Bowroju Suresh Kuarm

Chronic, low-grade inflammation has been implicated in aging and age-dependent conditions, including Alzheimer’s disease, cardiomyopathy, and cancer. One of the age-associated processes underlying chronic inflammation is protein aggregation, which is implicated in neuroinflammation and a broad spectrum of neurodegenerative diseases such as Alzheimer’s, Huntington’s, and Parkinson’s diseases. We screened a panel of bioactive thiadiazolidinones (TDZDs) from our in-house library for rescue of protein aggregation in human-cell and C. elegans models of neurodegeneration. Among the tested TDZD analogs, PNR886 and PNR962 were most effective, significantly reducing both the number and intensity of Alzheimer-like tau and amyloid aggregates in human cell-culture models of pathogenic aggregation. A C. elegans strain expressing human Aβ_1–42 in muscle, leading to AD-like amyloidopathy, developed fewer and smaller aggregates after PNR886 or PNR962 treatment. Moreover, age-progressive paralysis was reduced 90% by PNR886 and 75% by PNR962, and “healthspan” (the median duration of spontaneous motility) was extended 29% and 62%, respectively. These TDZD analogs also extended wild-type C. elegans lifespan by 15–30% (p < 0.001), placing them among the most effective life-extension drugs. Because the lead drug in this family, TDZD-8, inhibits GSK3β, we used molecular-dynamic tools to assess whether these analogs may also target GSK3β. In silico modeling predicted that PNR886 or PNR962 would bind to the same allosteric pocket of inactive GSK3β as TDZD-8, employing the same pharmacophore but attaching with greater avidity. PNR886 and PNR962 are thus compelling candidate drugs for treatment of tau- and amyloid-associated neurodegenerative diseases such as AD, potentially also reducing all-cause mortality.

Triiodoisocyanuric acid (TICA) controlled one-pot and easy-operational protocol has been developed for the synthesis of substituted phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) from styrenes with o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine respectively. The reaction involves co-bromination and oxidation for the formation of an a-bromo ketone as an intermediate in the presence of triiodoisocyanuric acid, followed by condensation with the o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine for the formation of phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) in 55-79% yield. This protocol environmentally benign and economically viable. Substituted quinoxalines were obtained in good to excellent yields with wide substrate scope and functional-group tolerance.

A series of 11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one derivatives (Va–m) that incorporate a variety of substituents have been synthesized under both conventional heating and microwave irradiation procedures. All these analogs were evaluated for their antimicrobial activity against the Gram-positive bacteria Bacillus subtilis (BS), Staphylococcus aureus (SA), and Staphylococcus epidermidis (SE), against the Gram-negative bacteria Escherichia coli (EC), Pseudomonas aeruginosa (PA), and Klebsiella pneumonia (KP), and against the fungal species Candida albicans (CA), Candida rugosa (CR), Rhizopus oryzae (RO), and Aspergillus niger (AN) and antitubercular activity against MTB H37Rv. Analog, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) was identified as a potent antibacterial agent (MIC_[BS] = 2.5 µg/mL, MIC_[SA] = 10 µg/mL, MIC_[SE] = 2.5 µg/mL, MIC_[EC] = 5 µg/mL, MIC_[PA] = 10 µg/mL, MIC_[KP] = 2.5 µg/mL), and a potent antifungal agent (MIC_[CA] = 15 µg/mL, MIC_[CR] = 15 µg/mL, MIC_[RO] = 10 µg/mL). Another analog, 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) was also identified as a potent antibacterial agent (MIC_[BS] = 2.5 µg/mL, MIC_[SA] = 15 µg/mL, MIC_[SE] = 2.5 µg/mL, MIC_[EC] = 10 µg/mL, MIC_[PA] = 15 µg/mL, MIC_[KP] = 20 µg/mL), and a potent antifungal agent (MIC_[CA] = 2.5 g/mL, MIC_[CR] = 10 µg/mL MIC_[RO] = 15 µg/mL and MIC_[AN] = 10 µg/mL). Based on the MIC data analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selena-diazol-11-one (Vj) were identified as the most potent antimicrobial agents in the series. All these 11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one derivatives (Va–m) were also evaluated for their antitubercular activity against MTB H37Rv. Analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) showed MIC of 3.12 µg/mL. These results suggest that analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) may be a potential multifunctional ligands for the development of highly effective antimicrobial and antitubercular activity.

