Attachment and entry of many viruses are mediated by their affinity for polysaccharides present on the surface of target cells. In this paper, we demonstrate that sulfated glucans isolated from rice (Oryza sativa) can be utilized as experimental drugs exerting strong antiviral activity. In particular, oleum-DMF-based extraction is described as a procedure for the generation of chemically engineered glucans from commercially available rice bran. The one-step procedure has the potential to provide a spectrum of related glucans with varying molecular masses and modifications, including sulfation. The sulfated glucans P444, P445, and P446 possess increased antiviral activity compared to a previously described glucan (S1G). P444, P445, and P446 were highly active against human cytomegalovirus (HCMV), moderately active against other members of the family Herpesviridae, while not active against unrelated viruses. Specific experimentation with HCMV-infected cells provided evidence that antiviral activity was based on inhibition of viral entry and that inhibition occurred in the absence of drug-induced cytotoxicity. These findings underline the high potential of sulfated glucans for antiviral research and drug development. In addition, the procedure described for the efficient transformation of glucan hydroxy groups to sulfate groups may be similarly beneficial for the chemical alteration of other natural products.

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Enhydra fluctuans leaves are traditionally sold on Indian markets for various health benefits. However, no phytochemical study on its high molecular weight compound has so far been performed. Chemical, chromatographic, ESI-TOF-MS, and NMR analyses of the water extracted carbohydrate polymer (CP) of E. fluctuans leaves showed the presence of a 24 kDa arabinogalactan having a (1,3)-linked β-d-Galp main chain, substituted at O-6 by (1,6)-linked β-d-Galp side chains. The latter residues were substituted at O-3 by (1,3)-, (1,5)-, and (1,3,5)-linked α-l-Araf chains, and nonreducing end-units of α-l-Araf and β-d-Galp. This polymer contained esterified phenolic acids. Biochemical analysis revealed similarity in antioxidative potential between the identified carbohydrate polymer and known standard antioxidants. The highly branched side chains and the phenolic acid residues of the arabinogalactan might be the functional sites. Fluorimetric and ultraviolet spectrometric analyses showed that the studied carbohydrate polymer can form complex with bovine serum albumin having binding constant K = 2.42 × 10(6)/M and changes its microenvironment. Thus, traditional aqueous extraction method provides a carbohydrate polymer, which stimulates a fair biological response: this could represent an interesting approach in phytotherapeutic treatments.

Terminalia chebula, a medicinal plant, is widely used in the management of various diseases. As the water extract of its dried ripe fruit is a frequently used preparation, we decided to look for bioactive polysaccharide in this extract. We demonstrate that the obtained polysaccharide fraction, CP, contained a highly branched arabinogalactan protein having a (1 → 3)-, (1 → 6)- and (1 → 3, 6)-linked β-D-Galp together with (1 → 5)- and (1 → 3)-linked α-L-Araf and nonreducing end units of α-L-Araf. This polymer possesses strong antitussive property. Our results showed that the number of citric acid-induced cough efforts decreased significantly after the oral application of polysaccharide fraction in a dose of 50 mg kg−1 body weight. Its antitussive efficacy was higher than cough suppressive effect of standard drug codeine. Therefore, traditional aqueous extraction method provides a major polysaccharide, which induces a pharmacological effect: this could represent an attractive approach in phytotherapeutic managements.

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