BMC Complement Altern Med. 2013 May 28;13:116. doi: 10.1186/1472-6882-13-116.
Oxidative stress has been implicated in the progression of various diseases, which may result in the depletion of endogenous antioxidants. Exogenous supplementation with antioxidants could result in increased protection against oxidative stress. As concerns have been raised regarding synthetic antioxidant usage, the identification of alternative treatments is justified. The aim of the present study was to determine the antioxidant efficacy of Burkea africana and Syzygium cordatum bark extracts in an in vitro oxidative stress model.
Cytotoxicity of crude aqueous and methanolic extracts, as well as polyphenolic-rich fractions, was determined in C2C12 myoblasts, 3T3-L1 pre-adipocytes, normal human dermal fibroblasts and U937 macrophage-like cells using the neutral red uptake assay. Polyphenolic content was determined using the Folin-Ciocalteau and aluminium trichloride assays, and antioxidant activity using the Trolox Equivalence Antioxidant Capacity and DPPH assays. The extracts efficacy against oxidative stress in AAPH-exposed U937 cells was assessed with regards to reactive oxygen species generation, cytotoxicity, apoptosis, lipid peroxidation and reduced glutathione depletion.
B. africana and S. cordatum showed enrichment of polyphenols from the aqueous extract, to methanolic extract, to polyphenolic-rich fractions. Antioxidant activity followed the same trend, which correlated well with the increased concentration of polyphenols, and was between two- to three-fold stronger than the Trolox antioxidant control. Both plants had superior activity compared to ascorbic acid in the DPPH assay. Polyphenolic-rich fractions were most toxic to the 3T3-L1 (IC50's between 13 and 21 μg/ml) and C2C12 (IC50's approximately 25 μg/ml) cell lines, but were not cytotoxic in the U937 and normal human dermal fibroblasts cultures. Free radical-induced generation of reactive oxygen species (up to 80%), cytotoxicity (up to 20%), lipid peroxidation (up to 200%) and apoptosis (up to 60%) was successfully reduced by crude extracts of B. africana and the polyphenolic-rich fractions of both plants. The crude extracts of S. cordatum were not as effective in reducing cytotoxic parameters.
Although oxidative stress was attenuated in U937 cells, cytotoxicity was observed in the 3T3-L1 and C2C12 cell lines. Further isolation and purification of polyphenolic-fractions could increase the potential use of these extracts as supplements by decreasing cytotoxicity and maintaining antioxidant quality.
氧化应激与各种疾病的进展有关，这可能导致内源性抗氧化剂耗竭。外源性补充抗氧化剂可能会增加对氧化应激的保护。由于对合成抗氧化剂的使用存在担忧，因此有理由寻找替代治疗方法。本研究的目的是确定 Burkea africana 和 Syzygium cordatum 树皮提取物在体外氧化应激模型中的抗氧化功效。
使用中性红摄取测定法在 C2C12 成肌细胞、3T3-L1 前脂肪细胞、正常人类真皮成纤维细胞和 U937 巨噬样细胞中测定粗水提物和甲醇提取物以及多酚丰富的馏分的细胞毒性。使用 Folin-Ciocalteau 和三氯化铝测定法测定多酚含量，使用 Trolox 等效抗氧化能力和 DPPH 测定法测定抗氧化活性。在用 AAPH 暴露的 U937 细胞中，评估提取物对氧化应激的功效，包括活性氧生成、细胞毒性、细胞凋亡、脂质过氧化和还原型谷胱甘肽耗竭。
B. africana 和 S. cordatum 从水提物到甲醇提取物再到多酚丰富的馏分，均富含多酚。抗氧化活性也呈现出相同的趋势，这与多酚浓度的增加密切相关，并且比 Trolox 抗氧化剂对照强两到三倍。与 DPPH 测定中的抗坏血酸相比，这两种植物均具有更强的活性。多酚丰富的馏分对 3T3-L1（IC50 值介于 13 和 21 μg/ml 之间）和 C2C12（IC50 值约为 25 μg/ml）细胞系的毒性最大，但在 U937 和正常人类真皮成纤维细胞培养物中没有细胞毒性。自由基诱导的活性氧（高达 80%）、细胞毒性（高达 20%）、脂质过氧化（高达 200%）和细胞凋亡（高达 60%）的生成被 B. africana 的粗提取物和两种植物的多酚丰富馏分成功减少。S. cordatum 的粗提取物在降低细胞毒性参数方面效果不佳。
尽管 U937 细胞中的氧化应激得到了缓解，但在 3T3-L1 和 C2C12 细胞系中观察到了细胞毒性。进一步分离和纯化多酚馏分可以降低细胞毒性并保持抗氧化质量，从而增加这些提取物作为补充剂的潜在用途。
