EVALUATION OF THE ANTIVIRAL ACTIVITIES OF GYNOSTEMMA PENTAPHYLLUM AND MORINGA OLEIFERA AGAINST THREE RNA VIRUSES

AUTHOR: OKOYE, EBELE LINDA  

DEPARTMENT: APPLIED MICROBIOLOGY AND BREWING

AFFILIATION: NNAMDI AZIKIWE UNIVERSITY, AWKA

The antiviral activity of the crude extracts of Gynostemma pentaphyllum Thumb. (GP) and Moringa oleifera Lam. (MO) on three RNA viruses (Yellow fever virus, Poliomyelitis virus and Human Immunodeficiency Virus) were evaluated. The antiviral properties were determined against yellow fever virus using three methods: – Protection of chicken egg embryo against viral infectivity by the extracts, protection of mice against viral infectivity by the extracts and percentage inhibition of viral induced haemagglutination by the extracts, while that of Polio virus was determined against the three sero-types of Poliovirus using the end-point cytopathic effect assay on L20B cell lines. For the HIV, recombinant lentiviral vector expressing the Green Fluorescent Protein (GFP) gene was constructed and the inhibition of viral vector infectivity by various concentrations of the extracts was evaluated in Hela cells by measuring the changes in GFP expression. Cytotoxicity of the extracts was also evaluated in parallel by the MTT {3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide} assay method. Phytochemical analysis of the extracts revealed the presence of saponins, alkaloids, glycosides, tannins, flavonoids, carbohydrates, reducing sugar, resins and proteins. The result of the egg embryo and mice protection studies against yellow fever viral infectivity showed that the extracts were able to give up to 100% protection to the embryonated eggs and mice at the various concentrations(200mg/ml,20mg/ml and 2mg/ml) used and hence prevented egg/mice mortality. The extracts gave a very good percentage inhibition of Yellow fever virus in embryonated eggs up to 90%. It was observed that the inhibition of Yellow fever virus decreased with decrease in concentration. Antiviral assay against Poliovirus showed that the methanolic extract of GP had the highest selectivity index (SI) (150) and least IC50(0.05) followed by the methanolic extract of MO (>125 and IC50 of <0.03) against Polio 1 Virus while ether extract of GP had the lowest SI (4.95 and IC50 of 0.19). For Polio 2 virus, the methanolic extract of MO had the highest SI (41.67 and IC50 of 0.09), followed by methanolic extract of GP while the ether extract of MO had the least SI (2.47 and IC50 of 0.38). Assay against Polio 3 virus also showed that the methanolic extract of MO had the highest SI (19.70 and IC50 of 0.19) followed by methanolic extract of GP which gave SI of 10 and IC50 of 0.75 while the ether extracts of both MO and GP gave the least SI (2.47 and IC50 of 0.38).Thus methanolic extract showed the best activity against the three serotypes of poliovirus. HIV-1 vector viral infectivity were inhibited by the extracts giving a range of selectivity indices of 4.26(EM), 4.65(MG), 5.04(MM), 5.80(AM), 5.92(AG) and 7.02(EG). Ether extract of GP gave the highest SI while ether extract of MO gave the least SI. This shows that the extracts selectively inhibited the viruses and that their activities against the viruses were not just a consequence of toxicity to the cells. The results showed Hela cell viability even at high concentrations of the extracts. The research has shown that the plants possess potent antiviral properties and could serve as possible sources of lead antiviral drugs against Yellow fever virus, Poliovirus and HIV.

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