Inhibition of Aldehyde Dehydrogenase Enzyme by Durian (Durio zibethinus Murray) Fruit Extract John S. Maninang a* , Ma.Concepcion C. Lizada b and Hiroshi Gemma a a: Pomology Laboratory, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, 305-8577 Ibaraki, Japan b: Department of Food Science and Nutrition, College of Home Economics, University of the Philippines Diliman, Quezon City 1101, Philippines *: Corresponding Author : gemma@sakura.cc.tsukuba.ac.jp tel. No. : +81 29 8534819 fax. No.: +81 29 8537225 Abbreviations: ALDH, aldehyde dehydrogenase; DE, durian extract; DER, disulfiram-ethanol reaction; K m , Michaelis constant ß-NAD or NAD, nicotinamide-adenine dinucleotide; Rf, retardation factor; V 0 , initial velocity; V max , maximum velocity 1