Chemical composition and toxicity of commercial Mentha spicata and Eucalyptus citriodora essential oils on Culex quinquefasciatus and non-target insects.

Current vector control strategies based on synthetic chemicals are not eco-friendly against non-target organisms; hence, alternative approaches are highly required. Commercially purchased oil of Mentha spicata (Spearmint) and Eucalyptus citriodora (Citriodora) were examined against the medical pest Cx. quinquefasciatus (Say) and their non-toxicity on the aquatic species was evaluated. Chemical screening with gas chromatography coupled with mass spectrometry (GC-MS) analysis revealed a total of 14 and 11 compounds in Citriodora and Spearmint oils, respectively, with the highest peak (%) at carvone (70.44%) and isopulegol (30.4%). The larvicidal activity on the fourth instar larvae of Cx. quinquefasciatus showed dose-dependent mortality and significance at a 100 ppm concentration 48 h post-treatment with Citriodora (76.4%, P ≤ 0.001) and Spearmint (100%, P ≤ 0.001). Additionally, the photomicrograph of the fourth instar larvae revealed significant physical abnormalities in the head and midgut tissues post-exposure to Spearmint and Citriodora oils. Moreover, the histological assay revealed severe damage in the epithelial cells and gut lumen 2 to 24 h post-treatment. The repellency percentage of adult Culex mosquitoes was prominent across both oils at 150 ppm 210 min post-exposure. Non-target toxicity on the aquatic predator showed both essential oils (Spearmint oil (17.2%) and Citriodora oil (15.2%)) are safer at the maximum treatment (200 ppm) compared to temephos (75.4% at 1 ppm). The in silico screening of phyto-compounds derived by both essential oils with BeeTox (online server) showed no contact toxicity to the honey bee Apis mellifera. Overall, the present research revealed that Spearmint and Citriodora essential oils and their active phyto-compounds were toxic to Cx. quinquefasciatus and harmless to the aquatic predator and honey bee.

Bioactive Molecules Derived from Plants in Managing Dengue Vector Aedes aegypti (Linn.).

Mosquitoes are the potential vectors of several viral diseases such as filariasis, malaria, dengue, yellow fever, Zika fever and encephalitis in humans as well as other species. Dengue, the most common mosquito-borne disease in humans caused by the dengue virus is transmitted by the vector Ae. aegypti. Fever, chills, nausea and neurological disorders are the frequent symptoms of Zika and dengue. Thanks to various anthropogenic activities such as deforestation, industrialized farming and poor drainage facilities there has been a significant rise in mosquitoes and vector-borne diseases. Control measures such as the destruction of mosquito breeding places, a reduction in global warming, as well as the use of natural and chemical repellents, mainly DEET, picaridin, temephos and IR-3535 have proven to be effective in many instances. Although potent, these chemicals cause swelling, rashes, and eye irritation in adults and children, and are also toxic to the skin and nervous system. Due to their shorter protection period and harmful nature towards non-target organisms, the use of chemical repellents is greatly reduced, and more research and development is taking place in the field of plant-derived repellents, which are found to be selective, biodegradable and harmless to non-target species. Many tribal and rural communities across the world have been using plant-based extracts since ancient times for various traditional and medical purposes, and to ward off mosquitoes and various other insects. In this regard, new species of plants are being identified through ethnobotanical surveys and tested for their repellency against Ae. aegypti. This review aims to provide insight into many such plant extracts, essential oils and their metabolites, which have been tested for their mosquitocidal activity against different life cycle forms of Ae. Aegypti, as well as for their efficacy in controlling mosquitoes.

Pharmacological evaluation of embelin - chitosan nanoparticles as an antidiabetic agent.

Embelin has been reported to possess variety of pharmacological activities such as androgenic antagonists, antiangiogenic, antibacterial, anticancer, anticonvulsant, antidiabetic, antidepressant, antihelmintic, antifertility, antihyperlipidemic, anti-inflammatory, antimalarial, antimitotic, antiobesity and antioxidant properties. The current research work aimed to study the hypoglycemic effect of embelin-chitosan nanoparticles (ECNPs) diabetic rats provoked by streptozotocin (STZ). Embelin nanoparticles (ENPs) were created by combining chitosan, a natural biopolymer, and glutaric acid, a new cross-linker. STZ 50 mg/kg was given intravenously into Sprague-Dawley rats weighing 250-300 g (75-90 days) to induce experimental diabetes. The antidiabetic efficacy of orally administered ECNPs in diabetic rats developed by STZ was investigated, as well as histological examination. When compared to diabetic control rats, ECNPs (25 mg/kg body weight and 50 mg kg body weight) and standard glibenclamide (10 mg/kg body weight) treated rodents exhibited a remarkable drop in glucose contents. Furthermore, histological research showed that ECNPs-treated rats were harmless up to amount of 25 mg/kg bwt. Thus current investigation reveals that ECNPs have antidiabetic potential and may be beneficial in treating hyperglycemia in people.

Bioefficacy of Epaltes divaricata (L.) n-Hexane Extracts and Their Major Metabolites against the Lepidopteran Pests Spodoptera litura (fab.) and Dengue Mosquito Aedes aegypti (Linn.).

