title: 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.
abstract: 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 B 1 [epicatechin-(4beta-->8)-catechin] (15-19 g/kg), and procyanidin B2 [epicatechin-(4beta-->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 IC 50 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.
authors.affiliation: Division of Toxicology, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Sunday Ene-Ojo
authors.initials: SE
authors.lastname: Atawodi
authors.forename: Beate
authors.initials: B
authors.lastname: Pfundstein
authors.forename: Roswitha
authors.initials: R
authors.lastname: Haubner
authors.forename: Bertold
authors.initials: B
authors.lastname: Spiegelhalder
authors.forename: Helmut
authors.initials: H
authors.lastname: Bartsch
authors.forename: Robert Wyn
authors.initials: RW
authors.lastname: Owen
mesh_terms: D000975:Antioxidants / Q000302:isolation & purification / Q000378:metabolism; D044946:Biflavonoids / Q000302:isolation & purification / Q000378:metabolism; D002110:Caffeine / Q000302:isolation & purification / Q000378:metabolism; D002392:Catechin / Q000302:isolation & purification / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000302:isolation & purification* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D030221:Cola / Q000737:chemistry*; D003124:Colorimetry; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000302:isolation & purification* / Q000378:metabolism*; D006801:Humans; D020128:Inhibitory Concentration 50; D009549:Nigeria; D010636:Phenols / Q000302:isolation & purification* / Q000378:metabolism*; D059808:Polyphenols; D044945:Proanthocyanidins / Q000302:isolation & purification / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D044946:Biflavonoids; D000697:Central Nervous System Stimulants; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D044945:Proanthocyanidins; D017382:Reactive Oxygen Species; D002110:Caffeine; C017674:procyanidin; D002392:Catechin