Determination of flavonoids by LC/MS and anti-inflammatory activity in Moringa oleifera

Moringa oleifera is an important multipurpose tropical tree under-recognized for its nutritional and medicinal properties. Leaves of moringa collected from sub-Sahara Africa were analyzed for phenolic components by HPLC-UV-MS. Twelve flavonoids were identified, including quercetin and kaempferol glucosides and glucoside malonates as major constituents. To facilitate quantitative analysis, acid hydrolysis during extraction of moringa samples was employed to convert the conjugates into their respective flavonoid aglycones, allowing accurate quantitation of total flavonoids as aglycones. Validation of the method demonstrated recoveries ranging from 92.6% to 107.5% for the two analytes. Using this method, total flavonoids from moringa collected from Ghana, Senegal and Zambia were determined and their content ranged from 0.18% to 1.64% (g/dry weight) across the respective environment or country of production and by variety. Moringa was found to exhibit anti-inflammatory activity of constituents-rich varieties. As flavonoid malonates are among the major constituents in the original plant material, a study examining thermal stability of flavonoid malonyl derivatives showed that these compounds were not thermally stable and easily cleaved to yield their respective flavonoid glycosides.