Metabolic profiling of Piper regnellii (Piperaceae) and its dual anti-inflammatory and anti-urolithiatic effects.

Piper regnellii ("Pariparoba"), is a shrub widely employed in traditional medicine, particularly in the form of leaf infusions or decoctions. These preparations are traditionally used for the treatment of wounds, infections, edema, skin lesions, pain, and other inflammatory conditions. Building upon traditional reports of P. regnellii associated with inflammatory conditions, this study combined chemical profiling and bioactivity assays to evaluate its inhibitory effects on key inflammatory mediators (PGE2 and LTB4), alongside its effects on the reduction of calcium oxalate (CaOx) crystals. The anti-urolithiatic activity of P. regnellii infusion was evaluated using urine containing calcium oxalate (CaOx) crystals at concentrations of 0.5, 1.0, and 1.5 mg/mL. The results were compared to negative and positive controls (sodium citrate and Cystone®). Anti-inflammatory activity was assessed using an ex vivo human whole blood assay, evaluating key inflammation mediators, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4). The infusion's chemical profile was determined by UHPLC-ESI-HRMS in positive ion mode, using a gradient chromatographic method. Data were processed using MZmine software, and chemical annotation was performed utilizing in-house and online databases. In the ex vivo anti-inflammatory assay, infusion samples significantly reduced LTB4 and PGE2 levels with significant statistical differences compared to the negative control (p ≤ 0.05). The infusion demonstrated inhibition percentages of 57.4% and 75.1% for the release of LTB4 and PGE2, respectively. In the in vitro anti-urolithiatic evaluation, all tested concentrations of P. regnellii showed statistically significant differences compared to the negative control (p ≤ 0.05), with the highest concentration (1.5 mg/mL) demonstrating the strongest crystal reduction capacity (90.4%) and a calculated IC50 value of 0.21 mg/mL for anti-urolithiatic activity. Metabolic profiling of the aqueous extract revealed the presence of multiple bioactive compounds. The predominant classes of annotated compounds found on P. regnellii infusion were flavonoids, and other classes of compounds were also found. From all detected metabolites, 12 could be annotated at level 2 of confidence. This study provides scientific evidence supporting the traditional use of P. regnellii infusion related to inflammatory conditions. Additionally, the evaluation of its anti-urolithiatic effects expands the preliminary pharmacological insights into this species. Collectively, these findings suggest that P. regnellii may represent a promising source of bioactive compounds for the development of multitarget strategies addressing both inflammatory processes and urolithiasis-associated mechanisms.