Stilbenes: Characterization, bioactivity, encapsulation and structural modifications. A review of their current limitations and promising approaches

Stilbenes are phenolic compounds naturally synthesized as secondary metabolites by the shikimate pathway in plants. Research on them has increased in recent years due to their therapeutic potential as antioxidant, antimicrobial, anti-inflammatory, anticancer, cardioprotective and anti-obesity agents. Amongst them, resveratrol has attracted the most attention, although there are other natural and synthesized stilbenes with enhanced properties. However, stilbenes have some physicochemical and pharmacokinetic problems that need to be overcome before considering their applications. Human clinical evidence of their bioactivity is still controversial due to this fact and hence, exhaustive basis science on stilbenes is needed before applied science. This review gathers the main physicochemical and biological properties of natural stilbenes, establishes structure-activity relationships among them, emphasizing the current problems that limit their applications and presenting some promising approaches to overcome these issues: the encapsulation in different agents and the structural modification to obtain novel stilbenes with better features. The bioactivity of stilbenes should move from promising to evident.

Oxyresveratrol: Sources, Productions, Biological Activities, Pharmacokinetics, and Delivery Systems

Oxyresveratrol has recently attracted much research attention due to its simple chemical structure and diverse therapeutic potentials. Previous reviews describe the chemistry and biological activities of this phytoalexin, but additional coverage and greater accessibility are still needed. The current review provides a more comprehensive summary, covering research from 1955 to the present year. Oxyresveratrol occurs in both gymnosperms and angiosperms. However, it has never been reported in plants in the subclass Sympetalae, and this point might be of both chemotaxonomic and biosynthetic importance. Oxyresveratrol can be easily obtained from plant materials by conventional methods, and several systems for both qualitative and quantitative analysis of oxyresveratrol contents in plant materials and plant products are available. Oxyresveratrol possesses diverse biological and pharmacological activities such as the inhibition of tyrosinase and melanogenesis, antioxidant and anti-inflammatory activities, and protective effects against neurological disorders and digestive ailments. However, the unfavorable pharmacokinetic properties of oxyresveratrol, including low water solubility and poor oral availability and stability, have posed challenges to its development as a useful therapeutic agent. Recently, several delivery systems have emerged, with promising outcomes that may improve chances for the clinical study of oxyresveratrol.

Plant-Derived Natural Products in Cancer Research: Extraction, Mechanism of Action, and Drug Formulation

Cancer is one of the main causes of death globally and considered as a major challenge for the public health system. The high toxicity and the lack of selectivity of conventional anticancer therapies make the search for alternative treatments a priority. In this review, we describe the main plant-derived natural products used as anticancer agents. Natural sources, extraction methods, anticancer mechanisms, clinical studies, and pharmaceutical formulation are discussed in this review. Studies covered by this review should provide a solid foundation for researchers and physicians to enhance basic and clinical research on developing alternative anticancer therapies.

A Systematic Review on Natural Antioxidant Properties of Resveratrol

Polyphenols, including anthocyanins, flavonoids and stilbenes, which constitute one of the most abundant and ubiquitous groups of plant metabolites, are an integral part of the human diet. Resveratrol (3,5,4'-trihydroxystilbene), a naturally occurring polyphenol produced by some plants as a self-defence agent, has an antifungal activity. Resveratrol has been found in some plants (such as grapevine, pine and peanuts) and is considered to have beneficial effects also on human health. The number of studies on resveratrol greatly increased in PubMed database since 1997, after the anticancer effect of this molecule was first reported. The interest in resveratrol in grape was originally sparked by epidemiological studies indicating an inverse relationship between long-standing moderate consumption of red wine and the risk of coronary heart disease; this effect has been ascribed to resveratrol, which possesses diverse biochemical and physiological properties, including antiplatelet and anti-inflammatory proprieties, and provides a wide range of health benefits ranging from chemoprevention to cardioprotection. Recently, resveratrol has been described as an anti-aging compound. The consumption of resveratrol (red wine) together with a Mediterranean diet or a fast-food meal (“McDonald'sMeal”) had a positive impact on oxidized (ox-) LDL and on the expression of oxidative and inflammatory genes. Therefore, this review summarized the most important scientific data about healing and preventive potential of resveratrol, acting as cardioprotective, neuroprotective, chemopreventive and antioxidant agent.

Resveratrol Oligosaccharide Induces mRNA Expression for SIRT

Piceid (resveratrol 3- O-β-D-glucoside) was glycosylated by cyclodextrin glucanotransferase to give oligosaccharides of resveratrol. Resveratrol oligosaccharides induced mRNA expression of SIRT1–6.

Cytotoxic Effect of Aeruginosin-865, Resveratrol and Capsaicin on Mouse Fibroblasts and Cells Derived from Fallow Deer

Natural substances offer interesting bioactivity patterns including antiproliferative, antioxidant or cytotoxic effects. However, the safety profile of many of them has not been extensively determined. In this study, the cytotoxic effect of Aeruginosin-865, resveratrol and capsaicin at different concentrations was tested on normal mouse cells (NIH/3T3) and tumour fibroblasts (WEHI-13VAR) as well as on liver- and kidney-derived cells from fallow deer. A lactate dehydrogenase cytotoxicity assay kit was used to measure cell death in response to treatment with the test substances. It was found that NIH/3T3 cells tolerated Aeruginosin-865 (10-200 μM) and resveratrol (5-100 μM) treatment without any cytotoxic effect, while capsaicin exerted a cytotoxic effect only at the highest tested concentration (200 μ M). Mouse fibrosarcoma cells were more sensitive to the cytotoxic effect of all three compounds where Aeruginosin-865 (100-200 μM) and resveratrol (50–100 μM) showed high-dose cytotoxicity and capsaicin showed low- and high-dose cytotoxicity (25 μM and 200 μ M). The three tested compounds at the highest concentrations were found to be cytotoxic to both liver- and kidney-derived cells from fallow deer. Overall, the results indicate that the cytotoxic effects of the three tested natural substances on cells derived from fallow deer and mouse tumour fibroblasts differ significantly from those exerted on normal fibroblasts. The results demonstrate the potential of these natural compounds as therapeutic agents and pave the way for future in vivo toxicological investigations.