Resumo

The herpes simplex virus type 1 (HSV-1) is one of the most regular human pathogens that infects individual of both sex, indistinctly of the age. The virus induces diseases varying form mild skin lesions to severe encephalitis, especially in immunocompromised patients. Acyclovir is the reference drug against the infection, however, resistant strains have been related. Therefore, several studies have been done by using natural products to counteract HSV-1 activity, including polysaccharide. We evaluated the antiherpetic effect of Adenanthera pavonina sulfated polysaccharide (PLSAp), in HEp-2 cell cultures. The cytotoxicity of compound was done by MTT assay and antiviral activity evaluated by plaque reduction assay (PRA) with different treatment protocols (time-of-addition, time-of-removal, virucidal effect, and, inhibition of adsorption and penetration assays). PLSAp did not show cytotoxic effect even at the highest tested concentration (500μg/ml) and presented a 50% inhibitory concentration (IC50) of 15μg/ml by PRA. The selectivity index (SI) found was ˃33. The PLSAp showed a therapeutic effect until 16 h post-infection (pi), inhibiting 100% of HSV-1 replication, at 200μg/ml. Inversely, the time-of-removal assay showed inhibition (94.8%) only when the compound was removed from 16 h pi. Differently of other PLS, with similar anti-HSV-1 activity, the PLSAp showed a low profile for prophylactic (30%), virucidal (34.2%) and inhibition of adsorption (24.4%) effects, respectively. For the inhibition of virus penetration, comparatively, a low level was also found (48.3%). Our results suggested PLSAp activity in different steps of the HSV-1 replication, especially after viral adsorption. It is thought that the effects of the compounds in different stages of viral replication is prone to select less mutation, therefore, minimizing the emergence of resistant strains. Further studies are under development to better understanding the PLSAp mechanism of action in the replication HSV-1.