antioxidant and cytotoxic activities of thai medicinal plants named khaminkhruea: arcangelisia flava, coscinium blumeanum and fibraurea tinctoria

The stems of Arcangelisia flava, Coscinium blumeanum and Fibraurea tinctoria, collectively known in southern Thailand as Khaminkhruea, were sequentially extracted with petroleum ether, chloroform, methanol, and boiling water to afford 12 crude extracts. All extracts have been assessed for antioxidant activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and cytotoxic activity against brine shrimp and human cancer cell line MCF-7 (breast adenocarcinoma). Methanol extract of A. flava (AFM), and methanol and chloroform extracts of C. blumeanum (CBM and CBC) exhibited moderate antioxidant activity with EC50 values of 25-55 μg/ml. Chloroform extracts of A. flava (AFC) and F. tinctoria (FTC), AFM, CBC and CBM showed pronounced cytotoxic activity against brine shrimp and MCF-7 cells with LC50 and IC50 values of 210-278 and 8-12 μg/ml, respectively. Bioassay-guided chemical investigation led to the isolation of berberine as a main compound of AFC, AFM, CBC and CBM. Palmatine and jatrorrhizine were found to be main alkaloids of FTC, and minor alkaloids of AFC, AFM, CBC and CBM. In addition, an ester triacontanyl caffeate was isolated for the first time from C. blumeanum (CBC). Chemical structures of the isolated compounds were determined by spectroscopic methods particularly NMR and mass spectrometry. Triacontanyl caffeate was mainly responsible for antioxidant activity of C. blumeanum with an EC50 value of 6.8 μg/ml. Jatrorrhizine possessed moderate antioxidant activity with an EC50 value of 98.0 μg/ml, whereas palmatine and berberine were found to be considerably less active (EC50 >100 μg/ml). The LC50 values of the four isolated compounds on brine shrimp were ranging from 37-206 μg/ml. The IC50 values of berberine, palmatine and jatrorrhizine against MCF-7 cells were in the range of 1-4 μg/ml. Triacontanyl caffeate was considerably less cytotoxic than the alkaloids with an IC50 value of 15.5 μg/ml.