Quality Assessment of a Locally Processed Nigerian Moringa Oleifera Leaf Powder Intended for Use in a Clinical Trial

Abstract

Background: Preclinical evidence indicates that Moringa oleifera leaf has antihypertensive effects, making the herbal material an attractive candidate for hypertension clinical trials. The quality of herbal medicines is an important consideration for human usage. Objective: To assess the quality of a Nigerian Moringa oleifera leaf powder by analysing the proximate, heavy metals, microbial and antioxidant contents. Materials and Methods: Moringa oleifera leaves were harvested from cultivated sources, and the harvested leaves were dried under shade. The dried material was milled into powder and was stored in airtight polythene bags. Analyses of the proximate, heavy metals and microbial contents were done using standard methods. Results were compared to WHO guidelines. Phenolic and flavonoid content determination was performed using colorimetric techniques. The antioxidant assay of the herbal material was done using 1, 1-diphenyl-2-picrylhydrazyl. Results: The proximate composition of the herbal material revealed 2.8% moisture content and 33.3% crude fibre. Heavy metals detected including lead, cobalt, copper, and cadmium were within the permissible limits of WHO standards. Microbial load, including total aerobic bacteria, fungi and indicator organisms, met the WHO standards. The phenolic content was 564.29 (SD=79.17) gallic acid equivalent, while the flavonoid content was 65.54 (SD=2.46) rutin equivalent per g of the test extract. The concentration of the test extract that scavenged 50% DPPH was 15.46 mg/ml. Conclusion: The locally processed Moringa oleifera leaf powder is of quality fit for oral consumption in humans. The appreciable amounts of phenolics and flavonoids in Moringa oleifera leaf further highlight its antihypertensive potentiality. Key words: Moringa oleifera, quality, antioxidant assay, hypertension, Nigeria