Abstract
Ultrasonic-assisted extraction (UAE) was developed to extract phenolic and flavonoid antioxidants from Clerodendrum cyrtophyllum Turcz leaves. The optimal experimental parameters for antioxidant extraction from C. cyrtophyllum leaves were measured using single-factor experimentation combined with response surface methodology (RSM). Total phenolic content (TPC) and total flavonoid content (TFC) assays were used to quantify antioxidant compounds. Next, antioxidant radical scavenging capacity was measured using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′ -azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) radicals. Optimized extraction conditions for UAE from C. cyrtophyllum leaves were as follows: 60.9% ethanol, 85.4 min, and 63.3°C for maximal TPC extraction (16.8±0.2 mg GAE/g DW); 67.7% ethanol, 82.9 min, and 63.0°C for maximal TFC extraction (49.3±0.4 mg RT/g DW); 48.8% ethanol, 85.1 min, and 63.9°C for maximal DPPH radical-scavenging capacity (86.8±0.2%); and 50.6% ethanol, 81.3 min, and 63.4°C for maximal ABTS radical-scavenging capacity (92.9±0.5%). Ethanol concentration was the most important factor in the extraction process. Our work offers optimal extraction conditions for C. cyrtophyllum as a potential source of natural antioxidants.
Highlights
Studies in the literature have long reported that free radicals are important in the progression of various diseases implicated with aging, such as cancer, cardiovascular disease, emphysema, cirrhosis, arthritis, diabetes mellitus, cataracts, inflammation, and brain disorders [1]
Single-factor experiments First, we investigated whether ethanol concentration, extraction temperature, and time could be optimized for phenolic and flavonoid antioxidant extraction using single-factor experiments to determine appropriate experimental ranges for subsequent analyses
Total phenolic content (TPC) and total flavonoid content (TFC) recovery was parabolic with a maximum value at 60% ethanol
Summary
Studies in the literature have long reported that free radicals are important in the progression of various diseases implicated with aging, such as cancer, cardiovascular disease, emphysema, cirrhosis, arthritis, diabetes mellitus, cataracts, inflammation, and brain disorders [1]. Synthetic antioxidants are frequently used in food and pharmaceutical products, but their use raises consumer questions regarding side effects and potential toxicities [3]. Safe, natural antioxidant alternatives are desired to protect the human body from oxidative stress and retard potential chronic diseases of aging. Antioxidants with plant origins are of considerable interest [4]. Especially plant phenolics and flavonoids, may be potential antioxidants with chemopreventive effects. The antioxidant activity of phenolics is mainly ascribed to their redox properties, which have been shown to quench oxygen-derived free radicals by donating hydrogen atoms or electrons [5]. Biomolecules fulfilling many functions, such as flavonoids, have been shown to be highly effective scavengers of a broad spectrum of oxidizing molecules and inhibitors of lipid peroxidation [6]
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