Flavonoid and stilbenoid production in callus cultures of Artocarpus lakoocha

Callus cultures of Artocarpus lakoocha Roxb., established from seedling explants and maintained on woody plant medium containing 1 mg/l 2,4-dichlorophenoxyacetic acid and 1 mg/l benzyladenine, were studied for their chemical constituents and biosynthetic potential of secondary metabolites. Four prenylflavones and prenylated stilbenes, along with nine known polyphenolic compounds, were isolated and elucidated for their structures through extensive analysis of their NMR and MS data. Among the 13 isolates, it appeared that seven of them are prenylated derivatives of 5,7,2′,4′-tetrahydroxyflavones, and four are prenylated derivatives of 2,4,3′,5′-tetrahydroxystilbene (oxyresveratrol), suggesting that the biosynthetic pathways of these two polyphenolic groups and their prenylating enzymes are highly expressed in A. lakoocha callus cultures. A study on the growth-product relationship of the callus cultures showed that the secondary metabolites were all formed simultaneously during the rapid growth phase of the culture cycle, with various prenylflavones, and a prenylated stilbene as major constituents. In assays for DPPH free radical scavenging activity and tyrosinase inhibitory potential, the stilbenoids appeared to possess moderate effects, whereas the flavonoids showed only weak activity.