Formulation and in vitro evaluation of an anti-inflammatory herbal suppository containing Peperomia pellucida

Adverse effects associated with the anti-inflammatory medicines highlight the need for safer alternatives. The present study aimed to evaluate the anti-inflammatory characteristics of Peperomia pellucida and to develop an anti-inflammatory herbal suppository using the plant extract.

Methanolic and aqueous extracts of P. pellucida were assessed using 5-lipoxygenase inhibition assay, human red blood cell (HRBC) membrane stabilization assay, and egg albumin denaturation assay. The aqueous extract was characterized by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) analysis. Test suppositories containing the aqueous extract of P. pellucida were formulated using several bases, physically characterized, and subjected to stability assessment for 60 days. Triplicate results were statistically analyzed at p < 0.05.

The highest percentage inhibition of hemolysis was exhibited by the aqueous extract at 5000 μg/mL (88.42%) compared to the methanolic extract (58.08%) at the same concentration in the HRBC membrane stabilization assay. This observation was further supported by the lower IC₅₀ value of the aqueous extract (861.1 μg/mL). GC-MS analysis indicated the presence of a high abundance of long-chain fatty acids in the aqueous extract, including palmitic and myristic acids. The formulated suppositories exhibited acceptable weight uniformity (1.73 ± 0.00 g), hardness (8.12 ± 0.00 N), pH (7.53 ± 0.05), liquefaction time (534.2 ± 3.4 s), melting point (36°C-42 °C), and ex vivo drug permeation. No significant differences were observed in the quality parameters between day 0 and day 60 (p > 0.05).

The relatively low IC₅₀ value of the aqueous extract of P. pellucida demonstrated strong membrane stabilization, suggesting that solvent selection significantly influences the efficacy of botanical drugs. Fatty acids identified by GC-MS may account for the observed biological membranes stabilizing activity. The successful formulation of the aqueous extract into a suppository was evidenced by its customary physicochemical properties. The results of ex vivo permeation study and the absence of significant changes following the 2-month stability period confirm the efficacy and integrity of the dosage form. These findings support the potential of P. pellucida as a source for the development of novel, plant-based rectal therapeutics for inflammation-related conditions.