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The detailed chemical investigations of the South China Sea soft corals Sinularia tumulosa and Sinularia depressa, yielded two new compounds, namely tumulosterol A (1) and 11’-hydroxy-α-tocopherylquinone (3), along with four related known ones (2, 5–7). Their structures were determined by extensive spectroscopic analysis and comparison with the spectral data previously reported in the literature. In bioassays, compound 1 displayed significant cytotoxic effects against H1975 and MDA-MB-231 cells with IC50 values of 6.0 and 6.3 µM, respectively. In addition, compound 3 exhibited interesting inhibitory effect on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264.7 cells with IC50 value of 9.5 µM.

Natural product dimers have intriguing structural features and often have remarkable pharmacological activities. We report here two uncommon marine gorgonian-derived symmetric dimers, weizhouochrones A (

A new cembrane-type diterpenoid, named iso-ximaonanolobatin G (1), and one known related one, namely ximaonanolobatin G (2), along with four known steroids, were isolated from the South China Sea soft coral Sinularia nanolobata. Their full structures were elucidated by extensive spectroscopic analysis, quantum mechanical (QM)-NMR methods, and by the comparison of the spectroscopic data with those reported in the literature.

Six new pairs of γ-pyrone polypropionate enantiomers with an unusual peroxyl bridge at the side chain, namely (±)-ocellatuperoxides A–F (1–6), were isolated and characterized from the South China Sea photosynthetic mollusk Placobranchus ocellatus. Extensive spectroscopic analysis, single crystal X-ray diffraction analysis, ECD- (electronic circular dichroism) comparison, and TDDFT (time-dependent density functional theory) ECD computation were used to determine the structures and absolute configurations of new compounds. In a cell viability assay, several compounds showed considerable anti-tumoral effects on human non-small cell lung cancer cells A549 with Gefitinib (7.4 μM) and Erlotinib (2.1 μM) as positive controls. Further RNA-sequencing analysis and gene expression evaluation indicated that the anti-tumoral activity of the most effective compound 3 was associated with the regulation of several important genes, such as FGFR1 and HDAC5.

Two novel rearranged Diels-Alder adducts, morunigrines A (1) and B (2), and four new prenylated flavonoids, morunigrols A-D (3-6), were isolated from the twigs of Morus nigra, together with four known prenylated phenolic compounds, including two flavonoids (7 and 8) and two 2-arylbenzofurans (9 and 10). Morunigrines A (1) and B (2) are a novel class of Diels-Alder adducts with unprecedented carbon skeletons featuring a rearranged chalcone-stilbene/2-arylbenzofuran core decorated with a unique methylbiphenyl moiety. The structures of the new compounds were assigned by analysis of spectroscopic data. The absolute configuration of compound 6 was determined by the measurement of specific rotation. A plausible biogenetic pathway for 1 and 2 is also proposed. Compounds 1 and 2 exhibited more potent protein tyrosine phosphatase 1B inhibitory activity with IC50 values of 1.8 ± 0.2 and 1.3 ± 0.3 μM, respectively, than that of the positive control oleanolic acid (IC50, 2.5 ± 0.1 μM).

Four new polyoxygenated cembranoids, namely sarcoboettgerol A (1), 12-epi-humilisin D (2), sarcoboettgerol B (3), and sarcoboettgerol C (4), together with one known related analogue, humilisin D (5), were isolated and characterized from the soft coral Sarcophyton boettgeri collected off Ximao island, Hainan Province, China. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, Cu kα single crystal X-ray diffraction analysis, and TDDFT-ECD calculations. A plausible biogenetic relationship of 3 and 4 was proposed.

Covering: 2011-2021Marine mollusks, which are well known as rich sources of diverse and biologically active natural products, have attracted significant attention from researchers due to their chemical and pharmacological properties. The occurrence of some of these marine mollusk-derived natural products in their preys, predators, and associated microorganisms has also gained interest in chemical ecology research. Based on previous reviews, herein, we present a comprehensive summary of the recent advances of interesting secondary metabolites from marine mollusks, focusing on their structural features, possible chemo-ecological significance, and promising biological activities, covering the literature from 2011 to 2021.

