Quantitative analysis of resveratrol derivatives in seed coats of tree peonies and their hypoglycemic activities in vitro/vivo

The tree peonies were well-known horticultural and medicinal plants. The tree peony seeds, as emerging woody oil crops, recently have been attracted great attention for their metabolites and bioactivities. In...

Natural Phytoalexin Stilbene Compound Resveratrol and its Derivatives as Anti-tobacco Mosaic Virus and Anti- Phytopathogenic Fungus Agents

Plant diseases caused by plant viruses and pathogens seriously affect crop yield and quality, and it is very difficult to control them. The discovery of new leads based on natural products is an important way to innovate pesticides. In this work, based on the resveratrol is a kind of natural phytoalexin, but it cannot be used as candidate for the development of new drug due to its poor druggability, novel resveratrol derivatives with improved water solubility and highly potent biological activity could be obtained by chemical modifying of chemical structure of resveratrol, the phenolic hydroxyl groups in the resveratrol structure are easily destroyed by oxidation, in order to improve its stability, ester formation is the most commonly used modification method in drug design, which can protect the hydroxyl groups from oxidation and improve its solubility, stability and druggability. The present study was designed to synthesize ester derivatives of E-resveratrol and evaluate their activities against TMV (Tobacco mosaic virus). A series of resveratrol ester derivatives have been successfully synthesized via a feasible chemical modification. Their structures were characterized by 1H NMR, 13C NMR and HRMS. The activity against tobacco mosaic virus (TMV) of these ester derivatives has been tested for the first time. The bioassay results showed part of the target compounds exhibited good to excellent in vivo activities against TMV. The optimum compounds III-2 (inhibitory rates of 50, 53, and 59% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively), III-4 (inhibitory rates of 57, 59, and 51% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively), and II-5 (inhibitory rates of 54, 52, and 51% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively) displayed higher activity than commercial plant virucide ribavirin (inhibitory rates of 38, 37, and 40% at 500 µg/mL for inactivation, curative, and protection activities in vivo, respectively). Compounds I-9 and I-10 also showed excellent activities. The systematic study provides strong evidence that these simple resveratrol derivatives could become potential TMV inhibitors. The novel concise structure provides another new template for antiviral studies.

Biosynthesis of resveratrol derivatives and evaluation of their anti-inflammatory activity

Resveratrol is a typical plant phenolic compound whose derivatives are synthesized through hydroxylation, O-methylation, prenylation, and oligomerization. Resveratrol and its derivatives exhibit anti-neurodegenerative, anti-rheumatoid, and anti-inflammatory effects. Owing to the diverse biological activities of these compounds and their importance in human health, this study attempted to synthesize five resveratrol derivatives (isorhapontigenin, pterostilbene, 4-methoxyresveratrol, piceatannol, and rhapontigenin) using Escherichia coli. Two-culture system was used to improve the final yield of resveratrol derivatives. Resveratrol was synthesized in the first E. coli cell that harbored genes for resveratrol biosynthesis including TAL (tyrosine ammonia lyase), 4CL (4-coumaroyl CoA ligase), STS (stilbene synthase) and genes for tyrosine biosynthesis such as aroG (deoxyphosphoheptonate aldolase) and tyrA (prephenate dehydrogenase). Thereafter, culture filtrate from the first cell was used for the modification reaction carried out using the second E. coli harboring hydroxylase and/or O-methyltransferase. Approximately, 89.8 mg/L of resveratrol was synthesized and using the same, five derivatives were prepared with a conversion rate of 88.2% to 22.9%. Using these synthesized resveratrol derivatives, we evaluated their anti-inflammatory activity. 4-Methoxyresveratrol, pterostilbene and isorhapontigenin showed the anti-inflammatory effects without any toxicity. In addition, pterostilbene exhibited the enhanced anti-inflammatory effects for macrophages compared to resveratrol.