Zhi Kai Guo

Immunosuppressive resveratrol aneuploids from Hopea chinensis.

Two novel resveratrol aneuploids, hopeachinols A (1) and B (2), as well as a potent immunosuppressive polyphenol diptoindonesin G (3) were characterized from the ethanol extract of Hopea chinensis stem barks. The structure of the polyphenols was accommodated by comprehensive spectroscopic analysis with the absolute stereochemistry determined by the CD approach coupled with theoretical ECD spectra computer-generated through the Gaussian 03 program. The distinct structure and biological profile of 3 recommended it as a starting molecule for the relevant drug discovery.

Bioactive alkaloids from the plant endophytic fungus Aspergillus terreus.

One new alkaloid, named 16 alpha-hydroxy-5 N-acetylardeemin ( 1), along with seven known metabolites ( 2- 8) was isolated from the fermentation broth of an endophytic fungus, ASPERGILLUS TERREUS. The structures of these metabolites were assigned on the basis of detailed spectroscopic analysis and by comparing spectroscopic data with those in the literature. Compound 1 displayed an inhibitory effect against acetylcholinesterase. Compounds 1- 8 also showed moderate or weak cytotoxic activity against KB and HSC-T6 cell lines.

Oligostilbenes from Vatica mangachapoi with xanthine oxidase and acetylcholinesterase inhibitory activities

Phytochemical examination of the branches and twigs of the tropical plant Vatica mangachapoi resulted in the isolation of three novel oligostilbenes named vaticahainols A–C (1–3) along with seventeen known oligostilbenes (4–20). The structures of the new compounds were elucidated on the basis of extensive spectroscopic data analysis, modified Moshers method, and quantum chemical computation. All of the isolated phytochemicals were screened for their xanthine oxidase (XO) and acetylcholinesterase (AChE) inhibitory activities.

Angucyclines from an insect-derived actinobacterium Amycolatopsis sp. HCa1 and their cytotoxic activity

One new angucyclinone derivative, amycomycin A (1), and one new angucycline, amycomycin B (2), along with 5 known compounds (3-7), were isolated from an actinobacterium Amycolatopsis sp. HCa1 associated with the grasshopper, Oxya chinensis. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR spectra. Compounds 1-7 were tested in vitro for their cytotoxic effects on five cell lines including human gastric adenocarcinoma cell line (BGC823), human hepatocarcinoma cell line (HepG2), human melanoma cell line (A375), human oral squamous carcinoma cell line (KB), and ghost cell line (Ghost-R5X4). Cell viability assays showed that compound 7 was active in four cell lines with IC(50) values less than 18.0 μM except in KB showing no activity up to 100 μM.

Anti-inflammatory flavonoids from Cryptocarya chingii.

Six flavonoids named cryptogiones A-F, and nine known compounds were isolated from an ethanol extract of stems of Cryptocaryachingii. The structures of the compounds were elucidated by interpretation of comprehensive spectroscopic data and X-ray analysis. A majority of these flavonoids contained an acetic acid/lactone moiety, a possible taxonomic marker. Anti-inflammatory effects of the compounds were evaluated using in vitro assays. At 20 μM concentration, three compounds significantly inhibited TNFα-induced NF-кB activation and LPS-induced IL-1β expression.

Neuraminidase Inhibitory Polyketides from the Marine-derived Fungus Phoma herbarum

Two new polyketides, arthropsadiol C (1) and massarilactone H (2), together with six known derivatives (3-8) were isolated from the culture broth of the marine-derived fungus Phoma herbarum. Their structures were elucidated on the basis of spectroscopic methods, including 2D NMR techniques. Compounds 2, 4, 5, and 8 showed moderate neuraminidase inhibitory activity with IC(50) values ranging from 4.15 to 9.16 µM.

Chaetoglocins A–D, Four New Metabolites from the Endophytic Fungus Chaetomium globosum

Chaetoglocins A-D (1- 4), four new secondary metabolites, were isolated from the solid-fermentation culture of Chaetomium globosum (strain no. IFB-E036), an endophytic fungus residing inside the root of Cynodon dactylon. The structures of these compounds were elucidated on the basis of detailed spectroscopic evidence and by comparing spectroscopic data with those in the literature. Compounds 1 and 2 displayed antimicrobial activity against the gram-positive bacteria with minimum inhibitory concentrations (MIC) between 8 and 32 µg/mL.

Cytotoxic angucyclines from Amycolatopsis sp. HCa1, a rare actinobacteria derived from Oxya chinensis.

Two new angucyclines, named (2R,3R)-2-hydroxy-8- O-methyltetrangomycin (1) and (2R,3R)-2-hydroxy-5-O-methyltetrangomycin (2), together with eight known compounds (3-10), were isolated from the culture of Amycolatopsis sp. HCa1, a rare actinobacteria isolated from the gut of Oxya chinensis. The new structures were elucidated through extensive spectroscopic data analysis, and their absolute configurations were assigned by application of the modified Moshers method and CD spectrum comparison. Their IN VITRO cytotoxic activities against four cell lines including human cervical cancer cell line (HeLa), human gastric adenocarcinoma cell line (SGC-7901), human lung adenocarcinoma cell line (SPC-A-1), and mouse macrophage cell line (RAW264.7) were then investigated. Compounds 3, 4, 9, and 10 showed potent cytotoxic activities towards the HeLa cells with IC (50) values of 0.27, 0.11, 0.56, and 0.39 µM, respectively.

New Flavonol and Diterpenoids from the Endophytic Fungus Aspergillus sp. YXf3

One new flavonol, chlorflavonin A (1), four new diterpenoids, aspergiloids E-H (3, 5-7), together with eight known compounds (2, 4, 8-13) were isolated from solid fermentation of Aspergillus sp. (strain no. YXf3), an endophytic fungus from Ginkgo biloba. Their structures were determined through detailed spectroscopic analysis combined with comparison of NMR spectra data with reported ones. All of them were screened on cytotoxicity against KB, SGC-7901, SW1116, and A549 cell lines; compounds 4, 9-11 exhibited moderate activities with IC50 values ranging from 6.74 to 46.64 µM.

Actinotetraoses A–H: Tetrasaccharide Derivatives from a Grasshopper-Associated Amycolatopsis sp. HCa1

Chemical investigation of the insect-derived actinomycete Amycolatopsis sp. HCa1 with NMR-guided fractionation led to the isolation of eight new tetrasaccharide derivatives containing an unusual nonreducing glucotetraose skeleton, named actinotetraoses A-H (1-8), and one known compound, tigloside (9). The structures of these compounds were determined on the basis of analyses of their spectroscopic data. The in vitro immunosuppressive activity and cytotoxicity of these compounds were evaluated by T cell viability and MTT assays, respectively. Only actinotetraose E (5) displayed weak immunosuppressive activity.