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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 (IC 50 = 19.61 µg/ml) caused marked DPPH radical scavenging potential than flower extract ((IC 50 = 257.13 µg/ml). IC 50 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: 2 nd instar larvae > 4 th instar larvae > pupae. Leaf extract displayed marked insecticidal activity when compared to flower extract as revealed by lower LC 50 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.

Aqueous botanical extracts, via different extraction methods, for control of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

“…A major component present in aqueous extracts of R. graveolens, the Trans-anethole, compound that has proven insecticidal activity (Cruz et al 2017; Dias et al 2019; Hana et al 2020). According to López et al (2010), Trans-anethole causes changes in different biological aspects of insects, such as, for example, the inhibition of acetylcholinesterase, which may be an explanation of its effectiveness on P. xylostella larvae observed in this study.The highest mortality observed in the present study was obtained from the aqueous extract of C. guianensis leaves prepared by decoction (H = 6.51; df = 2; p = 0.0384), and researchers such asRaghavendra et al (2017) reported insecticidal activity of leaf extracts of this species, with mortality of up to 100% of the second-instar larvae of Aedes aegypti (Linnaeus) (Diptera:Culicidae) with concentrations greater than 1mg/ml. In pests of agricultural interest, for nymphs and adults of Bemisia tabaci (Gennadius) (Hemiptera:Aleyrodidae) with aqueous extract of C. guianensis, there are reports of mortalities of 29.2% and 35.34%, respectively,(Yadav and Mendhulkar 2015).Treatments with aqueous botanical extracts and with different types of extraction did not alter the larval duration of P. xylostella, and some researchers such asPeres et al (2017) found that aqueous extracts of the leaves of Alibertia intermedia (Mart.)…”