Interaction with bovine serum albumin of an anti-oxidative pectic arabinogalactan from Andrographis paniculata.

A pectic arabinogalactan was obtained from the leaves of Andrographis paniculata by aqueous extraction followed by α-amylase treatment, deproteination, and anion exchange chromatography. Methylation analysis, Smith degradation, and NMR spectroscopy indicated that it was a highly branched arabinogalactan containing a (1→3)-linked ß-d-Galp main chain, substituted at O-6 by (1→6)-linked ß-d-Galp side chains. The latter residues were substituted at O-3 by (1→5)- and (1→3)-linked α-l-Araf chains, and non reducing end-units of α-l-Araf and ß-d-Galp. This homogeneous arabinogalactan (36 kDa), which contained phenolic acids, showed dose-dependent anti-oxidative properties. The phenolic acid moieties might be the functional sites. This arabinogalactan can form a complex with bovine serum albumin having binding constant K=6.48 × 10(6)/M. Thus, this study is an important step forward to investigate the involvement of arabinogalactan in processes including interaction with biologically important transport proteins.

Chemically engineered sulfated glucans from rice bran exert strong antiviral activity at the stage of viral entry.

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.

Structure, fluorescence quenching and antioxidant activity of a carbohydrate polymer from Eugenia jambolana.

Natural products provide an excellent source for novel antioxidants. Herein, we have studied the water-extracted carbohydrate polymer (WE) of Eugenia jambolana using chemical, chromatographic, and spectroscopic methods. A 116 kDa arabinogalactan containing p-coumaric and ferulic acids in monomeric and dimeric forms has been isolated. Cellulase generated oligomeric fragments containing ester linked phenolic acids were also characterized. The antioxidant capacity of this carbohydrate polymer is comparable to butylated hydroxy anisole and butylated hydroxy toluene. Interaction of WE with bovine serum albumin (BSA) was studied by fluorescence quenching measurement. Conformational change of BSA at high carbohydrate polymer concentration was indicated.

Sulfated polysaccharides from Laminaria angustata: Structural features and in vitro antiviral activities.

Sulfated polysaccharides potently inhibit the infectivity of herpes simplex virus (HSV) in cultured cells. In this study, we have analyzed sulfated xylogalactofucan and alginic acid containing fractions generated from Laminaria angustata, a marine alga. The xylogalactofucan that has apparent molecular mass of 56±5kDa and unusually low sulfate content contains, inter alia, 1,3-, 1,4- and 1,2-linked fucopyranosyl residues. The algin (molecular mass: 32±5kDa) contains gulo- (55.5%) and mannuronic (44.5%) acid residues. Introduction of sulfate groups enhanced the macromolecules capability to inhibit the infection of cells by HSV-1. The 50% inhibitory concentration (IC50) values of these macromolecules against HSV-1 were in the range of 0.2-25µgml-1 and they lacked cytotoxicity at concentrations up to 1000µgml-1. The sulfate content appeared to be an important hallmark of anti-HSV-1 activity. Our results suggest the feasibility of inhibiting HSV attachment to cells by direct interaction of polysaccharides with viral particles.

In vitro anti-oxidant activity, fluorescence quenching study and structural features of carbohydrate polymers from Phyllanthus emblica.

The water-extracted carbohydrate polymers (WE) of Phyllanthus emblica are analyzed using chemical, chromatographic, and spectroscopic methods. Anion-exchange-chromatography of WE yielded four fractions (F1-F4) with different chemical compositions and all of them contain phenolics. The major fraction F4 possesses 50% polysaccharide and 26% phenol, and is a glycoconjugate. The antioxidant capacities of WE and F4 are comparable to standard anti-oxidants. Notably, activities of F1-F4 correlate with their phenol content. Evidence for the complexation of F4 with bovine serum albumin is presented by fluorescence quenching measurement. The results also indicate conformational change of protein at high carbohydrate polymer concentration.

Structural features and in vitro antiviral activities of sulfated polysaccharides from Sphacelaria indica.

Many viruses display affinity for cell surface heparan sulfate proteoglycans with biological relevance to virus entry. This raises the possibility of the application of sulfated polysaccharides in antiviral therapy. In this study, we have analyzed xylogalactofucan- and alginic acid-containing fractions from Sphacelaria indica, a marine alga. The xylogalactofucan that has apparent molecular mass of 26±5 kDa and negative specific rotation [α](D)(32) -71° (c 0.2, H(2)O) contains, inter alia, (1→3)-linked L-fucopyranosyl and D-galactopyranosyl residues. The algin (molecular mass: 21±5kDa) contains 41% guluronic and 59% mannuronic acid residues. The 50% inhibitory concentration (IC(50)) values of these macromolecules and their chemically sulfated derivatives against herpes simplex virus type 1 (HSV-1) were in the range of 0.6-10 µg ml(-1) and they lacked cytotoxicity at concentrations up to 200 µg ml(-1). The antiviral activity was dependent on the sulfate contents of the polysaccharides. The results support the feasibility of inhibiting HSV infection by direct interaction of polysaccharides with viral particles.

In vivo anti-tussive activity and structural features of a polysaccharide fraction from water extracted Withania somnifera.

AIM OF THE STUDY: Anti-tussive drugs are amongst the most widely used medications worldwide; however no new class of drugs has been introduced into the market for many years. The present study aims at evaluating the structural features and in vivo anti-tussive activity of a polysaccharide fraction from water extracted Withania somnifera. MATERIALS AND METHODS: Herein, we have analyzed water extracted material of Withania somnifera using chemical, chromatographic, spectroscopic and biological methods. RESULTS: A polysaccharide fraction (F3) containing arabinosyl, galactosyl and galacturonosyl residues were obtained by anion exchange chromatography of the water extracted material. This polymer is branched and contained (1,5)-/(1,3,5)-linked arabinofuranosyl, (1,3)-/(1,6)-/(1,3,6)-linked galactopyranosyl residues together with small amount of terminal rhamnopyranosyl and terminal arabinofuranosyl residues. Peroral administration of this pectic arabinogalactan in a dose of 50 mg kg(-1) body weight (b.w.) decreased the number of cough efforts induced by citric acid in guinea pigs like that of codeine. CONCLUSIONS: This study provides a scientific basis for the past and present ethnomedical uses of this plant.

Water-extracted polysaccharides from Azadirachta indica leaves: Structural features, chemical modification and anti-bovine herpesvirus type 1 (BoHV-1) activity.

In this study, we have analyzed the pectic arabinogalactan isolated from Azadirachta indica and its chemically sulfated derivative. The native polysaccharide had an apparent molecular mass of 80 kDa and is made up of (1→5)-/(1→3,5)-linked α-L-arabinosyl, (1→3)-/(1→6)-/(1→3,6)-linked ß-D-galactosyl, and terminal-rhamnosyl and α-l-arabinosyl residues. These macromolecules showed activity against bovine herpesvirus type-1. Their inhibitory concentration 50% values ranging from 31.12 to 105.25 µg/ml were lower than the cytotoxicity values (>1600-1440 µg/ml). The anti-viral effect was exerted during virus adsorption to the cell. Anionic groups in particular the sulfate groups appeared to be very important for the anti-herpetic activity of these polymers.