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Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is one of the most destructive pests of various crops cultivated in Thailand. Spodoptera litura larvae, at early stages, attack the leaves and feed on every part of infested crops in later stages. Acorus calamus essential oil contains toxic asarones, which are generalistic cytotoxic compounds. However, the present study is the first attempt to look at safer metabolites from the rhizomes that could deter insect feeding. The objective was to use such compounds as safer residues on crops that would prevent the feeding of herbivorous lepidopterans. Accordingly, phenolic metabolites were isolated and evaluated to establish the feeding deterrence against polyphagous S. litura larvae. Methanol extract of A. calamus , chrysin, and 4-hydroxy acetophenone compounds were the most effective feeding deterrents with FD50 of 87.18, 10.33, and 70.77 µg/cm2, respectively, after 4 h of feeding on treated kale leaves in a no-choice leaf disc assay. Chrysin also reduced carboxylesterase activities (1.37-fold), whereas A. calamus methanol extract reduced glutathione- S -transferase activities (1.44-fold). Some larvae were also seen dead if they consumed the treated kale leaves. Feeding deterrent activity in the methanol extract of A. calamus was due to chrysin and 4-hydroxy acetophenone. The large-scale utilization of such compounds could help develop feeding deterrent strategies in the integrated pest management of lepidopterans. [ABSTRACT FROM AUTHOR]

Artocarpus lacucha, a plant in the Moraceae family, has traditionally been used in Southeast Asian medicine to treat various ailments. This study investigated the insecticidal potential against Spodoptera litura of several compounds extracted from A. lacucha using a topical application method. A sequential extraction method was employed with A. lacucha stems to identify the most toxic crude extract by using hexane, dichloromethane, ethyl acetate, and methanol solvents. Subsequently, the most toxic crude extract was analyzed for chemical composition by HPLC, followed by the isolation process. Among these crude extracts, the ethyl acetate crude extract was the most toxic to second-instar S. litura larvae (24-h LD50 value of ∼9.07 µg/larva). Our results showed that the catechin isolated from the ethyl acetate crude extract exhibited the highest toxicity against this insect (24-h LD50 value of ∼8.37 µg/larva). Additionally, catechin significantly decreased the activities of acetylcholinesterase, carboxylesterases, and glutathione S-transferase in the larvae. These findings suggest that catechin isolated from A. lacucha could be a potential insecticidal agent against S. litura. However, the toxicity and persistence of catechin under field conditions need to be further investigated to develop this novel insecticide. [ABSTRACT FROM AUTHOR]

The discovery of eco-friendly plant-based insecticides is currently booming in research with an attempt to replace synthetic chemical insecticides causing tremendous adverse effects. The present work studied the insecticidal potential of ginger, an important medicinal plant. Four crude extracts from Zingiber officinale rhizomes were evaluated for their contact toxicity against second instars of Spodoptera litura, Spodoptera exigua and Spodoptera frugiperda using the topical application. The hexane extract exhibited the strongest toxicity to S. exigua with the LD50 of 9.92 and 8.40 µg/larva at 24 and 48 h posttreatment, respectively, followed by S. frugiperda. Comparative toxicity of the most abundant secondary metabolites from the hexane extract, gingerols and shogaols, against both insects concluded that 8-shogaol (5) was identified as the most active compound against S. frugiperda with the LD50 of 7.68 and 3.96 µg/larva at 24 and 48 h posttreatment, respectively. [ABSTRACT FROM AUTHOR]

Plants produce arrays of secondary metabolites that act synergistically to deter and/or intoxicate herbivores. In this study, we evaluated the toxicity of piperine and β-asarone, individually and in binary mixtures, to examine their synergistic effects against larvae of two generalist herbivores, Spodoptera litura and Mythimna separata. Acute toxicity of piperine after topical application was lower than that of β-asarone for second instar larvae of both S. litura and M. separata (LD50 53.65 and 7.52 µg/larva, respectively, after 24 h). However, all mixtures produced synergistic, antifeedant effects. Mixtures of either 56.65 or 7.52 µg/larva of piperine + 18 µg/larva of β-asarone were highly synergistic in term of their acute toxicity (synergistic factor 11 and 44 for S. litura and M. separata, respectively). The more concentrated mixture also had the strongest antifeedant effects when presented on artificial diet to both species, S. litura and M. separata (56.64% and 62.30% at 24 h, respectively). Our results suggest that the combination of piperine and β-asarone is a greater deterrent than either pure compound alone. Use of this mixture may provide better crop protection rather than that offered by single compounds for controlling lepidopteran pests. [ABSTRACT FROM AUTHOR]

