Characterization and antiherpetic activity of native and chemically sulfated polysaccharide from Adenanthera pavonina.

The herpes simplex virus (HSV) is a widespread human pathogen and for many reasons the development of anti-herpetic drugs from natural products has been encouraged. Adenanthera pavonina ( Ap ) is a medicinal plant widely used in Brazil, among other uses. Herein, a native Ap seed polysaccharide (PLSAp) and its chemically sulfated derivate (SPLS Ap ) were studied by Fourier transform IR spectra (FT-IR), gel permeation chromatography (GPC) for molar mass determination and their intrinsic viscosity [η]. Biologically, the compounds were evaluated for anti-HSV activity, in HEp2 cell cultures. The cytotoxic concentrations (CC 50 ) and the inhibitory concentrations (IC 50 ) of the polysaccharides were determined by the colorimetric assay (dimethyl-thiazolyl-diphenyltetrazolium bromide) and plaque reduction assay (PRA), respectively. The SPLS Ap showed a better antiviral activity when compared to the PLS Ap with a CC 50 of 500 μg/ml, the IC 50 equal to 15μg/ml and the selectivity index (SI) of 33.3. The time-of-addition and the time-of-removal assays demonstrated the highest inhibitory activity between 8-16h after the infection. The inhibition of viral DNA and protein syntheses by SPLS Ap monitored by PCR and immunofluorescence assay (IFA), respectively, has also demonstrated. These findings demonstrated that the SPLS Ap inhibited HSV-1 infection in different steps of the replication and, therefore, represents a valuable compound for preclinical studies in anti-herpetic therapy.