Method optimization for the determinations of selected phytochemicals and antioxidant activities of wild Ethiopian Syzygium guineense fruit and seed under different drying conditions

Tilahun Belayneh Asfaw; Henock Woldemichael Woldemariam; Mesfin Getachew Tadesse; Fekade Beshah Tessema; Zelalem Gizachew Admassie; Tarekegn Berhanu Esho

doi:10.1016/j.heliyon.2023.e16227

Method optimization for the determinations of selected phytochemicals and antioxidant activities of wild Ethiopian Syzygium guineense fruit and seed under different drying conditions

Heliyon. 2023 May 23;9(6):e16227. doi: 10.1016/j.heliyon.2023.e16227. eCollection 2023 Jun.

Authors

Tilahun Belayneh Asfaw^{1

2

3}, Henock Woldemichael Woldemariam^{4

2}, Mesfin Getachew Tadesse^{1

2}, Fekade Beshah Tessema^{1

2

5}, Zelalem Gizachew Admassie⁶, Tarekegn Berhanu Esho^{1

2}

Affiliations

¹ Department of Industrial Chemistry, College of Applied Sciences, Addis Ababa Science and Technology University, P.O.Box 16417, Addis Ababa, Ethiopia.
² Center of Excellence for Biotechnology and Bioprocess, Addis Ababa Science and Technology University, P.O.Box 16417, Addis Ababa, Ethiopia.
³ Department of Chemistry, College of Natural and Computational Sciences, University of Gondar, Gondar, Ethiopia.
⁴ Department of Chemical Engineering, College of Biological and Chemical Engineering, Addis Ababa Science and Technology University, P.O.Box 16417, Addis Ababa, Ethiopia.
⁵ Department of Chemistry, Natural and Computational Sciences Faculty, Woldia University, Woldia, Ethiopia.
⁶ Agricultural Biotechnology, Bio and Emerging Technology Institute, Addis Ababa, Ethiopia.

Abstract

This study aimed to optimize the ultrasound-assisted extraction (UAE) parameters using response surface methodology (RSM) for the determination of ascorbic acid (AA), antioxidant activities/the half maximal effective concentration (EC50), total phenolic contents (TPC), and total flavonoid content (TFC) of Ethiopian wild Syzygium guineense fruit and seed processed under different drying conditions. The optimizations of the UAE methods for the determination of AA, antioxidant activities (EC50 values), TPC, and TFC were evaluated using response surface methodology (RSM). The extraction time of 15 min, the temperature of 35 °C, extraction solvent composition (methanol:water) of 75 to 25%, and solid-to-solvent ratios of 1:15 w/v were the optimum independent parameters. The experimental and the predicted data of TPC, EC50, and AA were in good agreement with the overall error below 0.01%. It also indicated a hypothesized distribution of predicted data fitted with experimental data. The average TPC, EC50, and AA content in S. guineense fruits and the seed varied from 581.25 ± 37.13 to 1917.40 ± 26.15 mg GAE/100 g, 4.02 ± 0.42 to 155.73 ± 5.11 mg/100 g, and 1.96 ± 0.02 to 0.94 ± 0.00 mg/mL, respectively. This study indicated that this underutilized wild fruit and its seeds can be an alternative source of AA and antioxidant compounds.

Keywords: Antioxidant activity; Optimization; Response surface methodology; Syzygium guineense; UHPLC-DAD.