Design and Synthesis of New Benzo[d]oxazole-Based Derivatives and Their Neuroprotective Effects on β-Amyloid-Induced PC12 Cells

A Sustainable Synthesis of Novel 2-(3,4-Disubstituted phenyl)benzoxazole Derivatives and Their Antiproliferative and Antibacterial Evaluation

This study describes the synthesis of O-alkylated benzaldehydes 1-8, Schiff bases 9-28, and benzoxazole derivatives 29-48 using microwave, ultrasound, and mechanochemical reactions, as well as reactions in deep eutectic solvents in excellent yields, and their antiproliferative and antibacterial activities. The in vitro evaluation of antiproliferative activity for the newly synthesised benzoxazole derivatives 29-48 against a diverse panel of human cancer cell lines, such as LN-229, Capan-1, HCT-116, NCI-H460, DND-41, HL-60, K-562, and Z-138 demonstrated that the majority of these benzoxazole derivatives displayed promising anticancer activity, particularly against non-small cell lung cancer (NSCLC) cells (NCI-H460). Notably, several derivatives showed enhanced activity compared to the included reference drug, etoposide. Considering the influence of substituents at position 5 of the benzoxazole ring and positions 3 and 4 of the phenyl ring on the antiproliferative activity, it is evident that derivatives 41-48 bearing a methoxy group at position 3 generally exhibit higher activity compared to compounds 29-40, which lack substitution at position 3. Furthermore, derivatives substituted at position 4 with a morpholine substituent, as well as those with an N,N-diethyl group, exhibited higher activity compared to other evaluated benzoxazole derivatives. The in vitro antibacterial evaluation against Gram-positive and Gram-negative bacteria revealed that benzoxazole derivative 47 exhibited notable activity, against the Gram-negative bacterium Pseudomonas aeruginosa (MIC = 0.25 μg/mL) and the Gram-positive bacterium Enterococcus faecalis (MIC = 0.5 μg/mL). The results point out that this class of benzoxazoles can be efficiently synthesized using eco-friendly methods and represent promising candidates for further design and optimization aimed at developing potent antiproliferative agents.

DBU-Promoted Deaminative Thiolation of 1H-Benzo[d]imidazol-2-amines and Benzo[d]oxazol-2-amines

A facile and efficient catalyst-/metal-/oxidant-free DBU-promoted deaminative thiolation reaction of 1H-benzo[d]imidazol-2-amines and benzo[d]oxazol-2-amines has been developed at room temperature conditions in a one-pot protocol. This practical three-component strategy represents a novel and environmentally friendly reaction pathway toward the straightforward synthesis of various 2-thio-1H-benzo[d]imidazoles and 2-thiobenzo[d]oxazoles using carbon disulfide as a sulfur source through C-N bond cleavage and C-S bond formation process. Different types of 1H-benzo[d]imidazol-2-amines, benzo[d]oxazol-2-amines, and organic bromides are suitable substrates. The gram-scale and late-stage modification experiments provide the potential applications based on this methodology in the field of organic and medicinal chemistry.

Rapid screening of neuroprotective components from Huang-Lian-Jie-Du Decoction by living cell biospecific extraction coupled with HPLC-Q-Orbitrap-HRMS/MS analysis

Huang-Lian-Jie-Du Decoction (HLJDD), a well-known traditional Chinese formulation, has been proved to exert neuroprotective effects, however, the bioactive components in HLJDD still remain to be elucidated. In the present study, a rapid and effective method involving live cell biospecific extraction and HPLC-Q-Orbitrap HRMS/MS was utilized to rapidly screen and identify the neuroprotective compounds from the HLJDD crude extract directly. Firstly, sixteen principal components in HLJDD crude extract were identified by HPLC-Q-Orbitrap HRMS/MS analysis. After co-incubation with PC12 cells, which have been validated as the key target cells for neurodegenerative diseases, seven compounds of them were demonstrated to exhibit binding affinity to the target cells. Furthermore, three representative compounds named baicalin, wogonoside, and berberine were subsequently verified to exert cytoprotective effects on PC12 cells injured by hydrogen peroxide via inhibiting oxidative stress and cell apoptosis, indicating that these screened compounds may possess a potential for the treatment of neurodegenerative diseases and were responsible, in part at least, for the neuroprotective beneficial effects of HLJDD. Taken together, our study provides evidence that live cell biospecific extraction coupled with LC-HRMS/MS technique is an efficient method for rapid screening potential bioactive components in traditional Chinese medicines.