Abstract

• The aim of this research is to isolate bioactive compound of the stems of Allamanda cathartica L. (Shwewa-pan) and to investigate some biological activities. According to the phytochemical tests, alkaloids, flavonoids, terpenoids, steroids, glycosides, organic acids, phenolic compounds, saponins, tannins and carbohydrates were found to be present in the stems. The ethanol and watery extracts of total phenolic content (31.98 ± 0.94 mg GAE/g, 18.91 ± 0.53 mg GAE/g), total flavonoid contents (226.67 ± 8.50 mg QE/g, 100.67 ± 9.29 mg QE/g), total steroid contents (278.81 ± 7.70 mg CE/g , 154.72 ± 13.31 mg CE/g) and total tannin contents (317.5 ± 0.00 mg TAE/g, 25.83 ± 14.4 mg TAE/g) were observed respectively. By thin layer and silica gel column chromatographic methods, one compound, 2, 5, 7 - trihydroxy - 3 - (4 - hydroxyphenyl) - 4H - chromen - 4 - one (0.22 %, m.pt 151 °C), was isolated from ethyl acetate extract of the stems and identified by 1H NMR, 13C NMR, HMQC, HMBC and EI MS spectroscopies. The antioxidant activity of ethanol extract (IC50 =10.97 µg/mL) determined by DPPH radical scavenging activity assay was higher than that of watery extract (IC50 = 68.37 µg/mL). All of the extracts have mild antimicrobial activity (inhibition zone diameters = 12~18 mm) against all of the microorganisms. According to the results of brine shrimp cytotoxicity bioassay, both ethanol and watery extracts have cytotoxic effect. It was found that EtOAc, PE and EtOH extract exhibited the inhibition of tumor formation. Both ethanol and watery extracts did not show antiproliferative activity, however, 2, 5, 7 - trihydroxy - 3 - (4 -hydroxyphenyl) - 4H - chromen - 4 - one showed activity against A 549 (IC50 = 41.7 µg/mL), MCF 7 (IC50 = 47.9 µg/mL) and Hela (IC50 = 8.91 µg/mL) human cancer cell lines.