Melanogenesis inhibitory and free radical scavenging activities of diarylheptanoids and other phenolic compounds from the bark of Acer nikoense.

Melanogenesis inhibitory and free radical scavenging activities of nine cyclic (1-9) and one acyclic diarylheptanoids (10), and two phenolic compounds, (+)-rhododendrol (11) and (+)-catechin (12), isolated from the ethyl acetate-soluble fraction of the MeOH extract of the bark of Acer nikoense MAXIM. (Aceraceae) were examined. Upon evaluation of compounds 1-12 on the melanogenesis in the B16 melanoma cells, two compounds, 2 and 8, exhibited marked inhibitory activity with 55.6% and 46.8% reduction, respectively, of melanin content at 25 microg/ml without inhibition of cell proliferation. In addition, upon an evaluation of eleven compounds, 1-7 and 9-12 against the scavenging activities of free radicals (against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical), compound 12 (IC(50) 9.0 microgM) followed by compounds 1, 3, 4, and 6 (IC(50) 40.2-44.0 microgM) showed potent scavenging activities.

Biotransformation of cycloartane-type triterpenes by the fungus Glomerella fusarioides.

Biotransformation of three cycloartane-type triterpenes, cycloartenol (1), 24-methylenecycloartanol (2), and cycloartenone (3), by the fungus Glomerella fusarioides was studied. Compound 1 was converted to 3, cycloart-25-ene-3beta,24-diol (4), and cycloartane-3beta,24,25-triol (5). Compound 2 was metabolized to cycloeucalenol (6) and two new compounds, 24-methylcycloartane-3beta,24,24(1)-triol (7) and 24(1)-methoxy-24-methylcycloartane-3beta,24-diol (8). Compound 3 was converted into two new metabolites, 4alpha,4beta,14alpha-trimethyl-9beta,19-cyclopregnane-3,20-dione (9) and 25-hydroxy-24-methoxycycloartan-3-one (14), and four known compounds, viz., cycloartane-3,24-dione (10), 24-hydroxycycloart-25-en-3-one (11), (23E)-25-hydroxycycloart-23-en-3-one (12), and 24,25-dihydroxycycloartan-3-one (13). The structures of four new metabolites, 7, 8, 9, and 14, were established by spectroscopic methods.