Harfoush Ahlam, Swaidan Aseel, Khazaal Salma, Salem Sokhn Elie, Grimi Nabil, Debs Espérance, Louka Nicolas, El Darra Nada
Department of Nutrition and Dietetics, Faculty of Health Sciences, Beirut Arab University, Tarik El Jedidah, Riad El Solh, P.O. Box 115020, Beirut 1107 2809, Lebanon.
Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut 1107 2809, Lebanon.
Antioxidants (Basel). 2024 Dec 23;13(12):1588. doi: 10.3390/antiox13121588.
Tea, one of the most popular beverages worldwide, generates a substantial amount of spent leaves, often directly discarded although they may still contain valuable compounds. This study aims to optimize the extraction of polyphenols from spent black tea (SBT) and spent green tea (SGT) leaves while also exploring their antioxidant and antibacterial properties. Response surface methodology was utilized to determine the optimal experimental conditions for extracting polyphenols from SBT and SGT. The total phenolic content (TPC) was quantified using the Folin-Ciocalteu method, while antioxidant activity was evaluated through the DPPH assay. Antibacterial activity was assessed using the disk diffusion method. Additionally, high-performance liquid chromatography (HPLC) was employed to analyze the phytochemical profiles of the SBT and SGT extracts. Optimal extraction for SBT achieved 404 mg GAE/g DM TPC and 51.5% DPPH inhibition at 93.64 °C, 79.9 min, and 59.4% ethanol-water. For SGT, conditions of 93.63 °C, 81.7 min, and 53.2% ethanol-water yielded 452 mg GAE/g DM TPC and 78.3% DPPH inhibition. Both tea extracts exhibited antibacterial activity against Gram-positive bacteria, with SGT showing greater efficacy against and slightly better inhibition of compared to SBT. No activity was observed against the Gram-negative bacteria and . HPLC analysis revealed hydroxybenzoic acid as the main phenolic compound in SBT (360.7 mg/L), while rutin was predominant in SGT (42.73 mg/L). The optimized phenolic-rich extracts of SBT and SGT demonstrated promising antioxidant and antibacterial potential, making them strong candidates for use as natural health boosters in food products.
茶是全球最受欢迎的饮品之一，会产生大量的茶渣，这些茶渣通常被直接丢弃，尽管它们可能仍含有有价值的化合物。本研究旨在优化从红茶茶渣（SBT）和绿茶茶渣（SGT）中提取多酚的工艺，同时探究其抗氧化和抗菌特性。采用响应面法确定从SBT和SGT中提取多酚的最佳实验条件。使用福林-酚法对总酚含量（TPC）进行定量，通过DPPH法评估抗氧化活性。采用纸片扩散法评估抗菌活性。此外，还使用高效液相色谱（HPLC）分析SBT和SGT提取物的植物化学特征。SBT的最佳提取条件为93.64℃、79.9分钟和59.4%乙醇-水，此时TPC达到404mg GAE/g DM，DPPH抑制率为51.5%。对于SGT，在93.63℃、81.7分钟和53.2%乙醇-水的条件下，TPC为452mg GAE/g DM，DPPH抑制率为78.3%。两种茶提取物均对革兰氏阳性菌表现出抗菌活性，与SBT相比，SGT对[具体细菌1]的效果更好，对[具体细菌2]的抑制作用略强。对革兰氏阴性菌[具体细菌3]和[具体细菌4]未观察到活性。HPLC分析表明，羟基苯甲酸是SBT中的主要酚类化合物（360.7mg/L），而芦丁在SGT中占主导地位（42.73mg/L）。优化后的富含多酚的SBT和SGT提取物显示出有前景的抗氧化和抗菌潜力，使其成为食品中用作天然健康促进剂的有力候选物。
