Abstract
Herein, the extraction of bioactive compounds from umbu fruit peel was optimized using thermal-assisted solid–liquid extraction. In parallel, antioxidant, antimicrobial, and inhibitory effects against α-amylase of optimized extract were also evaluated. The combination of operational conditions including the temperature (32–74 °C), ethanol concentration (13–97%), and solid/liquid ratio (1:10–1:60; w/v) was employed using a rotational central composite design for optimization. The extracts were evaluated for total phenolic compounds (TPC), total flavonoid compounds (TFC) and antioxidant capacity by ABTS•+, DPPH• and FRAP assays. The bioactive profile of the optimized extract was obtained by ultra-performance liquid chromatography coupled to quadrupole/time-of-flight mass spectrometry in electrospray ionization in both negative and positive modes. The statistically evaluated results showed that the optimal operational conditions for the recovery of bioactive compounds from umbu fruit peel included 74 °C, 37% ethanol, and a solid–liquid ratio of 1:38. Under these conditions, the obtained values were 1985 mg GAE/100 g, 1364 mg RE/100 g, 122 µmol TE/g, 174 µmol/TE g and 468 µmol Fe2+/g for TPC, TFC, ABTS•+, DPPH•, and FRAP assays, respectively. In addition, the optimized extract was effective against Gram-positive and Gram-negative bacteria (MBC ranged from 0.060 to 0.24 mg GAE/mL), as well as it was effective to inhibit α-amylase (IC50 value of 0.076 mg GAE/mL). The optimized extract showed to be mainly constituted by phenolic acids and flavonoids.
Highlights
IntroductionUmbu fruit from Brazilian semi-arid regions contains bioactive compounds such as rutin, quercetin, carotenoids, and vitamin C, as reported by Ribeiro et al [3]
In relation to the antioxidant capacity of the extracts of umbu fruit peel it was registered for ABTS+, DPPH and FRAP assays that this potential increased 12, 3.3 and 4.2 times, respectively
The highest value found for ABTS+ response in our work (109 μmol Trolox/g) was close to data reported by Ribeiro et al [3], who evaluated different fractions of umbu fruit
Summary
Umbu fruit from Brazilian semi-arid regions contains bioactive compounds such as rutin, quercetin, carotenoids, and vitamin C, as reported by Ribeiro et al [3] This rich composition confers relevant antioxidant potential to fruit. The antioxidant activity of this extract was evaluated using a peroxyl radical-mediated lipid peroxidation membrane model, being observed that umbu fruit peel and seed extracts provided more than 95% protection of the membrane for 15 min. These results were considered better than those obtained by positive controls (Trolox, vitamin C and resveratrol). The antioxidant effect was evaluated, as well as the effect of the optimized extract against clinically relevant microorganisms and enzymatic activity of α-amylase
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