[Bmim]Br Accelerated One-Pot Three-Component Cascade Protocol for the Construction of Spirooxindole-Pyrrolidine Heterocyclic Hybrids

Synthesis, computational docking and molecular dynamics studies of a new class of spiroquinoxalinopyrrolidine embedded chromanone hybrids as potent anti-cholinesterase agents

Novel structurally intriguing heterocycles embedded with spiropyrrolidine, quinoxaline and chromanone units were synthesized in good yields using a [Bmim]Br accelerated multicomponent reaction strategy. The key step of the reaction is 1,3-dipolar cycloaddition involving highly functionalized dipolarophile, viz. 3-benzylidenechroman-4-one, to afford spiroquinoxalinopyrrolidine embedded chromanone hybrid heterocycles. The formation of spiro products occurs via two C-C, two N-C and one C-N bonds possessing four adjoining stereogenic centers, two of which are spiro carbons. The newly synthesized spiro compounds showed potent acetylcholinesterase and butyrylcholinesterase inhibitory activities. Moreover, compounds with fluorine displayed the highest AChE (3.20 ± 0.16 μM) and BChE (18.14 ± 0.06 μM) inhibitory activities. Further, docking studies, followed by all-atom molecular dynamics, showed results that are consistent with in vitro experimental findings. Although docking scores for the synthesized derivatives were higher than those of the standard drug, MD MMPBSA results showed better binding of synthesized derivatives (-93.5 ± 11.9 kcal mol-1) compared to the standard drug galantamine (-66.2 ± 12.3 kcal mol-1) for AChE but exhibited similar values (-98.1 ± 11.2 and -97.9 ± 11.5 kcal mol-1) for BChE. These differences observed in drug binding with AChE/BChE are consistent with RMSD, RMSF, LIG plots, and FEL structural analysis. Taken together, these derivatives could be potential candidates as inhibitors of AChE and BChE.

Discovery of spirooxindole-pyrrolidine heterocyclic hybrids with potent antifungal activity against fungal pathogens

Fungal pathogens mainly Candida and Cryptococcus species causes serious life-threating infections to humans, especially in individuals who are immunocompromised. Increasing frequency of antifungal drug resistance along with paucity of FDA-approved drugs suggest a dire need for new antifungal drugs. Our screening of newly synthesized spirooxindole heterocyclic hybrid compounds revealed that the novel small molecule, DPA-3, has potent antifungal activity without inducing mammalian cell cytotoxicity. Furthermore, DPA-3 significantly reduced hyphal and biofilm formation of Candida albicans ATCC 10231 strain, out-competing two FDA approved antifungal drugs. The results of our study conclude that DPA-3 is a compelling candidate for further development as an antifungal drug.

In Vitro Molecular Biology Studies of Spirooxindole Heterocyclic Hybrids

 In the present report, we provide the results of the molecular biology studies of spiroheterocyclic hybrids, where the derivatives are found to possess potential anticancer activity towards cancer cells. A series of spiroxindole–pyrrolidine heterocyclic hybrids were evaluated for cell viability and proliferation against HepG2 cancer cells at concentrations in the range of 12.5–200 µg/mL over two different time periods of 24 and 48 h. In addition, the highly active compounds were also verified for their behavior towards noncancer cells (L929 cells), and it was found that the tested derivatives were not aggressive due to the observation of only limited cell loss, as compared to the cancer cells. Further analysis of the observed toxicity mechanism showed the apoptotic pathway was mediated by oxidative stress, with the involvement of caspases.