Antimicrobial activity of polypyrrole nanoparticles and aqueous extract of Moringa oleifera against Staphylococcus spp. carriers of multi-drug efflux system genes isolated from dairy farms.

Our objectives were to identify genes of the multi-drug efflux system and to evaluate the antimicrobial activities of polypyrrole nanoparticles (PPy-NPs) and aqueous extract of Moringa oleifera against Staphylococcus spp. isolated from dairy farms in Northeast Brazil. Initially, 162 Staphylococcus spp. isolates were subjected to in vitro antimicrobial sensitivity tests. Of these, 35 presented antimicrobial multi-drug resistance phenotypes. These 35 isolates were then referred for the detection of norA, norB, norC, msrA, mgrA, tet-38, and lmrS genes, all of which feature in multi-drug efflux systems. In the isolates carrying the genes, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PPy-NPs and Moringa oleifera aqueous extract were determined. In the molecular analysis of the 35 isolates norA, norC, tet-38, and msrA genes were detected and for the other genes norB, lmrS and mgrA there was no amplification. Antimicrobial activity was verified of PPy-NPs and aqueous extract of Moringa oleifera in Staphylococcus spp. carrying multi-drug efflux system genes. We concluded that there are multi-drug efflux system genes present in the Staphylococcus spp. from the agricultural environment in Northeast Brazil, and that aqueous extract of Moringa oleifera and PPy-NPs show bactericidal activity against these isolates.

Investigation of the ability of the oviposition-stimulant lectin from Moringa oleifera seeds (WSMoL) to bind with membrane proteins present in the legs of Aedes aegypti.

The mosquito Aedes aegypti L. is a vector transmitting diseases such as dengue, chikungunya and Zika virus fever. The water-soluble lectin from Moringa oleifera Lam. seeds (WSMoL) is larvicidal, ovicidal and can stimulate oviposition in A. aegypti. This study aimed to investigate whether WSMoL could bind to membrane proteins from A. aegypti legs. Initially, proteins from the legs were extracted using sodium deoxycholate, digitonin, dodecyl sodium sulfate (SDS) or Triton X-100. The protein concentration was found to be higher in the extract obtained using Triton X-100, which was applied to a WSMoL-Sepharose column. The adsorbed proteins were evaluated using gel filtration chromatography and polyacrylamide gel electrophoresis (PAGE) in presence of SDS. The similarity in the sequences of adsorbed proteins with those available in databases was determined. The proteins adsorbed on the matrix were eluted forming a single peak. Gel filtration chromatography and SDS-PAGE revealed the presence of proteins with molecular masses of approximately 20 kDa and polypeptide bands of 17.0 and 23.7 kDa, respectively. MS/MS analysis indicated similarity between these proteins and ABC carriers, which are expressed in the legs of mosquitos. WSMoL could bind to membrane proteins in the legs of A. aegypti females and induce oviposition through these interactions.

Antimicrobial potential of Alpinia purpurata lectin (ApuL): Growth inhibitory action, synergistic effects in combination with antibiotics, and antibiofilm activity.

The Alpinia purpurata inflorescence contains a lectin (ApuL), which has immunomodulatory activities on human cells. In the present work, it was evaluated the antibacterial and antifungal effects of ApuL against human pathogens. ApuL showed bacteriostatic activity against non-resistant (UFPEDA-02) and an oxacillin-resistant isolate (UFPEDA-672) of Staphylococcus aureus with minimal inhibitory concentrations (MIC50) of 50 and 400 µg/mL, respectively. In addition, it showed bactericidal effect on the non-resistant isolate (minimal bactericidal concentration: 200 µg/mL). For Candida albicans and Candida parapsilosis, ApuL showed fungistatic effect (MIC50: 200 and 400 µg/mL, respectively). The lectin was able to impair the viability of the microorganism cells, as indicated by propidium iodide (PI) staining. Analysis of growth curves, protein leakage, and ultrastructural changes supported that ApuL acts through distinct mechanisms on S. aureus isolates. Ultrastructural analysis of ApuL-treated Candida cells revealed malformations with elongations and bulges. ApuL-oxacillin combination showed synergistic effect on the oxacillin-resistant isolates UFPEDA-670 and 671, which were not sensitive to lectin alone. Synergism was also detected for ApuL-ceftazidime against a multidrug-resistant isolate of Pseudomonas aeruginosa. Synergistic action of ApuL-fluconazole was detected for C. parapsilosis, which was insensitive to the drug alone. Biofilm formation by S. aureus non-resistant isolate and C. albicans was remarkably inhibited by ApuL at sub-inhibitory concentrations. In conclusion, ApuL showed differential effects on non-resistant and resistant bacterial isolates, was active against Candida species, and showed synergistic action in combination with antibiotics.

