Daglia Maria, Papetti Adele, Grisoli Pietro, Aceti Camilla, Spini Valentina, Dacarro Cesare, Gazzani Gabriella
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Pavia, Via Taramelli 12, 27100 Pavia, Italy.
J Agric Food Chem. 2007 Dec 12;55(25):10208-13. doi: 10.1021/jf0722607. Epub 2007 Nov 15.
Coffee brew is a widely consumed beverage with multiple biological activities due both to naturally occurring components and to the hundreds of chemicals that are formed during the roasting process. Roasted coffee extract possesses antibacterial activity against a wide range of microorganisms, including Staphylococcus aureus and Streptococcus mutans, whereas green coffee extract exhibits no such activity. The naturally occurring coffee compounds, such as chlorogenic acids and caffeine, cannot therefore be responsible for the significant antibacterial activity exerted by coffee beverages against both bacteria. The very low minimum inhibitory concentration (MIC) found for standard glyoxal, methylglyoxal, and diacetyl compounds formed during the roasting process points to these alpha-dicarbonyl compounds as the main agents responsible for the antibacterial activity of brewed coffee against Sa. aureus and St. mutans. However, their low concentrations determined in the beverage account for only 50% of its antibacterial activity. The addition of caffeine, which has weak intrinsic antibacterial activity, to a mixture of alpha-dicarbonyl compounds at the concentrations found in coffee demonstrated that caffeine synergistically enhances the antibacterial activity of alpha-dicarbonyl compounds and that glyoxal, methylglyoxal, and diacetyl in the presence of caffeine account for the whole antibacterial activity of roasted coffee.
咖啡冲泡饮品是一种广泛消费的饮料，因其天然成分以及烘焙过程中形成的数百种化学物质而具有多种生物活性。烘焙咖啡提取物对包括金黄色葡萄球菌和变形链球菌在内的多种微生物具有抗菌活性，而生咖啡提取物则没有这种活性。因此，咖啡中天然存在的化合物，如绿原酸和咖啡因，不可能是咖啡饮品对这两种细菌产生显著抗菌活性的原因。烘焙过程中形成的标准乙二醛、甲基乙二醛和二乙酰化合物的最低抑菌浓度（MIC）非常低，这表明这些α-二羰基化合物是冲泡咖啡对金黄色葡萄球菌和变形链球菌具有抗菌活性的主要因素。然而，在饮品中测定的它们的低浓度仅占其抗菌活性的50%。将具有微弱固有抗菌活性的咖啡因添加到咖啡中发现的α-二羰基化合物混合物中，结果表明咖啡因可协同增强α-二羰基化合物的抗菌活性，并且在咖啡因存在的情况下，乙二醛、甲基乙二醛和二乙酰构成了烘焙咖啡的全部抗菌活性。
