ENHANCED PRODUCTION OF VASICINE, AN ALKALOID IN CALLUS AND SUSPENSION CULTURES OF Adhatoda zeylanica

Adhatoda zeylanica is an important medicinal plant and being used in the rural areas of India for several ailments. It belongs to the family Acanthaceae and is known as Vasaka in Sanskrit, Malabar nut in English. The leaves contain a pyrroloquinazoline alkaloid called Vasicine. It is a powerful expectorant, antiseptic, antiperiodic and antihelminthic. Besides seasonal variations, majority of the plant-based alkaloids can not be chemically synthesized. Tissue culture protocols for a number of medicinal plants were established, and this enabled the analysis of callus/cell suspension extracts for the presence of different classes of secondary products.. Therefore, research attempts for the production of secondary metabolites of pharmaceutical importance through tissue culture approach was taken up to enhance the production of vasicine. Callus cultures were established from leaves and petioles of A.zeylanica on Murashige and Skoog and B5 medium supplemented with auxins (2,4-D and NAA) and cytokinins (6-BA and kinetin).The synthesis of vasicine was more in leaf-derived callus grown on MS medium with 10.7µM NAA and 4.4 µM 6-BA along with 0.5ml/l of Ornithine(4.7mg/gDW). Suspension cultures were treated with different biotic and abiotic elicitors to increase the content of vasicine. Aspergillus niger at a concentration of 1.5ml/l gave maximum yield of 4.72mg/gDW of vasicine after an incubation of 48hrs. Chitosan yielded 5.54mg/gDW of vasicine at a concentration of 150mg/l for 48 hrs incubation.Synthesis of vasicine was detected and confirmed by thin layer chromatography,1H NMR, 13C NMR, electron ionization mass spectra and high pressure liquid chromatography analyses.