Abstract
An ultrasound-assisted extraction (UAE) method was developed to extract natural antioxidants from the Osmanthus fragrans flower. The effect of UAE on antioxidant activity of the extract from the Osmanthus fragrans flower was studied using a Trolox equivalent antioxidant capacity (TEAC) assay. Optimization conditions were firstly determined using a single-factor experiment, and response surface methodology was then used to evaluate interaction of several experimental parameters. Analysis of the coefficient of determination showed that second-order polynomial models produced a highly satisfactory fitting of the experimental data with regard to TEAC values (R2 = 0.9829, p < 0.0001). The optimal conditions were 39.1% ethanol, and extraction for 35.2 min at 59.4 °C. Under these conditions, the maximum TEAC value was 584.9 ± 6.0 μmol Trolox/g DW, which was higher than those obtained by the conventional extracting method (486.4 ± 12.6 μmol Trolox/g DW) and the Soxhlet extraction method (339.1 ± 16.2 μmol Trolox/g DW). The crude extract obtained could be used either as a food additive or in pharmaceuticals for the prevention and treatment of diseases caused by oxidative stress.
Highlights
Reactive oxygen species (ROS) could cause a myriad of damages to biological systems, and cause many chronic and degenerative diseases, such as cardiovascular disease, cancer, diabetes mellitus, ageing and neurodegenerative diseases [1,2,3]
The purpose of a single-factor experiment was to evaluate the effect of each factor on antioxidant capacity of the extract from the Osmanthus fragrans flower under ultrasound treatment, and to analyze the influence of four different variables
When the concentration of ethanol increased from 20% to 40%, the extraction efficiencies increased with an increase in ethanol (p < 0.05), which was followed by a decrease with an increase in ethanol from 40% to 70% (p < 0.05)
Summary
Reactive oxygen species (ROS) could cause a myriad of damages to biological systems, and cause many chronic and degenerative diseases, such as cardiovascular disease, cancer, diabetes mellitus, ageing and neurodegenerative diseases [1,2,3]. The scavenging of ROS is thought to be an effective measure to depress the level of oxidative stress of an organism. Previous studies have demonstrated that intake of fruit and vegetables was inversely associated with the risk of many chronic diseases, such as cancer and cardiovascular diseases [4,5,6,7]. Natural antioxidants in fruit and vegetables are considered to be responsible for these health benefits [8,9]. Antioxidants could serve as potential agents for prevention and treatment of oxidative stress-related diseases. Medicinal plants, microalgae and flowers were found to contain high contents of natural antioxidants [10,11,12,13]
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