A three-component cascade reaction for the synthesis of 1,3,4-selenadiazoles and their derivatives from arylaldehydes, hydrazine, and elemental selenium by using molecular iodine is reported.

Glycogen synthase kinase-3β (GSK3β) controls many physiological pathways, and is implicated in many diseases including Alzheimer’s and several cancers. GSK3β-mediated phosphorylation of target residues in microtubule-associated protein tau (MAPTAU) contributes to MAPTAU hyperphosphorylation and subsequent formation of neurofibrillary tangles. Inhibitors of GSK3β protect against Alzheimer’s disease and are therapeutic for several cancers. A thiadiazolidinone drug, TDZD-8, is a non-ATP-competitive inhibitor targeting GSK3β with demonstrated efficacy against multiple diseases. However, no experimental data or models define the binding mode of TDZD-8 with GSK3β, which chiefly reflects our lack of an established inactive conformation for this protein. Here, we used metadynamic simulation to predict the three-dimensional structure of the inactive conformation of GSK3β. Our model predicts that phosphorylation of GSK3β Serine9 would hasten the DFG-flip to an inactive state. Molecular docking and simulation predict the TDZD-8 binding conformation of GSK3β to be inactive, and are consistent with biochemical evidence for the TDZD-8–interacting residues of GSK3β. We also identified the pharmacophore and assessed binding efficacy of second-generation TDZD analogs (TDZD-10 and Tideglusib) that bind GSK3β as non-ATP-competitive inhibitors. Based on these results, the predicted inactive conformation of GSK3β can facilitate the identification of novel GSK3β inhibitors of high potency and specificity.

A series of novel hybrid 8-hydroxyquinoline-indole derivatives (7a–7e, 12a–12b and 18a–18h) were synthesized and screened for inhibitory activity against self-induced and metal-ion induced Aβ_1–42 aggregation as potential treatments for Alzheimer’s disease (AD). In vitro studies identified the most inhibitory compounds against self-induced Aβ_1–42 aggregation as 18c, 18d and 18f (EC₅₀ = 1.72, 1.48 and 1.08 µM, respectively) compared to the known anti-amyloid drug, clioquinol (1, EC₅₀ = 9.95 µM). The fluorescence of thioflavin T-stained amyloid formed by Aβ_1–42 aggregation in the presence of Cu²⁺ or Zn²⁺ ions was also dramatically decreased by treatment with 18c, 18d and 18f. The most potent hybrid compound 18f afforded 82.3% and 88.3% inhibition, respectively, against Cu²⁺- induced and Zn²⁺- induced Aβ_1–42 aggregation. Compounds 18c, 18d and 18f were shown to be effective in reducing protein aggregation in HEK-tau and SY5Y-APP_Sw cells. Molecular docking studies with the most active compounds performed against Aβ_1–42 peptide indicated that the potent inhibitory activity of 18d and 18f were predicted to be due to hydrogen bonding interactions, π–π stacking interactions and π–cation interactions with Aβ_1–42, which may inhibit both self-aggregation as well as metal ion binding to Aβ_1–42 to favor the inhibition of Aβ_1–42 aggregation.

(R)-Solanone was identified as a female-specific compound from aerations of virgin females of the scale insect, Aulacaspis murrayae Takahashi. The stereochemistry of the insect-produced solanone was confirmed to be (R) by comparison with synthesized racemic and chiral standards on a chiral stationary phase GC column. In bioassays, males were strongly attracted to a synthesized sample of (R)-solanone, demonstrating that this compound is a sex pheromone component for this species.

A simple, efficient and environmentally friendly process for the solid state synthesis of quinoxaline derivatives by the condensation reaction of the benzo[c][1,2,5]thiadiazole-4,5-diamine and 3-(ω-bromoacetyl)-coumarins in the presence of cellulose sulfuric acid by simple physical grinding of reactants using a mortar and pestle at room temperature in good to excellent yields with high purity. The catalyst is recyclable and reusable.

A simple and efficient method has been developed for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ols) by the condensation reaction between substituted aldehydes, and 1-phenyl-3-methylpyrazol-5-one in the presence of xanthan sulfuric acid (XSA) as a solid acid catalyst. This method is simple and cost-effective with short reaction times. Yields are excellent with high purity, and the catalyst could be easily recycled.