Evaluation of Anti-HSV-2 Activity of Gallic Acid and Pentyl Gallate

Abstract

Herpes simplex virus (HSV) is a DNA-containing enveloped virus that causes common viral infections in humans worldwide leading to a variety of diseases. HSV-1 and HSV-2 can be distinguished on the basis of clinical manifestations (the former is more frequently associated with oral cold sores, while the later causes genital ulcers) and biochemical and serological examinations. In most cases, HSV infection is usually benign or asymptomatic in immunocompetent individuals; however, in patients with an immature or compromised immune system, the infection can be serious and sometimes life-threatening. 1,2) Several nucleoside analogues have been approved for clinical use. Among those, acyclovir is widely used for the systemic treatment of HSV infections. It is a highly selective antiviral agent because it is specifically phosphorylated by viral thymidine kinase in infected cells. However, acyclovir-resistant HSV infection in immunocompromised patients such as transplanted patients and patients with AIDS has recently been observed. Therefore, it is desirable to develop new anti-HSV agents in order to substitute or complement the antiviral drugs available. 3,4)The synthetic n-alkyl esters of gallic acid (GA), also known as gallates, especially propyl, octyl and dodecyl gallates, are widely employed as antioxidants by food and pharmaceutical industries. 5,6) Besides the antioxidant activity, other biological activities have been described for this group of molecules, mainly anticancer, 7-10) antibacterial and antifungal properties. [11][12][13][14][15][16] There are few reports about the antiviral activity of these compounds. In 1988, the potent inhibition of HSV-1 and HSV-2 by methyl gallate was described. 17) In 2000, as part of the screening of phenolic compounds against HIV-1 integrase, gallic acid was found to be active. 18)More recently, the anti-HSV activity of several gallates was described by our research group, which proposed various structure-activity relationships regarding the antiviral, antioxidant and genotoxic effects.19) Furthermore, the pronounced anti-HSV-1 activity of octyl gallate, and its inhibitory effect against RNA viruses were also recently described. 20,21) In the present study, the anti-HSV-2 activity of gallic acid and pentyl gallate was evaluated followed by the determination of the site of antiviral activity of these compounds. MATERIALS AND METHODSCompounds GA and pentyl gallate (PG) (Fig. 1) were synthesized as previously described.19) The compounds (50 mM) were dissolved in dimethyl sulfoxide, stored at Ϫ20°C protected from light, and further diluted in culture medium prior to use.Cells and Virus African green monkey kidney cells (GMK AH1) were grown in Eagle's minimum essential medium (EMEM, Gibco BRL, Grand Island, NY, U.S.A.) supplemented with 2% fetal calf serum (FSC), 0.05% primaton substance (Kraft Inc., Norwich, CT, U.S.A.), 100 U/ml Göteborg, Sweden. Received November 23, 2007; accepted February 5, 2008; published online February 20, 2008 The synthetic n-alkyl esters of galli...

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