Small molecules targeting Pin1 as potent anticancer drugs.

Background: Pin1 is a member of the evolutionarily conserved peptidyl-prolyl isomerase (PPIase) family of proteins. Following phosphorylation, Pin1-catalyzed prolyl-isomerization induces conformational changes, which serve to regulate the function of many phosphorylated proteins that play important roles during oncogenesis. Thus, the inhibition of Pin1 provides a unique means of disrupting oncogenic pathways and therefore represents an appealing target for novel anticancer therapies. Methods: As Pin1 is conserved between yeast and humans, we employed budding yeast to establish a high-throughput screening method for the primary screening of Pin1 inhibitors. This effort culminated in the identification of the compounds HWH8-33 and HWH8-36. Multifaceted approaches were taken to determine the inhibition profiles of these compounds against Pin1 activity in vitro and in vivo, including an isomerization assay, surface plasmon resonance (SPR) technology, virtual docking, MTT proliferation assay, western blotting, cell cycle analysis, apoptosis analysis, immunofluorescence analysis, wound healing, migration assay, and nude mouse assay. Results: In vitro, HWH8-33 and HWH8-36 could bind to purified Pin1 and inhibited its enzyme activity; showed inhibitory effects on cancer cell proliferation; led to G2/M phase arrest, dysregulated downstream protein expression, and apoptosis; and suppressed cancer cell migration. In vivo, HWH8-33 suppressed tumor growth in the xenograft mice after oral administration for 4 weeks, with no noticeable toxicity. Together, these results show the anticancer activity of HWH8-33 and HWH8-36 against Pin1 for the first time. Conclusion: In summary, we identified two hit compounds HWH8-33 and HWH8-36, which after further structure optimization have the potential to be developed as antitumor drugs.

The modification of natural products for medical use.

Drug innovation is characterized by painstaking molecular-level syntheses and modifications as the basic components of research and development. Similarly, natural products are chemically tailored and modified based upon their structural and biological properties. To some extent, the modification of natural products is quite different from de novo structure-based drug discovery. This review describes the general strategies and principles for the modification of natural products to drugs, as illustrated by several successful medicines that originated from natural products.

[On the molecular drug design from viewpoint of precision medicine].

Precision medicine (PM) involves the application of "omics" analysis and system biology to analyze the cause of disease at the molecular level for targeted treatments of individual patient. Based on the targeted treatment PM is closely related to pharmaceuticals, which, as a therapeutic means and supply front, mainly embody the two aspects: drug discovery/development, and clinical administration. Innovation of new molecular entities with safety and specific efficacy is the prerequisite and guarantee for the PM practice; on the other hand, the outcome and clues in clinical PM feedback to new drug research. PM and drug research/application are interdependent and promote each other. Aimed at precision medicine, drug discovery and development involve well-known contents: the discovery and validation of targets, the association between target functions and indications (proof of concept), lead discovery and optimization, the association between preclinical investigations and clinical trials, the lean of industrialization and pharmacoeconomics. At the molecular level the therapeutic efficacy originates from the interactive binding between specific atoms or groups of the drug molecule and the complementary atoms or groups of the macromolecular target in three-dimensional space. The strict arrangement of such critical atoms, groups, or fragments reflect specific features for a precise binding to the corresponding target. An alteration of amino acid residues in mutational targets leads to the change in conformation of the target protein, and an accurate structure of drug is necessary for binding to the mutant species and avoiding off-targeting effect. For the tailoring of clinical treatment to the individual patient design and development of various new molecular entities are critical for treatment choice according to the molecular features of biological markers of patients. This article provides some examples and methods of drug design and development in the new period.

Artemisinin anti-malarial drugs in China.

Discovered by Youyou Tu, one of the 2015 Nobel Prize winners in Physiology or Medicine, together with many other Chinese scientists, artemisinin, artemether and artesunate, as well as other artemisinins, have brought the global anti-malarial treatment to a new era, saving millions of lives all around the world for the past 40 years. The discoveries of artemisinins were carried out beginning from the 1970s, a special period in China, by hundreds of scientists all together under the "whole nation" system. This article focusing on medicinal chemistry research, briefly introduced the discovery and invention course of the scientists according to the published papers, and highlighted their academic contribution and achievements.

[Drug innovation and reverse thinking].

Drug innovation involves an individual molecular operation, and every new molecular entity features a hard-duplicated track of R&D. The transformation from an active compound to a new medicine carries out almost in a chaotic system devoid of regularity and periodic alteration. Since new millennium the dominant position in drug innovation has been occupied by the first-in-class drugs, yet the number of launched follow-on drugs has been distinctly decreased. The innovation of first-in-class drugs is characterized by a high risk throughout the whole process. To achieve initiative and uniqueness of drug discovery, the strategy and method of the inverse thinking might be a feasible way, because the inertial and conformity thinkings in drug discovery normally lead to ensemble with similar drug category. However, the study from the flipside or opposite of things(e.g. targets or effects) brand new routes might be opened. This article is to describe the strategy of reverse thinking in drug discovery by some examples including opioid receptor antagonist eluxadoline, HSP90 activator, h ERG channel agonist, covalent drugs, and ultra-small drugs.

