Characterisation Of Mosquito Larvicidal Compounds From Cultures Of A Basidiomycete Coriolus Hirsutus

ABSTRACT

Mosquitoes transmit serious human diseases, resulting into millions of deaths globally

every year. The use of synthetic insecticides to control vector mosquitoes has caused

physiological resistance and adverse environmental effects in addition to high operational

costs. Mosquito larvicidal compounds from certain plant and fungal species have been

reported. Basidiomycetes fungi are known to synthesize a wide range of bioactive secondary

metabolites. The objective of this work was to investigate the mosquito larvicidal

compound(s) from the fungus Coriolus hirsutus belonging to the basidiomycete class of

fungi. Crude extracts prepared from fermented liquid nutrient media cultures of Coriolus

hirsutus were found to exhibit activity against the larvae of Aedes aegypti species of

mosquito. The active crude extracts were further subjected to bioactivity guided fractionation

that led to the purification of two larvicidal compounds. Chemical investigation using NMR

spectroscopy and MS experiments identified the two compounds, 17–(5–hydroxy–1,5-

dimethyl-hex-3-enyl)-4,4,8,10,13-pentamethyl-4,5,6,7,8,9,10,11,12,13,14,15,16,17-

tetradecahydro-3H-cyclopenta[α]phenanthren-3-ol and hexanoic acid. 17–(5–hydroxy–1,5-

dimethyl-hex-3-enyl)-4,4,8,10,13-pentamethyl-4,5,6,7,8,9,10,11,12,13,14,15,16,17-

tetradecahydro-3H-cyclopenta[α]phenanthren-3-ol had an LC50 and LC90 of 147.0 ppm and

285.3 ppm at 95%CI while hexanoic acid had an LC50 and LC90 of 237.8 ppm and 393.9 ppm

at 95%CI. The two larvicidal compounds obtained from Coriolus hirsutus may constitute

important alternatives to the synthetic insecticides under the integrated vector control

strategies.