Changing in the production of anticancer drugs (vinblastine and vincristine) in Catharanthus roseus (L.) G. Don by potassium and ascorbic acid treatments

Catharanthus roseus seedling was treated with different concentrations (1.5, 3.16, 15, and 30 mmol) and forms (K2SO4 and KNO3) of potassium (K+) via Hoagland's nutrient solution. Ascorbic acid (AsA) was sprayed twice (plant days 68 and 78) with different concentrations (750 and 1 500 mg/L) on the leaves. Vinblastine, vincristine, tryptophan contents, D4H and DAT genes expression, peroxidase activity, and H2O2 content of leaves were measured. Potassium in KNO3 form increased vinblastine (60%) and vincristine (50%), compared to 30% and 20% using K2SO4. Vinblastine and vincristine inhibit microtubule assembly and ultimately metaphase-arrested caused by the polymerisation. The genes expression was higher 3 times in KNO3 and 2.5 times in K2SO4 in excess of K+. Foliar application of 750 mg/L AsA led to an increase in vinblastine (20%) and vincristine (16%). Both concentrations of AsA had the same additional effect on the expression of D4H and DAT about 30% and 60%, respectively, compared to the control plant. Tryptophan decreased 2.5 times in excess of K+ and 35% due to the exterior of AsA. H2O2 decreased while peroxidase activity increased along with AsA treatment. A positive interaction existed between the K+ and AsA on the amount of vinblastine, vincristine, tryptophan, and gene expression.