Evaluation of Moringa oleifera seed lectin in traps for the capture of Aedes aegypti eggs and adults under semi-field conditions.

The water-soluble lectin isolated from Moringa oleifera seeds (WSMoL) is a larvicidal, ovicidal, and oviposition-stimulating agent against Aedes aegypti under laboratory conditions. This study investigated the effect of WSMoL in traps for the capture of A. aegypti eggs and adult females under semi-field conditions and determined whether gravid females could detect WSMoL by an olfactory response. WSMoL was isolated according to a previously described procedure using chitin chromatography. The bioassays were performed in large cages (12.5 m(3)). Two traps for collection of eggs (ovitrap) or adult mosquitoes (MosquiTRAP(TM)) were placed in a cage. One was filled with WSMoL (0.1 mg/mL) and the other with tap water (negative control). An infusion of Panicum maximum leaves was used as a positive control. Forty gravid females were then released in each cage. After 2 (for oviposition) or 3 h (for female capture), the traps were removed, and the number of eggs or females was counted. An olfactometry assay was performed to investigate whether the effect of WSMoL on gravid females was linked to an olfactory response. WSMoL showed an oviposition-stimulating effect (65 ± 14%) that was similar (p < 0.05) to that promoted by the P. maximum infusion (67 ± 11%). The efficiency of MosquiTRAP(TM) in capturing gravid females was not increased by WSMoL. The olfactometry assay indicated that the response of females to WSMoL did not involve the stimulation of olfactory sensilla. WSMoL effectively captured eggs when used in ovitraps under semi-field conditions; this property, together with the ovicidal and larvicidal activities of this lectin, makes it an interesting candidate for A. aegypti control.

Effect of Moringa oleifera lectins on survival and enzyme activities of Aedes aegypti larvae susceptible and resistant to organophosphate.

The indiscriminate use of synthetic insecticides to control Aedes aegypti has led to emergence of resistant populations. Moringa oleifera seeds contain the lectins WSMoL and cMoL. WSMoL has larvicidal activity on fourth-stage of A. aegypti organophosphate-susceptible larvae (Rockefeller L4). This study reports on the effects of cMoL on the survival of Rockefeller L4 as well as of WSMoL and cMoL on L4 from an organophosphate-resistant population (Rec-R). The effects of lectins on digestive (amylase, trypsin, and protease) and detoxifying (superoxide dismutase (SOD), α- and ß-esterases) enzymes from larvae were also determined. cMoL (0.1-0.8 mg/ml) did not kill Rockefeller L4 as well as WSMoL and cMoL (0.1-0.8 mg/ml) were not larvicidal for Rec-R L4. WSMoL stimulated protease, trypsin-like, and α-amylase from Rockefeller L4 while cMoL inhibited these enzymes. WSMoL had no effect on trypsin-like activity from Rec-R L4 but inhibited protease and α-amylase. Among digestive enzymes of Rec-R L4, cMoL inhibited only trypsin-like activity. cMoL inhibited SOD activities from Rockefeller and Rec-R L4 in a higher level than WSMoL while ß-esterase from Rockefeller L4 was more inhibited by WSMoL. The lectins promoted low stimulation or inhibition of α-esterase activities from both populations. In conclusion, Rockefeller and Rec-R larvae were distinctly affected by M. oleifera lectins, and larvicidal mechanism of WSMoL on Rockefeller L4 may involve deregulation of digestive enzymes. cMoL interfered mainly on SOD activity and thus it can be investigated as a synergistic agent for controlling populations whose resistance is linked to an increased detoxifying process mediated by this enzyme.

