Qingliang Xu

Bio: Qingliang Xu is an academic researcher from Chinese Ministry of Education. The author has contributed to research in topics: Nicotinic acetylcholine receptor & Nicotinic agonist. The author has an hindex of 5, co-authored 11 publications receiving 47 citations. Previous affiliations of Qingliang Xu include Ocean University of China.

Application of reverse docking for target prediction of marine compounds with anti-tumor activity

Abstract: A large number of structures of anti-cancer drug targets have been solved and deposited to the protein data bank already. Identification of the targets for marine compounds with anti-tumor activity presents a challenge for marine natural products scientists. In this study, fast and efficient computational reverse docking was applied to predict the probable targeting proteins of the marine compounds with anti-tumor activity. Crystal structures of the proteins involved in tumor genesis, growth and metastasis were collected from PDB to construct the anti-tumor protein database (APD) for reverse docking. Two non-commercial docking programs, AutoDock Vina and LeDock, were used to perform the docking. Our results suggest that reverse docking is efficient for target fishing of compounds with known anti-tumor activities. In addition, the results show that performance of reverse docking using LeDock is superior to that using AutoDock Vina. Overall, reverse docking is a fast and efficient computational method to identify the probable target of the compounds with anti-tumor activities, and it can be complementary to the biological testing methods.

Enhanced Activity against Multidrug-Resistant Bacteria through Coapplication of an Analogue of Tachyplesin I and an Inhibitor of the QseC/B Signaling Pathway.

Abstract: Tachyplesin I (TPI) is a cationic β-hairpin antimicrobial peptide with broad-spectrum, potent antimicrobial activity. In this study, the all d-amino acid analogue of TPI (TPAD) was synthesized, and its structure and activity were determined. TPAD has comparable antibacterial activity to TPI on 14 bacterial strains, including four drug-resistant bacteria. Importantly, TPAD has significantly improved stability against enzymatic degradation and decreased hemolytic activity compared to TPI, indicating that it has better therapeutic potential. The induction of bacterial resistance using low concentrations of TPAD resulted in the activation of the QseC/B two-component system. Deletion of this system resulted in at least five-fold improvement of TPAD activity, and the combined use of TPAD with LED209, a QseC/B inhibitor, significantly enhanced the bactericidal effect against three classes of multidrug-resistant bacteria.

α-Conotoxin Vc1.1 Structure-Activity Relationship at the Human α9α10 Nicotinic Acetylcholine Receptor Investigated by Minimal Side Chain Replacement.

Abstract: α-Conotoxin Vc1.1 inhibits the nicotinic acetylcholine receptor (nAChR) α9α10 subtype and has the potential to treat neuropathic chronic pain. To date, the crystal structure of Vc1.1-bound α9α10 nAChR remains unavailable; thus, understanding the structure-activity relationship of Vc1.1 with the α9α10 nAChR remains challenging. In this study, the Vc1.1 side chains were minimally modified to avoid introducing large local conformation perturbation to the interactions between Vc1.1 and α9α10 nAChR. The results suggest that the hydroxyl group of Vc1.1, Y10, forms a hydrogen bond with the carbonyl group of α9 N107 and a hydrogen bond donor is required. However, Vc1.1 S4 is adjacent to the α9 D166 and D169, and a positive charge residue at this position increases the binding affinity of Vc1.1. Furthermore, the carboxyl group of Vc1.1, D11, forms two hydrogen bonds with α9 N154 and R81, respectively, whereas introducing an extra carboxyl group at this position significantly decreases the potency of Vc1.1. Second-generation mutants of Vc1.1 [S4 Dab, N9A] and [S4 Dab, N9W] increased potency at the α9α10 nAChR by 20-fold compared with that of Vc1.1. The [S4 Dab, N9W] mutational effects at positions 4 and 9 of Vc1.1 are not cumulative but are coupled with each other. Overall, our findings provide valuable insights into the structure-activity relationship of Vc1.1 with the α9α10 nAChR and will contribute to further development of more potent and specific Vc1.1 analogues.

Synthesis of novel 10,11-methylenedioxy-camptothecin glycoside derivatives and investigation of their anti-tumor effects in vivo

Abstract: 10,11-Methylenedioxy-camptothecin (FL118) is a novel camptothecin analogue that possesses exceptional antitumor efficacy in human tumor xenograft models. The aim of the current study was to develop novel 20-substituted FL118 derivatives coupled with glycosyl-succinic acid esters with improved antitumor efficacy. These FL118 glycoside derivatives were designed, synthesized and their cytotoxicity evaluated in three tumor cell lines (A-549, MDA-MB-231 and RM-1). All of the derivatives showed superior in vitro cytotoxic activity and were more potent than irinotecan in A549 and MDA-MB-231 cells. In mouse prostate cancer cells RM-1, 10,11-methylenedioxy-camptothecin rhamnoside 11b displayed significant activities with IC50 of 48.27 nM. Western blot analysis demonstrated that 11b inhibited survivin expression and induced cancer cells apoptosis. Further cell cycle analyses clearly showed 11b induced G2/M phase cell cycle arrest. Molecule docking studies suggested that the binding mode of 11b was different from that of the crystal complex of ligand topotecan in Top1/DNA. Importantly, 11b showed high in vivo antitumor efficacy in the RM-1 mouse model with transplantation of prostate cancer (TGI = 44.9%) at dose of 9 mg kg−1 without apparent toxicity.

Rational Design of α-Conotoxin RegIIA Analogues Selectively Inhibiting the Human α3β2 Nicotinic Acetylcholine Receptor through Computational Scanning

Abstract: Engineering the selectivity of α-conotoxins for nicotinic acetylcholine receptors (nAChRs) presents considerable complexity and challenges, as it involves the optimization of their binding affiniti...

Progress in molecular docking

Abstract: In recent years, since the molecular docking technique can greatly improve the efficiency and reduce the research cost, it has become a key tool in computer-assisted drug design to predict the binding affinity and analyze the interactive mode. This study introduces the key principles, procedures and the widely-used applications for molecular docking. Also, it compares the commonly used docking applications and recommends which research areas are suitable for them. Lastly, it briefly reviews the latest progress in molecular docking such as the integrated method and deep learning. Limited to the incomplete molecular structure and the shortcomings of the scoring function, current docking applications are not accurate enough to predict the binding affinity. However, we could improve the current molecular docking technique by integrating the big biological data into scoring function.