Staphylococcus aureus resistance to current antibiotics has become the greatest global challenge facing public health. The development of new antimicrobial agents is urgent and important and is needed to provide additional therapeutic options. In our previous study, we found out that pterostilbene exhibited potent antibacterial activity, especially against methicillin-resistant Staphylococcus aureus (MRSA). According to previous studies, 1,2,3-triazole, with the characteristic of increasing the interaction with the target readily and enhancing water solubility, were widely used in the approved anti-bacterial drugs. Therefore, these results attract our interest to use the structure of pterostilbene as a scaffold for the hybrid 1,2,3-triazole moiety to develop a novel anti-MRSA infection agent. In this study, we demonstrated the design and synthesis of a series of triazolylpterostilbene derivatives. Among these compounds, compound 4d exhibited the most potent anti-MRSA activity with a minimum inhibitory concentration (MIC) value of 1.2–2.4 μg/mL and a minimum bactericidal concentration (MBC) value of 19.5–39 μg/mL. The structure–activity relationship and antibacterial mechanism were investigated in this study. Molecular docking studies were carried out to verify and rationalize the biological results. In this study, the results confirmed that our design could successfully increase the inhibitory activity and specificity against MRSA. Compound 4d could be used as a candidate for anti-bacterial agents and in depth vivo studies should be further investigated.

We describe herein the preparation of certain 2-substituted 3-arylquinoline derivatives and the evaluation of their anti-inflammatory effects in LPS-activated murine J774A.1 macrophage cells. Among these newly synthesized 2-substituted 3-arylquinoline derivatives, 2-(4-methoxy- benzoyl)-3-(3,4,5-trimethoxyphenyl)quinoline (18a) and 2-(4-fluorobenzoyl)-3-(3,4,5-trimethoxy- phenyl)quinoline (18b) are two of the most active compounds which can inhibit the production of NO at non-cytotoxic concentrations. Our results have also indicated that compounds 18a and 18b significantly decrease the secretion of pro-inflammatory cytokines (TNF-á and IL-6), inhibit the expression of iNOS, suppress the phosphorylation of MAPKs, and attenuate the activity of NF-êB by LPS-activated macrophages. Through molecular docking analysis, we found that 18b could fit into the middle of the TNF-á dimer and form hydrophobic interactions with Leu55, Leu57 chain A and B, Tyr59, Val123 chain B and D, Ile 155. These results suggest that both 18a and 18b are potential lead compounds in inhibiting LPS-induced inflammatory responses. Further structural optimization to discover novel anti-inflammatory agents is ongoing.

Several thalidomide derivatives were synthesized and evaluated for their anti-inflammatory activity. Introduction of the benzyl group to the parent thalidomide is unfavorable in which 2-(1-benzyl-2,6-dioxopiperidin-3-yl)isoindoline-1,3-dione (4a) was inactivated. However, the inhibitory activities on TNF-α and IL-6 expression in HaCaT cells were improved by the substitution of a chloro- or methoxy- group at the phenyl position of 4a. The IL-6 inhibitory activity decreased in an order of 5c (69.44%) > 4c (48.73%) > 6c (3.19%) indicating the 3-substituted derivative is more active than the 4-substituted counterpart, which in turn is more active than the 2-substituted counterpart. Among them, 2-[1-(3-chlorobenzyl)-2,6-dioxopiperidin-3-yl]isoindoline-1,3-dione (5c) was found to inhibit TNF-α and IL-6 expression in HaCaT cells with a higher potency than thalidomide and no significant cell cytotoxicity was detected at 10 μM. In psoriasis, Compound 5c reduced IL-6, IL-8, IL-1β and IL-24 in imiquimod-stimulated models. Our results indicated that compound 5c is a potential lead of novel anti-psoriasis agents. Structural optimization of compound 5c and its in vivo assay are ongoing.

