Trypsin inhibitor from Moringa oleifera flowers interferes with survival and development of Aedes aegypti larvae and kills bacteria inhabitant of larvae midgut

Abstract

Moringa oleifera flower extract, with trypsin inhibitor activity, is a larvicidal agent on Aedes aegypti. This work reports the isolation of trypsin inhibitor (M. oleifera flower trypsin inhibitor (MoFTI)) and its effect on A. aegypti egg hatching, viability of newly hatched larvae, survival of pupae, and growth of inhabitant bacteria from midgut of fourth-instar larvae (L4). MoFTI (K i, 2.4 μM), isolated by affinity chromatography on trypsin-agarose column, was an 18.2 kDa polypeptide on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Flower extract (at concentrations of 8.5-17.0 mg/mL) reduced egg hatchability while MoFTI (0.05-0.5 mg/mL) did not affect the hatching rate. Mortality of newly hatched larvae ranged from 3.5 to 19.1 % in the presence of the extract (4.0-17.0 mg/mL) and was also promoted by MoFTI (LC50, 0.3 mg/mL). After 72 h, larvae incubated with extract at 13.0 and 17.0 mg/mL were at stages L2 and L1, respectively, while in control they reached L3 instar. In the presence of MoFTI, at all concentrations tested, the larvae did not pass the first instar. Flower extract and MoFTI did not interfere on pupae survival. The extract and MoFTI inhibited the growth of L4 gut bacteria (minimum inhibitory concentrations of 3.47 and 0.031 mg/mL, respectively) but only the inhibitor showed bactericide effect (minimum bactericidal concentration of 1.0 mg/mL). The findings reported herein indicate that MoFTI constitutes a larvicidal principle from M. oleifera flowers against A. aegypti newly hatched larvae and is an antibacterial agent active against the microbiota from L4 gut.

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.…”

“…Recently, natural products such as plant extracts, essential oils, lectins and trypsin inhibitor have been studied as larvicidal agents against A. aegypti (Agra-Neto et al, 2014;Bianco et al, 2013;Chandrashekhar et al, 2011;Napoleão et al, 2012;Navarro et al, 2014;Pontual et al, 2014;Santos et al, 2012). Lactones, organic cyclic esters, have been also investigated as mosquito larvicides.…”

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].…”

A Review of Pharmacognostical Studies on Moringa oleifera Lam. flowers

“…21 Backed by this impressive biochemical profile, attempts begin to isolate purify and characterize these compounds but so far the list include only a few -rhamnetin 3-O-(2``-galloyl)-β-D-galactopyranosyl-4`-β-D-xylopyranoside, 26 Kaempferol-7-O-β-D-alloside, 27 quercetin 3-O-α-L rhamnosyl (1→ 6) β D-glucoside, 28 and a proteinaceous MoFTI. 29 On the other hand crude flower extracts has been put into all sort of pharmacognostical studies with several promising outcomes in the way. The scope of such studies can be easily accessed from the Table 1.…”