RESEARCH ARTICLE IN VITRO SCREENING OF ANTIVIRAL ACTIVITY OF LYOPHILIZED EXTRACTS OF AZHADIRACHTA INDICA AND QUERCUS LUSITANICA ON DENGUE 1 & 3 SEROTYPES *Shanthi, G. and Rajarajan, S. PG & Research Department of Microbiology and Biotechnology, Presidency College (Aut.), Chennai-5, Tamilnadu, India ARTICLE INFO ABSTRACT Dengue fever has become a global concern and can lead to a severe life threatening illness. The development of dengue vaccines is complicated by the antibody dependent enhancement effect. Thus the development of a plant based antiviral preparation promises a more potential alternative in combating dengue disease. The present study investigated the antiviral effects of standardized lyophilized aqueous, aqueous-ethanolic and ethanolic extracts of Azhadirachta indica and Quercus lusitanica on Dengue 1 & 3 strains in Vero cell line and compared with known antiviral drug Ribavirin. The antiviral activity of lyophilized aqueous extract of Azhadirachta indica showed better activity for Dengue 1 & 3 at a Maximum nontoxic dose concentration of 500μg/ml and the ethanolic extracts are partially inhibited at the concentration of 500μg/ml to dengue 1 but not in dengue 3. Whereas the aqueous-ethanolic extract of neem and three extracts of Quercus lusitanica did not show any inhibition on dengue 1 & 3. The antiviral activity of Ribavirin exhibited 15.6μg/ml & 7.5μg/ml for dengue 1 & 3 respectively. These data suggest that the lyophilized aqueous extracts of Azhadirachta indica possess the ability of inhibiting the activity of Dengue 1 & 3 by in vitro assays. This plant is worth to be further investigated and might be advantageous as an alternative drug for dengue treatment. Copyright © 2014 Shanthi, G. and Rajarajan, S. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. INTRODUCTION Dengue disease, regardless of its serotypes is transmitted from person to person by Ades aegypti and Ades albopictus mosquitoes in domestic environment (Halstead, 1997) and is an endemic in more than 110 countries with two –fifths of the world population at risk (Guzman, 2004). The World Health Organization (WHO) estimates that 50-100 million dengue infection occurs each year and that almost half the world’s population lives in countries where dengue is endemic. Currently close to 75% of the global population exposed to dengue are in the Asia Pacific region (Shasonk Sankar and Debashmita Dubey 2013). Similarly, a total of 4.6 fold increase in dengue cases has also been reported in America over the three decades (Gibbons, 2010). Dengue appears in two forms: the first class is dengue fever with symptoms that range from mild fever to high fever with retro-orbital pain, severe headache, maculopapular rashes, muscle and joint pain. The other more severe form, Dengue Haemorrhagic fever (DHF) and Dengue Shock syndrome (DSS) may present with abdominal bleeding, hemorrhage and circulatory failure, which is fatal if without prompt and proper management (Gubler, 1998). There are four serologic types of dengue virus, DENV- 1, 2, 3 and 4. A primary infection with any of the four *Corresponding author: Shanthi, G. PG & Research Department of Microbiology and Biotechnology, Presidency College (Aut.), Chennai-5 Tamilnadu, India. serotypes results in a lifelong immunity to that serotype, and temporary immunity to the others. However, this temporary immunity usually wanes after 6 months, at which point an individual is susceptible to the other three DENV serotypes (Murrel et al., 2011). The primary infection is most often asymptomatic, but sequential infections in the presence of heterologous dengue antibodies often lead to a more severe secondary infection causing DHF or DSS. Murrel et al. (2011) attributed this due to the antibody-dependent enhancement (ADE) effect. Studies of the outbreaks in endemic areas, such as South East Asia revealed that a primary infection with DENV-1 or DENV-3 frequently resulted in a more severe disease than if DENV-2 or DEV-4 where the primary infection (Vaughan et al., 1997). Hence this study focused foremost on to Dengue 1 and 3 serotype for remedies. Early studies have shown that extracts from different parts of plants could provide good antiviral results as compared to their synthetic analogues (Chiang et al., 2005). As such, the development of a plant-based antiviral preparation promises a more potential alternative in combating dengue disease. “Let food be your medicine and let medicine be your food” was the advice of the father of medicine, Hippocrates, over two millennia ago (Wang MY et al., 2002). Herbal and natural products of folk medicine have been used for Centuries in every culture throughout the world. Scientists and medical ISSN: 0975-833X Available online at http://www.journalcra.com International Journal of Current Research Vol. 6, Issue, 04, pp.6083-6087, April, 2014 INTERNATIONAL JOURNAL OF CURRENT RESEARCH Article History: Received 14 th January, 2013 Received in revised form 18 th February, 2014 Accepted 20 th March, 2014 Published online 23 rd April, 2014 Key words: Dengue virus, Azhadirachta indica, Quercus lusitanica, Extracts, In vitro assays, Ribavirin.