The rhizome of Bulbophylllum orchid is the rich source of cytotoxic bioactive compounds, the potential anticancer agents.

Bulbophyllum orchid is used as a folk medicine in Asia. However, the concentrations of bioactive constituents in the plant may vary in different tissues. Thus, this study determined the most cytotoxic tissue extract in Bulbophyllum blepharistes Rchb.f. and identified its cytotoxic bioactive compounds. The ethanol extract from rhizomes of B. blepharistes exhibits more cytotoxicity than extracts from the leaf and pseudobulb. Ten compounds isolated from the rhizome are phenanthrenes (1, 2), bibenzyls (3, 4, 5), phenylpropanoids (6), methyl benzoate (7), along with a mixture of three alkyl acrylates (8, 9, 10). Compound 2, lusianthridin (9,10-dihydro-7-methoxy-2,5-phenanthrenediol), which was reported here for the first time in Bulbophyllum , showed cytotoxicity to H69AR, HeLa, HL-60, HepG2, and MOLT-3 cells. Compound 1 and 5 (tristin) significantly inhibited the growth of MOLT-3. The rhizome of B. blepharistes appears to be a good source for the potential anticancer agents (i.e. lusianthridin). [Display omitted] • Among18 genera of Orchidaceae, the extract of Bulbophyllum showed the most cytotoxic effect. • The ethanolic extract from rhizome of Bulbophyllum orchid rich in bioactive compounds. • The cytotoxic of Bulbophyllum dihydrophenanthrene and bibenzyl effect to various cell lines. [ABSTRACT FROM AUTHOR]