Activation of nuclear factor erythroid-2-related factor 2 (NRF2) has been proven to be an effective means to prevent the development of cancer, and natural curcumin stands out as a potent NRF2 activator and cancer chemopreventive agent. In this study, we have synthesized a series of 4-anilinoquinolinylchalcone derivatives, and used a NRF2 promoter-driven firefly luciferase reporter stable cell line, the HaCaT/ARE cells, to screen a panel of these compounds. Among them, (E)-3-{4-[(4-acetylphenyl)amino]quinolin-2-yl}-1-(4-fluorophenyl)prop-2-en-1-one (13b) significantly increased NRF2 activity in the HaCaT cell with a half maximal effective concentration (EC₅₀) value of 1.95 μM. Treatment of compound 13b upregulated HaCaT cell NRF2 expression at the protein level. Moreover, the mRNA level of NRF2 target genes, heme oxygenase-1 (HO-1), glutamate-cysteine ligase catalytic subunit (GCLC), and glucose-6-phosphate dehydrogenase (G6PD) were significantly increased in HaCaT cells upon the compound 13b treatment. The molecular docking results exhibited that the small molecule 13b is well accommodated by the bound region of Kelch-like ECH-associated protein 1 (Keap1)-Kelch and NRF2 through stable hydrogen bonds and hydrophobic interaction, which contributed to the enhancement of affinity and stability between the ligand and receptor. Compound 13b has been identified as the lead compound for further structural optimization.

Pterostilbene, a natural metabolite of resveratrol, has been indicated as a potent anticancer molecule. Recently, several pterostilbene derivatives have been reported to exhibit better anticancer activities than that of the parent pterostilbene molecule. In the present study, a series of pterostilbene derivatives were designed and synthesized by the hybridization of pterostilbene, chalcone, and cinnamic acid. The cytotoxic effect of these hybrid molecules was determined using two oral cancer cell lines, HSC-3 and OECM-1. (E)-3-(2-((E)-4-Hydroxystyryl)-4,6-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (4d), with IC₅₀ of 16.38 and 18.06 μM against OECM-1 and HSC-3, respectively, was selected for further anticancer mechanism studies. Results indicated that compound 4d effectively inhibited cell proliferation and induced G2/M cell cycle arrest via modulating p21, cyclin B1, and cyclin A2. Compound 4d ultimately induced cell apoptosis by reducing the expression of Bcl-2 and surviving. In addition, cleavage of PARP and caspase-3 were enhanced following the treatment of compound 4d with increased dose. To conclude, a number of pterostilbene derivatives were discovered to possess potent anticancer potentials. Among them, compound 4d was the most active, more active than the parent pterostilbene.

We designed and synthesized a series of novel 3-arylquinoxaline derivatives and evaluated their biological activities as potential dengue virus (DENV) replication inhibitors. Among them, [3-(4-methoxyphenyl)quinoxalin-2-yl](phenyl)methanol (19a), [6,7-dichloro-3-(4-methoxyphenyl)quinoxalin-2-yl](phenyl)methanol (20a), and (4-methoxyphenyl)(3-phenylquinoxalin-2-yl)methanone (21b) were found to significantly inhibit the DENV RNA expression in Huh-7-DV-Fluc cells with a potency better than that of ribavirin. Compound 19a reduced DENV replication in both viral protein and messenger RNA (mRNA) levels in a dose-dependent manner and exhibited no significant cell cytotoxicity. Notably, compound 19a exhibited a half maximal effective concentration (EC₅₀) value at 1.29 ± 0.74 μM. We further observed that the inhibitory effect of 19a on DENV replication was due to suppression of DENV-induced cyclooxygenase-2 (COX-2) expression. Docking studies also showed that 19a caused hydrophobic interactions at the active sites with Arg29, Glu31, Tyr116, Leu138, Pro139, Lys454, Arg455, and Gln529. The calculated lowest binding energy between the 19a and COX-2 was −9.10 kcal/mol. In conclusion, compound 19a might be a potential lead compound for developing an anti-DENV agent.