BACKGROUND: Thymol is a known natural product with insecticidal activity against several insect species. A recent study on structural modifications of thymol to thymyl esters and their efficacy against Spodoptera litura suggested that such an approach could develop generalized novel insecticides/insect growth inhibitors and requires further studies to establish the efficacy against lepidopterans. RESULTS: Thymol and structurally modified eight esters were evaluated against beet armyworm, Spodoptera exigua using the topical application. Thymyl butanoate was the most toxic compound with a median lethal dose (LD50) of 2.33 and 1.62 μg/larva after 24 and 48 h posttreatment, respectively. All thymyl esters were potentially better than the parent compound thymol, except thymyl dibromoacetate, in their efficacy against Spodoptera exigua. Essentially, there were three levels of activity vis‐à‐vis the compounds used, that is, with the LD50 range of 1.5 to 5.0, 7.0 to 15.0, and > 20 μg/larva, respectively. Ovicidal activity and reduction in larval growth were also determined by treating third instars at sub‐lethal doses, that is, LD50 doses of second instars. Thymyl butanoate treated larvae inhibited glutathione S‐transferase, carboxylesterase, and acetylcholinesterase activities, whereas the other thymyl esters induced these enzymes. CONCLUSION: Thymyl butanoate exhibited higher toxicity against Spodoptera exigua and is the first to report about > 15.5× more toxicity than thymol and > 6.5× than thymyl cinnamate, which suggests that the efficacy was species‐specific versus the chemical structural variation of the esters. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Botanical insecticides as a means of controlling insects present an alternative approach that is safer than the use of synthetic insecticides. The present study identified the insecticidal activity of extracts of the rhizomes of Alpinia galanga (L.) Willd. and seven isolated phenylpropanoids against the second instar of Spodoptera litura Fab. by topical application. The ethyl acetate extract had the highest toxicity on this insect with LD50 values of 1.68 and 1.25 μg/larva after 24 and 48 h posttreatment, respectively. Among the seven phenylpropanoids separated from the ethyl acetate extract, 1′S-1′-acetoxychavicol acetate was identified as the most active compound with LD50 values of 1.63 and 1.40 μg/larva after 24 and 48 h posttreatment, respectively, followed by p-coumaryl diacetate. In addition, the two active compounds decreased glutathione S-transferase activity and increased acetylcholinesterase activity. p-Coumaryl diacetate also decreased carboxylesterase activity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Thymol, a natural phenolic monoterpene originating from Thymus vulgaris, is recognized as a safe and potent botanical insecticide to many insects. The structural modification of thymol into thymyl esters is a potential approach for the development of novel insecticides, which showed more toxicity than thymol. However, there are no reports on the insecticidal activity of thymyl esters to control Spodoptera litura. RESULTS: Thymol was structurally modified into ten thymyl esters by esterification using a new reagent, PPh3/Br3CSO2Ph. The insecticidal activity of these compounds was examined against the second instars of Spodoptera litura using a topical application. Among the ten thymyl esters evaluated, thymyl cinnamate was the most toxic with LD50 = 0.41 and 0.34 μg/larva after 24 and 48 h posttreatment, respectively. In addition, thymyl cinnamate‐treated larvae showed increasing carboxylesterase and acetylcholinesterase activities in vivo experiment, whereas glutathione S‐transferase activity showed no significant difference. CONCLUSION: Thymyl cinnamate were first reported to exhibit toxicity against S. litura 2.41–2.46 fold more efficient than thymol. However, the detailed biochemical interactions are necessary for further development of novel insecticides. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Objective: The present study investigated the effects of a local Thai vegetable, Tiliacora triandra (Colebr.) Diels, also known as Yanang, against cerebral ischemia/reperfusion injury in mice. Materials and Methods: Thirty male ICR mice were divided into three experimental groups of BLCCAO + 10% Tween 80, BLCCAO + T. triandra 300 mg/kg, and BLCCAO + T. triandra 600 mg/kg. Cerebral ischemia/reperfusion was induced by three minutes of bilateral common carotid artery occlusion (BLCCAO) followed by 18 days of reperfusion. Leaf extract was administered orally 24 hours after arterial occlusion and continued for 18 consecutive days. Cognitive abilities were evaluated using the Morris water maze. Histological analysis was conducted in the dorsal hippocampus subregions CA1, CA3, and DG and white matter regions (the corpus callosum, internal capsule, and optic tract) using 0.1% cresyl violet and 0.1% Luxol fast blue staining. Results: Results showed that T. triandra leaf extract at the doses of 300 and 600 mg/kg significantly enhanced spatial learning, and learning flexibility, and prevented neuronal death in the DG of mice following ischemia/reperfusion. Conclusion: T. triandra leaf extract enhanced spatial learning, and learning flexibility, and prevented DG neuronal death in a mice model of cerebral ischemia/reperfusion. [ABSTRACT FROM AUTHOR]

