Stereochemistry as a Determinant of the Anti-Leukemic Potency of Halopyridyl and Thiazolyl Thiourea Compounds

Structural Optimization of the Natural Product: Discovery of Almazoles C-D and Their Derivatives as Novel Antiviral and Anti-phytopathogenic Fungus Agents

Plant diseases seriously affect the growth of crops and the quality and yield of agricultural products. The search for plant-derived pesticide candidates based on natural products is a hot topic of current research. Marine natural products almazoles C-D were efficiently prepared and selected as the lead compounds in this work. Two series of almazole derivatives were designed and synthesized, and their antiviral and fungicidal activities were systematically evaluated. The results of anti-tobacco mosaic virus (anti-TMV) activity showed that almazoles C-D and their derivatives had good anti-TMV activities. Compounds 6, 15, 16a, 16b, 16g, 16l, 16n, 20a, 20d, 20i, and 20n exhibited better anti-TMV activities than the commercial antiviral agent ribavirin. Anti-TMV mechanism studies showed that compound 16b could induce the polymerization of 20S CP (coat protein, CP), thereby affecting the assembly of TMV virus particles. Molecular docking results showed that compounds 15, 16b, and 20n could combine with amino acid residues through hydrogen bonds to achieve an excellent anti-TMV effect. In addition, most of the almazole derivatives were found to have broad-spectrum fungicidal activities against eight kinds of plant pathogens (Fusarium oxysporum f. sp. cucumeris, Cercospora arachidicola Hori, Physalospora piricola, Rhizoctonia cerealis, Alternaria solani, Pyricularia grisea, Phytophthora capsici, and Sclerotinia sclerotiorum). This study provides an important evidence for the research and development of almazole alkaloids containing indole and oxazole structural groups as novel agrochemicals.

Cationic Bola Form Metallosurfactants Based on Isothiouronium, Synthesis and Anti-Microbial Activity

Two series of well-defined dimeric metallo-bolaamphiphiles (bola surfactants) with the coordinated metal ions (Cu, Co, Zn) were prepared. These oligomeric surfactants consist of simple monomeric cationic surfactant fragments which are coupled via the hydrophilic ammonium chloride head groups by C6 and C12 spacer groups of different lengths. FTIR and 1HNMR identification techniques confirmed the obtained products. Measurements of surface tensions showed that the synthesized Bola amphiphiles have the desired, relatively low critical micelle formation concentrations (CMC). Bola amphiphiles with long spacer groups (C12) have a pronounced surface activity. The properties of these cationic surfactant oligomers in aqueous solution such as micellization and surface activity were discussed in relation to spacer group. In addition, the synthesized compounds were examined for their anti-microbial activity using the agar diffusion technique.

Chiral Thioureas-Preparation and Significance in Asymmetric Synthesis and Medicinal Chemistry

For almost 20 years, thioureas have been experiencing a renaissance of interest with the emerged development of asymmetric organocatalysts. Due to their relatively high acidity and strong hydrogen bond donor capability, they differ significantly from ureas and offer, appropriately modified, great potential as organocatalysts, chelators, drug candidates, etc. The review focuses on the family of chiral thioureas, presenting an overview of the current state of knowledge on their synthesis and selected applications in stereoselective synthesis and drug development.

Antitumor activity of methyl (Z)-2-(isothioureidomethyl)-2-pentenoate hydrobromide against leukemia cell lines via mitotic arrest and apoptotic pathways

In a previous study, we described a series of 28 aryl- and alkyl-substituted isothiouronium salts with antitumor activity and selectivity toward a leukemia cell line. Among the synthesized compounds, methyl (Z)-2-(isothioureidomethyl)-2-pentenoate hydrobromide (IS-MF08) showed conspicuous activity. In the present study, we investigated the mechanism of action of IS-MF08. Our results showed that its mechanism most likely is related with the membrane receptor Fas and subsequent activation of the extrinsic cell death pathway, triggered by a decrease in the levels of the anti-apoptotic protein Bcl-2 and caspase-8 and -3 cascade activation, causing DNA damage and mitotic arrest. IS-MF08 also caused an increase in intracellular ROS, endoplasmic reticulum (ER) stress, and mitochondrial membrane permeabilization, resulting in organelle degradation as an attempt to reestablish cell homeostasis. Furthermore, cells exposed to IS-MF08 combined to an autophagy inhibitor were less susceptible to compound's cytotoxicity, suggesting that autophagy makes part of its mechanism of action. These data support the hypothesis that IS-MF08 acts by the apoptosis extrinsic pathway and possibly by autophagy as mechanisms of cell death.

Application of "hydrogen bonding interaction" in new drug development: design, synthesis, antiviral activity, and SARs of thiourea derivatives

A series of simple thiourea derivatives were designed based on the structure of natural product harmine and lead compound and synthesized from amines in one step. The antiviral activity of these thiourea derivatives was evaluated. Most of them exhibited significantly higher anti-TMV activity than commercial plant virucides ribavirin, harmine, and lead compound. The hydrogen bond was found to be important but not the more the better. The optimal compound (R,R)-20 showed the best anti-TMV activity in vitro and in vivo (in vitro activity, 75%/500 μg/mL and 39%/100 μg/mL; inactivation activity, 71%/500 μg/mL and 35%/100 μg/mL; curative activity, 73%/500 μg/mL and 37%/100 μg/mL; protection activity, 69%/500 μg/mL and 33%/100 μg/mL), which is significantly higher than that of Ningnanmycin. The systematic study provides strong evidence that these simple thiourea derivatives could become potential TMV inhibitors.

In Vivo Anti-Leukemia, Quantum Chemical Calculations and ADMET Investigations of Some Quaternary and Isothiouronium Surfactants

Anti-leukemia screening of previously prepared isothiouronium and quaternary salts was performed, and some salts exhibited promising activity as anticancer agents. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the HOMO-LUMO, IP and ESP mapping of these compounds. The ADMET properties were also studied to gain a clear view of the potential oral bioavailability of these compounds. The surface properties calculated included critical micelle concentration (CMC), maximum surface excess (Γmax), minimum surface area (Amin), free energy of micellization (ΔGomic) and adsorption (ΔGoads).

Synthesis and antiviral bioactivity of chiral thioureas containing leucine and phosphonate moieties

A series of novel chiral thioureas 3a-n bearing leucine and phosphonate moieties were synthesized in excellent yields. The structures of the compounds were completely characterized by elemental analysis, IR, ¹H-, ¹³C-, ³¹P- and ¹⁹F-NMR spectral data. A half-leaf method was used to determine the in vivo protective and curative efficacies of the title products against tobacco mosaic virus (TMV). The compounds 3l and 3n displayed good in vivo protection and curative effects against TMV with inhibitory rates of 60.1, 62.8% (protection) and 56.7, 53.6% (curative) at 0.5 mg/mL, respectively. To the best of our knowledge, this is the first report on the antiviral activity of chiral thioureas containing leucine and phosphonate moieties.