A total of forty novel glycyrrhetinic acid (GA) derivatives were designed and synthesized. The cytotoxic activity of the novel compounds was tested against two human breast cancer cell lines (MCF-7, MDA-MB-231) in vitro by the MTT method. The evaluation results revealed that, in comparison with GA, compound 42 shows the most promising anticancer activity (IC₅₀ 1.88 ± 0.20 and 1.37 ± 0.18 µM for MCF-7 and MDA-MB-231, respectively) and merits further exploration as a new anticancer agent.

Background: The structural modification of natural products with the aim to improve the anticancer activity is a popular current research direction. The pentacyclic triterpenoid compounds oleanolic acid (OA) and glycyrrhetinic acid (GA) are distributed widely in nature. Methods: In this study, various oleanolic acids and glycyrrhetinic acids were designed and synthesized by using the combination principle. The in vitro anticancer activities of new OA and GA derivatives were tested by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) method with SGC-7901 (gastric cancer), MCF-7 (breast cancer), Eca-109 (esophageal cancer), HeLa (cervical cancer), Hep-G2 (hepatoma cancer) and HSF (normal human skin fibroblast) cells. Results and conclusion: The screening results showed that the compound 3m presented the highest inhibitory activities against SGC-7901, MCF-7 and Eca-109 cell lines with IC₅₀ values of 7.57±0.64 µM, 5.51±0.41 µM and 5.03±0.56 µM, respectively. In addition, this compound also showed effective inhibition of Hep-G2 cells with an IC₅₀ value of 4.11±0.73 µM. Moreover, compound 5b showed the strongest inhibitory activity against Hep-G2 cells with an IC₅₀ value of 3.74±0.18 µM and compound 3l showed strong selective inhibition of the HeLa cells with the lowest IC₅₀ value of 4.32±0.89 µM. A series of pharmacology experiments indicated that compound 5b could induce Hep-G2 cells autophagy and apoptosis. These compounds will expand the structural diversity of anti-cancer targets and confirm the prospects for further research.

Saxitoxin (STX) is a potent marine biotoxin which can cause paralytic shellfish poisoning when consumed. With the development of research, STX has become more and more important in red tide detection, medical research, food safety and warfare agent application. However, new methods for the fast analysis of STX are required. In this study, we used laser optical tweezers Raman spectroscopy (LTRS) combined with surface-enhanced Raman scattering (SERS) to detect STX. Sharp Raman peaks of very strong intensity were achieved. The spectra were obtained in 2 seconds without accumulations. Tentative vibrational mode assignments of the observed peaks in SERS spectra of STX are described. The detection limit and the minimum quantitative limit of this method were 2 nM and 16 nM, respectively. This study supports LTRS-SERS as a new fast, convenient analytical method for STX and other toxicants and pollutants in the environment.

The similarities and differences in retention characteristics of p‐tert‐butyl‐calix[4]arene‐bonded and three other silica‐based phases have been elucidated by the use of linear solvation energy relationships (LSERs). These phases were investigated in a common mobile phase. The results of LSERs on p‐tert‐butyl‐calix[4]arene‐bonded phase shows resemblances and differences to other silica‐based reversed‐phases. The retention of solutes on all the silica‐based phases are dominated by two factors: the solute size and hydrogen bond acceptor basicity. But, for p‐tert‐butyl‐calix[4]arene‐bonded phase, the main retention governing factor is the solute size, which contribution accounts for 63% of the variance in log k values. The s coefficient is small, but positive, which is unlike the common reversed phase stationary phases. The r coefficient, which is small and positive, showed the new phase has greater π–π interaction to solutes than all other phases, and relatively high selectivity to polyaromatic hydrocarbons. The retention mechanism of the phase, mainly, is a partitioning mechanism.

A series of new glycyrrhetinic acids and oleanolic acids has been designed and synthesized based on the principles of combinatorial chemical synthesis. Their anticancer activities were further studied by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method with hepatocellular carcinoma (Hep-G2), breast cancer (MCF-7) cell lines and a normal hepatic cell (LO2). Cytotoxicity tests (in vitro) indicated that compound 6a showed the highest cytotoxicity with the lowest IC50 values of 23.34 µM on Hep-G2 cells, 12.23 µM on MCF-7 cells, and 44.47 µM on LO2, which would widen the structural diversity of these anticancer targets and confirm the perspectives of further investigations.