[Concise analysis for innovation of pioneering and follow-on drugs].

More attention has been paid to the pioneering drug innovation since the new millennium, while the creation space of fast-followed drugs is shrinking due to the serious risks observed in the clinical phases following marketing. Innovative drug discovery aiming at the brand new target is dependent on the breakthrough in basic biology, followed by chemical biology, and medicinal chemistry. This roadmap requires harmonious environment and free exploration atmosphere, while mandatory planning unlikely accelerates drug discovery. This article concisely analyzes several critical aspects of current status of drug discovery.

[Application of temperature sensitive yeast models with definite target in the screening of potential human Pin1 inhibitors].

This study is to explore new lead compounds by inhibition of Pin1 for anticancer therapy using temperature sensitive mutants. As Pin1 is conserved from yeast to human, we established a high-throughput screening method for Pin1 inhibitors, which employed yeast assay. This method led to the identification of one potent hits, 8-11. In vitro, 8-11 inhibited purified Pin1 enzyme activity with IC50 of (10.40 +/- 1.68) micromol x L(-1), induced G1 phase arrest and apoptosis, showed inhibitory effects on a series of cancer cell proliferation, reduced Cyclin D1 expression, was defined as reciprocally matched for protein-ligand complex in virtual docking analysis and reduced cell migration ability. In vivo, we could observe reduction of tumor volume after treatment with 8-11 in xenograft mice compared with vehicle DMSO treatment. Altogether, these results provide for the first time the involvement of 8-11 in the anticancer activity against Pin1.

[Challenges and strategies of drug innovation].

Drug research involves scientific discovery, technological inventions and product development. This multiple dimensional effort embodies both high risk and high reward and is considered one of the most complicated human activities. Prior to the initiation of a program, an in-depth analysis of "what to do" and "how to do it" must be conducted. On the macro level, market prospects, capital required, risk assessment, necessary human resources, etc. need to be evaluated critically. For execution, drug candidates need to be optimized in multiple properties such as potency, selectivity, pharmacokinetics, safety, formulation, etc., all with the constraint of finite amount of time and resources, to maximize the probability of success in clinical development. Drug discovery is enormously complicated, both in terms of technological innovation and organizing capital and other resources. A deep understanding of the complexity of drug research and our competitive edge is critical for success. Our unique government-enterprise-academia system represents a distinct advantage. As a new player, we have not heavily invested in any particular discovery paradigm, which allows us to select the optimal approach with little organizational burden. Virtue R&D model using CROs has gained momentum lately and China is a global leader in CRO market. Essentially all technological support for drug discovery can be found in China, which greatly enables domestic R&D efforts. The information technology revolution ensures the globalization of drug discovery knowledge, which has bridged much of the gap between China and the developed countries. The blockbuster model and the target-centric drug discovery paradigm have overlooked the research in several important fields such as injectable drugs, orphan drugs, and following high quality therapeutic leads, etc. Prejudice against covalent ligands, prodrugs, nondrug-like ligands can also be taken advantage of to find novel medicines. This article will discuss the current challenges and future opportunities for drug innovation in China.

Discovery of a potent dual EGFR/HER-2 inhibitor L-2 (selatinib) for the treatment of cancer.

To develop potent dual EGFR/HER-2 inhibitors with improved druggability, a series of new lapatinib analogs were designed and synthesized. Compared with lapatinib, L-2, L-4 and M-6 were more active against BT-474 or NCI-N87 cells. In vivo efficacy studies indicated that L-2 significantly suppressed tumor growth in NCI-N87 (94.8% inhibition) or SK-OV-3 xenograft (85.7% inhibition) without causing significant loss of body weight. And the inhibition rates of lapatinib in the two xenograft models were 89.7% and 78.8%, respectively. Moreover, further studies revealed that the potent in vivo activities of L-2 may be mainly attributed to its superior aqueous solubility and oral bioavailability. In addition, a high-yielding one-pot procedure was developed for the synthesis of lapatinib and its analogs.

[Ligand efficiency and lead optimization].

Pharmacological activity and druggability are two pivotal factors in drug innovation, which are respectively determined by the microscopic structure and macroscopic property of a molecule. Since structural optimization consists in a molecular operation in the space with multi-dimensions, and there exists a body of uncertainties for transduction from in vitro activity into in vivo pharmacological response. It is necessary for early stage in lead optimization to evaluate compound quality or efficiency using a kind of metrics containing multi-parameters. On the basis of the describing parameters of activity and druggability, this overview deals with the roles of thermodynamic signatures and binding kinetics of drug-receptor interactions in optimizing quality of compounds, signifying the significance in optimization of microscopic structures for drug discovery.