Covering: July 2010 to August 2021This article summarizes more than 200 cases of misassigned marine natural products reported between July 2010 and August 2021, sorting out errors according to the structural elements. Based on a comparative analysis of the original and the revised structures, major pitfalls still plaguing the structural elucidation of small molecules were identified, emphasizing the role of total synthesis, crystallography, as well as chemical- and biosynthetic logic to complement spectroscopic data. Distinct "trends" in natural product misassignment are evident between compounds of marine and plant origin, with an overall much lower incidence of "impossible" structures within misassigned marine natural products.

Two new cladiellin-type diterpenoids (1 and 2) and four known related compounds 3–6, were isolated from the South China Sea soft coral Cladiella krempfi. Compound 2 is the third example of cladiellins of an unusual peroxy group in the C-6 position in C. krempfi. The structures and absolute configurations of the new compounds were established by extensive spectroscopic analysis, X-ray diffraction, and/or chemical correlation. In bioassay, all the compounds were evaluated for cytotoxicity and epidermal growth factor receptor (EGFR) inhibitory activity. A molecular docking experiment was conducted to study the structure–activity relationship of cladiellin-type diterpenoids on EGFR inhibitory activity.

Twelve sesquiterpenoids with seven different carbon skeletons, including four isodaucanes (1-4), an aromadendrane (5), a guaiane (6), a cadalane (7), two eudesmanes (8 and 9), two bisabolanes (10 and 11), and a megastigmane (12), were isolated from the twigs and leaves of Aglaia lawii (Wight) C. J. Saldanha et Ramamorthy. Of these compounds, amouanglienoids A (1) and B (2) are new isodaucane sesquiterpenoids. This is the first report of isodaucanes from the genus Aglaia, and amouanglienoid A (1) represents the first isodaucane containing a Δ

Chemical investigation of the Hainan soft coral Sinularia hirta resulted in the isolation and identification of a library of sixteen structurally diverse terpenoids, including a dinorditerpenoid with an uncommon 17,19-dinorxeniaphyllane skeleton, namely sinuhirtone A (7), six new xeniaphyllane-type diterpenoids (1–6), one new norxeniaphyllanoid (8), two new norcaryophyllene-type sesquiterpenoids (9 and 10), together with six known related compounds (11–16). Compounds 1–3 are three new furanone-containing xeniaphyllane-type diterpenoids. The structures of the new compounds, including their absolute configurations, were determined by extensive spectroscopic analysis and a series of quantum chemical calculations, including quantum mechanical-nuclear magnetic resonance (QM–NMR), time-dependent density functional theory–electronic circular dichroism (TDDFT–ECD), and optical rotatory dispersion (ORD) methods. A plausible biosynthetic connection between new compounds 1–9 was also proposed. New compounds 2–4, 7, and 8 were evaluated for in vitro cytotoxicity against four cancer cell lines.

Natural polybrominated diphenyl ethers, often isolated from marine sponges, have been reported to possess various biological activities, such as antibacterial, antioxidant and antidiabetic effects. Via a high throughput screening of our marine natural product library, the polybrominated diphenyl ether 3 was found to display a KCNQ potassium channel activation effect. To obtain more compound 3 related natural products and their derivatives for further bioactivity study, a diversity-oriented synthesis was conducted, leading to the successful synthesis of five polybrominated diphenyl ether natural products (1-4, 6) and 30 new derivatives. Compound 3 was found to preferentially potentiate KCNQ1 potassium channel, whereas 17h relatively activated KCNQ2 potassium channel. The structure-activity relationship was analyzed assisted by molecular docking and 17h was further conducted for its agonistic mechanism study on KCNQ2 channel. This research work may give an insight for the discovery of marine polybrominated diphenyl ether derived new drug leads.

Benzoxepane derivatives were designed and synthesized, and one hit compound emerged as being effective in vitro with low toxicity. In vivo, this hit compound ameliorated both sickness behavior through anti-inflammation in LPS-induced neuroinflammatory mice model and cerebral ischemic injury through anti-neuroinflammation in rats subjected to transient middle cerebral artery occlusion. Target fishing for the hit compound using photoaffinity probes led to identification of PKM2 as the target protein responsible for anti-inflammatory effect of the hit compound. Furthermore, the hit exhibited an anti-neuroinflammatory effect in vitro and in vivo by inhibiting PKM2-mediated glycolysis and NLRP3 activation, indicating PKM2 as a novel target for neuroinflammation and its related brain disorders. This hit compound has a better safety profile compared to shikonin, a reported PKM2 inhibitor, identifying it as a lead compound in targeting PKM2 for the treatment of inflammation-related diseases.

