Department of Chemistry, Faculty of Science and Letters, Eskisehir Osmangazi University, 26480 Eskisehir, Turkey.
Department of Biochemistry, Faculty of Pharmacy, Anadolu University, 26470 Eskisehir, Turkey.
Anticancer Agents Med Chem. 2021;21(12):1581-1593. doi: 10.2174/1871520620666201029102400.
A pentacyclic lupenane-type natural triterpenoid, betulin, has attracted attention in the field of medicinal chemistry since it exhibited a variety of biological activities, including anticancer activity.
The aim of this present work was to obtain derivatives of betulin through bacterial biotransformation and investigate its anticancer activity against A549, HepG2 and 5RP7 cancer cell lines.
Bacterial biotransformation studies were continued in an MBH broth medium for 7 days at 35oC. Anticancer activities of betulin against A549, HepG2 and 5RP7 cell lines were carried out using XTT assay, and their selectivity was determined using a healthy cell line of NIH/3T3. Cell proliferation ELISA, BRDU (colorimetric) assay was used for measuring proliferation in replicative cells in which DNA synthesis occurs. Flow cytometric analysis was used for measuring apoptotic cell percentages, caspase 3 activation and mitochondrial membrane potential.
Bacterial biotransformation studies with 7 bacteria of Staphylococcus aureus ATCC 6538, Proteus vulgaris NRRL B-123, Bacillus subtilis NRRL B-4378, Streptomyces griseolus NRRL B-1062, Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 43300 and Bacillus velezensis NRRL B-14580 produced no metabolite. In in vitro anticancer activity studies, betulin was found to exert anticancer activity against A549, HepG2 and 5RP7 cell lines with IC50 values of 207.7, 125.0 and 28.3 μg/mL, whereas SI values were found to be 30, 50 and 223, respectively. Early and late apoptotic percentages of betulin were found as 9.6, 12.1 and 85.4% on A549, HepG2 and 5RP7, respectively, while caspase 3 positive cell percentages were 2.3, 28.7 and 13.3% for IC50 concentrations. In addition, betulin caused G1 cell cycle arrest (49.5%) on 5RP7 cell line.
The results have been shown that betulin activities against A549 and HepG2 cell lines were nonselective and limited its cytotoxic activity against healthy cells, but it is possible to say that it exerted selective activity against 5RP7 cell (28.33±1.53 μg/mL). Betulin effects on apoptosis were found to be dosedependent, while its effect on caspase 3 activation, mitochondrial membrane potential, and cell cycle arrest on G0/G1 phase was not dependent on doses. Therefore, betulin could be a good candidate for the treatment of H-ras active cancer types.
白桦脂烷五环三萜类天然萜类化合物白桦脂醇在医学化学领域引起了关注，因为它表现出多种生物活性，包括抗癌活性。
本研究旨在通过细菌生物转化获得白桦脂醇衍生物，并研究其对 A549、HepG2 和 5RP7 癌细胞系的抗癌活性。
在 35°C 的 MBH 肉汤培养基中继续进行细菌生物转化研究 7 天。使用 XTT 测定白桦脂醇对 A549、HepG2 和 5RP7 细胞系的抗癌活性，并使用 NIH/3T3 健康细胞系测定其选择性。细胞增殖 ELISA、BRDU（比色法）测定用于测量发生 DNA 合成的复制细胞中的增殖。流式细胞术分析用于测量凋亡细胞百分比、caspase 3 激活和线粒体膜电位。
用 7 株金黄色葡萄球菌 ATCC 6538、普通变形杆菌 NRRL B-123、枯草芽孢杆菌 NRRL B-4378、灰色链霉菌 NRRL B-1062、大肠杆菌 ATCC 8739、金黄色葡萄球菌 ATCC 43300 和 Bacillus velezensis NRRL B-14580 进行细菌生物转化研究，未产生代谢产物。在体外抗癌活性研究中，白桦脂醇对 A549、HepG2 和 5RP7 细胞系表现出抗癌活性，IC50 值分别为 207.7、125.0 和 28.3 μg/mL，而 SI 值分别为 30、50 和 223。白桦脂醇对 A549、HepG2 和 5RP7 的早期和晚期凋亡百分比分别为 9.6%、12.1%和 85.4%，而 IC50 浓度下 caspase 3 阳性细胞百分比分别为 2.3%、28.7%和 13.3%。此外，白桦脂醇使 5RP7 细胞系的 G1 细胞周期停滞（49.5%）。
结果表明，白桦脂醇对 A549 和 HepG2 细胞系的活性是非选择性的，限制了其对健康细胞的细胞毒性活性，但可以说它对 5RP7 细胞系（28.33±1.53 μg/mL）具有选择性活性。白桦脂醇对细胞凋亡的影响呈剂量依赖性，而对 caspase 3 激活、线粒体膜电位和 G0/G1 期细胞周期阻滞的影响则不依赖于剂量。因此，白桦脂醇可能是治疗 H-ras 活性癌型的良好候选药物。
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