Optimization of Solvent Systems Used in the Extraction of Kleinhovia hospita Leaves: Implication on Flavonoid, Phenolic Contents, and Antioxidant Properties

Kleinhovia hospita L. is known to contain various phytochemical compounds with potential antioxidant activity. The efficiency of extracting these bioactive compounds can be influenced by the solvent system used during extraction. This study aimed to perform a comparative evaluation of different water–ethanol solvent systems for extracting phenolic and flavonoid compounds from Kleinhovia hospita leaves and to investigate their antioxidant activity. Dried leaf powder was extracted using four solvent compositions viz. water (100:0), water–ethanol (50:50), water–ethanol (30:70), and ethanol (0:100). The extracts were evaluated for extraction yield, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity using DPPH, ABTS, and FRAP assays. The results showed that solvent composition influenced extraction yield, phytochemical content, and antioxidant activity. Ethanol-rich solvent systems generally gave higher phenolic (22.79 ± 0.04 mg GAE/g) and flavonoid contents (28.040 ± 0.58 mg QE/g) and exhibited stronger antioxidant activity compared with aqueous solvent systems. However, further analytical validation using more advanced chromatographic techniques is required for accurate quantitative determination. These findings suggest that ethanol-based solvent systems may be more suitable for extracting antioxidant compounds from Kleinhovia hospita leaves and may serve as a reference for future phytochemical and antioxidant studies.