Study of liquid culture system for micropropagation of the medicinal plant Solanum nigrum L. and its effect on antioxidant property

Solanum nigrum Linn., known for hepatoprotective and antioxidant properties, is extensively harvested from the wild. Supply is far short of demand, necessitating requirement of efficient in vitro propagation protocols. Nodal explants from wild S. nigrum plants were cultured in vitro in MS medium supplemented with 3.0 mg L^?1 IAA, 0.5 mg L^?1 BAP and gelled with 0.8 % agar. After 30 days, shoots buds were transferred to liquid MS medium of same composition. Subsequent subculture was carried out every 6 days. Shoot doubling time in solid and liquid media was calculated. Total phenolics, proanthocyanidin and flavonoid contents, ABTS^.+ and hydrogen peroxide radical scavenging antioxidant capacity of wild and in vitro aqueous leaf extracts were estimated and compared. In MS agar, 18 shoot buds were produced per explant after 30 days of culture, with shoot doubling time of 7.11 days. In liquid media, 21 shoots per explant were produced in 6 days, with a 5-fold higher multiplication rate and shoot doubling time of 1.37 days. Leaves were morphologically similar to those of wild plants. Total phenolics, proanthocyanidin and flavonoid contents of in vitro leaf extracts was 5–10 times higher than that of wild plants while ABTS^.+ and H₂O₂ radical scavenging activity was similar in both extracts. Liquid media is better suited for in vitro propagation of S. nigrum since enhanced multiplication rate was observed with shorter subculture intervals. Moreover, plants retained normal morphology and antioxidant property.