Jun-Ming Guo

A Novel Antioxidant Isobenzofuranone Derivative from Fungus Cephalosporium sp.AL031

Bioassay-guided fractionation of metabolites from the fungus Cephalosporium sp.AL031 isolated from Sinarundinaria nitida led to the discovery of a new isobenzofuranone derivative, 4,6-dihydroxy-5-methoxy-7-methylphthalide (1), together with three known compounds: 4,5,6-trihydroxy-7-methyl-1,3-dihydroisobenzofuran (2), 4,6-dihydroxy-5-methoxy-7-methyl-1,3-dihydroisobenzofuran (3) and 4,5,6-trihydroxy-7-methylphthalide (4). The structure of the new compound 1 was determined based on MS, 1D and 2D NMR spectral data. Compounds 1–4 showed potent antioxidant activity with EC50 values of 10, 7, 22 and 5 μM by 1,1-diphenyl-2-picryhydrazyl (DPPH) radical-scavenging assay.

A Novel 18-Norclerodane Diterpenoid from the Roots of Tinospora sagittata var. yunnanensis

A novel 18-nor-clerodane diterpenoid named sagitone (1) was isolated from the 95% ethanol extract of dry roots of Tinospora sagittata var. yunnanensis together with the five known diterpenoids columbin (2), palmatoside C (3), fibleucin (4), tinophylloloside (5) and epitinophylloloside (6). The structure of the new compound 1 was determined based on MS, IR, 1D and 2D NMR spectral data. The compounds 1~6 did not show significant cytotoxic activity against cancer cell lines K562 and HL-60.

New Clerodane Diterpenes from Tinospora sagittata var. yunnanensis

Four new clerodane diterpenes, namely sagittatayunnanosides A-D (1-4), were isolated from the roots of Tinospora sagittata var. yunnanensis, together with two known compounds, tinospinoside C (5) and tinospinoside E (6). The structures of the four new compounds were well elucidated by extensive analyses of the MS, IR, and 1D and 2D NMR data. The cytotoxic and antifouling activities of compounds 1-6 were evaluated.

Two New Sphingolipids from the Leaves of Piper betle L.

Two new sphingolipids, pipercerebrosides A (1) and B (2), were isolated from the leaves of Piper betle L. Their structures, including absolute configurations, were determined by spectroscopic analysis and chemical degradation. These two compounds did not show significant cytotoxic activity against the cancer cell lines K562 and HL-60 in a MTT assay.

A novel lignan glycoside with antioxidant activity from Tinospora sagittata var. yunnanensis

A novel lignan glysocide, namely sagitiside A (1), together with two known ones, (+)-lyoniresinol-2α-O-β-D-glucopyranoside (2) and (+)-5′-methoxyisolariciresinol 3α-O-β-D-glucopyranoside (3), was isolated from the 95% ethanol extract of dry roots of Tinospora sagittata var. yunnanensis. The structure of the new compound (1) was determined based on MS, 1D and 2D NMR spectral data. Compounds 1–3 showed antioxidant activity with EC50 values 55, 75 and 80 µM by 1,1-diphenyl-2-picryhydrazyl (DPPH) radical-scavenging assay.

Cytotoxic flavanes from Uraria clarkei

Two new flavanes, (2R)-4′-hydroxy-2′,5,7-trimethoxyflavane (1) and (2R,4R)-2′,4′-dihydroxy-5,7-dimethoxyflavan-4-ol (2), were isolated from Uraria clarkei, together with two known compounds 5,7-dimethoxy-4′-hydroxyflavan (3) and 5,7,4′-trimethoxyflavan (4). The structures of the new flavanes were characterized by analyses of the MS, IR, UV, CD, 1D, and 2D NMR data. Cytotoxicity test suggested that compounds 1–4 possessed slight activity against K-562 and Hela cell lines, with the IC50 values ranging from 26.6 to 56.3 μM.