Objective: The consumption of coffee has increased globally because of its flavor and health benefits. The present study aimed to investigate the phenolic compounds and biological activity of four varieties of Coffea arabica L. (Heirloom 1-4) from the flora of Africa. Methods: Ethanolic extracts of the green and roasted coffee beans were screened in vitro for their total phenols and flavonoids using Folin-Ciocalteu and AlCl3 assays, respectively. In addition, the antioxidant activity of the extracts was evaluated by three complementary tests DPPH free radical-scavenging, βcarotene/linoleic acid, and metal chelating activity. The antibacterial activity of the aqueous extracts of the samples against two gram-positive and two gramnegative bacteria was also studied by the disk diffusion method. Results: Results showed that the ethanolic extracts from both green and roasted beans of the variety Heirloom 4 contain the highest amounts of phenols and flavonoids. In addition, the antioxidant activity assays indicated that the activity of the studied extracts was lower than ascorbic acid (a standard synthetic antioxidant) in the metal-chelating activity and the DPPH radical scavenging assay. However, the oxidation of linoleic acid in the β-carotene/linoleic acid system was inhibited by all studied extracts. Furthermore, the aqueous extracts of the green and roasted beans of all varieties showed proper antibacterial activity against the bacterial strains tested. Conclusion: In conclusion, several factors including altitude, variety, extraction methods, and type of solvent used affected the bioactivity of the coffee extracts. All antioxidant activity assays showed a close relationship with the phenolic content of green and roasted samples. Antioxidant activity assays indicated that the green or roasted bean extracts of coffee have potent free radical scavenging activity. Moreover, the differences in the antioxidant activity of green and roasted bean extracts in the same variety could be attributed to the roasting process.
