Purify, characterize health-promoting polysaccharides.
In nutrition, polysaccharides are digested and used as potential energy sources. There are many benefits to these macro-molecules. They can reduce cholesterol levels and blood pressure, and stabilize blood sugar. Water-extractable polysaccharides have emerged as an important class of compounds, present in plant material, which have biological activity.
Canadian scientists hypothesized that water-extractable polysaccharides may play a role in the health benefits associated with the consumption of fruit. Their efforts provide the information necessary to help define the relationship between the chemical characteristics of polysaccharides and their bioactivity. And it appears that polysaccharides may act as health-promoting compounds in fruits. More research is needed on this front.
To test their theory, the researchers used a hot water extraction technique to obtain water-extractable polysaccharides from sweet cherries, apples, raspberries and ginseng berry pulp. The crude polysaccharides were purified into neutral and acidic fractions using chromatography on a column packed with commercial flow media. The polysaccharides were evaluated for their chemical composition and structural features. The antioxidant activity, determined by various assays, and the potential of the polysaccharides to serve as glucosidase inhibitors also were determined.
The scientists also determined the influence of the polysaccharides on caspase 3 activation, which is an important marker of myocardial apoptosis--the death of heart cells. All of the polysaccharides contained protein and phenolics, and, in most cases, the acidic fractions contained higher levels of these compounds.
The sugar monomer and uronic acid content of the purified polysaccharides was influenced by both the type of fruit and fraction. The neutral polysaccharides from the cherry, apple and raspberry samples had higher molecular weight compared to their respective acidic fractions. The opposite was seen for the ginseng berry pulp polysaccharides.
All of the polysaccharides possessed antioxidant activity. Of the fractions, only the acidic cherry and apple polysaccharides demonstrated glucosidase inhibition with values comparable to those of the acarbose control. Of the fractions, the acidic polysaccharides obtained from certain varieties of sweet cherries and raspberry showed the best protection from caspase 3 activation. Further information. Kelly Ross, Agriculture and Agri-Food Canada, Summerland Research and Development Centre, 4200 Highway 97, PO Box 5000, Summerland, British Columbia V0H 1Z0, Canada; phone: 250-494-6411; fax: 250-494-0755; email: email@example.com.