Cytotoxic saponin against lung cancer cells from Dioscorea birmanica Prain & Burkill.

OBJECTIVE

To investigate the cytotoxic activity against lung cancer cells of Dioscorea birmanica Prain & Burkill extract and its compounds.

METHODS

Cytotoxic activity was tested against two types of lung cancer cell line (A549 and CORL-23), one type of normal lung cell (MRC-5) by sulforhodamine B assay. Bioassay guide fractionation was used for isolating cytotoxic compounds. The structure elucidation of active ingredients was proven by spectrophotometry technique.

RESULTS

The results found that the ethanolic extract of Dioscorea birmanica Prain & Burkill (DBE) showed high cytotoxic activity against lung cancer cells; A 549 and COR-L23 (IC50 = 7.45 +/- 0.31, 8.71 +/- 0.29 microg/ml, respectively) but no cytotoxic activity against normal cancer cells MRC-5 (IC50 = 94.76 +/- 1.25 micro/ml). Six fractions from DBE were isolated by vaccuum liquid chromatography with ordering polarity of solvent and were coded as DB1-DB6, respectively. The fraction DB5 showed high cytotoxic against A 549 and COR-L23 (IC50 = 6.14 +/- 0.08 and 16.44 +/- 1.23 microg/ml, respectively) but less toxic to normal cell. Diosgenin-3-O-alpha-L-rhamnosyl (1-->2)-beta-D-glucopyranoside or Prosapogenin A of dioscin (DBS1) was isolated from DB5 fraction and had highest cytotoxic activity against those two types of lung cancer cells (IC50 = 1.81 +/- 0.03, 1.84 +/- 0.05 microg/ml), respectively) but less cytotoxic against normal lung cells MRC-5 (IC50 = 37.09 +/- 0.67 microg/ml).

CONCLUSIONS

The steroid saponin from Dioscorea birmanica showed cytotoxic activity against human lung cancer cells but less toxic against normal lung cells.