The present research investigated the chemical characterization and insecticidal activity of n-Hexane extracts of Epaltes divaricata (NH-EDx) along with their chief derivatives n-Hexadecanoic acid (n-HDa) and n-Octadecanoic acid (n-ODa) against the dengue vector Aedes aegypti and lepidopteran pest Spodoptera litura. Chemical screening of NH-EDx through GC-MS analysis delivered nine major derivatives, and the maximum peak area percentage was observed in n-Hexadecanoic acid (14.63%) followed by n-Octadecadienoic acid (6.73%). The larvicidal activity of NH-EDx (1000 ppm), n-HDa (5 ppm), and n-ODa (5 ppm) against the A. aegypti and S. litura larvae showed significant mortality rate in a dose-dependent way across all the instars. The larvicidal activity was profound in the A. aegypti as compared to the S. litura across all the larval instars. The sublethal dosages of NH-EDx (500 ppm), n-HDa (2.5 ppm), and n-ODa (2.5 ppm) also showed alterations in the larval/pupal durations and adult longevity in both the insect pests. The enzyme activity revealed that the α- and ß-carboxylesterase levels were decreased significantly in both the insect pests, whereas the levels of GST and CYP450 uplifted in a dose-dependent manner of NH-EDx, n-HDa, and n-ODa. Correspondingly, midgut tissues such as the epithelial layer (EL), gut lumen (GL), peritrophic matrix (Pm), and brush border membrane (BBM) were significantly altered in their morphology across both A. aegypti and S. litura against the NH-EDx and their bioactive metabolites. NH-EDx and their bioactive metabolites n-HDa and n-ODa showed significant larvicidal, growth retardant, enzyme inhibition, and midgut toxicity effects against two crucial agriculturally and medically challenging insect pest of ecological importance.

Target Activity of Isaria tenuipes (Hypocreales: Clavicipitaceae) Fungal Strains against Dengue Vector Aedes aegypti (Linn.) and Its Non-Target Activity Against Aquatic Predators.

The present investigation aimed to determine the fungal toxicity of Isaria tenuipes (My-It) against the dengue mosquito vector Aedes aegypti L. and its non-target impact against the aquatic predator Toxorhynchitessplendens. Lethal concentrations (LC50 and LC90) of My-It were observed in 2.27 and 2.93 log ppm dosages, respectively. The sub-lethal dosage (My-It-1 × 104 conidia/mL) displayed a significant oviposition deterrence index and also blocked the fecundity rate of dengue mosquitos in a dose-dependent manner. The level of major detoxifying enzymes, such as carboxylesterase (α-and ß-) and SOD, significantly declined in both third and fourth instar larvae at the maximum dosage of My-It 1 × 105 conidia/mL. However, the level of glutathione S-transferase (GST) and cytochrome P-450 (CYP450) declined steadily when the sub-lethal dosage was increased and attained maximum reduction in the enzyme level at the dosage of My-It (1 × 105 conidia/mL). Correspondingly, the gut-histology and photomicrography results made evident that My-It (1 × 105 conidia/mL) heavily damaged the internal gut cells and external physiology of the dengue larvae compared to the control. Moreover, the non-target toxicity against the beneficial predator revealed that My-It at the maximum dosage (1 × 1020 conidia/mL) was found to be less toxic with <45% larval toxicity against Tx.splendens. Thus, the present toxicological research on Isaria tenuipes showed that it is target-specific and a potential agent for managing medically threatening arthropods.

Toxicological screening of marine red algae Champia parvula (C. Agardh) against the dengue mosquito vector Aedes aegypti (Linn.) and its non-toxicity against three beneficial aquatic predators.

Larval toxicity of ethanolic extract of C. parvula (Ex-Cp) was prominent in the second and the third instars at the maximum lethal dosage of 100 ppm with 98 and 97 % mortality rate respectively. The LC50 and LC90 was displayed at 43 ppm and 88 ppm dosage respectively. Correspondingly, the sub-lethal dosage (65 ppm) of Ex-Cp significantly alters the carboxylesterase (α and ß), GST and CYP450 enzyme level in both III and IV instar larvae in dose-dependent manner. Similarly, the Ex-Cp displayed significant repellent activity (97 %) with a maximum level of protection time (210 min). Photomicrography assay of Ex-Cp (65 ppm) were toxic to dengue larvae as compared to control. The non-target toxicity of Ex-Cp against the beneficial mosquito predators displayed less toxicity at the maximum dosage of 600 ppm as compared to Temephos. Thus the present research delivers the target and non-target toxicity of red algae C. parvula against the dengue mosquito vector.

Inhibition of UVB-induced oxidative damage and apoptotic biochemical changes in human lymphocytes by 2,5-dihydroxy-3-undecyl-1,4-benzoquinone (embelin).

PURPOSE: The present study investigates the inhibition of Ultraviolet B (UVB, 290-320 nm) radiation-induced oxidative damage in peripheral blood human lymphocytes by embelin extracted from Embelia ribes. MATERIALS AND METHODS: Embelin was extracted, purified and characterized. Prior to inhibitory assessment, a maximum concentration of embelin that was non-toxic was determined. Six experimental groups, including respective controls were made to assess the inhibitory effect of embelin for the selected concentrations of 10 and 20 µg/ml. For the experimental groups; lymphocytes (1 × 10(6) cells) were pre-treated with the chosen concentration of embelin for a period of 60 min and then exposed to UVB for 30 min. UVB radiation inhibitory effect of embelin assessed by measuring antioxidant and lipid peroxidation levels, deoxyribonucleic acid (DNA) damage, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) at scheduled time points after irradiation. RESULTS: Pre-treatment of lymphocytes with embelin prevents UVB-induced oxidative damage. An increase in antioxidant levels in irradiated cells in the presence of embelin and UV absorbance of embelin could be the reason for the decrease in lipid peroxidation level and prevention of DNA damage by UVB radiation. CONCLUSION: Embelin prevents oxidative stress induced by UVB irradiation via its antioxidant property.