Impact of Drought on Secondary Metabolites in Medicinal plant Desmodium gangeticum (L.) DC

Background/Objective: Various Secondary metabolites in Desmodium gangeticum (L.) DC. make this plant medicinally important. Also, this plant is naturally subjected to drought-like conditions; the main abiotic stress relates to low water availability to plants. However, literature is scarce regarding studies on drought stress impact on secondary metabolites content in Desmodium gangeticum (L.) DC. Methods: Plants were exposed to water regimes to generate drought-like conditions, i.e. 200, ml water was given at 3-day intervals for mild stress, 4-day intervals for moderate stress and 6-day intervals for severe stress. The flavonoids, phenolic and alkaloid content of the leaf were estimated at 15 and 30 days after drought stress (DAS). Findings: Desmodium gangeticum plant expressed differential responses in leaves number and size, secondary metabolite contents to water deficit based on the duration of stress applied. Leaves grown per plant decreased as the severity of drought stress increased (mild-11, moderate-8, severe-6 leaves) compared to control (14 leaves). Flavonoid content increased significantly at 15 DAS and decreased significantly by 50% at 30 DAS. Meanwhile, 15 and 30 days after drought stress (DAS), a significant decrease was observed in phenol and alkaloid content. Novelty: Our study highlights the intricate relationship between drought stress and the biosynthesis of biologically active secondary metabolites, flavonoids, phenolic and alkaloids, which can influence the therapeutic properties of Desmodium gangeticum. Keywords: Drought stress; Desmodium gangeticum (L) DC; Secondary metabolites; Flavonoids; Phenols; Alkaloids