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M Kozuka

Publications and source records attributed to M Kozuka.

At least 91 records · Page 5Linked to original sources
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Studies on inhibitors of skin-tumor promotion. Inhibitory effects of triterpenes from Cochlospermum tinctorium on Epstein-Barr virus activation.

Arjunolic acid, an oleanene-type triterpene isolated from the rhizome of Cochlospermum tinctorium, its triacetate derivative, and their methyl esters were tested using the short-term in vitro assay on EBV-EA activation in Raji cells induced by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Their inhibitory effects on skin tumor promotors were found to be greater than those of previously studied natural products.

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Studies on inhibitors of skin tumor promotion, VI. Inhibitory effects of quinones on Epstein-Barr virus activation.

To search for possible antitumor promoters, we carried out a primary screening of fifty-one quinones (anthraquinones, naphthoquinones, azaanthraquinones, and azafluorenones) and related compounds, using their possible inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells. Some of these quinones, notably 5-hydroxy-1,2-methylenedioxy-anthraquinone [9], shikonin [29], 2-acetylfuranonaphthoquinone [32], 5,8-dihydroxycleistopholine [37], and 5,8-dihydroxy-2-methyl-1-azaanthraquinone [45], were observed to significantly inhibit the EBV-EA activation at low doses. The position and number of hydroxyl groups on phenyl rings of these quinones affected the inhibitory activity on EBV-EA activation. The investigation indicates that 9, 29, 32, 37, and 45 might be valuable anti-tumor promoters.

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Studies on inhibitors of skin tumor promotion, IX. Neolignans from Magnolia officinalis.

Three neolignans, known as magnolol [1], honokiol [2] and the new monoterpenylmagnolol [3], were isolated from the bark of Magnolia officinalis as inhibitors of Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA). The structure of 3 was determined from 2D nmr spectral data and difference nOe experiments. The MeOH extract of this plant and magnolol exhibited remarkable inhibitory effects on mouse skin tumor promotion in an in vivo two stage carcinogenesis test. This investigation indicates that these neolignans and the extract might be valuable antitumor promoters.

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