Altering Amino Acid Profile in Catharanthus Roseus (L.) G. Don Using Potassium and Ascorbic Acid Treatments

Catharanthus roseus (L.) G. Don is the main source of alkaloids anticancer drugs. Alkaloids are derived from amino acids and can lead to changes in these valuable compounds.

This experiment evaluated the variation of amino acids under potassium and ascorbic acid treatments.

Different concentrations (1.5, 3.16, 15 and 30 mM) and forms (K₂SO₄ and KNO₃) of potassium (K⁺) were added to plants via Hoagland’s nutrient solution. Ascorbic acid (AsA) (750 mg L^-1) was sprayed on the leaves surfaces on days 68 and 78. Amino acids were extracted from 90-day-old plant leaves, and different amino acids were determined by High-Performance Liquid Chromatography with fluorescence detection.

Amino acids increased in K⁺ deficiency (1.5 mM), but changes in negatively charged amino acids were lower. In contrast, N-rich amino acids showed the biggest change. In excessive K⁺, branched-chain and aromatic amino acids decreased, while the least amount of the other amino acids was observed in the plants treated with optimum K⁺.

The exterior of AsA and excessive K⁺ cause branched-chain and aromatic amino acids, aspartic acid and glutamic acid to decrease.