Acuminatol and other antioxidative resveratrol oligomers from the stem bark of Shorea acuminata

Phytochemical and pharmacological profile of genus shorea: A review of the recent literature

In tropical Southeast Asia, Shorea is the most economically important tree and the largest genus in the Dipterocarpaceae family. It comprises about 150-200 species, of which majority are distributed in Malaysia, with others found in Sumatra and Borneo (Kalimantan) in Indonesia. Research on the chemical constituents of Shorea plants has been ongoing for many years. To date, a total of 113 different compounds, including 83 stilbenes and their resveratrol oligomers, 18 triterpenes/terpenoids, 7 coumarins 3 flavonoids and 2 steroids have been isolated and successfully elucidated from 26 different species of this genus. The diversity of the stilbene resveratrol oligomers in the Shorea genus is primarily due to the difference in the amount of resveratrol constituent units, which include dimers, trimers and tetramers. In addition to the species' traditional usage in the treatment of illnesses, such as diarrhea, toothaches, skin diseases, ear troubles and wounds, the extracts and secondary metabolite compounds isolated from various parts of the plant species are known to have a very potent antioxidant, antimicrobial, anticancer, anti-diabetic, anti-obesity, antiulcer, hepatoprotective and nephroprotective activities. This review aims to summarize the most recent research made from 1999 to date on the secondary metabolite compounds isolated from different species of genus Shorea, as well as the bioactivity (in vitro and in vivo) of the crude extracts and the isolated secondary metabolite compounds.

Computation-guided asymmetric total syntheses of resveratrol dimers

Although computational simulation-based natural product syntheses are in their initial stages of development, this concept can potentially become an indispensable resource in the field of organic synthesis. Herein we report the asymmetric total syntheses of several resveratrol dimers based on a comprehensive computational simulation of their biosynthetic pathways. Density functional theory (DFT) calculations suggested inconsistencies in the biosynthesis of vaticahainol A and B that predicted the requirement of structural corrections of these natural products. According to the computational predictions, total syntheses were examined and the correct structures of vaticahainol A and B were confirmed. The established synthetic route was applied to the asymmetric total synthesis of (−)-malibatol A, (−)-vaticahainol B, (+)-vaticahainol A, (+)-vaticahainol C, and (−)-albiraminol B, which provided new insight into the biosynthetic pathway of resveratrol dimers. This study demonstrated that computation-guided organic synthesis can be a powerful strategy to advance the chemical research of natural products.

Although computational simulation-based natural product syntheses are in their initial stages of development, this concept can potentially become an indispensable resource in the field of organic synthesis. Here the authors report asymmetric total syntheses of several resveratrol dimers based on a comprehensive computational simulation of their biosynthetic pathways.

Resveratrol oligomer structure in Dipterocarpaceaeous plants

Oligostilbenoids are a group of natural products derived from the oxidative coupling of C6-C2-C6 units found in some plant families. A structurally diverse chemical pool is produced after the successive regioselective and stereoselective oligomerization of resveratrol. This review describes the current status and knowledge of the structure of resveratrol oligomers (ROs) in Dipterocarpaceaeous plants (DPs). Beginning with the recently validated formation of ROs in DPs, each downstream conversion is described from the perspective of the resveratrol coupling mode. Particular emphasis is placed upon the regioselectivity of monomer- and dimer-derived radical-radical coupling processes, which are responsible for producing dimers, trimers, and tetramers with various cyclic frame skeletons, as well as related processes that result in highly condensed scaffolds, such as hexamers and octamers. Trimers in oxidized, dearomatized, and rearranged forms are also summarized, as well as the biogenic relationship between the compounds. Furthermore, emphasis is placed on the O- and C-glucosides of ROs, as well as on the hetero-coupled ROs. In addition, several stereoisomers that originate from asymmetric carbons and the stereochemistry with respect to the conformation due to the chiral axis are described. Besides, NMR spectroscopic properties such as coalescence and anisotropy are briefly described. Approaches to determine absolute configuration are also summarized.

Shoreanol A and B, unprecedented oligostilbenoids from the twigs of Shorea obtusa Wall

Chemical investigation of the twigs extract of tropical dipterocarpaceous plant Shorea obtusa Wall led to the isolation of two previously undescribed oligostilbenoids, including a structurally unusual resveratrol aneuploid named shoreanol A (1) and a new resveratrol trimer derivative named shoreanol B (2). Their structures and relative configurations were determined by comprehensive spectroscopic analysis and comparison with previously reported compound. Shoreanol A (1) was identified as a rare natural resveratrol aneuploid possessing a novel carbon skeleton through condensation of three resveratrol monomer and one benzyl moiety, which is the first example in the Dipterocarpaceae. While shoreanol B (2) was characterized to be the first example of stilbene trimer bearing an epoxy group in the genus Shorea.

