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12.5, 6.25, and 6.25µM, respectively. Similar results were observed when this 2kD peptide was assayed against bovine herpes virus (BHV), an enveloped virus like HSV-1, while this peptide had weak activity against non-enveloped poliovirus type 1. Thus these results indicate that 2kD peptide of Sorghum bicolor was able to inhibit the initiation and the spread of infection, and also had an in vitro prophylactic effect against HSV-1 infection [Filho et al., 2008]. The sulphated galactans from a marine alga Bostrychia montagnei are found to inhibit herpes virus multiplication in cell culture and replication in vitro [Duarte et al., 2001]. While the polysaccharide of Cedrela tubiflora leaves inhibit HSV-2 replication at non-cytotoxic dose, indicating that the anti-HSV activity of polysaccharides correlates with molecular weight and sulfate content. Recently Thompson and Dragar [2004] reported that a seaweed Undaria pinnatida containing a sulfated polysaccharide galactofucan had anti-HSV-1activity. Further study revealed that it inhibit viral binding and entry into the host cell (IC50 32µg/ml), and highly active against HSV-2 (IC50 0.5µg/ml; P<0.001). On the other hand a water soluble anionic polysaccharide from Prunella vulgaris L. (Labiatae) inhibit HSV-1 at 100 µg/ml and HSV-2 at 10 µg/ml by plaque inhibition assay [Xu et al., 1999] while the anionic polysaccharide of the same herb collected from Japan showed specific anti-HSV activity (IC50 10µg/ml) by competing for cell surface receptor [Chiu et al., 2004]. Interestingly the polysaccharide fraction prepared from P. vulgaris revealed that the viral antigen increased time-dependently in the infected HSV-1 and HSV-2 cells, and polysaccharide fraction (25-100µg/ml) reduced such antigen expression (EC50 20.6 and 20.1µg/ml), along with the antigen expression of acyclovir-resistant strain of HSV-1 (24.8-92.6%). It shows that polysaccharide fraction has a different mode of anti-HSV action from acyclovir [Chiu et al., 2004].
Conclusions The diseases caused by human herpesviruses (HSV, VZV, CMV, EBV and Kaposi’s Sarcoma- associated herpes virus) are the global concern for their contiguous nature, recurrence ability, mutability and silent epidemic potential. These diseases are sometimes fatal, especially in neonates and immunocompromised patients. The ‘cure’ or development of effective vaccines are not yet possible, hence, cost effective natural or complementary antivirals to prevent resistance development with reduced toxicity are of immediate need. Moreover, the antivirals used against herpesviruses are expensive with high toxicity. Therefore, development of safe, effective and inexpensive antivirals is among the top global priorities of drug development. Hence, scientists from divergent fields are investigating herbal medicinal products, with an eye to their antiherpesvirus usefulness. The extensive research for last 4 decades leads to the discovery of a few agents with antiherpes virus activity. The polyphenolic Caffeic acid, CAPE, Catechin, Quercetin, Epicatechin dimers, Procyanidins, Apigenin,