The plant cell wall–A potential source for pharmacologically active polysaccharides

Mitogenic and comitogenic activities of polysaccharides from some European herbaceous plants

From the leaves of Plantago lanceolata, the green parts of Rudbeckia fulgida, the aerial parts of Salvia officinalis and the roots of Valeriana officinalis, crude polysaccharides have been isolated by extraction with water and further purified and fractionated by various techniques. The water-soluble polysaccharides obtained were examined for their immunomodulatory activities using the in vitro mitogenic and comitogenic rat thymocyte tests. The results indicate that in spite of the considerable differences in chemical composition and structural properties, the tested polysaccharides exhibited similar significant immunomodulatory properties with a particularly high adjuvans activity in the case of the Rudbeckia and Salvia polysaccharides. The pectic polysaccharide-rich complex from Valeriana was shown to also stimulate the immune function of bone marrow cells.

Immunomodulatory activity of acidic xylans in relation to their structural and molecular properties

The structure/function relationship of two acidic heteroxylan types, the arabino-(glucurono)xylan from corn cobs (AGX) and 4-O-methylglucuronoxylans (GXs) from beechwood and three medicinal herbs (Rudbeckia, Altheae, and Mahonia), has been studied. The effect of the molecular mass of AGX, as well as the content and distribution of the 4-O-methylglucuronic acid side chains in GXs on the immunological activity of these xylans was characterized by their biological response in the mitogenic and comitogenic thymocyte in vitro tests. Depolymerization of AGX by ultrasonication resulted in unequivocal decrease of the immunomodulatory activity, whereas already a short treatment by endo-beta-1,4-xylanase brought about a significant increase in its activity when applied in the highest dose. In the case of the GX samples, neither the uronic acid content nor the distribution pattern of the uronic acid side chains was found to be determinant for the expression of their immunomodulatory activity.

Ultrasound-assisted extraction of water-soluble polysaccharides from the roots of valerian (Valeriana officinalis L.)

The insoluble plant residues, obtained after preparation of medicinal tinctures from the roots of valerian (Valeriana officinalis L.) by classical and ultrasound-assisted extraction with aqueous ethanol in a pilot plant, were subsequently treated with hot water to isolate the accessible polysaccharide cell wall components. At almost equal amounts of the hot-water extractable material, the yields of the recovered polysaccharides were lower in the ultrasonical experiment. This is due to the fact that a part of accessible polysaccharides were already solubilised by the aqueous ethanol and recoverable from the medicinal tincture. Therefore, the net yield of extracted polysaccharides was enhanced in the ultrasonical procedure. This fact as well as the sugar composition and structural features of the isolated polysaccharides suggest that ultrasonication have attacked the integrity of cell walls, released and degraded its most accessible polysaccharides (pectic polysaccharides and starch) and increased also the extractibility of its less accessible components--xylan, mannan and glucan. The water-soluble polysaccharide fractions from both the conventional and ultrasonical experiments exhibit significant immunostimulatory activities in mitogenic and comitogenic thymocyte tests.

High molecular compounds (polysaccharides and proanthocyanidins) from Hamamelis virginiana bark: influence on human skin keratinocyte proliferation and differentiation and influence on irritated skin

Although extracts from Hamamelis bark have long been used in therapy of skin diseases and in cosmetic formulas there are only few pharmacological investigations verifying the activity of distinct Hamamelis bark constituents. Therefore two major classes of constituents, namely polymeric proanthocyanidins and polysaccharides were isolated from Hamamelis bark and tested concerning their influence on proliferation and differentiation of cultured human keratinocytes. While the polysaccharide fraction, consisting mainly of arabans and arabinogalactans, did not effect human keratinozytes, the proanthocyanidins strongly increased the proliferation of the cells, while the differentiation was not influenced significantly. Within a preliminary cumulative in vivo study on SLS-irritated skin, proanthocyanidins (ProcyanoPlus) were proven to reduce transepidermal water loss and erythema formation. Furthermore, a clinical scoring indicated that procyanidins can influence irritative processes significantly.