Inhibitory effects of constituents of Morinda citrifolia seeds on elastase and tyrosinase

A 50% ethanolic extract (MCS-ext) from seeds of Morinda citrifolia (‘‘noni’’ seeds) showed more potent in vitro inhibition of elastase and tyrosinase, and 1,1-diphe-nyl-2-picrylhydrazyl (DPPH) radical scavenging activity than extracts of M. citrifolia leaves or flesh. Activity-gui-ded fractionation of MCS-ext using in vitro assays led to the isolation of ursolic acid as an active constituent of elastase inhibitory activity. 3,30-Bisdemethylpinoresinol, americanin A, and quercetin were isolated as active con-stituents having both tyrosinase inhibitory and radical scavenging activities. Americanin A and quercetin also showed superoxide dismutase (SOD)-like activity. These active compounds were isolated from noni seeds for the first time.

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