Effects of Oven-Drying on the Phytochemical and Phenolic Acid Contents of Ethanol Extracts of the Root, Stalk and Leaves of Cymbopogon citratus

Drying techniques play vital roles in the post-harvest processing of medicinal plants because they control microbial growth and enzymatic breakdown of plant nutrients. Cymbopogon citratus possesses diverse medicinal values in different cultures. However, little is known about the effect of drying methods on the phytochemical and phenolic acid content of lemongrass. The study comparatively evaluated the effect of drying methods on phytochemical and phenolic acids in the stalk, root and leaf extract of Cymbopogon citratus. The phytochemical test was done by standard techniques while the phenolic acids were analyzed by the high-performance liquid chromatographic (HPLC) method. The presence of flavonoids, glycosides, alkaloids, saponins, phenols, and tannins was detected via qualitative phytochemical analyses. The results of the quantitative phytochemical analysis showed that the concentrations of terpenoids (2.63 to 2.00 mgLI/g extract) and saponins (4.60 to 3.79 mg DE/g extract) were significantly (p < 0.05) lower in all oven-dried samples. There was a significant difference (p < 0.05) in the alkaloids, saponins and terpenoids contents of shade- and oven-dried samples. The HPLC analysis of phenolic acids revealed higher concentrations of total phenolic (0.09 vs 25.35 mg GAE/g extract), caffeic (1.0 x 10-4 vs 4.5 x 10-4 mg/g extract) and coumaric (1.9 x 10-4 vs 4.5 x 10-4 mg/g extract) acids in the oven-dried compared with shade-dried samples. The study showed that the variations in the phytochemical and phenolic acids constituents of shade- and oven-dried tissues of C. citratus may provide useful data germane for determining lead compounds during post-harvest processing.