EFFECT OF Moringa oleifera FLOWER EXTRACT ON LARVAL TRYPSIN AND ACETHYLCHOLINESTERASE ACTIVITIES IN Aedes aegypti

Abstract

Aedes aegypti control is crucial to reducing dengue fever. Aedes aegypti larvae have developed resistance to organophosporous insecticides and the use of natural larvicides may help manage larval resistance by increasing elements in insecticide rotation programs. Here, we report on larvicidal activity of Moringa oleifera flower extract against A. aegypti L(1), L(2), L(3), and L(4) as well as the effect of flower extract on gut trypsin and whole-larval acetylcholinesterase from L(4.) In addition, the heated flower extract was investigated for larvicidal activity against L(4) and effect on larval gut trypsin. Moringa oleifera flower extract contains a proteinaceous trypsin inhibitor (M. oleifera flower trypsin inhibitor, MoFTI), triterpene (β-amyrin), sterol (β-sitosterol) as well as flavonoids (kaempferol and quercetin). Larvicidal activity was detected against L(2), L(3), and L(4) (LC(50) of 1.72%, 1.67%, and 0.92%, respectively). Flower extract inhibited L(4) gut trypsin (MoFTI K(i) = 0.6 nM) and did not affect acetylcholinesterase activity. In vivo assay showed that gut trypsin activity from L(4) treated with M. oleifera flower extract decreased over time (0-1,440 min) and was strongly inhibited (98.6%) after 310 min incubation; acetylcholinesterase activity was not affected. Thermal treatment resulted in a loss of trypsin inhibitor and larvicidal activities, supporting the hypothesis that flower extract contains a proteinaceous trypsin inhibitor that may be responsible for the deleterious effects on larval mortality.

Effects of α,β-unsaturated lactones on larval survival and gut trypsin as well as oviposition response of Aedes aegypti

“…Extracts and compounds with larvicidal activity against A. aegypti have been reported to disrupt the activity of larval digestive enzymes and it is well known that larvae of A. aegypti produce trypsin-like enzymes which are essential for digestive process and thus nutrition and development (Agra-Neto et al, 2014;Kunz, 1978;Napoleão et al, 2012;Pontual et al, 2012Pontual et al, , 2014. The lactone 5a was able to inhibit L4 gut trypsin (Fig.…”

“…The assay was performed according to Pontual et al (2012). Groups of 50 live L4 were immobilized by incubation (10 min) at 4°C and their guts were removed with the aid of a needle and stereomicroscope.…”

First insights into insecticidal activity against Aedes aegypti and partial biochemical characterization of a novel low molecular mass chymotrypsin‐trypsin inhibitor purified from Lonchocarpus sericeus seeds

“…One of the strategies to eliminate this mosquito is the use of synthetic insecticides belonging to the classes organochlorines, organophosphates and pyrethroids, which generally act on the nervous systems of insects . Although effective, the inadequate management of these insecticides led to the emergence of resistant insect populations, and as a consequence of increased resistance of pests to chemical insecticides, research on natural and biodegradable insecticides that promote larval mortality and avoid the emergence of resistant strains has increased …”

Mini Review on Antimicrobial Activity and Bioactive Compounds of Moringa oleifera

“…Several studies have reported that the extract of Moringa oleifera flowers with trypsin inhibitor activity show larvicidal activity on Aedes ageypti [46,47]. Agra-Neto et al confirmed that lectins WSMoL and cMoL from Moringa oleifera seeds show larvicidal activity on fourth-stage Aedes ageypti larvae by affecting the digestive and detoxifying related enzymes of larvae [18,48].…”