Thesis (M.Eng.)--Chulalongkorn University, 2012

In order to supply new information on the biological activity of Colocasia gigantea (Araceae) extract, This study investigates the optimal solvent system for phenolic compounds extraction, antimicrobial activity and cytotoxicity of C. gigantea’s extract. The methanol-water binary solvents of varying methanol fractions were used for phenolic compounds extraction. The optimal extraction of the solvent can be described by the solvent polarity represented by the solubility parameter. The optimal condition for the solvent to extract total phenolic compounds from C. gigantea was predicted at solubility parameter 33.6 and 42.5 MPa⁰⋅⁵ in the tuber part and leaf respectively. The antimicrobial activity of C. gigantea was determined by disc diffusion method. All extracts from leaf of C. gigantea were found to be more effective than extracts from tuber against Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633 and Staphylococcus aureus ATCC 25923. In the study of cytotoxicity, we investigated cytotoxicity of C. gigantea extract on cervical cancer (Hela), melanoma (A375) and human white blood cell (WBC) in vitro. The experimental results showed that not at all part of C. gigantea had cytotoxicity on Hela and A375 cells whereas some of C. gigantea extract from leaf (especially used dichloromethane as a solvent) could promote Hela and A375 cells proliferation significantly. Additionally, only the extract (used n-hexane as a solvent) from the tuber had cytotoxicity on Hela and A375 cells and also enhanced WBC cells proliferation.