Abstract:
Fungi, especially higher ones, have received a lot of attention in the recent decades due to the advances of biotechnological techniques. This is because secondary metabolism in fungal biotechnological cultures is manipulable and produces an array of compounds with diverse as well as novel chemical and biological properties. The activities can be taped into to address the myriad problems afflicting local communities in Kenya especially in agrochemical and medical sectors. Disease burden in rural settings remain a major development challenge and there is need to develop appropriate technologies to provide solutions. Diseases and disease-causing agents are spreading very fast and this is complicated by the problems of resistance to drugs by the pathogens and the vectors. For example the mosquito vector is becoming increasingly resistant to both synthetic and natural insecticides. There is also increasing evidence of resistant to conventional antibiotics of pathogenic microbes that is stimulating the development of strategies that target new or unexploited fungal bio-resources. In this light a basidiomycete, Trametes species (JO5066) was cultured in submerged cultures and the secondary metabolites extracted using conventional chemistry techniques like solvent-solvent extraction and liquid-solid adsorption techniques. Crude extracts were found to be actually active against larvae, culture filtrate 30-50% at 50 ppm and mycelium extract 30-70% at 500 ppm. The crude extracts were then fractionated, guided by mosquito larvicidal and antimicrobial activity. Larvicidal and antimicrobial assays were also carried out for the crude extracts and the purified compounds. The chemical structures of the purified compounds were elucidated using standard spectroscopic techniques: 1D (1H; 13C) and 2D (HSQC, COSY, NOESY, HMBC; DEPT) NMR experiments, assignments. Based on the NMR experiments two compounds, 2,3-dihydro-3,3-dimethyl-1Hindene- 1,2,6-triol (compound 29) and p-tolylmethanol (compound 30) were elucidated. The larvicidal assay for 2,3-dihydro-3,3-dimethyl-1H-indene-1,2,6-triol was done and LC50 and LC90 values were calculated and found to be 235 ppm and 674 ppm respectively. The larvicidal assay for p-tolylmethanol was not done due to low yield. The study has demonstrated that secondary metabolites from the basidiomycete (J05066) can be used as mosquito larvicidal compounds and consequently help in controlling mosquito borne diseases.