Two new scalarane sesterterpenes, hyrtiosins F and G (1 and 2), along with two known related compounds, hyrtiosin D and sesterstatin 6 (3 and 4), were isolated from the Hainan marine sponge Hyrtios erecta. The structures of new compounds 1 and 2 were determined by detailed analysis of 1D and 2D NMR spectra and by comparison of the spectroscopic data with those reported in the literatures.

The present investigation of the South China Sea soft coral Sarcophyton trocheliophorum resulted in the discovery of six new polyoxygenated diterpenes, namely sartrocheliols A–E (1, 3, 5–8) along with four known ones, 2, 4, 9, and 10. Based on extensive spectroscopic data analysis, sartrocheliol A (1) was identified as an uncommon capnosane diterpene, while sartrocheliols B–E (3, 5–8) were established as cembrane diterpenes. They displayed diverse structural features not only at the distinctly different carbon frameworks but also at the various types of heterocycles, including the epoxide, γ-lactone, furan, and pyran rings. Moreover, their absolute configurations were determined by a combination of quantum mechanical-nuclear magnetic resonance (QM-NMR) approach, modified Mosher’s method, and X-ray diffraction analysis. In the anti-tumor bioassay, compound 4 exhibited moderate cytotoxic activities against A549, H1975, MDA-MB-231, and H1299 cells with the IC50 values ranging from 26.3 to 47.9 μM.

Phidianidines A and B are novel marine indole alkaloids with various biological activities. Based on their potential anti-inflammatory properties, a series of phidianidine derivatives were designed, synthesized, and tested for their effects on IL-17A production in PMA/ionomycin-stimulated T-cell-lymphoma EL-4 cells. Compounds 9a and 22c exhibited excellent anti-inflammatory activity and low toxicity, with IC

A new alkaloid featured with a dibenz[c,e]azepin-5-one scaffold, namely emililactam A (3), together with a known pyrrolidine alkaloid (emilisonchine, 1) and a known flavonoid alkaloid [8-(2″-pyrrolidinone-5″-yl)-quercetin, 2] were isolated from the aerial parts of Emilia sonchifolia. Compounds 1 and 2 were isolated as racemic forms which were further separated, for the first time, to their corresponding enantiomers [(+)-1/(-)-1 and (+)-2/(-)-2], respectively, by using chiral-phase HPLC. The structure of new compound 3 was elucidated by extensive spectroscopic analysis. In addition, the absolute configurations of optically pure (+)-1/(-)-1 and (+)-2/(-)-2 were determined by the time-dependent density functional theory electronic circular dichroism (TDDFT-ECD) calculations. In an in vitro bioassay, compounds (+)-1, (-)-1, (±)-1, and 3 exhibited moderate neuroprotective effects against corticosterone-induced injuries of PC12 cells.

The first investigation of the South China Sea soft coral Sarcophyton boettgeri afforded five new capnosane diterpenes, sarboettgerins A–E (1–5), together with one known related compound, pavidolide D (6). Their structures, including absolute configurations, were elucidated by the extensive spectroscopic analysis, 13C NMR calculations, and X-ray diffraction. Among them, new compounds 1–5 were featured by the rarely encountered Z-geometry double bond Δ1 within the 5/11-fused bicyclic capnosane carbon framework. Plausible biogenetic relationships of all isolates were proposed, and they might give an insight into future biomimetic synthesis of these novel compounds. In an in vitro bioassay, compound 5 displayed potent anti-neuroinflammatory activity against LPS-induced NO release in BV-2 microglial cells, which might be developed as a new type of potential neuroprotective agent in future.

Three unusual diterpenes with rare sarsolenane and capnosane skeletons, namely mililatensols A–C (1–3), were isolated from the South China Sea soft coral Sarcophyton mililatensis, leading to the first record of sarsolenane and capnosane diterpenes from the title animal. The structures of compounds 1–3 were established by extensive spectroscopic analysis and comparison with the literature data. Moreover, the absolute configuration of 2 was determined by TDDFT ECD calculations. In an in vitro bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages. In the preliminary virtual screening of inhibitory potential against SARS-CoV-2 by molecular docking, the results showed these three diterpenes were potential SARS-CoV-2 Mpro inhibitors.

