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 β-carboxylesterases, and phosphatase activities in the 4^th 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.

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.

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 β-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. β-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.