Content of Polyphenolic Compounds in the Nigerian Stimulants Cola nitida ssp. alba, Cola nitida ssp. rubra A. Chev, and Cola acuminata Schott & Endl and Their Antioxidant Capacity

• Published in: Journal of agricultural and food chemistry 2007-11, Vol.55 (24), p.9824-9828
• Main Authors: Atawodi, Sunday Ene-ojo, Pfundstein, Beate, Haubner, Roswitha, Spiegelhalder, Bertold, Bartsch, Helmut, Owen, Robert Wyn
• Format: Article
• Language: English
• Subjects: antioxidant activity; Antioxidants - isolation & purification; Antioxidants - metabolism; Biflavonoids - isolation & purification; Biflavonoids - metabolism; bioactive constituent; Biological and medical sciences; Caffeine; Caffeine - isolation & purification; Caffeine - metabolism; catechin; Catechin - isolation & purification; Catechin - metabolism; catechins; Central Nervous System Stimulants - isolation & purification; Central Nervous System Stimulants - metabolism; Chromatography, High Pressure Liquid - methods; Cola - chemistry; Cola acuminata; Cola nitida; Colorimetry; Dose-Response Relationship, Drug; epicatechin; Flavonoids - isolation & purification; Flavonoids - metabolism; Food industries; free radicals; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; HPLC; HPLC-ESI-MS; Humans; Inhibitory Concentration 50; kola nut; kola nuts; Nigeria; Phenols - isolation & purification; Phenols - metabolism; Polyphenols; Proanthocyanidins - isolation & purification; Proanthocyanidins - metabolism; procyanidins; reactive oxygen species; Reactive Oxygen Species - metabolism; secondary metabolites; stimulant plants
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf0721038

Varieties of kola nuts (Cola nitida alba, Cola nitida rubra A. Chev, and Cola acuminata Schott & Endl), a group of popular Nigerian and West African stimulants, were analyzed for their content of secondary plant metabolites. The three varieties of the kola nuts contained appreciable levels of (+)-catechin (27–37 g/kg), caffeine (18–24 g/kg), (−)-epicatechin (20–21 g/kg), procyanidin B1 [epicatechin-(4β→8)-catechin] (15–19 g/kg), and procyanidin B2 [epicatechin-(4β→8)-epicatechin] (7–10 g/kg). Antioxidant capacity of the extracts and purified metabolites was assessed by two HPLC-based and two colorimetric in vitro assays. Extracts of all varieties exhibited antioxidant capacity with IC50 values in the range 1.70–2.83 and 2.74–4.08 mg/mL in the hypoxanthine/xanthine oxidase and 2-deoxyguanosine HPLC-based assays, respectively. Utilization of HPLC-based assays designed to reflect in situ generation of free radicals (e.g., HO•), as opposed to general assays (DPPH, FRAP) in common use which do not, indicate that, of the major secondary plant metabolites present in kola nut extracts, caffeine is potentially the more effective cancer chemopreventive metabolite in terms of its antioxidant capacity.