Essential oils from Acacia nilotica (Fabales: Fabaceae) seeds: May have insecticidal effects?

In the present study Acacia nilotica seed derived essential oils were tested against Spodoptera litura, Tenebrio molitor, Oxycarenus hyalinipennis, and Aphis fabae, as well as their effects on non-target species Eudrilus eugeniae and Artemia salina at 24 h post treatment. The seed essential oil produced insecticidal activity against A. fabae (LC50 = 41.679, LC90 = 75.212 µl/mL), O. hyalinipennis (LC50 = 37.629, LC90 = 118.485 µl/mL), T. molitor (LC50 = 56.796, LC90 = 201.912 µl/mL), and S. litura (LC50 = 62.215, LC90 = 241.183 µl/mL). Essential oils do not cause a remarkable effect on E. eugeniae and A. salina cytotoxicity. The essential oils produced a lower effect on Artemia salina (LC50 = 384.382, LC90 = 1341.397 µl/mL) and no lethal effects were observed on E. eugeniae. The histopathological evaluation showed no sub-lethal effects of essential oils on earthworm gut tissues. GC-MS analysis results revealed that the major chemical constituent was hexadecane (19.560%) and heptacosane (17.214%) and FT-IR analysis revealed the presence of alkanes and alkyles, aromatics, and amides functional groups that may be involved in insecticidal activity. Overall, the results showed that the seed derived essential oil has excellent insecticidal action against major agricultural insect pests and may therefore offer an environmentally benign alternative to conventional insecticide.

Bio-efficacy of insecticidal molecule emodin against dengue, filariasis, and malaria vectors.

Emodin, a compound isolated from Aspergillus terreus, was studied using chromatographic and spectroscopic methods and compound purity (96%) was assessed by TLC. Furthermore, high larvicidal activity against Aedes aegypti-AeA (LC50 6.156 and LC90 12.450 mg/L), Culex quinquefasciatus-CuQ (8.216 and 14.816 mg/L), and Anopheles stephensi-AnS larvae (6.895 and 15.24 mg/L) was recorded. The first isolated fraction (emodin) showed higher pupicidal activity against AeA (15.449 and 20.752 mg/L). Most emodin-treated larvae (ETL) showed variations in acetylcholine esterase, α and ß-carboxylesterases, and phosphatase activities in the 4th instar, indicating the intrinsic differences in their biochemical changes. ETL had numerous altered tissues, including muscle, gastric caeca, hindgut, midgut, nerve ganglia, and midgut epithelium. Acute toxicity of emodin on brine shrimp Artemia nauplii (54.0 and 84.5 mg/L) and the zebrafish Danio rerio (less toxicity observed) was recorded. In docking studies, Emodin interacted well with odorant-binding-proteins of AeA, AnS, and CuQ with docking scores of - 8.89, - 6.53, and - 8.09 kcal mol-1, respectively. Therefore, A. terreus is likely to be effective against mosquito larvicides.

Eco-friendly synthesis of Ag-NPs using Endostemon viscosus (Lamiaceae): Antibacterial, antioxidant, larvicidal, photocatalytic dye degradation activity and toxicity in zebrafish embryos.

Nanotechnology is a multidisciplinary area of study that has grown significantly in serving many functions and impacting human society. New fields of science have been facilitated by the clean, non-toxic, and biocompatible nature of plant-derived nanoparticles. The present study deals with the first green synthesis of silver nanoparticles (Ag-NPs) using Endostemon viscosus, and their synthesized Ag NPs were characterized by different spectral methods (UV-vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction Spectroscopy (XRD), Transmission Electron Microscopy (TEM) and Energy dispersive X-ray Spectroscopy (EDAX). The change initially observed the production of Ag-NPs in color from green to ash and then confirmed by SPR band at 435 nm in UV-vis spectral analysis. The FTIR findings indicate that many functional groups belong to the pharmaceutically useful phytochemicals, which interact as reducing, capping, and stabilizing agents in synthesizing silver nanoparticles. The predominant peaks in the XRD pattern belong to the planes 210°, 111°, 200°, 241°, and 311° and thus demonstrated the Ag-NPs FCC crystal structure. TEM analysis exhibited spherical-shaped particles with an average size of 13 nm, and the EDAX band showed a distinctive metallic silver peak at 3.0 keV. The antibacterial activity of Ag-NPs tested to show a maximum zone of inhibition of 19 mm for Staphylococcus aureus and 15 mm for Escherichia coli at 100 µg/mL, respectively. Bio-fabricated Ag-NPs were assessed for antioxidant activity (DPPH with % inhibition 57.54% and FRAP with % inhibition 70.89%). The biosynthesized Ag-NPs demonstrated potential larvicidal efficacy against Aedes aegypti with more than 90% at 250 µg/mL. Histological profiles were altered while treating with Ag-NPs at 250 µg/mL. The photocatalytic activity of synthesized E. viscosus Ag-NPs was tested against methylene blue (MB) and crystal violet (CV), and the maximum degradation efficiency was found as 90 and 94%, respectively. Furthermore, the toxicity test on zebrafish embryos demonstrated that aberrations have only been induced at concentrations higher than 500 µg/mL. We conclude that the greenly produced Ag-NPs may find use in biomedical applications based on bacteria and cost-effective industrial wastewater treatment.

