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Abstract 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, (11 S ,12 S ,1 E ,3 E ,7 E)-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. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Covering: 2011–2021 Marine 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. [ABSTRACT FROM AUTHOR]

Three new dammarane-type triterpene ginsenosides, together with six known ginsenosides, were isolated from the leaves of Panax ginseng C.A. Meyer. The new saponins were named as ginsenoside Rh11, ginsenoside Rh12, and ginsenoside Rh13. Their structures were elucidated as (20S)-3β,6α,12β,20-tetrahydroxydammara-25-ene-24-one 20-O-β-d-glucopyranoside (1), (20S)-3β,12β,20,24,25-pentahydroxydammarane 20-O-β-d-glucopyranoside (2), and (20S,23E)-3β,12β,20,25-tetrahydroxydammara-23-ene 20-O-β-d-glucopyranoside (3) on the basis of 1D and 2D NMR experiments and mass spectra. The known ginsenosides were identified as ginsenoside M7cd, ginsenoside Rg6, ginsenoside Rb3, gypenoside XVII, gypenoside IX, and 20-(E)-ginsenoside F4. [ABSTRACT FROM AUTHOR]

Introduction: Kamebakaurin is an active constituent of both Rabdosia japonica and Rabdosia excisa, which are utilized in Chinese traditional medicine for improving symptoms in patients with allergies. We investigated the molecular mechanisms of the anti-allergic effects of kamebakaurin using BMMCs. Methods: The degranulation ratio, histamine release, and the interleukin (IL)-4, leukotriene B4 (LTB4), and cysteinyl leukotriene productions on antigen-triggered BMMC were investigated. Additionally, the effects of kamebakaurin on signal transduction proteins were examined by Western blot and binding to the Syk and Lyn kinase domain was calculated. The effects of kamebakaurin on antigen-induced hyperpermeability were investigated using mouse model. Results: At 10 μm, kamebakaurin partially inhibited degranulation, histamine release, and IL-4 production. At 30 μm, kamebakaurin partially reduced LTB4 and cysteinyl leukotriene productions and suppressed degranulation, histamine release, and IL-4 production. Phosphorylation of both Syk Y519/520 and its downstream protein, Gab2, was reduced by kamebakaurin, and complete inhibition was observed with 30 μm kamebakaurin. In contrast, phosphorylation of Erk was only partially inhibited, even in the presence of 30 μm kamebakaurin. Syk Y519/520 is known to be auto-phosphorylated via intramolecular ATP present in its own ATP-binding site, and this auto-phosphorylation triggers degranulation, histamine release, and IL-4 production. Docking simulation study indicated kamebakaurin blocked ATP binding to the ATP-binding site in Syk. Therefore, inhibition of Syk auto-phosphorylation by kamebakaurin binding to the Syk ATP-binding site appeared to cause a reduction of histamine release and IL-4 production. Kamebakaurin inhibited antigen-induced vascular hyperpermeability in a dose-dependent fashion but did not reduce histamine-induced vascular hyperpermeability. Conclusion: Kamebakaurin ameliorates allergic symptoms via inhibition of Syk phosphorylation; thus, kamebakaurin could be a lead compound for the new anti-allergic drug. [ABSTRACT FROM AUTHOR]

A detailed chemical investigation of the Sanya Bay nudibranch Hexabranchus sanguineus yielded thirteen new sesquiterpenoids, namely sanyagunins A−H, sanyalides A−C, and sanyalactams A and B, along with eleven known related ones. Sanyalactams A and B feature an unprecedented hexahydrospiro[indene‐2,3′‐pyrrolidine] core. The structures of new compounds were established by a combination of extensive spectroscopic data analysis, quantum mechanical‐nuclear magnetic resonance methods, the modified Mosher's method, and X‐ray diffraction analysis. Based on analysis of NOESY correlations and the modified Mosher's method, the stereochemistry of two known furodysinane‐type sesquiterpenoids were revised. A plausible biogenetic relationship between these sesquiterpenoids wasproposed and discussed, and a chemo‐ecological relationship of the title animal and its possible sponge preys has been analyzed. In bioassays, sanyagunin B showed moderate antibacterial activity, whereas 4α‐formamidogorgon‐11‐ene exhibited potent cytotoxicity with IC50 values ranging from 0.87 to 1.95 μM. [ABSTRACT FROM AUTHOR]

Five undescribed dolabellane-type diterpenoids (1 – 5), together with three related known ones (6 – 8), were isolated from the soft coral Clavularia viridis. Their structures and stereochemistry were elucidated by extensive spectroscopic analysis and NMR calculation with DP4+ probability analysis. The absolute configurations of 1 and 5 were unambiguously determined by X-ray crystallographic analysis. A plausible biosynthetic connection between undescribed compounds 1 – 5 was proposed. Five undescribed dolabellane-type diterpenoids (1 – 5), together with three related known ones (6 – 8), were isolated and structurally characterized from the soft coral Clavularia viridis. [Display omitted] • Five undescribed dolabellane-type diterpenoids were isolated from the soft coral Clavularia viridis. • The X-ray crystallographic and NMR calculation analysis were applied to establish the stereochemistry. • All compounds were evaluated for their cytotoxicity and PTP1B inhibitory activity. [ABSTRACT FROM AUTHOR]

Three new scalarane-type sesterterpenes, namely Hyrtiosins H−J (1−3), along with thirteen known related compounds (4−16), were isolated from the South China Sea sponge Hyrtios erecta. Their structures were elucidated by extensive spectroscopic analysis and by the comparison of their spectroscopic data with those reported in the literature. The stereochemistry of heteronemin (9) was determined for the first time by X-ray crystallography study using Cu K α radiation. In bioassay, compound 5 and 10 displayed considerable inhibitory activity against human protein tyrosine phosphatase 1B (PTP1B) enzyme with IC 50 values of 19.68 μM, and 8.81 μM, respectively. [Display omitted] • Sixteen scalarane sesterterpenes, including three new ones, were isolated from the South China Sea Sponge Hyrtios erecta. • The configurations of compounds were determined by extensive spectroscopic analysis and comparison withthe reported data. • Compounds 5 and 10 displayed significant inhibitory activity against human protein tyrosine phosphatase 1B (PTP1B) enzyme. [ABSTRACT FROM AUTHOR]