Antimicrobial, radical scavenging, and insecticidal activity of leaf and flower extracts of Couroupita guianensis Aubl.

Abstract

Objectives: The objective of the present study was carried out to investigate antimicrobial, radical scavenging, and insecticidal activity of leaf and flower of Couroupita guianensis Aubl. (Lecythidaceae). Methods: Extraction of leaf and flower was carried out by maceration process using methanol. Antibacterial and antifungal activity of extracts was carried out by agar well-diffusion method and poisoned food technique, respectively. Radical scavenging activity of extracts was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging assays. Insecticidal activity of extracts was evaluated in terms of larvicidal and pupicidal effects against Aedes aegypti. Results: Leaf extract displayed marked antibacterial activity when compared to flower extract. Highest and least inhibitory activity of extracts was observed against Staphylococcus epidermidis and Escherichia coli, respectively. Both extracts displayed antifungal activity with highest activity exhibited by leaf extract. Highest and least susceptibility were shown by Curvularia sp. and Fusarium sp., respectively. Both extracts scavenged DPPH and ABTS radicals dose dependently. Leaf extract (IC50 = 19.61 μg/ml) caused marked DPPH radical scavenging potential than flower extract ((IC50= 257.13 μg/ml). IC50 value of ABTS radical inhibition of leaf and flower extract was found to be 7.63 and 53.34 μg/ml, respectively. Larvicidal and pupicidal activity by extracts was concentration dependent. The susceptibility of larvae and pupae to extract was in the order: 2nd instar larvae > 4th instar larvae > pupae. Leaf extract displayed marked insecticidal activity when compared to flower extract as revealed by lower LC50 values. Conclusion: Overall, leaf extract exhibited marked bioactivities than flower extract. The plant can be used to treat microbial infections and oxidative damage and to manage fungal diseases. The plant can be used against mosquito vectors which transmit arboviral diseases.