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Inspired by the reported antiviral activity of pyrimidines and triazolopyrimidines, two series of 2-anilinopyrimidines (5a-e) and 1-aryl-[1,2,4]triazolo[4,3-a]pyrimidines (14a-k) were designed and synthesized as potential antiviral agents. X-ray crystallographic study of compounds (14d) and (14k) confirmed the structure of the desired isomer and revealed the coplanarity of the fused [1,2,4]triazolo[4,3-a]pyrimidine rings with the aryl side group. DFT studies revealed insights into the mechanism of the micro-reversible cyclisation step using DFT [B3LYP-D3(BJ)/6-31++G(d,p)]. The pharmacokinetic properties and calculation of drug likeness scores (DLS) of (5a-e) and (14a-k) suggested good traditional drug-like properties and led to the synthesis of derivatives (14a-k) which were evaluated for their anti-viral activity with the most potent derivatives subjected to cytotoxicity screening. Compounds (14a), (14c), (14e), (14f) and (14k) showed moderate to strong antiviral activity with EC50 values 38 - 186 μM. Compound (14e) (DLS = 0.29) showed the best anti-CHIKV activity (EC50 = 38 μM) and lowest cytotoxicity (CC50 > 300 μg/ml) against against breast cancer cell lines, MCF-7 and MD-AMB-231 and normal cell line EA.hy926. Simplification of [1,2,4]triazolo[4,3-a]pyrimidine ring, led to series (5a-e) (DLS = 0.03 - 0.77). Derivatives (5a-d) showed fair anti-CHIKV activity (EC50 > 200 μM), while (5e) emerged as the most active antiviral agent, however the most cytotoxic.

Antifreeze proteins (AFPs) are of great importance for applications in cryomedicine or the food industry. They are frequently used to lower the freezing point by preventing the growth of larger ice crystals; thus, it is paramount to determine their thermal hysteretic characteristics. However, the experimental analysis of the thermal hysteresis-an effect that is characteristic for AFPs-remains a challenging process. An easy-to-use test method for measuring the thermal hysteresis of AFPs was developed and tested with the type III AFPs. Traditional methods that have been used until now have their disadvantages and limitations. The new measurement method described in this paper allows detection of the complete cooling, freezing, heating, and melting process in a single measurement. This makes it possible to directly determine the thermal hysteresis as a functional effect of the antifreeze proteins. Measurements of the thermal hysteresis were performed by applying ultrasound to initiate the crystallization process of the antifreeze protein solution. This ultrasound technique also allows a crystallization process to be performed at defined temperature. The demonstrated results were highly reproducible and could be clearly read off the measurement curves. As a future perspective, this enables the design of automatic test devices that can be also miniaturized.