Comparison of total flavonoid content and DPPH● sequestration in Arabica, Robusta, and Liberica coffee beans

Coffee beans obtained from the Coffea genus of plants are a key source of flavonoids, which are synthesized within many plants as a secondary metabolite. Flavonoids are a group of polyphenolic compounds primarily studied for their antioxidant, anti-tumor, and neuro-therapeutic properties, amongst other properties. Coffee contains a wide variety of flavonoids, such as catechins, quercetin, and myricetin. Given ecological and genomic differences across species of coffee plants, such as the Coffea arabica, Coffea canephora, and Coffea liberica species, variations in their metabolic pathways affect chemical composition of the beans acquired from each plant. In turn, this affects bioavailability and composition of active compounds within different species, with the possibility of rendering one species more pharmacologically favorable. We hypothesized that such differences may significantly affect the flavonoid content within different species, and therefore, their antioxidant capacities within the body. We conducted total flavonoid content assays to quantify holistic composition of flavonoids across different species. We also utilized a DPPH• (2,2-diphenyl-1-picrylhydrazyl) free radical assay to characterize antioxidant capacity by measuring each extract’s ROS-sequestering capabilities. Robusta coffee beans obtained from the C. canephora plant elicited the highest absorbance value within the flavonoid content assay, signaling greater flavonoid content within Robusta coffee. Moreover, Robusta coffee also presented greater inhibition percentages than other species in the DPPH free radical assay, indicating higher antioxidant capacity within Robusta coffee. Ultimately, these results suggest that the radical sequestering potential of Robusta coffee provides valuable insight into the viability of coffee as a therapeutic agent.