Izu Gloria O, Mfotie Njoya Emmanuel, Tabakam Gaetan T, Nambooze Jennifer, Otukile Kgalaletso P, Tsoeu Seiso E, Fasiku Victoria O, Adegoke Ayodeji M, Erukainure Ochuko L, Mashele Samson S, Makhafola Tshepiso J, Sekhoacha Mamello P, Chukwuma Chika I
Centre for Quality of Health and Living (CQHL), Faculty of Health and Environmental Sciences, Central University of Technology, Bloemfontein 9301, South Africa.
Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9301, South Africa.
Antioxidants (Basel). 2024 Apr 12;13(4):456. doi: 10.3390/antiox13040456.
Oxidative stress is pivotal in the pathology of many diseases. This study investigated the antioxidant phytochemistry of avocado ( Mill.) peel. Different solvent extracts (dichloromethane, ethyl acetate, methanol, and water) of avocado peel were subjected to total phenol and flavonoid quantification, as well as in vitro radical scavenging and ferric reducing evaluation. The methanol extract was subjected to gradient column chromatographic fractionation. Fraction 8 (eluted with hexane:chloroform:methanol volume ratio of 3:6.5:0.5, respectively) was subjected to LC-MS analysis. It was assessed for cellular inhibition of lipid peroxidation and lipopolysaccharide (LPS)-induced ROS and NO production. The DPPH radical scavenging mechanism of chlorogenic acid was investigated using Density Functional Theory (DFT). The methanol extract and fraction 8 had the highest phenol content and radical scavenging activity. Chlorogenic acid (103.5 mg/mL) and 1--caffeoylquinic acid (102.3 mg/mL) were the most abundant phenolics in the fraction. Fraction 8 and chlorogenic acid dose-dependently inhibited in vitro (IC = 5.73 and 6.17 µg/mL) and cellular (IC = 15.9 and 9.34 µg/mL) FeSO-induced lipid peroxidation, as well as LPS-induced ROS (IC = 39.6 and 28.2 µg/mL) and NO (IC = 63.5 and 107 µg/mL) production, while modulating antioxidant enzyme activity. The fraction and chlorogenic acid were not cytotoxic. DFT analysis suggest that an electron transfer, followed by proton transfer at carbons 3'OH and 4'OH positions may be the radical scavenging mechanism of chlorogenic acid. Considering this study is bioassay-guided, it is logical to conclude that chlorogenic acid strongly influences the antioxidant capacity of avocado fruit peel.
氧化应激在许多疾病的病理过程中起着关键作用。本研究调查了鳄梨（Mill.）果皮的抗氧化植物化学特性。对鳄梨果皮的不同溶剂提取物（二氯甲烷、乙酸乙酯、甲醇和水）进行了总酚和黄酮类化合物的定量分析，以及体外自由基清除和铁还原能力评估。对甲醇提取物进行梯度柱色谱分离。馏分8（分别用己烷：氯仿：甲醇体积比为3:6.5:0.5洗脱）进行液相色谱 - 质谱分析。评估其对脂质过氧化以及脂多糖（LPS）诱导的活性氧（ROS）和一氧化氮（NO）产生的细胞抑制作用。使用密度泛函理论（DFT）研究了绿原酸的二苯基苦味酰基自由基（DPPH）清除机制。甲醇提取物和馏分8的酚含量和自由基清除活性最高。绿原酸（103.5 mg/mL）和1 - 咖啡酰奎尼酸（102.3 mg/mL）是该馏分中含量最丰富的酚类物质。馏分8和绿原酸在体外（IC = 5.73和6.17 µg/mL）和细胞水平（IC = 15.9和9.34 µg/mL）上呈剂量依赖性地抑制硫酸亚铁（FeSO）诱导的脂质过氧化，以及LPS诱导的ROS（IC = 39.6和28.2 µg/mL）和NO（IC = 63.5和107 µg/mL）的产生，同时调节抗氧化酶活性。该馏分和绿原酸无细胞毒性。DFT分析表明，电子转移，随后在碳3'OH和4'OH位置进行质子转移可能是绿原酸的自由基清除机制。鉴于本研究是生物测定指导的，可以合理地得出结论，绿原酸对鳄梨果皮的抗氧化能力有强烈影响。
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