Antinociceptive activity of extracts and secondary metabolites from wild growing and micropropagated plants of Renealmia alpinia

Abstract

Ethnopharmacological relevance: Renealmia alpinia is native to the American continent and can be found from Mexico to Brazil, and in the Caribbean islands. It is known as "matandrea" in Colombia, and it has been commonly used in traditional medicine to treat painful diseases and ailments. Based on its traditional uses, it is of interest to evaluate the pharmacologic effects of this plant and its secondary metabolites.

Materials and methods: Methanol and aqueous extracts of wild and micropropagated R. alpinia (leaves) were obtained and chemically compared by High Performance Thin Layer Chromatography (HPTLC). The antinociceptive activity of these extracts was examined using an in vivo assay (Siegmund test). Additionally, the dichloromethane extract of R. alpinia was fractionated and pure compounds were isolated by chromatographic methods. The structure elucidation of isolated compounds was performed by NMR experiments and spectroscopic techniques and comparison with the literature data. Purified compounds were evaluated for their in vitro binding affinity for opioids and cannabinoids receptors.

Results: The dichloromethane extract of the plant's aerial part afforded sinostrobin (1), naringenin 7,4'-dimethyl ether (2), 2',6'-dihydroxy-4'-methoxychalcone (3), 4-methoxy-6-(2-phenylethenyl)-2H-pyran-2-one (4), naringenin 7-methyl ether (5) and 3,5-heptanediol, 1,7-diphenyl (6), which were isolated using chromatographic methods. Their chemical structures were established by physical and spectroscopic techniques. The antinociceptive effects observed in mice by extracts of wild and micropropagated plants were similar. The compounds isolated from R. alpinia do not show affinity to opioid or cannabinoid receptors.

Conclusion: Aqueous and methanol extracts of R. alpinia provide antinociceptive and analgesic effects in an in vivo model. These results contribute additional insight as to why this plant is traditionally used for pain management. Also, this is the first comprehensive report of a phytochemical study of R. alpinia.

Keywords: 2′,6′-dihydroxy-4′-methoxychalcone (3) (PubChem CID: 5316793); 4-methoxy-6-(2-phenylethenyl)-2H-pyran-2-one (4) (PubChem CID: 164901); Antinociceptive; Cannabinoid receptor; HPTLC; In vitro propagation; Opioid receptor; Pinostrobin (1) (PubChem CID: 4101463); Renealmia alpinia; naringenin 7,4′-dimethyl ether (2) (PubChem CID: 14057196); naringenin 7-methyl ether (5) (PubChem CID: 14057196).