Safety, Analgesic, and Anti-Inflammatory Effects of Aqueous and Methanolic Leaf Extracts of Hypericum revolutum subsp. keniense

Abstract

In light of the enduring obstacles encountered in analgesia and anti-inflammatory therapeutics despite the strides made in contemporary medical sciences, the quest for alternative efficacious strategies is an imperative pursuit. Thus, this study investigated the safety profiles, as well as the analgesic and anti-inflammatory attributes, of aqueous and methanolic leaf extracts derived from Hypericum revolutum subsp. keniense—a botanical entity entrenched in historical ethnomedicinal practices in the Kenyan context. The assessment of acute oral toxicity of these extracts was conducted in accordance with the Up- and-Down method advocated by the Organisation for Economic Cooperation and Development (OECD), utilizing Swiss albino mice as the experimental subjects. Subsequent investigation entailed the evaluation of antinociceptive and anti-inflammatory properties employing the acetic acid-induced writhing and carrageenan-induced paw oedema methodologies, respectively, in the same murine model. The findings of this study evince the safety of both aqueous and methanolic extracts, with LD50 values surpassing 2000 mg/kg body weight and the absence of discernible signs of toxicity. Furthermore, a notable dose-dependent (P<0.05) manifestation of analgesic effects was observed for both extracts, with the aqueous variant demonstrating heightened potency compared to its methanolic counterpart (P<0.05). Moreover, the anti-inflammatory efficacy escalated significantly with escalating extract doses and prolonged treatment duration (P<0.05), wherein the aqueous extract showcased superior effectiveness vis- à-vis the methanolic extract across all dosage regimens and temporal checkpoints (P<0.05). Therefore, this investigation underscores the latent promise of the examined extracts as reservoirs of safe and efficacious analgesic and anti-inflammatory agents, thereby meriting further meticulous exploration. Subsequent research endeavours ought to pivot towards elucidating the phytochemical constituents underpinning the observed effects, alongside unravelling their mechanistic underpinnings across a spectrum of animal models and clinical milieus.