Screening for antiviral activity of sweet lemon grass (Cymbopogon nardus (L.) Rendle) fractions

Abstract

A study was carried out to test the cytotoxicity and antiviral effects of sweet lemon grass (Cymbopogon nardus (L.) Rendle) fractions. A total of 51 fractions were obtained after two sequential runs of flash chromatography. Further fractionation on selected fractions by preparative Thin Layer Chromatography (TLC) resulted in 40 sub fractions. The cytotoxicity towards Vero cells of the different fractions ranged from highly toxic (N3 and N29; 30 μg mL-1) to considerably non toxic (N16, N17 and N19; 1 mg mL-1). For antiviral activity test the cells were inoculated with 10 μL measles virus 1000 TCID50 and treated with 1.0 LC50. 0.1 LC50 or 0.01 LC50 concentrations of each fraction. Most fractions protected cell death due to measles inoculation when compared with the untreated controls, but were less effective when compared to the control guanidine hydrochloride treatment of 0.1 mg mL-1. Treatment of Vero cells with fractions at 0.1 LC50 gave higher cell survival when compared to the other concentrations, which were 1.0 LC50 or 0.01 LC50. At 0.1 LC50, the C. nardus fractions were most effective when cells (C) were treated with the fractions (F) before being inoculated with the virus (V), which was treatment {(C+F) + V}. Using this method, more fractions with higher efficacy (+++) was obtained when compared with the methods {(C+V) + F} or {C + (V+F)}. Similar, treatment of cell culture with sub fractions before virus inoculations showed better antiviral effect that treatment after viral inoculations. This suggests that fractions and sub fractions were more effective in protecting cells against entry of virus particles into inoculated cells than other phases in the viral replication. © 2006 Asian Network for Scientific Information.