Publications by authors named "Manabu Oshikubo"

A new lanostane-type triterpene acid, (20xi)-3-oxolanosta-7,9(11),24-trien-21-oic acid (1; dehydrotrametenonic acid), along with a known triterpene acid, dehydroeburiconic acid (2), were isolated from the epidermis of the sclerotia of Poria cocos. The structure of 1 was analyzed on the basis of spectroscopic methods. Compounds 1 and 2 inhibited calf DNA polymerase alpha and rat DNA polymerase beta, with the 50% inhibition values of 45.

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A new triterpene acid, lucidenic acid P (1a), and two new triterpene acid methyl esters, methyl lucidenates P (1b) and Q (2b), were isolated and characterized from the fruiting body of the fungus Ganoderma lucidum. Their structures were elucidated on the basis of spectroscopic methods. In addition, eight known triterpene acids, lucidenic acids A (3a), C (4a), D(2) (5a), E(2) (6a), and F (7a) and ganoderic acids E (9a), F (10a), and T-Q (11a), and six known triterpene acid methyl esters, methyl lucidenates A (3b), D(2) (5b), E(2) (6b), F (7b), and L (8b) and methyl ganoderate F (10b), were isolated and identified from the fungus.

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The structures of two novel 3,4-seco-lanostane-type triterpenes isolated from the sclerotium of Poria cocos were established to be 16alpha-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid (1; poricoic acid G) and 16alpha-hydroxy-3,4-seco-24-methyllanosta-4(28),8,24(24(1))-triene-3,21-dioic acid (2; poricoic acid H) on the basis of spectroscopic methods. These two, and eight other known compounds isolated from the sclerotium, poricoic acid B (3), poricoic acid A (4), tumulosic acid (5), dehydrotumulosic acid (6), 3-epidehydrotumulosic acid (7), polyporenic acid C (8), 25-hydroxy-3-epidehydrotumulosic acid (9), and dehydroabietic acid methyl ester (10), showed potent inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Evaluation of the cytotoxicity of compounds 1 and 4 against human cancer cell lines revealed that 1 was significantly cytotoxic to leukemia HL-60 cells [GI(50) (concentration that yields 50% growth) value 39.

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