Evaluating Bioactive Potential of Lichen Secondary Metabolites for the Formulation of Mosquito Repellent

Background: Mosquitoes belong to the major disease transmitters causing millions of deaths every year. The cost of commercially available pyrethroids, environmental regulations and toxicity of commercial repellents force researchers to develop potential repellents of natural origin. Lichens comprise of bioactive compounds exhibiting multifarious biomedical potential. Objectives: In this present study, Parmotrema species was analyzed for its biomedical potential including antioxidant, anti-inflammatory and repellent activity. Materials and Methods: Antioxidant activity was evaluated by DPPH, FRAP assay. Anti-inflammatory activity was assessed by albumin denaturation and protease inhibition assay. The repellent potential evaluated against third and fourth-instar larvae of Aedes ageypti. Conclusion: Antioxidant activity by DPPH assay and FRAP assay exhibited IC₅₀ of 16.08 µg/mL and 24.6 µg/mL respectively. Anti-inflammatory potential via inhibition of albumin denaturation and protease inhibition assay shown maximum inhibition at 100 µg/mL with IC₅₀ value of 17.02 µg/mL and 27.5 µg/mL respectively. The repellent test confirmed that at 100 µg/mL, 90% of mortality rate was recorded. The repellent cream formulated form lichen extract exhibited 86.6% protection and smoke toxicity test demonstrated 26.6% protection against Aedes ageypti. Thus, the study evidenced the proven biomedical potential of methanolic lichen extract.