Natural compounds bearing maleimide rings are a series of secondary metabolites derived from fungi/marine microorganisms, which are characterized by a general structure –CO–N(R)–CO–, and the R group is normally substituted with alkyl or aryl groups. Maleimide compounds show various biological activities such as antibacterial, antifungal, and anticancer activity. In this review, the broad-spectrum antimicrobial activities of 15 maleimide compounds from natural sources and 32 artificially synthesized maleimides were summarized, especially against Candida albicans, Sclerotinia sclerotiorum, and Staphylococcus aureus. It highlights that maleimide scaffold has tremendous potential to be utilized in the development of novel antimicrobial agents. Graphical abstract

In the present study, 45 maleimides have been synthesized and evaluated for anti-leishmanial activities against L. donovani in vitro and cytotoxicity toward THP1 cells. All compounds exhibited obvious anti-leishmanial activities. Among the tested compounds, there were 10 maleimides with superior anti-leishmanial activities to standard drug amphotericin B, and 32 maleimides with superior anti-leishmanial activities to standard drug pentamidine, especially compounds 16 (IC₅₀ < 0.0128 μg/mL) and 42 (IC₅₀ < 0.0128 μg/mL), which showed extraordinary efficacy in an in vitro test and low cytotoxicities (CC₅₀ > 10 μg/mL). The anti-leishmanial activities of 16 and 42 were 10 times better than that of amphotericin B. The structure and activity relationship (SAR) studies revealed that 3,4-non-substituted maleimides displayed the strongest anti-leishmanial activities compared to those for 3-methyl-maleimides and 3,4-dichloro-maleimides. 3,4-dichloro-maleimides were the least cytotoxic compared to 3-methyl-maleimides and 3,4-non-substituted maleimides. The results show that several of the reported compounds are promising leads for potential anti-leishmanial drug development.

The application of pesticides is critical during the growth of high-quality grape for wine making. However, pesticide residues have significant influence on the wine flavor. In this study, gas chromatography-mass spectrometry (GC-MS) was performed and the obtained datasets were analyzed with multivariate statistical methods to investigate changes in flavor substances in wine during fermentation. The principal component analysis (PCA) score plot showed significant differences in the metabolites of wine treated with various pesticides. In trials using five pesticides (hexaconazole, difenoconazole, flutriafol, tebuconazole, and propiconazole), more than 86 metabolites were changed. Most of these metabolites were natural flavor compounds, like carbohydrates, amino acids, and short-chain fatty acids and their derivatives, which essentially define the appearance, aroma, flavor, and taste of the wine. Moreover, the five pesticides added to grape pulp exhibited different effects on the metabolic pathways, involving mainly alanine, aspartate and glutamate metabolism, butanoate metabolism, arginine, and proline metabolism. The results of this study will provide new insight into the potential impact of pesticide residues on the metabolites and sensory profile of wine during fermentation.