Oviposition-stimulant and ovicidal activities of Moringa oleifera lectin on Aedes aegypti.

BACKGROUND: Natural insecticides against the vector mosquito Aedes aegypti have been the object of research due to their high level of eco-safety. The water-soluble Moringa oleifera lectin (WSMoL) is a larvicidal agent against A. aegypti. This work reports the effects of WSMoL on oviposition and egg hatching of A. aegypti. METHODOLOGY/PRINCIPAL FINDINGS: WSMoL crude preparations (seed extract and 0-60 protein fraction), at 0.1 mg/mL protein concentration, did not affect oviposition, while A. aegypti gravid females laid their eggs preferentially (73%) in vessels containing isolated WSMoL (0.1 mg/mL), compared with vessels containing only distilled water (control). Volatile compounds were not detected in WSMoL preparation. The hatchability of fresh eggs deposited in the solutions in the oviposition assay was evaluated. The numbers of hatched larvae in seed extract, 0-60 protein fraction and WSMoL were 45 ± 8.7 %, 20 ± 11 % and 55 ± 7.5 %, respectively, significantly (p<0.05) lower than in controls containing only distilled water (75-95%). Embryos were visualized inside fresh control eggs, but not within eggs that were laid and maintained in WSMoL solution. Ovicidal activity was also assessed using stored A. aegypti eggs. The protein concentrations able to reduce the hatching rate by 50% (EC50) were 0.32, 0.16 and 0.1 mg/mL for seed extract, 0-60 protein fraction and WSMoL, respectively. The absence of hatching of stored eggs treated with WSMoL at 0.3 mg/mL (EC99) after transfer to medium without lectin indicates that embryos within the eggs were killed by WSMoL. The reduction in hatching rate of A. aegypti was not linked to decrease in bacteria population. CONCLUSIONS/SIGNIFICANCE: WSMoL acted both as a chemical stimulant cue for ovipositing females and ovicidal agent at a given concentration. The oviposition-stimulant and ovicidal activities, combined with the previously reported larvicidal activity, make WSMoL a very interesting candidate in integrated A. aegypti control.

Larvicidal activity of lectins from Myracrodruon urundeuva on Aedes aegypti.

Aedes aegypti transmits etiologic agents of yellow fever and dengue. Vaccine for dengue virus is not available and vector control is essential to minimize dengue incidence. This report deals with the larvicidal activity of lectins isolated from Myracrodruon urundeuva bark (MuBL) and heartwood (MuHL). The lectins were isolated by ammonium sulphate treatment of crude extracts followed by chromatography on chitin. MuBL and MuHL were evaluated by electrophoresis under native (PAGE) and denaturing conditions (SDS-PAGE). Carbohydrate specificity of lectins was evaluated by hemagglutinating activity (HA) inhibition assay using N-acetyl-d-glucosamine and by affinity chromatography on N-acetyl-D-glucosamine immobilized in agarose gel. Larvicidal activity against A. aegypti was investigated with the extracts, salt fractions and isolated lectins. MuBL and MuHL were characterized by PAGE as basic proteins of molecular masses of 14.0 and 14.4 kDa, respectively. The interaction of lectins with N-acetylglucosamine was detected by inhibition of HA by monosaccharide and lectin adsorptions on N-acetyl-D-glucosamine matrix. All M. urundeuva preparations promoted larvae mortality. LC16, LC50 and LC84 values of 0.077, 0.125, 0.173 for MuBL and 0.03, 0.04 and 0.05 mg/mL for MuHL were obtained. To our knowledge this is the first report of larvicidal activity of lectins against A. aegypti.