title: Comparison of antioxidant activity between green and roasted coffee beans using molecular methods.
abstract: Coffee is one of the most popular and widely consumed beverages worldwide due to its pleasant taste and aroma. A number of studies have been performed to elucidate the possible beneficial effects of coffee consumption on human health and have shown that coffee exhibits potent antioxidant activity, which may be attributed mainly to its polyphenolic content. However, there is also evidence to suggest that coffee roasting (the procedure which turns green coffee beans to the dark, roasted ones from which the beverage derives) may alter the polyphenolic profile of the beans (e.g., via the Maillard reaction) and, concomitantly, their antioxidant activity. In the present study, the antioxidant activity of 13 coffee varieties was examined in both green and roasted coffee bean extracts using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+)- radical scavenging assays. In addition, 5 selected varieties were also examined for their protective effects against peroxyl and hydroxyl radical‑induced DNA strand cleavage. Finally, C2C12 murine myoblasts were treated with non‑cytotoxic concentrations of the most potent extract in order to examine its effects on the cellular redox status by measuring the glutathione (GSH) and reactive oxygen species (ROS) levels by flow cytometry. Our results revealed that, in 8 out of the 13 coffee varieties, roasting increased free radical scavenging activity as shown by DPPH and ABTS•+ assays. Moreover, we found that when one coffee variety was roasted for different amounts of time, the increase in the antioxidant activity depended on the roasting time. By contrast, in 5 varieties, roasting reduced the antioxidant activity. Similar differences between the roasted and green beans were also observed in the free radical‑induced DNA strand cleavage assay. The observed differences in the antioxidant activity between the different coffee varieties may be attributed to their varying polyphenolic content and composition, as well as to the different molecules produced during roasting. In addition, in the cell culture assay, the tested coffee extract led to increased GSH levels in a dose-dependent manner, indicating the enhancement of cellular antioxidant mechanisms.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa 41221, Greece.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Priftis
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa 41221, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Stagos
authors.affiliation: Coffee Island S.A., Patras 26334, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Konstantinopoulos
authors.affiliation: Department of Dangerous Substances, Mixtures and Articles, Directorate of Environment, General Chemical State Laboratory of Greece, Athens 11521, Greece.
authors.forename: Christina
authors.initials: C
authors.lastname: Tsitsimpikou
authors.affiliation: Laboratory of Clinical Virology, University of Crete, Medical School, Heraklion 71409, Greece.
authors.forename: Demetrios A
authors.initials: DA
authors.lastname: Spandidos
authors.affiliation: Department of Forensic Sciences and Toxicology, Medical School, University of Crete, Heraklion 71003, Greece.
authors.forename: Aristides M
authors.initials: AM
authors.lastname: Tsatsakis
authors.affiliation: Department of Forensic Sciences and Toxicology, Medical School, University of Crete, Heraklion 71003, Greece.
authors.forename: Manolis N
authors.initials: MN
authors.lastname: Tzatzarakis
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa 41221, Greece.
authors.forename: Demetrios
authors.initials: D
authors.lastname: Kouretas
mesh_terms: D000818:Animals; D001713:Biphenyl Compounds / Q000737:chemistry; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003069:Coffee / Q000737:chemistry*; D053837:DNA Cleavage; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D006358:Hot Temperature; D017665:Hydroxyl Radical / Q000737:chemistry; D051379:Mice; D010851:Picrates / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D010957:Plasmids / Q000737:chemistry; D059808:Polyphenols / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D001713:Biphenyl Compounds; D003069:Coffee; D016166:Free Radical Scavengers; D010851:Picrates; D010936:Plant Extracts; D059808:Polyphenols; D017665:Hydroxyl Radical; C004931:1,1-diphenyl-2-picrylhydrazyl