Identifying multiple-target ligands via computational chemogenomics approaches.

Despite the rapidly growing knowledge of functional and structural information regarding pharmaceutically relevant targets during the past decade, target-based drug discovery has remained a high-cost and low-yield process. Particularly, single-target drugs often turn out to be less effective in treating complicated diseases such as cancers, metabolic disorders and CNS diseases. However, discovering compounds that are effective against multiple desired targets raises an enormous challenge to the current mode of drug innovation. Computational chemogenomics approaches aim at predicting all potential interactions between small molecular ligands and biomolecular targets, thus the derived information can be directly applied to "design in" (i.e. engineer desirable binding spectrum) and "design out" (i.e. eliminate the unwanted interactions) specific biological activities. The present review will focus on introducing the recent methodological development and successful applications of structure-based and ligand-based approaches on predicting the ligand binding profiles, which is the very first and essential step toward rationally designing the multiple-target ligands. Structure-based methods (e.g. binding site mapping and inverse molecular docking) generally require the structures of known targets to navigate the receptor-ligand binding space, while ligand-based approaches (e.g. chemical similarity analysis and pharmacophore search) can only rely on the series of active compounds to derive the structural characteristics for describing certain biological activities.

[Modification of natural products for drug discovery].

Pharmacological activity and druggability are two essential factors for drug innovation. The pharmacological activity is definitely indispensable, and the druggability is destined by physico-chemical, biochemical, pharmacokinetic and safety properties of drugs. As secondary metabolites of animals, plants, microbes and marine organisms, natural products play key roles in their physiological homeostasis, self-defense, and propagation. Natural products are a rich source of therapeutic drugs. As compared to synthetic molecules, natural products are unusually featured by structural diversity and complexity more stereogenic centers and fewer nitrogen or halogen atoms. Naturally active substances usually are good lead compounds, but unlikely meet the demands for druggability. Therefore, it is necessary to modify and optimize these structural phenotypes. Structural modification of natural products is intent to (1) realize total synthesis ready for industrialization, (2) protect environment and resources, (3) perform chemical manipulation according to the molecular size and complexity of natural products, (4) acquire novel structures through structure-activity relationship analysis, pharmacophore definition, and scaffold hopping, and (5) eliminate unnecessary chiral centers while retain the bioactive configuration and conformation. The strategy for structural modification is to increase potency and selectivity, improve physico-chemical, biochemical and pharmacokinetic properties, eliminate or reduce side effects, and attain intellectual properties. This review elucidates the essence of natural products-based drug discovery with some successful examples.

[Drug promiscuity].

It is essential for a successful drug to possess two basic characteristics: satisfactory pharmacological action with sufficient potency and selectivity; good druggability with eligible physicochemical, pharmacokinetic and safety profiles, as well as structural novelty. Promiscuity is defined as the property of a drug to act with multiple molecular targets and exhibit distinct pharmacological effects. Promiscuous drugs are the basis of polypharmacology and the causes for side effects and unsuitable DMPK. Drug promiscuity originates from protein promiscuity. In order to accommodate, metabolize and excrete various endo- and exogenous substances, protein acquired the capability during evolution to adapt a wide range of structural diversity, and it is unnecessary to reserve a specific protein for every single ligand. The structures of target proteins are integration of conservativity and diversity. The former is represented by the relatively conservative domains for secondary structures folding, which leads to overlapping in ligand-binding and consequent cross-reactivity of ligands. Diversity, however, embodies the subtle difference in structures. Similar structural domain may demonstrate different functions due to alteration of amino acid sequences. The phenomenon of promiscuity may facilitate the "design in" of multi-target ligands for the treatment of complicated diseases, whereas it should be appropriately handled to improve druggability. Therefore, one of the primary goals in drug design is to scrutinize and manipulate the "merits and faults" of promiscuity. This review discusses the application of promiscuity in drug design for receptors, enzymes, ion channels and cytochrome P450. It also briefly describes the methods to predict ligand promiscuity based on either target or ligand structures.

Generation and validation of the first predictive pharmacophore model for cyclin-dependent kinase 9 inhibitors.

A three-dimensional (3D) pharmacophore modelling approach was applied to a diverse data set of known cyclin-dependent kinase 9 (CDK9) inhibitors. Diversity sampling and principal components analysis (PCA) were employed to ensure the rational selection of representative training sets. Twelve statistically robust pharmacophore models were generated using the HypoGen algorithm. The resulting models showed high homology and indicated great convergence in ascertaining pharmacophoric features essential for CDK9 inhibitory activity. One of the best models (Hypo 6) was assessed further by external predictive capability, randomization test, as well as its performance in virtual screening. The capability of the resulting models to reliably predict the inhibitory activity of external data sets and discriminate active structures from general databases would assist the identification and optimization of novel CDK9 inhibitors.

