Antiviral activity and mode of action of a peptide isolated from Helianthus annus

HSV-1 is generally associated with primary and recurrent mucocutaneous facial, ophthalmic or genital lesions, but under certain conditions can produce serious infections of the central nervous system, causing acute necrotizing encephalitis and meningitis in patients with immune deficiencies [1,2]. Most of the treatments for HSV-1 are based on acyclovir (ACV) and ACV-like nucleoside analogues, but these are toxic, and some immunocompromised patients with recurrent HSV lesions develop resistance to ACV [3]. Antimicrobial proteins have been discovered in plants, insects and animals as important components of the innate defense system [4]. We have investigated the activity of crude extracts, a fraction, and an isolated peptide from seeds of Helianthus annuus against HSV-1. The plaque reduction assay showed a dose-dependent effect against HSV-1 with EC₅₀ values 21.5µg/mL for crude extracts, 15.9µg/mL for the fraction and 4.8µg/mL for the isolated peptide. In an evaluation of the antiviral mode of action, the isolated peptide showed EC₅₀ values of 5.3µg/mL before the infection, 4.5µg/mL during the infection and 78.6µg/mL for a direct viricidal effect. The cellular toxicity of the peptide showed a CC₅₀ value of 3.278µg/mL, thus exceeding the EC₅₀ value by 683 times. Based on the results of this study, the isolated peptide appears to be an alternative for the development of new antiviral drugs.

Acknowledgements: CNPq, CAPES, PRONEX/Fundação Araucária.

References: [1] Jenssen, H. et al. (2004) Antiviral Res. 64:119–126.

[2] Ammendolia, M.G. et al. (2007) Antiviral Res. 76:252–262.

[3] Zhu, W. et al. (2006) Phytomedicine 13:695–701.

[4]Camargo Filho, I. et al. (2008) Phytomedicine 15:202–208.