Further chemical investigation of the South China Sea soft coral Lemnalia flava resulted in the isolation and characterization of two new cembranoids, namely, xishaflavalins G and H (1 and 2), along with three known related compounds (3-5). The structures of the new compounds were elucidated by detailed spectroscopic analysis and by the comparison of their spectroscopic data with those reported in the literature. The discovery of cembrane-type diterpenes from soft coral of the genus Lemnalia was reported for the first time. In addition, compound 5 exhibited moderate inhibitory effects on the ConA-induced T lymphocytes and/or lipopolysaccharide (LPS)-induced B lymphocytes proliferation.

Three new diterpenoids with an unusual capnosane skeleton named lobophytrols A-C (1-3) were isolated from the South China Sea soft coral Lobophytum sp. along with one known related diterpene, (11S,12S,1E,3E,7E)-11,12-epoxycembra-1,3,7-triene (7). Their structures were elucidated on the basis of spectroscopic analysis and by comparison with those reported in the literature.

A new brominated polyacetylene xestonariene J (1), bearing a rare 2,4-dibromo-1-ene-3-yne terminal in the molecule, along with two known related analogues (2 and 3), was obtained from Chinese marine sponge Xestospongia testudinaria. Its structure was determined on the basis of detailed spectroscopic analysis and comparison with literature data.

Different chemotypes of Sinularia flexibilis exist in the Hainan island. Thus, a collection of this soft coral from a location different from the one of our previous study afforded three novel cembranoid esters featuring a n-butyl alcohol moiety, a structural element rare in natural products of both terrestrial and marine origin. The structures of the new compounds were elucidated by detailed spectroscopic analysis and by the comparison of their spectroscopic data with those reported in the literature. In addition, the absolute stereochemistry of the previously reported diepoxycembrene (9) was first time determined by the X-ray diffraction analysis. In bioassays, compounds 6-8 exhibited strong anti-inflammatory effect with IC values of 2.7, 4.7, and 4.2 μM, respectively, whereas compound 5 displayed cytotoxicity against several cancer cells with IC values ranging from 8.9 to 27.4 μM. A preliminary structural-activity relationship (SAR) was also described.

Mangrove ecosystems are widely distributed in the intertidal zone of tropical and subtropical estuaries or coasts, containing abundant biological communities, for example, mangrove plants and diverse groups of microorganisms, featuring various bioactive secondary metabolites. We surveyed the literature from 2010 to 2022, resulting in a collection of 134 secondary metabolites, and classified them into two major families in terms of the biological sources and 15 subfamilies according to the chemical structures. To highlight the structural diversity and bioactivities of the mangrove ecosystem-associated secondary metabolites, we presented the chemical structures, bioactivities, biosynthesis, and chemical syntheses.

Eleven novel cembranoid derivatives were designed, synthesized, and evaluated for their inflammation related activities on the basis of our isolated and previously reported anti-inflammatory marine cembranoids. In bioassay, compound 11 displayed the most promising inhibitory effects with IC50 value of 1.1 μM for the TNF-α inhibitory activity. The further mechanism study of 11 on the inflammatory signaling transduction of RAW264.7 cells was also performed. This research may give an insight for the discovery of marine cembranoid derived anti-inflammatory drug leads.

A further systematically chemical investigation of the South China Sea soft coral Sinularia erecta led to the discovery of two rare casbane diterpenoids with an uncommon 8,10-peroxide bridge, sinuereperoxides B (1) and C (2), five new casbanes with other oxygenated patterns (3–7), and seven known casbanes (8–14). The structures and absolute configurations of 1–7 were established by extensive spectroscopic data analyses, X-ray diffraction analysis, and/or quantum chemical calculations. In bioassay, compounds 2, 7, 11 and 12 exhibited considerable anti-inflammatory activity by the inhibition of TNF-α release, with IC50 values of 33.8 μM, 5 μM, 9.9 μM and 8 μM.

Three complex polyoxygenated diterpenoids possessing uncommon tetradecahydro-2,13:6,9-diepoxybenzo[10]annulene scaffold, namely ximaoornatins A–C (1–3), one new eunicellin-type diterpene, litophynin K (4), and a related known compound, litophynol B (5) were isolated from the South China Sea soft coral Sinularia ornata. The structures and absolute configurations of 1–4 were established by extensive spectroscopic analysis, X-ray diffraction analysis, and/or modified Mosher’s method. A plausible biosynthetic relationship of 1 and its potential precursor 4 was proposed. In a bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages and PTP1B inhibitory effects.

