Recent advances in quinazoline/quinazolinone hybrid heterocycles in medicinal chemistry and their pharmacological diversification.

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A series of rhodanine‐3‐acetic acid derivatives were synthesized via Knoevenagel condensation of rhodanine‐3‐acetic acid with various substituted aromatic aldehydes. The synthesized derivatives were screened in vitro for understanding the inhibitory potential towards pancreatic lipase (PL), a key enzyme responsible for the digestion of dietary fats. Derivative 8f exhibited a potential inhibitory activity towards PL (IC50 = 5.16 µM), comparable to that of the standard drug, orlistat (0.99 µM). An increase in the density of the aromatic ring resulted in potential PL inhibition. The enzyme kinetics of 8f exhibited a reversible competitive‐type inhibition, similar to that of orlistat. Derivative 8f exhibited a MolDock score of ‐125.19 kcal/mol in docking studies, and the results were in accordance with their PL inhibitory potential. Furthermore, the reactive carbonyl group of 8f existed at a distance adjacent to Ser152 (≈3 Å) similar to that of orlistat. Molecular dynamics simulation (10 ns) of the 8f‐PL complex revealed a stable binding conformation of 8f in the active site of PL (maximum root mean square displacement of ≈2.25 Å). The present study identified novel rhodanine‐3‐acetic acid derivatives with promising PL inhibitory potential, and further lead optimization might result in potent PL inhibitors.

A series of thiazolidinedione-indole hybrids are designed and synthesized as a potential inhibitor for pancreatic lipase (PL).

Pancreatic Lipase (PL) is a key enzyme responsible for the digestion of 50%–70% of dietary triglycerides, hence its inhibition is considered as a viable approach for the management of obesity. A series of indole‐TZD hybrid analogues were synthesized, characterized and evaluated for their PL inhibitory activity. Knoevenagel condensation of various substituted indole‐3‐carboxaldehyde with substituted thiazolidinediones resulted in the formation of titled analogues. Analogues 6d and 6e exerted potent PL inhibitory activity (IC50‐6.19 and 8.96 µM, respectively). Further, these analogues exerted a competitive mode of PL inhibition. Moreover, molecular modelling studies were in agreement with the in vitro results (Pearson's r = .8682, p < .05). The fluorescence spectroscopic analysis further supported the strong binding affinity of these analogues with PL. A molecular dynamics study (20 ns) indicated that these analogues were stable in a dynamic environment. Thus, the present study highlighted the potential role of indole‐thiazolidinedione hybrid analogues as potential PL inhibitors and further optimization might result in the development of new PL inhibitory lead candidates.

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Genus Alstonia is comprised of around 155 species throughout the world. Phytochemical screening of Alstonia genus has demonstrated the presence of diverse phytochemicals that include at least 800 distinct metabolites. The main classes of metabolites are alkaloids, iridoids, flavonoids, fatty acids, etc. Secondary metabolites from this genus also bring positive results when employed as anticancer, anti-spasmodic, antitussive, antiarthritic, antioxidant, etc. Alstonia boonei is listed as an antimalarial drug in African pharmacopoeia. In China, a formulation consists of A. scholaris leaves-Dengtaiye tablets are used for the treatment of cough and fever symptoms. Recently, A. scholaris leaves-derived indole alkaloids have been registered as an investigational new botanical drug (No. 2011L01436) and China Food and Drug Administration (CFDA) has approved its phase I/II clinical trials for the treatment of respiratory diseases. Pharmacokinetic and safety analysis of this botanical drug in healthy human subjects have revealed a safe profile under the dose regimen experiment. Apart from that, strictamine, an indole alkaloid isolated from A. scholaris exhibited a similar in vitro antiviral activity to that of acyclovir. The present chapter is mainly focused on the critical analysis of various secondary metabolites isolated from Alstonia (approximately 15 species). Apart from that, pharmacological, toxicological and intellectual property rights studies have also been included.

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