UGT76B1, a promiscuous hub of small molecule-based immune signaling,glucosylates N-hydroxypipecolic acid,and balances plant immunity

Glucosylation modulates the biological activity of small molecules and frequently leads to their inactivation. The Arabidopsis thaliana glucosyltransferase UGT76B1 is involved in conjugating the stress hormone salicylic acid (SA) as well as isoleucic acid (ILA). Here, we show that UGT76B1 also glucosylates N-hydroxypipecolic acid (NHP), which is synthesized by FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1) and activates systemic acquired resistance (SAR). Upon pathogen attack, Arabidopsis leaves generate two distinct NHP hexose conjugates, NHP-O-β-glucoside and NHP glucose ester, whereupon only NHP-O-β-glucoside formation requires a functional SA pathway. The ugt76b1 mutants specifically fail to generate the NHP-O-β-glucoside, and recombinant UGT76B1 synthesizes NHP-O-β-glucoside in vitro in competition with SA and ILA. The loss of UGT76B1 elevates the endogenous levels of NHP, SA, and ILA and establishes a constitutive SAR-like immune status. Introgression of the fmo1 mutant lacking NHP biosynthesis into the ugt76b1 background abolishes this SAR-like resistance. Moreover, overexpression of UGT76B1 in Arabidopsis shifts the NHP and SA pools toward O-β-glucoside formation and abrogates pathogen-induced SAR. Our results further indicate that NHP-triggered immunity is SA-dependent and relies on UGT76B1 as a common metabolic hub. Thereby, UGT76B1-mediated glucosylation controls the levels of active NHP, SA, and ILA in concert to balance the plant immune status.     

Leading role of natural products in pharmaceutical,biotechnological, and cosmeceutical applications (GPSS-2021)

Phytochemistry Reviews -     

Importance of ethnopharmacological studies in drug discovery: role of medicinal plants

Phytochemistry Reviews - Ethnopharmacology can be basically defined as “the interdisciplinary scientific exploration of the biologically active agents that are traditionally employed”....     

Liver gamma-glutamyl transpeptidase activity following chronic treatment with acetylsalicylic acid in rats

In the present study, rats were administered acetylsalicylic acid (ASA), at low and high doses, by means of a gastric tube for 30 days. Chronic administration of a high dose of ASA (200 mg/kg body weight) resulted in a significant increase in liver plasma membrane gamma-glutamyl transpeptidase activity, cholesterol, and phospholipid levels. The enzymatic activity and lipid levels appeared not to be affected by ASA when given at a lower dose (50 mg/kg body weight). The changes in the enzymatic activity of plasma membrane were positively correlated to membrane cholesterol content. These findings suggest that the hepatotoxicity of high doses of ASA should not be overlooked during clinical use of the drug.     

Arachidonic acid metabolites and colchicine in Behçet's disease (BD)

Vasculitis is accepted to be the basis of Behçet's disease (BD) which is a multisystem disease, and the arachidonic acid(AA) metabolites acting as balancing mediators in the organism are accepted to be responsible for the vasculitis.In this study, we examined the prostaglandin E₂ (PGE₂) and leukotriene C₄ (LTC₄) levels of the patients with BD before and after colchicine therapy. We found a statistical decrease in the PGE₂ and LTC₄ levels after colchicine therapy compared to the previous levels, concluding that colchicine inhibits the inflammation and the polymorphonuclear leukocyte (PML) chemotaxis by inhibiting the cyclooxygenase and lipoxygenase patways.