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The present study focuses on the emitted and endogenous scent profiles of Uvaria hamiltonii flowers. Among the 34 compounds identified, sesquiterpenoids were found to dominate the floral volatiles composition. Profiles from endogenous scent volatiles showed higher number of compounds than the emitted ones. The anthocyanin pigment responsible for the flower colour was also explored. It was found that a single anthocyanin compound, cyanidin-3-O-glucoside, was principally responsible for petal colour. Total phenolic content was evaluated and antioxidant capacities were studied with the help of DPPH, FRAP and ABTS assays. The total phenolic content and the antioxidant capacity were higher in methanolic extract as compared to aqueous, petroleum ether and ethyl acetate extracts of U. hamiltonii flowers.

Hoppea fastigiata (Griseb.) C.B. Clarke, an annual medicinal herb belonging to Gentianaceae, is mostly found in South-Asian countries. The genus possesses a unique class of compounds called xanthones, which are known for their potential against Alzheimer's and Parkinson's diseases. Three major xanthones were isolated and structurally confirmed as 1,5,7-trihydroxy-3-methoxyxanthone, 1,5-dihydroxy-3,7-dimethoxyxanthone, and 1,3,5-trihydroxy-8-methoxyxanthone from the in vitro shoot cultures which showed potential inhibitions against acetylcholinesterase, monoamine oxidase A, and monoamine oxidase B enzymes. Upon treatment with different elicitors, yeast extract (YE) was found to be most effective which led to a 20-fold increase of 1,3,5-trihydroxy-8-methoxy xanthone. YE treatment caused a rapid burst of reactive oxygen species (ROS) and the subsequent increase in xanthone contents. Phenylalanine ammonia lyase activity remained suppressed and 4-coumarate: CoA ligase activity remained unaffected after elicitation. However, shikimate dehydrogenase and shikimate kinase activities increased after elicitation. This suggested phenylalanine-independent biosynthesis of xanthones. Subsequent treatment of shoots cultures with different inhibitors of superoxide radicals (O 2À), hydrogen peroxide (H 2 O 2) generation, and calcium channel was found to suppress accumulation of xanthones. Thus, calcium mediated generation of H 2 O 2 followed by the activation of shikimate pathway enzymes is the key early step of xanthone biosynthesis in H. fastigiata.

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