Yanghua Yi

Bioactive nonanolide derivatives isolated from the endophytic fungus Cytospora sp.

Cytospolides F-Q (6-17) and decytospolides A and B (18 and 19), 14 unusual nonanolide derivatives, were isolated from Cytospora sp., an endophytic fungus from Ilex canariensis. The structures were elucidated by means of detailed spectroscopic analysis, chemical interconversion, and X-ray single crystal diffraction. The solution- and solid-state conformers were compared by the combination of experimental methods (X-ray, NMR) supported by DFT calculations of the conformers. Absolute configurations were assigned using the modified Moshers method and solution- and solid-state TDDFT ECD calculations. In an in vitro cytotoxicity assay toward the tumor cell lines of A549, HCT116, QGY, A375, and U973, the γ-lactone 17 demonstrated a potent growth inhibitory activity toward the cell line A-549, while nonanolide 16 with (2S) configuration showed the strongest activity against cell lines A-549, QGY, and U973. A cell cycle analysis indicated that compound 16 can significantly mediate G1 arrest in A549 tumor cells, confirming the important role of the C-2 methyl in the growth inhibition toward the tumor line. The discovery of an array of new nonanolides demonstrates the productivity of the fungus, and it is an example of chemical diversity, extending the nonanolide family by derivatives formed by ring cleavage, oxidation, esterification, and Michael addition.

Antifungal triterpene glycosides from the sea cucumber Bohadschia marmorata.

Four new holostan-type triterpene glycosides, marmoratoside A ( 1), 17 alpha-hydroxy impatienside A ( 2), marmoratoside B ( 3), 25-acetoxy bivittoside D ( 4), together with two known triterpene glycosides, impatienside A ( 5) and bivittoside D ( 6), were isolated from the sea cucumber Bohadschia Marmorata Jaeger. On the basis of spectroscopic analyses, including two-dimensional NMR techniques, and chemical reactions, the structures of the new triterpene glycosides were elucidated. Compounds 1, 2, 5, and 6 exhibited significant antifungal activity against six strains (0.70 < or = MIC (80) < or = 2.81 microM).

Proline-containing cyclopeptides from the marine sponge Phakellia fusca.

Four new cyclopeptides, phakellistatins 15-18 (2-5), together with five known cyclopeptides, phakellistatin 13 (1), hymenistatin 1, and hymenamides G, H, and J, were isolated from the South China Sea sponge Phakellia fusca. Their structures were elucidated by HR-ESIMS, NMR, and MALDI-TOF/TOF sequence analysis. The absolute configurations of the amino acid residues of 2-5 were assigned to be l by enantioselective HPLC analysis.

Antifungal nortriterpene and triterpene glycosides from the sea cucumber Apostichopus japonicus Selenka

A nortriterpene glycoside, 26-nor-25-oxo-holotoxin A1 (1), four triterpene glycosides, including both holostane and non-holostane types analogues, holotoxins D-G (2-5), together with three known triterpene glycosides, holotoxins A1 and B (6, 7), and cladoloside B (8), were isolated from the warty sea cucumber Apostichopus japonicus Selenka, a traditional tonic with high economic value in China. The structures of the new compounds were elucidated by a combination of detailed spectroscopic analysis and chemical methods. This is the first report of a nortriterpene glycoside isolated from sea cucumbers. These compounds showed potent antifungal activities in the in vitro biotest. A preliminary structure-activity analysis suggests that the 18(20) lactone group and the Δ(25) terminal double bond may increase the activity. The component of the carbohydrate chain seems play an important role whereas the double bond transformation from Δ(9(11)) to Δ(7) in the aglycone moiety contributes little to the bioactivity.

Two new bioactive triterpene glycosides from the sea cucumber Pseudocolochirus violaceus

By activity-guided fractionation, two new triterpene glycosides, violaceusides A (1) and B (2), were isolated from the sea cucumber Pseudocolochirus violaceus as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. By extensive 2D NMR techniques and chemical evidence, the structures of the two new glycosides were established as 16β-acetoxy-3-O-[3-O-methyl-β-d-glucopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-β-d-quinovopyranosyl-(1 → 2)-4-O-sodiumsulphate-β-d-xylopyranosyl]-holosta-7,24-diene-3β-ol (1) and 16β-acetoxy-3-O-[3-O-methyl-β-d-glucopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 2)-4-O-sodiumsulphate-β-d-xylopyranosyl]-holosta-7,24-diene-3β-ol (2), respectively. The two glycosides also exhibited significant cytotoxicity against HL-60 and BEL-7402 cancer cell lines.

