Polygonum posumbu (an ethnomedicinal plant) extract shows antihypertensive potential via ACE inhibition supported by antioxidant activity and LC-MS/MS metabolite profiling

Polygonum posumbu is recognized for its therapeutic efficacy, particularly in traditional medicine for the treatment of hypertension. The aim of the current study was to examine the antihypertensive activity, antioxidant activity, antimicrobial activity of the plant and to characterize their bioactive phytochemical constituents using UHPLC-Orbitrap LC-MS/MS. P. posumbu leaf was extracted using 80% methanol and then studied for phytochemical makeup, antihypertensive activity, the antioxidant activities and antimicrobial activities. The phytochemical profile of the extract was further characterized using UHPLC-Orbitrap LC-MS/MS. The extract showed significant angiotensin-converting enzyme (ACE) inhibitory activity (IC 50 = 298.46 ± 1.38 µg/mL), indicating a possible function for it in the treatment of hypertension. The existence of major secondary metabolites, such as tannins and alkaloids, was established by preliminary phytochemical screening. Several in vitro tests, including ABTS. + radical cation decolorization, hydroxyl radical scavenging, ferric reducing antioxidant power (FRAP), nitric oxide scavenging, superoxide anion radical scavenging, and phosphomolybdenum assays, were used to assess the extract’s antioxidant capacity. Strong free radical scavenging and lowering capacity was demonstrated by the extract’s noteworthy IC 50 values (ABTS. + - 134.96 ± 3.86 µg/mL, hydroxyl radical − 482.64 ± 6 µg/mL, Nitric oxide radical − 11.53 ± 0.48 mg/mL, superoxide anion radical − 181.98 ± 4.08 µg/mL) and the considerable antioxidant activity given by FRAP (18.66 µmol Fe2+/TE) and Phosphomolybdenum assay (126 ± 2.5 mg AAE/g extract). The extract’s broad-spectrum therapeutic potential is further demonstrated by its antibacterial effectiveness against specific microbial strains. Significant variations in the assessed parameters were found by statistical analysis ( p < 0.001). UHPLC-Orbitrap LC-MS/MS profiling tentatively identified 13 antihypertensive compounds, including gallic acid, rosemarinic acid, naringenin, ferulic acid, luteolin, oleanolic acid, quercetin, neochlorogenic acid, kaempferol, caryophyllene oxide, chrysin, ursolic acid, and apigenin, etc., supporting the potent ACE inhibitory and antioxidant activities of the extract. Overall, the results point to P. posumbu as a prospective source of naturally occurring bioactive chemicals with strong antihypertensive, antibacterial, and antioxidant qualities. This study demonstrated that P. posumbu leaves are rich source of naturally occurring bioactive compounds that exhibit potent antihypertensive, antibacterial, and antioxidant activities. The LC-MS profile provides phytochemical evidence supporting the observed ACE inhibitory and antioxidant activities, warranting further in vivo studies and isolation of the active constituents.