Hypotensive Activity of Moringa oleifera Lam (Moringaceae) Root Extracts and its Volatile Constituents

Purpose: To explore the hypotensive activity and chemical composition of Moringa oleifera Lam (Moringaceae) roots.Methods: The fresh roots of M. oleifera was cut into small pieces and successively extracted with petroleum ether (PE) and dichloromethane (DC). PE extract was further divided into MRP and MRP -1. DC extract showed a thick mass during evaporation which was separated as MRDC - IN. The mother liquor left was divided into MRDC and MRDC -1. All residues were analyzed by gas chromatographymass spectroscopy (GC-MS) using ZB-5 column. Identification of each extract and fraction was based on comparison of their retention indices (RI), by co-injecting authentic compounds, as well as by comparing literature data available in NIST Standard Reference Database. Hypotensive activity was determined on urethane-anesthetized normotensive Sprague Dawly rats.Results: Petroleum ether (MRP) and dichloromethane (MRDC) extracts of M. oleifera roots showed 50.06 ± 3.48 and 48.16 ± 1.79 % fall in mean arterial blood pressure (MABP), respectively, at a dose of 30 mg/kg (p < 0.01 and p < 0.05, respectively) compared with control. GC-MS analysis of MRP and MRDC extracts and fractions resulted in the identification of seventy four (74) compounds. Methyl hexadecanoate (7, 20.3 %) , stigmastan - 3, 5, diene (24, 19.32 %), methyl 14-hydroxy-5-tetradecenoate (9, 19.22 %), 1 , 11 diphenyl undecane (47, 18.78 %) and cyclopentanyl hexadecane (39, 14.44 %) were the major constituents among the various hydrocarbons, fatty acids, esters, alcohols, aldehydes, isothiocyanate, aromatics, steroids, terphenyl and sulphur-containing compounds. Conclusion: The findings reveal the hypotensive potential of M. oleifera roots and the presence of specific hydrocarbons, fatty acid esters, thioureides, steroids and isothiocyanates in active fractions. Further study is required to determine the suitability of the plant as an antihypertensive remedy.Keywords: Moringa oleifera, Methyl hexadecanoate, Methyl 14-hydroxy-5-tetradecenoate, Petroleum ether, Stigmastan - 3, 5, diene, Cyclopentanyl hexadecane