Abstract

• The present work focused on the study of chemical constituents from the leaf of Dregea volubilis (L.f.) Benth. ex Hook.f. (Gwe-dauk-nwe) and detoxification activity to aflatoxin producing microorganisms in agricultural products and cytotoxicity to liver cancer cell line (HepG2). The leaf of the plant was collected from Kyunkalay village, Hlegu Township, Yangon Region in July 2018. The leaf sample was cleaned, dried and made to powder. Phytochemical investigation of D. volubilis leaf was performed and it was found that carbohydrates, flavonoids, glycosides, phenolic compounds, reducing sugars, saponins, steroids, tannins, terpenoids, and organic acids were present, however, cyanogenic glycosides and starch were absent. In addition, the elements such as Ca (38.32 %), K (33.72 %), Cl (12.31 %), Al (11.24 %), S (1.95 %), Zn (0.98 %) are found as major elements and small amount of other elements are found as Fe (0.77 %), Mn (0.44 %), Rb (0.11 %), Br (0.08 %), Sr (0.08 %) were also found using ED XRF method. Essential oil of D. volubilis leaves was extracted by steam distillation method and the organic components (7-chloro benzofuran, Phenol,2,4-bis(1,1-dimethylethyl), 6,10,14-trimethyl-2- pentadecanone, dibutyl-phthalate, 1-eicosene, phytol and uridine compounds) in it were identified by GC-MS method. The antioxidant activities of watery and ethanol extracts of the leaf sample were determined by DPPH assay method. The IC50 value of water and ethanol extracts were found to be 582.12 and > 1000 μg/mL, respectively. In vitro detoxification activity of essential oil and extracts (PE,CHCl3, MeOH and H2O extracts) of D. volubilis leaf was tested by aflatoxin producing fungus. Yeast, Aspergillus flavus and Aspergillus niger were cultured from corn, peanut and chilli using direct culture method. CHCl3, MeOH extracts and essential oil of D. volubilis leaf showed detoxification activity on these yeast and fungus microorganisms (inhibition zone diameter 11 mm to 19 mm) as well as PE and H2O extracts (inhibition zone diameter 11mm to 14 mm). Determination of minimum inhibitory concentration (MIC) of essential oil on two species of organisms, namely A. niger and A. flavus was carried by potato dextrose agar well diffusion method. The essential oil with different concentrations (1 x 105 to 0.2 μg/mL) showed inhibition zone diameter in the range of 12 to 15 mm. The MIC values for essential oil was found to be 2.5 x 104 µg/mL. (inhibition zone diameter ~ 12 mm). The cytotoxicity of MeOH extract from D. volubilis leaf against hepatoma liver cancer cell HepG2 was evaluated by MTT assay. The IC50 value of MeOH extract was found to be 168.05 µg/mL for 24 h treated time.