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Phytoalexin

About: Phytoalexin is a research topic. Over the lifetime, 1161 publications have been published within this topic receiving 63405 citations. The topic is also known as: phytoalexins.


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Journal ArticleDOI
TL;DR: A natural free radical scavenger, ascorbic acid (AsA) shows both counteractive and enhancing effects on JA‐inducible phytoalexin production, depending on its concentration, which suggests that active oxygen species (AOS) may play important roles in phy toalex in production by JA in rice leaves.

94 citations

Journal ArticleDOI
TL;DR: Two phytoalexins are reported, wasalexin A and arvelexin (4-methoxyindolyl-3-acetonitrile), their syntheses and antifungal activity against isolates of P. lingam/L.

94 citations

Journal ArticleDOI
TL;DR: The inhibitory effect of resveratrol on hydrogen peroxide‐induced apoptosis is not due to its antioxidant activity, but contrarily via a pro‐oxidant effect that creates an intracellular environment nonconducive for apoptotic execution.
Abstract: We have recently shown that efficient apoptotic signaling is a function of a permissive intracellular milieu created by a decrease in the ratio of superoxide to hydrogen peroxide and cytosolic acidification. Resveratrol, a phytoalexin found in grapes and wines, triggers apoptosis in some systems and inhibits the death signal in others. In this regard, the reported inhibitory effect on hydrogen peroxide-induced apoptosis has been attributed to its antioxidant property. Here, we provide evidence that exposure of human leukemia cells to low concentrations of resveratrol (4-8 micro M) inhibits caspase activation and DNA fragmentation induced by incubation with hydrogen peroxide or upon triggering apoptosis with a novel compound that kills via intracellular hydrogen peroxide production. At these concentrations, resveratrol elicits pro-oxidant properties as evidenced by an increase in intracellular superoxide concentration. This pro-oxidant effect is further supported by our observations that the drop in intracellular superoxide and cytosolic acidification induced by hydrogen peroxide is completely blocked in cells preincubated with resveratrol. Thus, the inhibitory effect of resveratrol on hydrogen peroxide-induced apoptosis is not due to its antioxidant activity, but contrarily via a pro-oxidant effect that creates an intracellular environment nonconducive for apoptotic execution.

92 citations

Journal ArticleDOI
Yegang Du1, Hung Chu1, Mingfu Wang1, Ivan K. Chu1, Clive Lo1 
TL;DR: SbFNSII appears to share a similar catalytic mechanism with the licorice and Medicago truncatula FNSIIs (CYP93B subfamily) by converting flavanones to flavone through the formation of 2-hydroxyflavanones.
Abstract: Following inoculation with the anthracnose pathogen Colletotrichum sublineolum, seedlings of the sorghum resistant cultivar SC748-5 showed more rapid and elevated accumulation of luteolin than the susceptible cultivar BTx623. On the other hand, apigenin was the major flavone detected in infected BTx623 seedlings. Luteolin was demonstrated to show stronger inhibition of spore germination of C. sublineolum than apigenin. Because of their pathogen-inducible and antifungal nature, both flavone aglycones are considered sorghum phytoalexins. The key enzyme responsible for flavone biosynthesis has not been characterized in monocots. A sorghum pathogen-inducible gene encoding a cytochrome P450 protein (CYP93G3) in the uncharacterized CYP93G subfamily was identified. Transgenic expression of the P450 gene in Arabidopsis demonstrated that the encoded protein is a functional flavone synthase (FNS) II in planta. The sorghum gene was then termed SbFNSII. It is a single-copy gene located on chromosome 2 and the first FNSII gene characterized in a monocot. Metabolite analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in precursor ion scan mode revealed the accumulation of 2-hydroxynaringenin and 2-hydroxyeriodictyol hexosides in the transgenic Arabidopsis plants. Hence, SbFNSII appears to share a similar catalytic mechanism with the licorice and Medicago truncatula FNSIIs (CYP93B subfamily) by converting flavanones to flavone through the formation of 2-hydroxyflavanones.

92 citations

Journal ArticleDOI
TL;DR: Peanut stilbenoids, as well as related natural and synthetic stilbene derivatives, display a diverse range of biological activities, and are evaluated for their effects on economically important plant pathogenic fungi and as mammalian opioid receptor competitive antagonists.
Abstract: The peanut plant (Arachis hypogaea L.), when infected by a microbial pathogen, is capable of producing stilbene-derived compounds that are considered antifungal phytoalexins. In addition, the potential health benefits of other stilbenoids from peanuts, including resveratrol and pterostilbene, have been acknowledged by several investigators. Despite considerable progress in peanut research, relatively little is known about the biological activity of the stilbenoid phytoalexins. This study investigated the activities of some of these compounds in a broad spectrum of biological assays. Since peanut stilbenoids appear to play roles in plant defense mechanisms, they were evaluated for their effects on economically important plant pathogenic fungi of the genera Colletotrichum, Botrytis, Fusarium, and Phomopsis. We further investigated these peanut phytoalexins, together with some related natural and synthetic stilbenoids (a total of 24 compounds) in a panel of bioassays to determine their anti-inflammatory, cytotoxic, and antioxidant activities in mammalian cells. Several of these compounds were also evaluated as mammalian opioid receptor competitive antagonists. Assays for adult mosquito and larvae toxicity were also performed. The results of these studies reveal that peanut stilbenoids, as well as related natural and synthetic stilbene derivatives, display a diverse range of biological activities.

92 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202321
202256
202119
202013
201922
201815