Radical Scavenging, Antimicrobial and Insecticidal Efficacy of <i>Parmotrema cristiferum</i> and <i>Dirinaria applanata</i>

Abstract

Lichens are self-supporting symbiotic association of mycobiont and photobiont. The present study was conducted to investigate antimicrobial, insecticidal and radical scavenging potential of methanol extract of two macrolichens viz. Parmotrema cristiferum (Taylor) Hale and Dirinaria applanata (Fée) D.D. Awasthi. Antibacterial activity was tested against a panel of 5 bacteria by Agar well diffusion assay. Minimum inhibitory concentration was determined against 2 bacteria by broth dilution method. Antifungal efficacy was determined against 5 molds by Poisoned food technique. Free radical scavenging activity was screened by DPPH radical scavenging assay. Total phenolic content was estimated by Folin-Ciocalteau reagent method. Insecticidal activity was determined against 2nd instar larvae of Aedes aegypti Among lichen extracts, D. applanata exhibited stronger inhibition of bacteria as evidenced by wider zones of inhibition and low MIC values. Extract of D. applanata suppressed the mycelial growth of test fungi to higher extent when compared to extract of P. cristiferum The scavenging of DPPH radicals was also marked in case of D. applanta when compared to P. cristiferum. The content of total phenolics was also higher in D. applanata than that of P. cristiferum. Lichen extracts showed concentration dependent larvicidal effect. D. applanata exhibited stronger larvicidal effect than P. cristiferum. Overall, D. applanata displayed marked bioactivities when compared to P. cristiferum. This could be mainly due to high phenolic content. The macrolichens of this study appear to be promising sources of bioactive agents.