Binding characteristics of pyrrole-scaffold hepatitis B virus capsid inhibitors and identification of novel potent compounds.

Hepatitis B virus (HBV) capsid assembly modulators (CAMs) are currently being evaluated in clinical trials as potential curative therapies for HBV. This study used in silico computational modeling to provide insights into the binding characteristics between the HBV core protein and two pyrrole-scaffold inhibitors, JNJ-6379 and GLP-26, both in the CAM-Normal (CAM-N) series. Molecular dynamics simulations showed that the pyrrole inhibitors displayed similar general binding-interaction patterns to NVR 3-778, another CAM-N, with hydrophobic interactions serving as the major driving force. However, consistent with their higher potency, the pyrrole inhibitors exhibited stronger nonpolar interactions with key residues in a solvent-accessible region as compared to NVR 3-778. This feature was facilitated by distinct hydrogen bond interactions of the pyrrole scaffold inhibitors with the residue 140 in chain B of the HBV core protein (L140B). Based on these findings, novel CAM-N compounds were designed to mimic the interaction with L140B residue while maximizing nonpolar interactions in the solvent-accessible region. Several 1H-pyrrole-2-carbonyl substituted pyrrolidine-based compounds with various hydrophobic side chains were synthesized and evaluated. Through analyses of the structure-activity and structure-druggability relations of a series of compounds, CU15 emerged as the most promising lead CAM-N compound, exhibiting sub-nanomolar potency and good pharmacokinetic profiles. Overall, the study demonstrated a practical approach to leverage computational methods for understanding key target binding features for rationale-based design, and for guiding the identification of novel compounds.

Organocatalytic Visible Light Enabled SNAr of Heterocyclic Thiols: A Metal-Free Approach to 2-Aminobenzoxazoles and 4-Aminoquinazolines.

The direct amination reaction of heterocyclic thiols has been developed in the presence of the nonhazardous photocatalyst Rose Bengal under irradiation of visible light. The reaction provides a straightforward approach to pharmaceutically and synthetically useful 2-aminobenzoxazole and 4-aminoquinazoline derivatives from the corresponding heterocyclic thiols with amines in good to excellent yields. Our photochemical reaction can be successfully adapted into a continuous flow reactor which is applicable for large-scale chemical industry. The key benefits of this reaction include the use of metal-free, low-cost Rose Bengal catalyst and practical operation (ambient temperature, open flask, and undried solvents).

Synthesis of phosphaguanidines by hydrophosphination of carbodiimides with phosphine boranes.

The direct addition of anionic secondary phosphine boranes to carbodiimides yields both chiral and achiral phosphaguanidine boranes under ambient temperature conditions. An analogous preparation of menthol-derived phosphinite boranes is also described. These products can be deborinated to give the corresponding phosphines, and subsequently oxidized to give phosphine oxides. The robustness of this method was further demonstrated in the synthesis of structurally novel cyclic phosphaguanidines.

Quercitylcinnamates, a new series of antidiabetic bioconjugates possessing α-glucosidase inhibition and antioxidant.

Antidiabetic agents possessing dual functions, α-glucosidase inhibition and antioxidant, have been accepted to be more useful than currently used antidiabetic drugs because they not only suppress hyperglycemia but also prevent risk of complications. Herein, we design antidiabetic bioconjugates comprising of (+)-proto-quercitol as a glucomimic and cinnamic analogs as antioxidant moieties. Fifteen quercitylcinnamates were synthesized by direct coupling through ester bond in the presence of DCC and DMAP. Particular quercityl esters 6a, 7a and 8a selectively inhibited rat intestinal maltase and sucrose 4-6 times more potently than their parents 6, 7 and 8. Of synthesized bioconjugates, 6a was the most potent inhibitor against maltase and sucrose with IC50 values of 5.31 and 43.65 µM, respectively. Of interest, its inhibitory potency toward maltase was 6 times greater than its parent, caffeic acid (6), while its radical scavenging (SC50 0.11 mM) was comparable to that of commercial antioxidant BHA. Subsequent investigation on mechanism underlying inhibitory effect of 6a indicated that it blocked maltase and sucrose functions by mixed inhibition through competitive and noncompetitive manners.

Concise synthesis of (+)-conduritol F and inositol analogues from naturally available (+)-proto-quercitol and their glucosidase inhibitory activity.

An effective synthesis of (+)-conduritol F, (+)-chiro- and (+)-epi-inositols from naturally available (+)-proto-quercitol is described. This synthetic method provides a concise synthesis of cyclitols in enantiomerically pure form. Of the synthesized cyclitols, (+)-conduritol F potently inhibits type I α-glucosidase with an IC(50) value of 86.1 µM, which is five times greater than the standard antidiabetic drug, acarbose.