Enhancement in the visible light induced photocatalytic and antibacterial properties of titanium dioxide codoped with cobalt and sulfur.

In this study, the sol-gel technique was used to develop Cobalt Sulfur codoped Titanium Dioxide (Co-S codoped TiO2) photocatalysts. For structural analysis of the prepared resultant TiO2 samples, XRD, FTIR, UV-Vis DRS, SEM, HR-TEM and EDX measurements were used to describe the produced photocatalysts. The characterization findings indicate that the synthesized nanoparticles possessed great crystallinity, high purity, and superior optical characteristics. For the methylene blue (MB) degradation process, Co-S codoped TiO2 nanoparticles were tested for their photocatalytic degradation performance. The Co-S codoped TiO2 nanoparticles had improved catalytic activity when compared with pure, Co-doped, S-doped TiO2 and decomposed 93% of MB in 120 min. When compared to pure and doped TiO2, the catalysts of Co-S codoped TiO2 showed a synergistic effect and improved the performance of the catalysts. Furthermore, the antibacterial applications of synthesized Co-S codoped TiO2 nanoparticles was studied against E. coli (Gram negative) and S. aureus (Gram positive) bacteria and exhibited strong antibacterial activity against the selected strains.

Larvicidal and histopathology effect of endophytic fungal extracts of Aspergillus tamarii against Aedes aegypti and Culex quinquefasciatus.

BACKGROUND: Mosquitoes biolarvicides remain the most important method for mosquito control. The previous studies have shown Aspergillus sp.-expressed larvicidal properties against mosquito species. The present study evaluated larvicidal and histopathological effect of an endophytic fungus Aspergillus tamarii isolated from theCactus stem (Opuntia ficus-indica Mill). METHOD: The molecular identification of isolated A. tamarii was done by PCR amplification (5.8s rDNA) using a universal primer (ITS-1 and ITS-2). The secondary metabolites of A. tamarii was tested for larvicidal activity against Aedes aegypti and Culex quinquefasciatus. Larvicidal bioassay of different concentrations (- 100, 300, 500, 800 and 1000 µg/mL) isolated extracts were done according to the modified protocol. Each test included a set of control groups (i.e. DMSO and distilled water). The lethal concentrations (LC50 and LC90) were calculated by probit analysis. Experimental monitoring duration was 48 h. RESULTS: The ethyl acetate extract from A. tamarii fungus resulted - excellent mosquitocidal effect against Ae. aegypti and Cx. quinquefasciatus mosquitoes, with least LC50 and LC90 values. -After 48 h, the Ae. aegypti expressed better results (LC50 = 29.10, 18.69, 16.76, 36.78 µg/mL and the LC90 = 45.59, 27.66, 27.50, 54.00 µg/mL) followed by Cx. quinquefaciatus (LC50 = 3.23, 24.99, 11.24, 10.95 µg/mL and the LC90 = 8.37, 8.29, 21.36, 20.28 µg/mL). The biochemical level of A. tamarii mycelium extract on both larvae was measured and the results shown a dose dependent activity on the level of AchE, α- and ß-carboxylesterase assay. Gas Chromatography and Mass Spectroscopy (GC-MS) profile of A. tamarii extract reflected three compounds i.e. preg-4-en-3-one, 17. α-hydroxy-17. ß-cyano- (7.39%), trans-3-undecene-1,5-diyne (45.77%) and pentane, 1,1,1,5-tetrachloro- (32.16%) which which might had attributed to larvae mortality. CONCLUSION: The findings of - present study shows that the use of endophytic A. tamarii fungal metabolites for control of dengue and filariasis vectors is promising and needs a semifield and small scale filed trials.

Evaluation of Salmonella bongori derived biosurfactants and its extracellular protein separation by SDS-PAGE using petridishes: A simply modified approach.

Presently, through the preliminary screening assays, the Salmonella bongori BH11 was found to be an effective biosurfactants (BSFs) producer. The secreted BSFs were extracted using methanol: chloroform and characterized through FTIR, TLC, HPLC and GCMS analyses. Further, the extracellular protein was extracted (TCA/acetone method), estimated (Lowry's method) and separated (standard and modified SDS-PAGE). Through the obtained characteristic FTIR peaks (1107.09cm-1), its content was presumed to be glycolipids and as rhamnose/rhamnolipids through the TLC-Rf value. GCMS revealed 6 compounds, in which Toluene (32%) and 5-(2-Thienyl) pentanoic acid (23%) are the major ones. The crude BSFs exhibited preponderant antibacterial effects on Staphylococcus aureus and Serratia marcescens. Also, it inhibited the biofilm formation of S. aureus, Pseudomonas aeruginosa, P. fluorescens and S. marcescens. Considerably, 76% mortality of IV instar larvae of Culex quinquefasciatus was recorded from BSFs, when compared to SDS. The presently followed protein separation technique using two petridishes might attract the attention of the researchers, as it would emerge as a standard procedure in future. This is the first report on the screening of BSFs from Salmonella bongori that showed antagonistic property, larvicidal potentials and the presently followed modified SDS-PAGE protein separation technique is a simple, reliable and cost effective one.