Terpenes and biogenically related phenols commonly found in plant essential oils are known to be toxic to insect pests. Accordingly thymol was tested for acute toxicity via topical application to diamondback moth,Plutella xylostellaL. (Lepidoptera: Plutellidae) and its parasitoid,Cotesia plutellae(Kurdjunov) (Hymenoptera: Braconidae under laboratory conditions. Topical application to adult female parasitoidsversussecond instars ofP. xylostellashowed that thymol was about 62 times less toxic to the parasitoid than to the host larvae with 24 h LD50of 0.052 and 0.0008M, respectively. Although thymol was less toxic to the parasitoid, some biological parameters of the progeny at sublethal doses of surviving parasitoids were impaired such as rate of emergence and development time of larvae and pupae. The impact on detoxification enzymes was also studied and there was no significant induction in cytochrome P450 and carboxylesterase activities in both treated male and female wasps. Results obtained suggest that parasitoid is able to withstand the impact of thymol significantly. [ABSTRACT FROM PUBLISHER]

Background: Dengue is a major problem for humanity. Most people use insecticides to eliminate larvae of Aedes aegypti, which requires heavy chemicals use that affects the environment and human health. Therefore, in this research, the focus was on the larvicidal efficacy of pure compounds from the leaves and twigs of Maerua siamensis against the larvae of A. aegypti.Results: Larval mortality was observed after a 24-h exposure. The 1H-indole-3 acetonitrile glycosides cappariloside A and cappariloside B and the triterpene lupeol showed strong larvicidal effects (24-h LC50 = 71.14, 99.79 and 133.03 ppm). After 48 h, cappariloside B caused the most potential mortality with an LC50 of 1.56 ppm and lupeol had the highest lethal concentration at LC50 = 158.71 ppm. Additionally, consistency was observed between the toxicity tests and detoxification enzyme activity. Most compounds, except for lupeol and vanillin, reduce the activity of glutathione-s-transferase, whereas no significant differences were between control and treated groups for carboxylesterase.Conclusions: Cappariloside A and cappariloside B are good potential larvicide agents. They showed larvicidal activity against Ae. aegypti larvae with LC50 = 71.14 and 99.79 ppm at 24 and 48 h, respectively. [ABSTRACT FROM AUTHOR]

Objective: The present study investigated possible neuroprotective effects of ethanolic extract of Tiliacora triandra leaf against cerebral ischemic-reperfusion injury in mice., Materials and Methods: Forty male Institute of Cancer Research (ICR) mice were randomly divided into five groups: (1) Sham + 10% Tween 80, (2) bilateral common carotid artery occlusion (BCCAO) + 10% Tween 80, (3) BCCAO + T. triandra 300 mg/kg, (4) BCCAO + T. triandra 600 mg/kg and (5) BCCAO + quercetin 10 mg/kg. Cerebral ischemic-reperfusion (IR) was induced by 30 min of BCCAO followed by 45 min of reperfusion. After IR induction, total brain protein, calcium, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH), as well as brain infraction and histopathological changes in vulnerable brain areas, such as the cerebral cortex and hippocampus, were evaluated., Results: The results showed that 2 weeks of pretreatment with T. triandra leaf extract at doses of 300 and 600 mg/kg significantly reduced calcium and MDA, but increased GSH and SOD and CAT activities. The extract significantly attenuated brain infarction and neuronal death in the cerebral cortex and hippocampus., Conclusion: We demonstrated the neuroprotective effects of T. triandra leaf extract against cerebral IR injury in mice.