A detailed chemical research of the soft coral Sinularia crassa collected from the South China Sea yielded a series of cembrane-type diterpenoids, including four new cembranoids, namely sinulacrassins A − C (1, (+)-2, (+)-4) and ent-xishaflavalin G ((+)-3), along with five known analogs ((-)-3, 5–8). Their structures were elucidated by detailed spectroscopic analysis, chemical methods, and the comparison with those literature data. The absolute configuration of 1 was established by time-dependent density functional theory electronic circular dichroism (TDDFT/ECD) calculation, and the absolute configuration of (+)-2 was determined using the modified Mosher's method. The bioassay results revealed that (+)-2 and 5 were novel α-glucosidase inhibitors with IC50 values of 10.65 ± 0.16 and 30.31 ± 1.22 μM, respectively. In addition, (+)-2 and 5 were nontoxic towards human normal hepatocyte (LO2) cells at 100 μM. The present results highlighted the unusual coexistence of α and β configurations of C-1 in cembranoids from soft coral in the Order Alcyonacea, and provided new chemotype for the development of α-glucosidase inhibitors used in anti-diabetes treatment.

Seven new cembrane-type diterpenes, lobophytolins C–I (3–9), and one new prenylated-guiane-type diterpene, lobophytolin J (10), along with six known related ones (1, 2, 11–14), have been isolated from the soft coral Lobophytum sp. collected off the Xisha Island in the South China Sea. Their structures were elucidated by extensive spectroscopic analysis and quantum mechanical (QM)-NMR methods. The absolute configuration of lobophytolin H (8) was determined by the application of the modified Mosher’s method and chemical transformation. Lobophytolin D (4) exhibited promising cytotoxicities in in vitro bioassays against HT-29, Capan-1, A549, and SNU-398 human cancer cell lines with IC50 values of 4.52, 6.62, 5.17, and 6.15 μM, respectively., This work was financially supported by the Natural Science Foundation of China (Nos. 81991521, 81520108028, 21672230), the National Key Research and Development Program of China (No. 2018YFC0310903), the Drug Innovation Major Project (No. 2018ZX09711-001-001-009), the SKLDR/ SIMM Project (No. SIMM1903ZZ-04) and the Spanish Ministry of Science and Innovation (PID2019-109476RB-C21). A.H.D thanks the CSIC for a JAE-intro grant to C.C.G. This study made use of the SGAI-CSIC supercomputing facilities.

A phytochemical investigation on the MeOH extract of the red alga Laurencia composita Yamada led to the discovery of six new highly halogenated sesquiterpenoids, including two bisabolane-type sesquiterpenoids (1 and 2), one nerolidol derivative (7), and three chamigrane-type sesquiterpenoids (9, 10, and 18), together with 13 known sesquiterpenoids. Their structures, including relative configuration, were elucidated by extensive spectroscopic analysis, and by comparison with data for related known compounds. The absolute configuration at C-10 of laurecomposin A (1) was determined by the modified Mosher's method. Halonerolidol (7) is the first naturally occurring halogenated nerolidol derivative, while compositacin L (9) represents the third example of chamigranes having a C-10 carbonyl group. Antifungal, antibacterial, and receptor tyrosine kinase inhibitory activities of these isolates were evaluated. The results showed that compounds 1–3 and 5 exhibited significant antifungal activity against Microsporum gypseum (Cmccfmza) with MIC values of 4, 8, 8, and 4 μg/mL, respectively. Additionally, compounds 1–3 and 5 also displayed promising antibacterial activity against Gram-positive bacteria Staphylococcus aureus Newman strain with MIC values ranging from 10.9 to 26.8 μg/mL.

Covering: 2010 to 2020The class of 2,11-cyclized cembranoids is particularly widespread in marine Octocorallia, especially Alcyonacea and Gorgonacea, and has been extensively studied. Following a previous review published in 2010, the accumulated knowledge from the past decade will be presented here. All 2,11-cyclized cembranoids share a bicyclo[8.4.0]tetradecane core that is in most of the known compounds oxidatively modified to result in the 15-oxatricyclo[6.6.1.02,7]pentadecane system. Multiple further oxidation and acylation patterns can be observed, while halogenated compounds are surprisingly rare. One new sulfur-containing and a few seco-compounds have also been reported. The biosynthetic pathways to this fascinating class of natural products have not been studied to date, but a plausible biosynthetic hypothesis is presented that allows for a structured discussion of the compounds according to their carbon skeletons and oxidation patterns. Biological activities towards 2,11-cyclized diterpenes are also included.

