Methodology development of quality control, quality assurance and standards for Moringa oleifera seeds using liquid chromatography

Abstract

Natural products or traditional medicine has been used for centuries to treat various ailments by mankind. The World Health Organization estimates that in recent times 80% of people in emerging economies rely on traditional medicine as their primary health care [1]. However, unlike pharmaceutical products which have methods in place for quantification of the active compounds traditional medicine still requires a lot of focus in this area. Moringa oleifera is one of those species that have been used traditionally to cure various ailments for centuries. Even though extensive phytochemical and pharmacological studies have been conducted on the different parts of the plant, there is still no analytical method that enables the quantification of the compounds in the Moringa products in the market. The aim of this research was to develop an HPLC separation method that can be used to quantify the compounds found in the Moringa oleifera products. Compounds were extracted from the seeds of Moringa oleifera using the maceration method with a mixture of water and ethanol (1:1 v/v). The compounds were isolated using preparative HPLC. The structures of the compounds were elucidated using FTIR, NMR and MS. An HPLC separation method for quantification of the isolated compounds was developed and validated. The method was applied to the crude extract to quantify the isolated compounds in the extract. The following compounds 3-caffeoylquinic acid, 4-(α-L-Rhamnosyloxy) benzyl isothiocyanate, O-ethyl-[4-(α-L-Rhamnosyloxy) benzyl] thiocarbamate and O-butyl-[4-(α-L-Rhamnosyloxy) benzyl] thiocarbamate were isolated at percentage purities ranging from 90 to 99%. The HPLC separation method for quantification showed a linear relationship between peak area and concentration of the compounds with regression coefficients ranging from 0.9977 to 0.9994. The method is also precise with % RSD values between 0.01 and 1.16%. The method was shown to be specific to the compounds of interest. The percentage distribution of compounds in 50 mg of the seeds extract was between 0.25 and 1.10 % w/w. This study successfully developed and validated an HPLC separation method for four compounds found in the seeds of Moringa oleifera and quantified them in the crude extract of the seeds found in Zambia. This method can be used for identification and quantification of these four compounds in any of the Moringa products. As far as it could be ascertained this is the first time that such a method has been developed for these compounds