Chemical characterization of n-alkane compounds in the leaves of Holoptelea integrifolia and its repellence against Japanese encephalitis vector

Epicuticular wax extract bearing n-alkane compounds were isolated from leaves of Holoptelea integrifolia and its chemical characterization was done by GC-MS analysis. Seven n-alkane compounds were isolated from epicuticular wax of H. integrifolia, which are Undecane [C11H24], Decane 5-methyl- [C11H24], Dodecane [C12H26], Undecane, 3,6-dimethyl- [C12H26], Hexadecane, 2,6,10,14-tetramethyl- [C20H42], Tridecane [C13H28], and Tetradecane [C14H30]. Different concentrations of crude extract as well as epicuticular wax extract bearing n-alkane each @ 2, 4 and 5 ppm cm-2 applied on human hand surface for repellence against Culex vishnui (vectors of JE) and at different time of exposure, gave a maximum protection of 73.33 per cent in the case of crude extract, and 94.33 per cent with epicuticular wax extract, both at 5 ppm cm-2, up to five hours of exposure.