In vitro antiviral activity of bael (Aegle marmelos Corr) upon human coxsackieviruses B1-B6.

The in-vitro antiviral activity of a series of compounds in samples extracted from various parts of the Indian holy tree, Bael (Aegle marmelos corr.) were evaluated for their efficacy against human coxsackieviruses B1-B6. The inhibitory concentrations (IC50) for leaves (L1 and L2) stem and stem bark (S1, S2, S3 and S4) fruit (F1 and F2micro) root and root bark (R1 and R2) and pure compound, the marmelide were 1000 microg/ml (for L1 and L2), 1000 microg/ml (for S1, S2, S3 and S4), 1000 microg/ml (for F1) and 500 microg/ml (for F2) 250 microg/ml (for R1) and 500 microg/ml (for R2) and 62.5 microg/ml for marmelide respectively by plaque inhibition assay at 96 hrs. On the other hand, the corresponding value for Ribavirin, a standard antiviral drug, was 2000 microg/ml for the same viruses at the same time period. These concentrations did not exhibit any toxicity to Vero cells, the host subtoxic concentrations were 5000 microg/ml for leaf and stem fractions 2000 microg/ml for fruit fractions 500 and 1000 microg/ml for root fractions 250 microg/ml for marmelide and 2000 microg/ml for Ribavirin. The cytotoxic concentrations were 8000 microg/ml for leaf and stem compounds 4000 mg/ml for fruit; 1000 microg/ml and 2000 microg/ml for root 500 microg/ml for marmelide and 4000 microg/ml for ribavirin at 96 hrs. These were also confirmed by trypan blue dye exclusion test and further passaging of cells. Additionally pretreatment of host cells, virus inactivation, yield reduction and effect of time of addition assays against coxsackievirus B3 suggested that marmelide was most effective as a virucidal agent besides interfering at early events of its replicative cycle like adsorption, penetration, at various steps in single cycle growth curve and effect of time of addition.

'In vitro' antiviral activity of neem (Azadirachta indica. A. Juss) leaf extract against group B coxsackieviruses.

The antiviral and virucidal effect of methanolic extract fraction of leaves of neem (Azadirachta indica A. Juss) (NCL-11) was studied regarding its activity and possible mechanism of action against Coxsackie B group of viruses. NCL-11 inhibited plaque formation in 6 antigenic types of Coxsackie virus B at a concentration of 1000 micrograms/ml at 96 hrs. 'in vitro'. Additionally virus inactivation, yield reduction and effect of time of addition assays suggested that NCL-11 was most effective against coxsackie virus B-4 as a virucidal agent besides interfering at an early event of its replicative cycle. The evidence suggested that presence of a battery of compounds besides flavonoids, triterpenoids and their glycosides in NCL-11 have antiviral action for coxsackie B group of viruses 'in vitro.' The minimal inhibitory concentrations were not toxic to Vero (African green monkey kidney), cells; subtoxic concentration was 8,000 micrograms/ml and cytotoxic concentration 10,000 micrograms/ml, which was confirmed by trypan blue dye exclusion test.