Department of Microbiology, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
BMC Complement Altern Med. 2018 Mar 9;18(1):82. doi: 10.1186/s12906-018-2154-4.
Oxidative stress in an intracellular environment created by the accumulation of reactive oxygen species results in oxidative damage to biomolecules which ultimately become a hallmark for severe diseases like cancer, aging, diabetes, and cardiovascular and neurodegenerative diseases.
Various in vitro assays were employed to assess the antioxidant potential of strain, DNA protective activity was demonstrated using DNA nicking assay and cytotoxicity of the extract was evaluated using MTT assay. Further identification of the compounds was done using UPLC analysis.
The extract of Streptomyces cellulosae strain TES17 demonstrated significant antioxidant activity with percentage inhibition of 78.47 ± 0.23, 91.08 ± 0.98 and 82.08 ± 0.93 for DPPH, ABTS and superoxide radical assays at 5 mg/mL, respectively. Total antioxidant and reducing power were found to be 76.93 ± 0.76 and 231.96 ± 0.51 mg AAE/100 mg of dry extract, respectively. Moreover, the extract was shown to inhibit lipid peroxidation upto 67.18 ± 1.9% at 5 mg/mL. TPC and TFC measured in the extract was 55 mg GAE/100 mg and 11.17 ± 4.05 mg rutin/100 mg, respectively. The protective nature of the TES17 extract to oxidative stress induced damaged DNA was shown by percentage of supercoiled DNA i.e. Form I was increased from 26.38 to 38.20% at concentrations ranging from 2 μg to 10 μg. TES17 extract also showed the cytotoxic activity against lung cancer cell line with 74.7 ± 1.33% inhibition whereas, limited toxicity was observed against normal cell line with percentage viability of 87.71 ± 6.66 at same concentration (30 μg/mL) tested. The antioxidant capacity of extract was well correlated with its TPC and TFC and this in turn was in keeping with the UPLC analysis which also revealed the presence of phenolic compounds that were responsible for the antioxidant and cytotoxic potential of S. cellulosae strain TES17.
The present study describes that S. cellulosae strain TES17 isolated from the rhizosphere of Camellia sinensis (tea) plant; produces potent compounds with antioxidant activity, further might be developed into therapeutic drugs to combat oxidative stress.
细胞内环境中活性氧物质的积累会导致氧化应激，从而导致生物分子的氧化损伤，最终成为癌症、衰老、糖尿病以及心血管和神经退行性疾病等严重疾病的标志。
采用各种体外测定法评估菌株的抗氧化潜力，通过 DNA 切口测定法证明 DNA 保护活性，并用 MTT 测定法评估提取物的细胞毒性。进一步使用 UPLC 分析进行化合物鉴定。
链霉菌 TES17 的提取物表现出显著的抗氧化活性，在 5mg/mL 时，对 DPPH、ABTS 和超氧自由基测定的抑制率分别为 78.47±0.23%、91.08±0.98%和 82.08±0.93%。总抗氧化能力和还原力分别为 76.93±0.76 和 231.96±0.51mg AAE/100mg 干提取物。此外，该提取物在 5mg/mL 时可抑制脂质过氧化，抑制率高达 67.18±1.9%。提取物中 TPC 和 TFC 的测量值分别为 55mgGAE/100mg 和 11.17±4.05mg 芦丁/100mg。TES17 提取物对氧化应激诱导的受损 DNA 的保护性质表现为超螺旋 DNA 的比例增加，即从 26.38%增加到 38.20%，浓度范围从 2μg 到 10μg。TES17 提取物对肺癌细胞系也表现出细胞毒性活性，抑制率为 74.7±1.33%，而在相同浓度（30μg/mL）下，对正常细胞系的毒性有限，细胞活力为 87.71±6.66%。提取物的抗氧化能力与其 TPC 和 TFC 密切相关，这与 UPLC 分析结果一致，UPLC 分析还表明存在酚类化合物，这些化合物是 S. 纤维素菌株 TES17 抗氧化和细胞毒性潜力的原因。
本研究描述了从茶树根际分离出的链霉菌 TES17 菌株产生具有抗氧化活性的有效化合物，进一步可能开发成治疗氧化应激的药物。
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