Eleven new cembrane diterpenes, namely, sarcoehrenins A-J (1-9, 11) and (2S,11S,12S)-isosarcophytoxide (10), along with six known compounds, gibberosene B (12), (13S)-cembra-1,3,7,11-tetraen-13-ol (13), (+)-sarcophtol (14), cembrene-C (15), (1R,4R,2E,7E,11E)-cembra-2,7,11-trien-4-ol (16) and (1S,4R,2E,7E,11E)-cembratrien-4-ol (17) were isolated from the soft coral Sarcophyton ehrenbergi collected from Weizhou Island, Beibu Gulf, South China Sea. The structures of these compounds were elucidated by a combination of detailed spectroscopic analyses, chemical methods, and comparison with reported data. The absolute configuration of compound 2 was established by the modified Mosher's method in association with TDDFT ECD calculation, while the absolute configuration of compound 3 was assigned by TDDFT ECD approach. In in vitro bioassays, compounds 13 and 17 showed potent TNF-α inhibitory activities being similar to that of positive control dexamethasone. A preliminary structural-activity relationship was also described.

A series of novel marine phidianidine derivatives were designed, synthesized, and evaluated for their immunosuppressive activities during our search of potential immunosuppressive agents with high efficacy and low toxicity from marine sources. These compounds were tested for their inhibitory activity on Con A-induced T cell and lipopolysaccharide-induced B cell proliferation. Compounds 14a and 18c, displaying the most promising inhibitory effects and low toxicities, were further found to possess immune-regulatory activities upon cross-linking of T cell receptor (TCR) and B cell receptor (BCR) on purified T and B cells, respectively.

Three new polyoxygenated diterpenes (1, 3 and 4) of eunicellin-type, namely, 8-n-butyryl-litophynol A, 6-keto-litophynol B and 6-epi-litophynol B, respectively, together with two related known ones (2 and 5), were isolated from the soft coral Cladiella krempfi collected off the Weizhou island, Guangxi Zhuang Autonomous Region, China. The structures of the new compounds were elucidated by extensive spectroscopic analysis and chemical correlation. In bioassay, all the new compounds displayed moderate anti-inflammatory effects.

Three new cholestane-type sterols bearing an unusual ∆22–24-oxo side chain, namely, dictyoptesterols A–C (1–3), were isolated from the brown alga Dictyopteris undulata Holmes, together with five known strutural analogues (4–8). Their structures were elucidated on the basis of by extensive spectroscopic analysis. The absolute configurations of the steroidal nuclei of the new compounds were proposed by a comparison of NMR data with those of related known compounds as well as biogenetic considerations. All of the isolates were evaluated in vitro for their potential to inhibit protein tyrosine phosphatase-1B (PTP1B) activity. The results showed that compounds 1–5 exhibited different levels of PTP1B inhibitory activities with IC50 values ranging from 3.03 ± 0.76 to 15.01 ± 2.88 μM. In particular, compounds 3 and 4 showed promising inhibitory effects towards PTP1B with IC50 values of 3.03 ± 0.76 and 3.72 ± 0.40 μM, respectively, when compared to the positive control oleanolic acid (IC50, 2.83 ± 0.39 μM). The chemotaxonomic significance of these isolated ∆22–24-oxo cholestanes has also been discussed.

3-Nor-spongiolide A (1), belonging to the extremely rare 3-nor-spongian carbon skeleton, and spongiolides A (2) and B (3), having γ-butenolide instead of furan ring as usual for ring D, together with six related known metabolites were isolated from South China Sea sponge Spongia officinalis as its metabolic components. Their structures were elucidated on the basis of extensive spectroscopic analysis. The absolute configurations of three new compounds 1–3 were determined by ECD calculations.

