Hydro-ethanolic Extraction Modulates Phytochemicals and Bioactivities of Pogostemon cablin Leaves

Abstract

Pogostemon cablin (Blanco) Benth. is a medicinal plant notable for its diverse secondary metabolites. However, investigations of its bioactive properties beyond essential oils remain scarce. Solvent polarity, especially ethanol concentration in hydro-ethanolic systems, plays a key role in influencing phytochemical composition and related biological activities. This study evaluated the impact of ethanol concentration on the phytochemical profile and bioactivities of P. cablin leaf extracts obtained using ultrasonic-assisted extraction. Quantitative analysis indicated that the HC2 extract (1:1, v/v ethanol–water) contained the highest Total Phenolic Content (TPC) (243.89 ± 56.61 mg GAE g-1 extract) and Total Flavonoid Content (TFC) (26.16 ± 1.98 mg QE g-1). Antioxidant capacity, assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, exhibited an increasing trend with higher ethanol proportions. Among the extracts, HC3, prepared at a 3:1 (v/v) ethanol-to-water ratio, demonstrated the most pronounced activity, with a DPPH IC₅₀ of 29.52 ± 0.20 µg mL-1, FRAP value of 608.55 ± 2.41 µg TE g-1, and ABTS value of 88.80 ± 0.49 µg TE g-1. Liquid chromatography–tandem mass spectrometry (LC–MS/MS)-based phytochemical profiling revealed a complex metabolite composition dominated by phospholipids, phenolics, flavonoids, amino acids, and coumarins. The extracts exhibited concentration-dependent antimicrobial activity against Streptococcus mutans, Klebsiella pneumoniae, and Candida albicans, with 50–75% hydroethanolic extracts showing notable inhibition. Overall, ethanol concentration markedly influences phytochemical composition and associated bioactivities, highlighting the importance of optimizing solvent systems.