Abstract
Chlorogenic acids from coffee show high antioxidant activity that contributes to inhibition of oxidative stress, which results in anticancer, antidiabetic and antiobesity coffee activities. Coffee roasting causes their partial decomposition and partial incorporation into Maillard reaction products also of high antioxidant activity, and it is still not clear whether more favorable impact on health is associated with the consumption of green or roasted coffee. The aim of the study was to evaluate the impact of coffee roasting process and also of the degree of chlorogenic acid esterification on bioactivity of coffee extracts. Extracts of green and roasted coffee and their fractions containing mono- and dichlorogenic acids (six extracts) were obtained by purification and optional fractionation of crude extracts using preparative centrifugal partition chromatography technique. The extracts were evaluated in vitro in terms of scavenging capacity, influence on lipids accumulation in 3T3L1 adipocytes, cytoprotective potential decreasing oxidative stress induced by cellular pro-oxidants in βTC3 cells, and in vivo by selected physiological indices in rats fed diets supplemented with the extracts. Roasted coffee extracts, in particular hydrophilic fraction containing monochlorogenic acids and Maillard reaction products, showed the highest scavenging capacity and contributed to the highest level of antioxidants in the hydrophilic fraction of rats serum and may be potentially used as anticancer nutraceutical with oxidative stress inhibitor activity. Non-fractionated green coffee extract exhibited antidiabetic activities including inhibition of adipogenesis, while in vivo it significantly lowered the levels of triglycerides, glucose and oxidized glutathione.
Highlights
Green coffee contains hydroxycinnamic acids, such as caffeic and ferulic acid, mainly in a form of mono- and diesters with quinic acid, referred to as chlorogenic acids (CHAs) [1, 2]
Crude extracts of green and roasted coffee were purified by preparative centrifugal partition chromatography (CPC) chromatograph connected with a fraction collector
Fractions rich in CHAs selected based on high UV absorbance at 320 nm were collected to give purified extracts of green and roasted coffee (GCE and roasted coffee extract (RCE), respectively) [27]
Summary
Green coffee contains hydroxycinnamic acids, such as caffeic and ferulic acid, mainly in a form of mono- and diesters with quinic acid, referred to as chlorogenic acids (CHAs) [1, 2]. CHAs exhibit a broad range of biological activities: antibacterial, antifungal, hepatoprotective, antithrombotic, antiinflammatory and antioxidant activities [3,4,5,6,7,8]. The antioxidant activity of particular CHAs is similar, diesters containing two caffeic acid molecules and four hydroxyl groups may have stronger antioxidant activity monoesters. Roasting coffee causes significant losses of CHAs largely resulting from their incorporation into high molecular mass material, including melanoidins [14]. On the basis of available studies it is not clear, if green or roasted coffee is more beneficial for health, because both chlorogenic acids and
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