Antioxidant and Cytoprotective Activities of Grapevine Stilbenes

Oligostilbenoids in Vitis vinifera L. Pinot Noir grape cane extract: Isolation, characterization, in vitro antioxidant capacity and anti-proliferative effect on cancer cells

The following oligostilbenoids were isolated from extracts of Vitis vinifera L. Pinot Noir grape canes produced at a pilot-plant scale: (E)-ε-viniferin, (E)-resveratrol, (E)-piceatannol, ampelopsin A, vitisin B, pallidol, (E)-δ-viniferin, (E)-ω-viniferin, (E)-trans-cis-miyabenol C, isorhapontigenin, scirpusin A, and a new isomer named isoscirpusin A. The antioxidant capacity of the isolated stilbenoids was studied by three different assays, and their 50% inhibition concentration (IC₅₀) against cancer cells was determined by MTT reduction assay. Besides (E)-resveratrol, stilbenoids have outstanding antioxidant capacity in the ORAC-FL assay. The strongest antiproliferative effect was observed for (E)-piceatannol and ampelopsin A against the bladder cancer cell line J82. (E)-Piceatannol has inhibitory effect on human lung cancer SK-MES-1 cells. Moreover, the whole extract has antiproliferative effect on all tested cell lines. In conclusion, beside (E)-resveratrol, grape cane extract contains oligostilbenoids with potential health benefits. This underexploited viticultural residue has the potential to produce valuable phytochemicals or ingredients in functional foods.

Natural antioxidants in prevention of accelerated ageing: a departure from conventional paradigms required

The modern lifestyle is characterised by various factors that cause accelerating ageing by the upregulation of oxidative stress and inflammation-two processes that are inextricably linked in an endless circle of self-propagation. Inflammation in particular is commonly accepted as aetiological factor in many chronic disease states, such as obesity, diabetes and depression. In terms of disease prevention or treatment, interventions aimed at changing dietary and/or exercise habits have had limited success in practise, mostly due to poor long-term compliance. Furthermore, other primary stimuli responsible for eliciting an oxidative stress or inflammatory response-e.g. psychological stress and anxiety-cannot always be easily addressed. Thus, preventive medicine aimed at countering the oxidative stress and/or inflammatory responses has become of interest. Especially in developing countries, such as South Africa, the option of development of effective strategies from plants warrants further investigation. A brief overview of the most relevant and promising South African plants which have been identified in the context of inflammation, oxidative stress and chronic disease is provided here. In addition, and more specifically, our group and others have shown considerable beneficial effects across many models, after treatment with products derived from grapes. Of particular interest, specific cellular mechanisms have been identified as therapeutic targets of grape-derived polyphenols in the context of inflammation and oxidative stress. The depth of these studies afforded some additional insights, related to methodological considerations pertaining to animal vs. human models in natural product research, which may address the current tendency for generally poor translation of positive animal model results into human in vivo models. The importance of considering individual data vs. group averages in this context is highlighted.