Cytotoxicity Studies and Antiviral Activity of Sesbania grandiflora

Abstract

Sesbania grandiflora (Linn) is a tree known for many medicinal properties, and all parts of the tree are used in folk medicine and Ayurveda, for various conditions such as diarrhoea, dysentery, smallpox and other eruptive fevers, nasal catarrh, bronchitis and pain. Antiviral activity and cytotoxicity of hexane, ethyl acetate, acetone and methanol extracts from the leaf, bark and flower of Sesbania grandiflora were studied. The leaf, bark and flower were separately extracted by solvents; Hexane, Ethyl Acetate, Acetone, and Methanol; sequentially. The extracts were analysed for their cytotoxic concentration by the MTT method, and antiviral activity against viruses, Herpes Simplex Virus type 1 (HSV 1) and Coxsackie virus B2 (Cox B2) in Vero cells, by inhibition of CPE. The quantity of viral nucleic acid produced was monitored in relation to untreated virus controls using real-time PCR. The study found significant antiviral activity for the different plant extracts, justifying its use in traditional medicine for various syndromes of viral aetiology. Apart from a previously reported antiviral activity of the methanol extract of flowers, this study reports the presence of compounds with significant antiviral activity in the acetone extract of leaf, acetone and ethyl acetate extracts of bark and ethyl acetate extract of flower as well. The acetone extract of the leaf showed antiviral activity against both HSV 1 and Cox B2 giving protection of 50% and 90% respectively (IC50 0.073 mg/ml). The bark ethyl acetate extract gave 100% and 60% protection (IC50 0.046 mg/ml); bark acetone extract gave 90% and 100% protection (IC50 0.1 & 0.052 mg/ml) against HSV 1 and Cox B2, respectively. Among the flower extracts, ethyl acetate extract gave 100% protection against HSV 1 and gave 80% protection against Cox B2 (IC50 0.2 mg/ml). The real-time PCR assay which quantifies the inhibition of viral DNA production had an excellent correlation with CPE production. All four extracts showed significant activity against HSV type 1 and Coxsackie B2 viruses with Therapeutic Indices ranging from 1:1 to 1:4, which is very promising for drug development, as the above therapeutic index is in the crude extract.