Bixa orellana L. from northern Brazil: morphological analysis, phenolic content, antioxidant and antibacterial activities

Bixa orellana L. (Bixaceae), also known as “urucum” (Brazil), “annatto” (USA), or “axiote” (Mexico), contains seeds rich in carotenoids, mainly bixin. This study showed the morphological analysis, total phenolic content (Folin-Ciocalteu assay), and in vitro antioxidant activity (DPPH and phosphomolybdenum assays) and antimicrobial activity (MIC) from seeds of three annatto phenotypes (red, yellow, and green), using solvents of different polarity (hexane, ethyl acetate, methanol, and hydroethanolic). All phenotypes showed oval fruits, and the red phenotype presented a different petiole color from the others. The total phenolic content was remarkably high in the methanolic fraction of green fruit (30.10 ± 0.05 mg EAG g −1 extrato, p < 00.5). DPPH method exhibited a more significant antioxidant capacity for the methanolic fraction of green fruit (IC 50 97.81 ± 1.86 µg mL −1 , EC 50 2.44 ± 0.04, and ARP 40.90 ± 0.77) when compared to others. The total antioxidant activity (phosphomolybdenum assays) showed the highest percentage inhibition rate for the hexane fraction of green fruit (68.04 ± 0.09) and the methanolic fraction of red fruit (67.98 ± 0.33), without a significant difference between both ( p > 0.05). The three hydroethanolic seed extracts from three phenotypes showed high antibacterial properties against Gram-positive Staphylococcus aureus Newman, with MIC values ranging from 4.9 to 6.6 µg mL −1 . The results on phenolic content and free radical scavenging ability of obtained fractions from the seeds of B. orellana from northern Brazil agree with data from other studies, moreover also showed the high antimicrobial activity of hydroethanolic extracts from the seeds of this species against S. aureus.