including the absolute configuration were elucidated by extensive spectroscopic analysis combined with quantum-chemical calculations. (2E,4E)-6-hydroxy-2-methylocta-2,4-dienoic acid (3), a key intermediate of the biosynthesis of 1 and 2, was also obtained from the endophyte.

Three new ent-kaurane diterpenoids, (4α)-19-nor-ent-kaurane-4,16,17-triol (1), (4α,16α)-17-(acetyloxy)-19-nor-ent-kaurane-4,16-diol (2), and 17-hydroxy-ent-kaur-15-en-19-al (3), together with 11 known compounds, were isolated from the stem bark of Annona squamosa L. The structures of 1–3 were identified by analysis of their spectroscopic data. All compounds were evaluated for cytotoxic activity against human lung cancer (95-D) and ovarian cancer (A2780) cell lines, and compounds 3, 5, 7, 11–14 exhibited promising antiproliferative activities with IC50 values ranging from 0.38 to 34.66 μM.

Five new diterpenoids including two Cephalotaxus troponoids (1 and 2), two 17-nor-cephalotane-type diterpenoids (3 and 4), and an abietane-type diterpenoid (5), two new lignans (6 and 7), and a new trisnorneoligan (8) along with eight known compounds were identified from the twigs and leaves of Cephalotaxus fortunei. The structure of 11-hydroxyhainanolidol was revised as 10-hydroxyhainanolidol (9) by X-ray crystallographic data. Compounds 3 and 4 are the first examples of 17-nor-cephalotane-type diterpenoids that are likely the biosynthesis precursors of the co-occurring troponoids (e.g., 1, 2, and 9). Compound 1 exhibited cytotoxic activities against HL-60 and A-549 cells with IC50 values of 0.77 ± 0.05 and 1.129 ± 0.057 μM, respectively.

A new enantiomeric pair of spirodiketones, (+)- and (-)-denobilone A (1 and 2), three new phenanthrene derivatives (3-5), and three new biphenanthrenes (22-24), along with 11 known phenanthrene derivatives (6-16), five known bibenzyl derivatives (17-21), and four known biphenanthrenes (25-28), were isolated from Dendrobium nobile. The structures of 1-5 and 22-24 were elucidated using comprehensive spectroscopic methods. (+)-Denobilone and (-)-denobilone A (1 and 2) were isolated as a pair of enantiomers by chiral HPLC. The absolute configurations of (+)- and (-)-denobilone A (1 and 2) were determined by comparing their experimental and calculated electronic circular dichroism spectra. The absolute configuration of denobilone B (3) was determined by X-ray crystallographic analysis. The inhibitory activities of all compounds against nine phytopathogenic fungi and three cancer cell lines were evaluated.

Chemical investigation into the minor constituents of Aphanamixis grandifolia yielded three new diterpenoid dimers, aphadilactones E-G (1-3) featuring a new carbon skeleton. Their structures and absolute configurations were fully established by comprehensive spectroscopic data analysis and ECD calculation. Discovery of another two new dimers (4 and 5) suggested the structure of recently reported aphanamene A to be re-investigated. Compounds 1-5 showed moderate antimalarial activities with low micromolar IC50 values.

A new sesquiterpenoid, 1 β ,5 α -guaiane-4 β ,10 α -diol-6-one ( 1 ), was isolated from 70% EtOH extract of the rhizomes of Acorus calamus . The structure was determined on spectroscopic methods, especially 2D NMR techniques. The absolute configuration of 1 was confirmed by TDDFT quantum chemical calculation of its ECD spectrum. Compound 1 showed promising anti-diabetic activity on a insulin-mediated glucose consumption model of HepG2 cells.