Towards Establishing Chemical Markers for Antidiabetic Plants: A Comparative Analysis of the Chemical Fingerprints of Three Validated Antidiabetic Plants, Nauclea latifolia, Azadirachta indica and Moringa oleifera

A drawback to the mainstreaming of medicinal plants into modern medicine is the issue of standardization of crude plant extracts. The aim of this study was to compare chemical fingerprints of the ethanolic leaf extracts of three known antidiabetic plants namely Nauclea latifolia, Azadirachta indica and Moringa oleifera and to establish if they are some common phytochemicals, with antidiabetic activities, that could be used as active biomarkers for antidiabetic plants and subsequently for standardization of the plant preparations. The dried pulverized leaves were macerated in 80% ethanol and subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Chromatograms of extracts showed 51, 35 and 53 peaks of identified phytochemical compounds for Nauclea latifolia, Azadirachta indica and Moringa oleifera respectively. However, only thirteen (13) phytoconstituents namely 3,7,11,15-tetramethyl-2-hexadecen-1-ol, phytol, hexadecanoic acid methyl ester, hexadecanoic acid ethyl ester,  ethyl 14-methyl hexadecanoate, cyclopropaneoctanoic acid, hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester, 9,12-octadecadienoic acid, octade-canoic acid, vitamin E, campesterol, stigmasterol and gamma sitosterol were common to all three plants. All except three of these common phytoconstituents (ethyl 14-methyl hexadecanoate, cyclopropan-eoctanoic acid and campesterol) have been shown in the literature to have anti-diabetic activity. It is proposed that anyone or combination of these ten common phytochemicals be used as active therapeutic markers for standardization of the three plants and by extension other anti-diabetic plants if this same commonalities can be established for the plants. Based on the narrow percentage range in the three plants, Vitamin E(3.45- 3.79%) and 3,7,11,15-tetramethyl-2-hexadecen-1-ol(0.87- 1.99%) should be better active diabetic marker candidates for standardization of the three plants.