Pre-emergence application of (thio)urea analogues compromises the development of the weed species Bidens pilosa, Urochloa brizantha, and Urochloa decumbens.

Invasive species (weeds) contribute to great losses in crop productivity, and one of the strategies for controlling their distribution in the field involves the use of herbicides. However, the development of new formulations for the control of weeds is challenged by environmental issues, increases in the resistance of weeds to herbicides, and poor selectivity of herbicides towards invasive species. Here, by using pre-emergence experiments, we assessed the phytotoxicity of two (thio)urea analogues (2A10 and 2B2) against the weed species Bidens pilosa (a dicot), Urochloa brizantha and Urochloa decumbens (monocots). Similar to diuron (400 µM), which is a commercial urea analogue herbicide, the urea analogue 2A10 (>200 µM) was lethal to B. pilosa. Although 2A10 failed to disrupt the germination of U. brizantha seeds, this compound (≥600 µM) inhibited the accumulation of chlorophyll a and b and carotenoids and resulted in the development of seedlings that presented relatively short roots and small, chlorotic leaves. Moreover, the thiourea analogue 2B2 (≥600 µM) reduced the germination percentage of U. decumbens seeds and delayed their germination, and at a concentration of 800 µM, this analogue impaired root growth and blocked the formation of lateral roots. The presence of an oxygen atom in the urea moiety of the 2A10 structure is critical for its marked activity against B. pilosa seeds, as 2B2 bears a sulphur atom instead and marginally inhibits seed germination. Neither 2A10 nor 2B2 was toxic to the non-weed species Lactuca sativa (lettuce; a dicot), and the latter even exerted beneficial effects by stimulating leaf expansion. Therefore, the evaluated (thio)urea analogues are promising for the design and development of new phytotoxic compounds for the pre-emergent control of the spread of B. pilosa (2A10) or the post-emergence control of U. brizantha (2A10) and U. decumbens (2B2).

Thimerosal changes protein conformation and increase the rate of fibrillation in physiological conditions: Spectroscopic studies using bovine serum albumin (BSA).

The interaction between bovine serum albumin (BSA) and thimerosal (TM), an organomercury compound widely employed as a preservative in vaccines, was investigated simulating physiological conditions and using different spectroscopic techniques. The results, employing molecular fluorescence showed the interaction occurs by static quenching through electrostatic forces (ΔH < 0 and ΔS > 0), spontaneously (ΔG = -4.40 kJ mol-1) and with a binding constant of 3.24 × 103 M-1. Three-dimensional fluorescence studies indicated that TM causes structural changes in the polypeptide chain of the BSA, confirmed by circular dichroism that showed an increase in α-helix (from 43.9 to 47.8%) content after interaction process. Through synchronized fluorescence and employing bilirubin as a protein site marker, it was confirmed the preferential interaction of TM in the subdomain IB of BSA. The interaction mechanism proposed in this work is based on the reaction of TM with BSA through of free Cys34 residue, forming the adduct BSA-HgEt with the thiosalicylic acid release, which possibly interacts electrostatically with positive side chain amino acids of the modified protein. Finally, it was proven that both TM and EtHgCl accelerate the protein fibrillation kinetics in 42 and 122%, respectively, indicating the toxicity of these compounds in biological systems.

A mini-review on Biginelli adducts with notable pharmacological properties.

Since the disclosure of Biginelli reaction by the chemist Pietro Biginelli, functionalized 3,4-dihydropyrimidin-2(1H)-ones/thiones (DHPMs) have emerged as prototypes for the design of compounds with a broad variety of biological activities. This mini-review describes over 100 Biginelli adducts demonstrated to be promising anticancer, inhibitors of calcium channel, anti-inflammatory, antimicrobial and antioxidant agents. Thus, this compilation presents the most notable in vitro and in vivo results for such fascinating class of organic compounds.

Biological activities of eco-friendly synthesized Hantzsch adducts.

Fourteen Hantzsch adducts with different substituents at the C-4 position were synthesized through multicomponent reactions by using citric or lactic acid as catalysts. To the best of our knowledge, this is the first report on the synthesis of such a class of compounds based on multicomponent reactions catalyzed by non-toxic organic acids. The potential to scavenge reactive nitrogen/oxygen species (RNS/ROS) and the ability to inhibit cancer cell growth were then investigated. Among the synthesized compounds, adduct 15 was the most promising free radical scavenger, while adduct 20 was shown to have a wider spectrum of action on the cancer cells studied. These results highlight Hantzsch adducts as lead compounds for obtaining new free radical scavengers and anticancer agents.