Evaluation of Antimicrobial and Antioxidant potential of native and micropropagated plants of Tylophora indica

Abstract

The present study was conducted on an important medicinal plant namely Tylophora indica (Burm. f) Merrill belonging to family Asclepiadaceae with an aim to establish an efficient and reproducible in vitro protocol for its mass cloning and evaluation of antimicrobial and antioxidant potential of in vivo and in vitro plants. Tylophora indica is commonly known as ‘Antmool’ or ‘Dama Bel’ and it is known to have several pharmacological effects including anti-asthmatic, anti-inflammatory, antioxidant, diuretic, antimicrobial, anti-leukemia, immunosuppressive, anti-tumor and anti cancerous. Due to the lack of adequate propagation efforts and overexploitation of natural wild populations, T. indica is rapidly disappearing and is now listed as one of the plant species in India vulnerable to extinction. Therefore, we present an efficient and reproducible protocol for the mass propagation of this plant under in vitro conditions. Leaf explants were excised from 5 year old field grown healthy plant and thereafter planted on variously supplemented Murashige and Skoog’s (MS) medium for De novo adventitious shoot formation directly from the leaf explants. MS medium augmented with BAP either alone or in combination with adenine sulphate was most effective in inducing de novo adventitious shoots through the formation of meristemoids from leaf explants, where uncountable numbers of green healthy shoots developed on subsequent subculturing. The regenerated shoots were carefully rescued from the culture vessels and subjected to rooting on half strength MS medium or MS medium supplemented with either IBA or IAA. The best rooting response (95%) was observed on MS medium supplemented with IBA where cluster of long healthy roots was formed. Half strength MS medium also showed equally good response inducing rooting in 88% of cultures but the number of roots formed were less. Rooted plantlets were successfully acclimatized through various hardening stages and were successfully transferred to the field conditions depicting 90% survival rate with no phenotypic variations observed. The other objective of the present study was to evaluate the antimicrobial potential of native and micropropagated plants of Tylophora indica against bacterial (Staphylococcus aureus and Escherichia coli) and fungal strains (Aspergillius niger and Penicillium species). Antimicrobial activity of crude leaf extract was investigated using agar well diffusion method. All the extracts showed inhibitory activity for both bacterial and fungal strains but very less inhibitory activity was observed for Escherichia coli. The extract prepared by method Rao and Brook, 1970 exhibited a higher inhibition against both bacterial and fungal strains at all concentrations (25 μg/ml, 50 μg/ml and 100 μg/ml) and the methanol extract exhibited a significant inhibition activity against S. aureus, Aspergillius niger and Penicillium species. Least activity was observed by acetone extract of both in vitro and in vivo raised plant of Tylophora indica at all concentrations against bacterial as well as fungal strains. In current study, antioxidant activity (DPPH assay) has been carried out for the crude extract of roots of in vitro raised plant of Tylophora indica. The methanol extract of roots have exhibited significant antioxidant activity in DPPH method. The results indicates that the extracts firmly posses strong antioxidant effects. The higher free radical scavenging activity i.e. 75% was seen at 1000 μg/ml concentration. The results obtained from the present study indicates that the Tylophora indica, the plant root extract can be potential source of natural antioxidant activity. For appropriate determination of antioxidant capacity, the extractiON technique, its conditions, solvent used, and particular assay methodology are important.