Bioactive 11,20-Epoxy-3,5(16)-diene Briarane Diterpenoids from the South China Sea Gorgonian Dichotella gemmacea

Seven new briarane diterpenoids, gemmacolides G-M (1-7), were isolated together with two known analogues, juncin O and junceellolide C, from the South China Sea gorgonian Dichotella gemmacea. The structures of the new compounds were elucidated by detailed analysis of spectroscopic data and comparison with reported data. In an in vitro bioassay, these compounds exhibited different levels of growth inhibition activity against A549 and MG63 cells. In particular, compound 4 was more active than the positive control adriamycin against A549 cells. Compounds 4 and 7 also exhibited weak antimicrobial activity against the bacterium Bacillus megaterium and the fungus Septoria tritici, respectively.

Argusides D and E, Two New Cytotoxic Triterpene Glycosides from the Sea Cucumber Bohadschia argusJaeger

Two new triterpene glycosides, argusides D and E (1 and 2, resp.), have been isolated from the sea cucumber Bohadschia argus Jaeger collected in the South China Sea. Their structures have been established by spectral analysis (ESI‐MS, and 1D‐ and 2D‐NMR) and chemical evidence. Compounds 1 and 2 both possess an holostane‐type triterpene aglycone with a C(9)C(11) bond, an OH group at C(12), and tetrasaccharide moieties, but differ in the side chains. The two glycosides exhibited significant cytotoxicities against four human tumor cell lines, A549, HCT‐116, HepG2, and MCF‐7.

Hippolides A-H, acyclic manoalide derivatives from the marine sponge Hippospongia lachne.

Eight new acyclic manoalide-related sesterterpenes, hippolides A-H (1-8), together with two known manoalide derivatives, (6E)-neomanoalide (9) and (6Z)-neomanoalide (10), were isolated from the South China Sea sponge Hippospongia lachne. The absolute configurations of 1-8 were established by the modified Moshers method and CD data. Compound 1 exhibited cytotoxicity against A549, HeLa, and HCT-116 cell lines with IC50 values of 5.22×10(-2), 4.80×10(-2), and 9.78 μM, respectively. Compound 1 also showed moderate PTP1B inhibitory activitiy with an IC50 value of 23.81 μM, and compound 2 showed moderate cytotoxicity against the HCT-116 cell line and PTP1B inhibitory activity with IC50 values of 35.13 and 39.67 μM, respectively. In addition, compounds 1 and 5 showed weak anti-inflammatory activity, with IC50 values of 61.97 and 40.35 μM for PKCγ and PKCα, respectively.

Bioactive briarane diterpenoids from the South China Sea gorgonian Dichotella gemmacea

Six new briarane diterpenoids, gemmacolides T-Y (1-6), were isolated together with three known analogs, juncenolide J (7), praelolide (8), and junceellolide C (9), from the South China Sea gorgonian Dichotella gemmacea. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. The absolute configuration was suggested based on biosynthetic considerations. In an in vitro bioassay, compounds 3 and 6 showed potent growth inhibition towards tumor cell lines of A549 and MG63, being stronger than the positive control of adriamycin. These compounds also exhibited weak antimicrobial activity against the bacterium Escherichia coli and the fungi Microbotryum violaceum and Septoria tritici.

Bioactive polyoxygenated steroids from the South China sea soft coral, Sarcophyton sp.

Seven new polyoxygenated steroids (1–7) were isolated together with seven known analogues (8–14) from the South China Sea soft coral, Sarcophyton sp. The structures of the new compounds were identified on the basis of extensive spectroscopic analysis and comparison with reported data. All the steroids are characterized with 3β,5α,6β-hydroxy moiety, displaying carbon skeletons of cholestane, ergostane, gorgostane and 23,24-dimethyl cholestane. In the in vitro bioassay, metabolites exhibited different levels of antimicrobial activity against bacterial species Escherichia coli and Bacillus megaterium, and fungal species Microbotryum violaceum and Septoria tritici. No inhibition was detected towards microalga Chlorella fusca. Preliminary structure-activity analysis suggests that the 11α-acetoxy group may increase both antibacterial and antifungal activities. The terminal-double bond and the cyclopropane moiety at the side chain may also contribute to the bioactivity.