Growth and asiaticoside production in multiple shoot cultures of a medicinal herb, Centella asiatica (L.) Urban, under the influence of nutrient manipulations.

Growth and in vitro asiaticoside accumulation in multiple shoot cultures of Centella asiatica (L.) Urban was studied as a function of nutrient manipulations in the culture media. Shoot cultures raised in liquid Murashige and Skoog medium supplemented with 2.5 mg/l kinetin attained a growth index (GI) of 6.06 along with the highest asiaticoside content of 3.8 mg/g dry weight on the 35th day of the culture cycle. The shoot growth and asiaticoside accumulation were found to be influenced by the relative proportions of NH(4)(+)-N:NO(3)(-)-N or Cu(2+) concentration in the medium. Asiaticoside content in shoots increased from 5.3 to 8.9 and 8.7 mg/g dry weight when total nitrogen concentration of 60 mM in the control medium was reduced to 50 and 40 mM with a corresponding change in NH(4) (+):NO(3)(-) ratio from 20:40 to 20:30 or 20:20, respectively. Total nitrogen level higher than 60 mM drastically reduced the asiaticoside concentration in these in vitro shoot cultures. Medium devoid of Cu(2+) significantly favored higher asiaticoside accumulation in the cultured tissue (7.05 mg/g dry weight) along with an improved biomass production (GI = 7.7) when compared with shoots reared on the control medium with 0.10 μM Cu(2+) (GI = 5.8; asiaticoside content = 4.4 mg/g dry weight). Carbohydrate enrichment of the medium by increasing the sucrose concentration from 3.0 to 5.0 or 7.0% was also beneficial for biomass and asiaticoside production with GI = 17.1 and 16.9 and asiaticoside content = 7.2 and 5.2 mg/g dry weight, respectively, in comparison to control cultures maintained on medium containing 3.0% sucrose. The procedure described here provides a viable production platform for generating clean and quality material from Centella with high bioactive content.