Melanogenesis-inhibitory saccharide fatty acid esters and other constituents of the fruits of Morinda citrifolia (noni).

Five new saccharide fatty acid esters, named nonioside P (3), nonioside Q (4), nonioside R (8), nonioside S (10), and nonioside T (14), and one new succinic acid ester, butyl 2-hydroxysuccinate (=4-butoxy-3-hydroxy-4-oxobutanoic acid) (31), were isolated, along with 26 known compounds, including eight saccharide fatty acid esters, 1, 2, 5, 6, 7, 9, 12, and 13, three hemiterpene glycosides, 15, 17, and 18, six iridoid glycosides, 21-25, and 27, and nine other compounds, 20, 28, 29, and 32-37, from a MeOH extract of the fruit of Morinda citrifolia (noni). Upon evaluation of these and five other glycosidic compounds, 11, 16, 19, 26, and 30, from M. citrifolia fruit extract for their inhibitory activities against melanogenesis in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), most of the saccharide fatty acid esters, hemiterpene glycosides, and iridoid glycosides showed inhibitory effects with no or almost no toxicity to the cells.

Melanogenesis inhibitory activities of iridoid-, hemiterpene-, and fatty acid-glycosides from the fruits of Morinda citrifolia (Noni).

A new iridoid glycoside, 9-epi-6alpha-methoxy geniposidic acid (4), three new hemiterpene glycosides, 3-methylbut-3-enyl 2'-O-(beta-D-glucopyranosyl)-beta-D-glucopyranoside (nonioside K) (6), 3-methylbut-3-enyl 6'-O-(beta-D-xylopyranosyl)-beta-D-glucopyranoside (nonioside L) (8), and 3-methylbut-3-enyl 6'-O-(beta-D-xylofuranosyl)-beta-D-glucopyranoside (nonioside M) (9), and two new saccharide fatty acid esters, 6'-O-(beta-D-glucopyranosyl)-1'-O-[(2xi)-2-methylbutanoyl]-beta-D-glucopyranose (nonioside N) (16) and 6'-O-(beta-D-xylopyranosyl)-1'-O-[(2xi)-2-methylbutanoyl]-beta-D-glucopyranose (nonioside O) (17), were isolated from a methanol extract of the fruits of Morinda citrifolia (noni), along with 11 known compounds, namely, three iridoid glycosides (1-3), two hemiterpene glycosides (5 and 7), and five saccharide fatty acid esters (10-15). Upon evaluation of compounds 1-17 on the melanogenesis in the B16 melanoma cells induced with alpha-melanocyte-stimulating hormone (alpha-MSH), 13 compounds (1, 3, 4, 6-14, and 17) exhibited marked inhibitory effects with 34-49% reduction of melanin content at 100 muM with no or almost no toxicity to the cells (91-116% of cell viability at 100 microM).