Safety Assessment and Analgesic Anti-inflammatory Efficacy of Machilus macrantha Root Extract: In Vitro and In Vivo Studies

Background: In the management of pain and inflammation, the use of chemically derived anti-inflammatory and analgesics has limitations, which supports the use of plant-based phytoconstituents. In Ayurveda, the metabolites of Machilus macrantha root extract are less pharmacologically explored. Aim: Evaluate the phytochemicals, antioxidant, anti-inflammatory, and analgesic effects of aqueous root extract of M. macrantha by in vitro/in vivo models to validate traditional uses and assess it as a safer natural alternative. Objectives: Phytochemical screening, in vitro antioxidant assays, in vivo anti-inflammatory (carrageenan oedema), in vivo analgesic (writhing/hot plate) and therapeutic efficacy. Methods: The aqueous root extract of M. macrantha was evaluated for qualitative phytochemical tests and antioxidant potential. The screening of anti-inflammatories using an in vitro denaturation assay and carrageenan paw oedema in rats (180-200 g body weight) with a dose of 100, 200 and 400 mg/kg p.o. diclofenac sodium 10 mg/kg reference. The analgesic efficacy was assessed by acetic acid writhing and the hot plate method in rats (n=6), and statistical analysis was performed by ANOVA followed by Dunnett’s test with a significance of p-value p<0.05. Results: The phytochemical investigations reveal the presence of good phenolic content in the aqueous root extract of M. macrantha, and the availability of good phytoconstituents. No observation of clinical signs of toxicity at a dose of 2000mg/kg body weight, with stronger H2O2 scavenging activity of the aqueous extract at 100μg/ml, was found to be good, with 54.77% and 62.83% at 100 in the reducing power assay. The maximum decrease in protein denaturation (86.38 ± 2.31%) was observed at 100 μg/ml concentration, with the highest writhing inhibition of 33.42% at a 400mg/kg dose of root extract than another dose. The analgesiometer hot plate animal latency was significantly higher at the 400mg/kg dose than at lower doses. Conclusions: The notable phytoconstituents in the root extract of M. macrantha include stigmasterol, β-sitosterol, Machigline and Machiline, flavonoids, and polyphenols, known to prevent activation of the cycloxygenase-2 enzyme responsible for analgesic and anti-inflammatory properties. Major Findings: The aqueous root extract of M. macrantha aqueous root extract demonstrated significant antioxidant, analgesic, and anti-inflammatory activities, attributed to the presence of phytoconstituents. The extract showed strong H₂O₂ scavenging activity, maximum inhibition of protein denaturation (86.38 ± 2.31%), significant reduction in carrageenan-induced paw oedema, and dose-dependent analgesic activity in hot plate and writhing models, without producing toxicity at 2000 mg/kg.