Abstract

Kola seeds are highly valued in most African communities due to their medicinal benefits and socio-cultural application during ceremonies. Apart from their neuro-stimulatory effect, the other health benefits such as antioxidant activities which are closely associated with the level of phenolic constituents have also been widely reported. The main purpose of this study is to determine the quantity of quercetin, caffeic acid, gallic acid, ferulic acid, rutin and chlorogenic acid in Cola nitida, Garcinia kola and Buchholzia coriacea using HPLC-DAD. Ethanolic extracts of the selected kola plants was obtained by cold maceration and analysed by HPLC-DAD in accordance with standard methods. The regression coefficient (r2) from the calibration curve for caffeic acid = 0.999, chlorogenic acid = 0.998, gallic acid = 0.999, ferulic acid = 0.998, quercetin = 0.996 and rutin = 0.997. The repeatability gave % RSD of 0.6, 1.63, 0.44, 1.55, 3.65 and 4.67 for caffeic acid, chlorogenic acid, gallic acid, ferulic acid, quercetin and rutin respectively. The quantity of these compounds in C. nitida was caffeic acid (101.24 mg/g), chlorogenic acid (36.35 mg/g), gallic acid (16.99 mg/g) ferulic acid (1.47 mg/g) while quercetin and rutin were not detected. In Garcinia kola, caffeic acid was (0.84 mg/g), gallic acid (1.02 mg/g), ferulic acid (21.83 mg/g), quercetin (53.24 mg/g), rutin (0.49 mg/g) and chlorogenic acid was not detected. B. coriaceae had caffeic acid (1.03 mg/g), chlorogenic acid (0.33 mg/g), gallic acid (1.07 mg/g) while ferulic acid, quercetin and rutin were not detected. Using this analytical method, the quantities of some phenolics and flavonoids compounds were determined, and the most abundant compound in the three species of kola was caffeic acid in C. nitida and quercetin in Garcinia kola. This study also showed that C. nitida contains high amounts of phenolics compounds as compare to the other species of kola seeds investigated in the study.

Key word:  Phenolic acids, flavonoids, high-performance liquid chromatography- diode-array detector (HPLC-DAD), Cola nitida, Garcinia cola, Buchholzia coriacea.