Resveratrol and Related Stilbenoids, Nutraceutical/Dietary Complements with Health-Promoting Actions: Industrial Production, Safety, and the Search for Mode of Action

This paper reviews the potential of stilbenoids as nutraceuticals. Stilbenoid compounds in wine are considered key factors in health-promoting benefits. Resveratrol and resveratrol-related compounds are found in a large diversity of vegetal products. The stilbene composition varies from wine to wine and from one season to another. Therefore, the article also reviews how food science and technology and wine industry may help in providing wines and/or food supplements with efficacious concentrations of stilbenes. The review also presents results from clinical trials and those derived from genomic/transcriptomic studies. The most studied stilbenoid, resveratrol, is a very safe compound. On the other hand, the potential benefits of stilbene intake are multiple and are apparently due to downregulation more than upregulation of gene expression. The field may take advantage from identifying the mechanism of action(s) and from providing useful data to show evidence for specific health benefits in a given tissue or for combating a given disease.

Biologically active oligostilbenes from the stems of Vatica mangachapoi and chemotaxonomic significance

Phytochemical investigation of the stems of Vatica mangachapoi (Dipterocarpaceae) led to the isolation and structural elucidation of twenty-seven oligostilbenes (1-27), including a new natural compound 1. The structure of 1 was elucidated on the basis of spectroscopic analyses including NMR, MS and ECD data, and the known compounds were identified by comparisons with those reported in the literature. The absolute configuration of 1 was first time determined by a combination of NOESY spectrum and quantum chemical computation. Among of isolates were tested for their anti-osteoporosis and anti-HIV-1 activities in vitro by the MTT method. Moreover, the chemotaxonomic significance of these compounds was summarised.

Update on Phytochemistry and Pharmacology of Naturally Occurring Resveratrol Oligomers

Resveratrol oligomers (REVs), a major class of stilbenoids, are biosynthesized by regioselective oxidative coupling of two to eight units of resveratrol monomer. Due to their unique structures and pleiotropic biological activities, natural product chemists are increasingly focusing on REVs in the last few decades. This study presents a detailed and thorough examination of REVs, including chemical structures, natural resources, and biological activities, during the period of 2010–2017. Ninety-two new REVs compounds, including 39 dimers, 23 trimers, 13 tetramers, six resveratrol monomers, six hexamers, four pentamers, and one octamer, have been reported from the families of Dipterocarpaceae, Paeoniaceae, Vitaceae, Leguminosae, Gnetaceae, Cyperaceae, Polygonaceae Gramineae, and Poaceae. Amongst these families, Dipterocarpaceae, with 50 REVs, accounts for the majority, and seven genera of Dipterocarpaceae are involved, including Vatica, Vateria, Shorea, Hopea, Neobalanocarpus, Dipterocarpus, and Dryobalanops. These REVs have shown a wide range of bioactivities. Pharmacological studies have mainly focused on potential efficacy on tumors, bacteria, Alzheimer’s disease, cardiovascular diseases, and others. The information updated in this review might assist further research and development of novel REVs as potential therapeutic agents.

Cyperaceae Species Are Potential Sources of Natural Mammalian Arginase Inhibitors with Positive Effects on Vascular Function

The inhibition of arginase is of substantial interest for the treatment of various diseases of public health interest including cardiovascular diseases. Using an ex vivo experiment on rat aortic rings and an in vitro assay with liver bovine purified arginase, it was demonstrated that several polyphenolic extracts from Cyperus and Carex species possess vasorelaxant properties and mammalian arginase inhibitory capacities. Phytochemical studies performed on these species led to the identification of eight compounds, including monomers, dimers, trimers, and tetramers of resveratrol. The potential of these stilbenes as inhibitors of mammalian arginase was assessed. Five compounds, scirpusin B (5), ε-viniferin (4), cyperusphenol B (6), carexinol A (7), and the new compound virgatanol (1), showed significant inhibition of arginase, with percentage inhibition ranging from 70% to 95% at 100 μg/mL and IC₅₀ values between 12.2 and 182.1 μM, confirming that these stilbenes may be useful for the development of new pharmaceutical products.