Chemical constituents from Diospyros fragrans Gurke (Ebenaceae)

A new naphtalenone derivative named fragranone, alongside seventeen known compounds: ten triterpenoids, one monoglycerol, one polyterpenoid, one carotenoid, two steroids and two polyols were isolated from the leaves and roots of Diospyros fragrans. Four semi-synthetic derivatives obtained from the acetylation and allylation of betulinic acid, allylation of ursolic acid and acetylation of vismiaefolic acid are also reported. The structures of the compounds were established using their MS and NMR spectral data. The chemotaxonomic relevance of the compounds is also discussed in this paper. The extracts, as well as the isolates and the semi-synthetic compounds were evaluated for their antibacterial and cytotoxic activities. The obtained results showed a moderate anti-bacterial activity for myrtifolic acid and the semi-synthetic compound betulinic acid acetate against Bacillus subtilis DSMZ 704 with a diameter zone of inhibition of 9 and 10 mm, respectively. Ursolic acid and corosolic acid exhibited a moderate cytotoxicity against human colorectal adenocarcinoma cells HT-29 and the cervix carci-noma cells KB-3-1 with inhibitory concentration 50 values of 34.4 and 50.9 mu M for ursolic acid, and 16.5 and 14.6 mu M for corosolic acid, respectively.