Department of Pharmacognosy, Faculty of Pharmacy, Yeditepe University, Kayışdağı, İstanbul TR-34755, Turkey.
Department of Medicinal Plants, Faculty of Agriculture, Selçuk University, Konya TR-42070, Turkey.
Phytomedicine. 2019 May;58:152872. doi: 10.1016/j.phymed.2019.152872. Epub 2019 Feb 21.
Glycyrrhiza (licorice) species are rich in bioactive secondary metabolites and their roots are used traditionally for the treatment of several diseases. In recent years, secondary metabolites of licorice are gaining popularity, especially due to their significant cytotoxic and antitumor effects. However, Glycyrrhiza iconica, an endemic species to Turkey, was not investigated in terms of its anticancer secondary metabolites previously.
This study aimed to isolate the cytotoxic compounds from G. iconica through bioactivity-guided fractionation and to elucidate mechanisms of action of the most potent compounds.
Total MeOH extract and CHCl, EtOAc, n-buOH and rHO subextracts were prepared from G. iconica roots. Sequential chromatographic techniques were conducted for the isolation studies. The chemical structures of the isolates were established based on NMR and HR-MS analysis. Sulforhodamine B assay was used to evaluate the cytotoxic activity of extracts, main fractions as well as isolates against hepatocellular (Huh7), breast (MCF7) and colorectal (HCT116) cancer cell lines. The mechanisms underlying the cytotoxicity of the most active compounds in Huh7 cells were elucidated by using Hoechst staining, Fluorescence-activated cell sorting and Western blot assays.
A new dihydrochalcone, iconichalcone (1) along with 15 known phenolic compounds were isolated from the active CHCl, EtOAc and n-buOH subextracts. Compounds 2-5, 7-16 were found to be responsible for the in vitro cytotoxic activity of G. iconica against all tested cancer cell lines with IC values ranging from 2.4 to 33 µM. Amongst these compounds, licoricidin (10), dehydroglyasperin C (12), iconisoflaven (13) and 1-methoxyficifolinol (15) were found to be the most active compounds according to SRB and real time bioactivity assays and submitted to further mechanistic investigations in Huh7 cells. Compounds 10, 12, 13 and 15 caused accumulation of cells in different phases of cell cycle. Moreover, 10, 12, 13 and 15 induced apoptosis through caspase activation. Besides, 12 showed activation of p53 expression and thus G/M arrest as well as a condensed nuclei, established very promising results.
The results demonstrated that the aforementioned compounds, particularly 12 could be potential lead molecules for anticancer drug development that deserve further in vivo and clinical investigations.
甘草属植物富含生物活性次生代谢物，其根传统上用于治疗多种疾病。近年来，甘草的次生代谢物越来越受到关注，特别是因为它们具有显著的细胞毒性和抗肿瘤作用。然而，土耳其特有的甘草种 Glycyrrhiza iconica 以前并没有在其抗癌次生代谢物方面进行研究。
本研究旨在通过生物活性导向分离从 G. iconica 中分离出细胞毒性化合物，并阐明最有效化合物的作用机制。
从 G. iconica 根部分别制备总 MeOH 提取物和 CHCl、EtOAc、n-buOH 和 rHO 提取物。进行连续色谱技术进行分离研究。根据 NMR 和 HR-MS 分析确定分离物的化学结构。使用磺酰罗丹明 B 测定法评估提取物、主要馏分以及分离物对肝癌（Huh7）、乳腺癌（MCF7）和结直肠癌（HCT116）癌细胞系的细胞毒性活性。通过 Hoechst 染色、荧光激活细胞分选和 Western blot 分析阐明最活跃化合物在 Huh7 细胞中的细胞毒性作用机制。
从活性 CHCl、EtOAc 和 n-buOH 提取物中分离出一种新的二氢查尔酮，即 iconichalcone（1）以及 15 种已知的酚类化合物。化合物 2-5、7-16 被发现负责 G. iconica 对所有测试的癌细胞系的体外细胞毒性活性，IC 值范围为 2.4-33µM。在这些化合物中，根据 SRB 和实时生物活性测定，licoricidin（10）、dehyroglyasperin C（12）、iconisoflaven（13）和 1-methoxyficifolinol（15）被认为是最有效的化合物，并进一步在 Huh7 细胞中进行了机制研究。化合物 10、12、13 和 15 导致细胞在细胞周期的不同阶段积累。此外，化合物 10、12、13 和 15 通过半胱天冬酶激活诱导细胞凋亡。此外，12 显示出 p53 表达的激活，从而导致 G/M 期阻滞和核浓缩，显示出非常有前途的结果。
结果表明，上述化合物，特别是 12，可能是抗癌药物开发的潜在先导分子，值得进一步的体内和临床研究。