A series of novel tetrandrine (Tet) derivatives were synthesized through Suzuki -Miyaura reaction and evaluated for their cytotoxicity against human non-small cell lung carcinoma (NSCLC) A549 cells. Interestingly, most of derivatives showed similar cytotoxicity to Tet against NSCLC A549 cells, and particularly, compounds Y5, Y6, Y9 and Y11 showed the most significant cytotoxic effects with IC50 values ranging from 3.87 to 4.66 mM. The present study is expected to contribute to the future design of more effective anticancer agents in lung cancer chemotherapy.

One new sorbicillin derivative, 2-deoxy-sohirnone C (1), one new diketopiperazine alkaloid, 5S-hydroxynorvaline-S-Ile (2), and two naturally occurring diketopiperazines, 3S-hydroxylcyclo(S-Pro-S-Phe) (3) and cyclo(S-Phe-S-Gln) (4), together with three known compounds were isolated from the Chinese mangrove endophytic fungus Penicillium sp. GD6. Their structures were determined on the basis of extensive spectroscopic analyses and by comparison with literature data. The absolute configuration of 3-hydroxyl moiety in 3 was determined by Mosher's method, while the absolute stereochemistry of 2 and 4 was established by comparison with the CD spectra of natural and synthesized diketopiperazines. Compound 1 showed moderate antibacterial activity against Methicillin-resistant Staphylococcus aureus with a MIC value of 80 μg·mL-1.

A series of highly oxidative new cembranoids with diverse structural features such as a dienoate moiety (sarcophytonolides S – U, 1–3) or an α,β-unsaturated e-lactone (sartrolides H – J, 4–6) were obtained from Hainan soft coral Sarcophyton trocheliophorum, along with known related analogues 7–13. It is an extremely challenging work to determine the absolute configurations of these metabolites. For compounds 1, 3 and 4, solution TDDFT calculation of ECD and specific rotation were applied in combination with conformational analysis and NMR data to determine their relative and absolute configurations, leading to the revision of relative configuration of 14. The absolute configurations of compounds 8–10 were determined by the solid-state TDDFT-ECD approach, and that of 8 was further confirmed by single-crystal X-ray diffraction experiment with Cu Kα radiation. In the bioassays, compound 8 exhibited not only moderate protein tyrosine phosphatase 1B (PTP1B) inhibitory activity (IC50 = 15.4 μM) but also moderate antibacterial activity against Staphylococcus aureus Newman strain (MIC50 = 250 μM).

Chemical study of a Hainan sponge Halichondria sp. resulted in the isolation of eight new formamidobisabolene-based sesquiterpenes halichines A–E (1–3, 7, 8), ent-axinyssine G [(−)-4], ent-axinyssine J [(−)-5], and ent-axinyssine K [(−)-6], along with five related known ones [(+)-4, (+)-5, (+)-6, 10, 11]. Their structures were determined on the basis of extensive spectroscopic analyses, and the absolute configuration of halichine A (1) was determined by Snatzke's method. In bioassay, compounds 3 and 7 displayed considerable anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated BV-2 microglia cells.

A detailed chemical investigation of two specimen of South China Sea sponges Halichondria sp. (No. 19-XD-47 and No. 17-XD-87) have resulted in the isolation of three new sterols, namely, halichsterols A (1), B (2) and C (3), together with seven related known ones (4–10). Their structures were determined by extensive spectroscopic analysis and by comparison with the spectral data reported in the literature. In bioassay, compound 2 displayed significantly anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells.

Five new uncommon cembranoids, named lobophycrasins A–D (1 and 3–5) and (−)-humilisin A (2), together with a known related one (6), have been isolated from Hainan soft coral Lobophytum crassum. Their structures were elucidated by extensive spectroscopic analysis, NMR calculation with DP4+ probability analysis, TDDFT-ECD (time-dependent density functional theory-electronic circular dichroism) calculations and comparison with the reported data. Further, with the aid of X-ray diffraction analysis, the structure of lobocrasol (6), which was announced possessing novel unprecedented skeleton, was firmly revised as 6a. In addition, a plausible biogenetic connection among these isolates was also proposed.

Two new cembranoids, ximaosarcophytols A (1) and B (2), together with three related known ones (3-5), were isolated from the soft coral Sarcophyton trocheliophorum collected off the Ximao Island, Hainan Province, China. Their structures including the absolute configurations were elucidated by extensive spectroscopic analysis, TDDFT/ECD (time-dependent density functional theory/electronic circular dichroism) calculations and comparison with the reported data.