Bioactivity guided isolation of cytotoxic terpenoids and steroids from Premna serratifolia.

BACKGROUND

Despite several phytochemical studies of Premna serratifolia Linn. (Verbenaceae), the isolation of active constituents of this plant remains to be explored.

OBJECTIVE

The study isolates cytotoxic terpenoids and steroids from the leaves of Premna serratifolia.

METHODS

Unsaponifiable matter of hexane soluble fraction obtained from methanol extract was subjected to isolation by column chromatography and preparative TLC. Three compounds PS-01 A, PS-01B and PS-02 A were isolated. PS-01 A and PS-01B were identified by comparative TLC with authentic marker compounds followed by NMR analysis. Further PS-01B was analyzed by HR-GCMS. PS-02 A was subjected to HR-LCMS. All isolated compounds/fractions were evaluated for cytotoxic activity by BSL bioassay and using cell lines A549, HepG2 and L6.

RESULTS

Three compounds were isolated from the leaf extract by bioactivity-guided fractionation. Two of which, namely, PS-01 A (oleanolic acid) and PS-02 A (unknown) were found to be terpenoids and PS-01B was identified as steroid (stigmasterol). PS-02 A compound is to be purified and characterized further. All three compounds PS-01 A, PS-01B, PS-02 A showed cytotoxicity by BSL bioassay (LC50 value of 54.49, 30.83, 16.32 ppm, respectively) and by cell line study where isolate PS-02 A has shown more cytotoxicity with LC50 values of 66.77 and 53.72 μg/mL with A549 and HepG2 cells, respectively, when compared with other isolates.

CONCLUSIONS

Bioactivity guided fractionation of Premna serratifolia leaves succeeded into isolation of two terpenoids and one steroid compound with significant cytotoxic activity. Here we report the isolation of these cytotoxic terpenoids/steroids from this plant for the first time which could be developed as anticancer agents.