Department of Food Science and Engineering, School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China; Department of Food Science and Technology, Faculty of Applied Sciences and Technology, Ho Technical University, Ho HP217, Volta Region, Ghana.
Department of Food Science and Engineering, School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China; Institute of Food Physical Processing, Jiangsu University, Zhenjiang 212013, Jiangsu, China.
Food Res Int. 2020 Nov;137:109598. doi: 10.1016/j.foodres.2020.109598. Epub 2020 Aug 6.
The effects of ultrasound-assisted (UAE), subcritical water (SWE) and ultrasound assisted-subcritical water (UA-SWE) treatments on tartary buckwheat polyphenol yield, composition, antioxidant activity and cytotoxicity in human liver carcinoma cells were studied. Folin Ciocalteu assay was used to measure total free phenol content (TFPC), and ABTS, DPPH, FRAP and TEAC assays were used to measure antioxidant activity (AA). Polyphenol characterization was done by LC-MS and cell antioxidant activity (CAA) and cytotoxicity were done using the 2,2'-Azobis-(2-amidinopropane) dihydrochloride [ABAP] and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide [MTT] assays respectively. The highest polyphenol yield was obtained by SWE (53.3 mg g), followed by UA-SWE (31.8 mg g), UAE (19.3 mg g) and HWE (4.2 mg g). Also, SWE had the highest TFPC (7.9 mgGAE/gdw). UAE and UA-SWE showed no differences with TFPC being 6.6 and 6.8 mgGAE/gdw, respectively. The control method (HWE) had the largest number of phenolic compounds identified (25), followed by UAE, SWE and UA-SWE which had 20, 13 and 11 phenolics respectively. Beside phenolic acids, all treatments extracted a number of flavonoids such as flavan-3-ols (catechin-7-O-glucoside, epigallocatechin-3-gallate, epigallocatechin, epicatechin), flavonols (kaempferol-3-O-glucoside, kaempferol, kaempferol-3-rutinoside, rutin, quercetin, quercetin-3-O-glucuronide hyperin), flavones (vitexin, isovitexin, orientin, isoorientin) and anthocyanins (cyanidin-3-O-rutinoside, Cyanidin 3-O-galactoside, cyanidin-3-O-glucoside). SWE gave the highest AA for all tests. However, the AA of those obtained by UAE and UA-SWE did not vary (P < 0.05), but were higher than HWE. Different extracts had best AA at different concentrations (HWE, 300; UAE, 250; SWE, 150; UA-SWE, 200 μg/mL). The IC of AA were 270.8 ± 21.3, 198.1 ± 16.0, 97.9 ± 13.5, and 150.4 ± 12.8 μg/mL, respectively for HWE, UAE, SWE and UA-SWE. Generally, SWE and UA-SWE showed the highest cytotoxic activities, followed by UAE, with HWE being the lowest. IC of cytotoxicity were 76.1 ± 3.3, 79.5 ± 7.0 and 92.6 ± 4.9 µg/mL for SWE, UA-SWE and UAE, respectively. SWE is a promising method for polyphenol extraction and its combination with ultrasound should be optimized for high yield and conservation of bioactivity.
超声辅助（UAE）、亚临界水（SWE）和超声辅助亚临界水（UA-SWE）处理对苦荞多酚产量、组成、抗氧化活性和人肝癌细胞毒性的影响。福林-希夫试剂法用于测定总游离酚含量（TFPC），ABTS、DPPH、FRAP 和 TEAC 法用于测定抗氧化活性（AA）。通过 LC-MS 对多酚进行表征，通过 2,2'-偶氮双（2-脒基丙烷）二盐酸盐 [ABAP] 和 3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴盐 [MTT] 测定细胞抗氧化活性（CAA）和细胞毒性。SWE 获得的多酚产量最高（53.3 mg g），其次是 UA-SWE（31.8 mg g）、UAE（19.3 mg g）和 HWE（4.2 mg g）。此外，SWE 的 TFPC 最高（7.9 mgGAE/gdw）。UAE 和 UA-SWE 的 TFPC 没有差异，分别为 6.6 和 6.8 mgGAE/gdw。对照方法（HWE）鉴定的酚类化合物数量最多（25），其次是 UAE、SWE 和 UA-SWE，分别为 20、13 和 11 种酚类化合物。除了酚酸外，所有处理方法都提取了一些类黄酮，如黄烷-3-醇（儿茶素-7-O-葡萄糖苷、表没食子儿茶素-3-没食子酸酯、表没食子儿茶素、表儿茶素）、黄酮醇（山奈酚-3-O-葡萄糖苷、山奈酚、山奈酚-3-鼠李糖苷、芦丁、槲皮素、槲皮素-3-O-葡萄糖醛酸苷、圣草酚）、黄酮（牡荆素、异牡荆素、异荭草素、荭草素）和花青素（矢车菊-3-O-鼠李糖苷、矢车菊 3-O-半乳糖苷、矢车菊 3-O-葡萄糖苷）。SWE 在所有测试中均表现出最高的 AA。然而，UAE 和 UA-SWE 获得的 AA 没有差异（P < 0.05），但高于 HWE。不同提取物在不同浓度下具有最佳的 AA（HWE，300；UAE，250；SWE，150；UA-SWE，200 μg/mL）。AA 的 IC 分别为 270.8 ± 21.3、198.1 ± 16.0、97.9 ± 13.5 和 150.4 ± 12.8 μg/mL，分别为 HWE、UAE、SWE 和 UA-SWE。一般来说，SWE 和 UA-SWE 表现出最高的细胞毒性活性，其次是 UAE，而 HWE 最低。细胞毒性的 IC 分别为 76.1 ± 3.3、79.5 ± 7.0 和 92.6 ± 4.9 μg/mL，分别为 SWE、UA-SWE 和 UAE。SWE 是一种很有前途的多酚提取方法，应优化其与超声的结合，以获得高产率和生物活性的保护。
