Preliminary Phytochemical Screening and Analgesic Activity of the Methanol Extract of Solenostemon monostachyus (Whole Plant)

Background & Aim: Solenostemon monostachyus is an important herb that is used in the treatment of various ailments such as pain, cough, asthma and arthritis amongst the Bini people of Edo State, Nigeria. Hence this study, designed to evaluate the methanol extract of the whole plant of Solenostemon monostachyus in the management of pain.

Experimental: 220 g of the pulverized plant was first defatted by extracting with hexane (to remove the nonpolar constituents) using a Soxhlet apparatus, after which methanol was used to extract the defatted plant material. The percentage yield of the hexane and methanol extracts were 3.32% and 10.18% respectively. The methanol extract was then subjected to phytochemical screening, acute toxicity and antinociceptive tests (acetic acid-induced and hot plate models).

Results: Phytochemical screening of the methanol extract revealed the presence of glycosides, saponins, flavonoids, steroids, terpenoids and alkaloids. The methanol extract caused a significant (p < 0.05) dose-dependent reduction in pain induced by acetic acid (peripherally mediated) and hot plate (centrally mediated). These effects were comparable to the effects of the standard drugs (Acetylsalicylic acid 100 mg/kg and Pentazocine 10 mg/kg) used in the study.

Conclusion: This study has confirmed the presence of useful phytochemicals in the methanol extract of the plant material. These phytochemicals could either serve as templates for the synthesis of drugs or as drugs themselves. Also, the study validated the ethnomedicinal use of the whole plant of Solenostemon monostachyus as well as it's polar constituents in the methanol extract, for the treatment of pain.