The synthesis of puerarin derivatives and their protective effect on the myocardial ischemia and reperfusion injury.

Puerarin is a naturally occurring isoflavone and is frequently used for the treatment of cardiovascular symptoms in China. By the structural modification of the puerarin molecule at different positions, seven new puerarin derivatives were obtained, and their cardioprotective activities (in vitro and in vivo) were respectively evaluated. The finding that the activities of 3 and 8 markedly exceeded puerarin suggested that the acylated modification of phenolic hydroxyl at C-7 in the puerarin molecule may improve the cardioprotective activity, which will be an important reference for further structural optimization.

[Synthesis and activity of some new histone deacetylases inhibitors].

To explore novel histone deacetylase (HDAC) inhibitors with anti-tumor activity, twelve target compounds were synthesized, and their structures were confirmed by 1H NMR, MS and elemental analyses. Evaluation results in vitro showed that compound Ia exhibited potent inhibition against HDAC and is worth for further investigation. And compounds IIa, IIb, IIIa-IIIi possessed moderate HDAC inhibitory activity.

[Strategy of molecular drug design: activity and druggability].

Intrinsic activity and druggability represent two essences of innovative drugs. Activity is the fundamental and core virtue of a drug, whereas druggability is essential to translate activity to therapeutic usefulness. Activity and druggability are interconnected natures residing in molecular structure. The pharmaceutical, pharmacokinetic and pharmacodynamic phases in vivo can be conceived as an overall exhibition of activity and druggability. Druggability actually involves all properties, except for intrinsic activity, of a drug. It embraces physico-chemical, bio-chemical, pharmacokinetic and toxicological characteristics, which are intertwined properties determining the attributes and behaviors of a drug in different aspects. Activity and druggability of a drug are endowed in the chemical structure and reflected in the microscopic structure and macroscopic property of a drug molecule. The lead optimization implicates molecular manipulation in multidimensional space covering activity, physicochemistry, biochemistry, pharmacokinetics and safety, and embodies abundant contents of medicinal chemistry.

[Strategy of molecular drug design: dual-target drug design].

Physiology-based and target-based drug discovery constitutes two principal approaches in drug innovation, which are mutually complementary and collaborative. With the target-based approach, a lot of new molecular entities have been marketed as drugs. However, many complicated diseases such as cancer, metabolic disorders, and CNS diseases can not be effectively treated or cured with one medicine acting on a single target. As simultaneous intervention of two (or multiple) targets relevant to a disease has shown improved therapeutic efficacy, the innovation of dual-target drugs has become an active field. Dual-target drug can modulate two receptors, inhibit two enzymes, act on an enzyme and a receptor, or affect an ion channel and a transporter. From viewpoint of molecular design, there are three approaches to construct a dual-target drug molecule. A connective molecule can simply be realized by combining two active molecules or their pharmacophores with a linker; while an integrated molecule comes into an entity either by fusing or by merging the common structural or pharmacophoric features of two active molecules, depending on the extent of the common features. The latter approach facilitates the reduction of molecular size and molecular weight and the optimal overlap between the pharmacodynamic and pharmacokinetic spaces, which will certainly elevate the probability of being a drug.

[Design of multiple targeted drugs].

Drugs designed to act on individual molecular targets usually can not combat multigenic diseases such as cancer, or diseases that affect multiple tissues or cell types such as diabetes. Increasingly, it is being recognised that a balanced modulation of several targets can provide a superior therapeutic effect and side effect profile compared to the action of a selective ligand. The multi-target drugs which impact multiple targets simultaneously are better at controlling complex disease systems and are less prone to drug resistance. Here, we compare the disadvantage of the selective ligands and the predominance of multi-targets drugs in detail and introduce the approaches of designing multiple ligands and the procedure of optimization particularly. A key challenge in the design of multiple ligands is attaining a balanced activity at each target of interest while simultaneously achieving a wider selectivity and a suitable pharmacokinetic profile. On this point, the multi-target approach represents a new challenge for medicinal chemists, pharmacologists, toxicologists, and biochemists.

[Comparative pharmacophore analysis of dual dopamine D2/5-HT(2A) receptor antagonists].

Dual dopamine D2/5-HT2A receptor antagonists have potent activity and are referred to atypical antipsychotics due to their lower propensity to elicit EPS and their moderate efficacy toward negative symptoms. However, an on-going challenge in developing atypical antipsychotics drugs is to maintain the favorable profiles and avoid of cardiovascular risk. In this paper, comparative pharmacophore analysis of dual dopamine D2/5-HT2A receptor antagonists, hERG K+ channel blockers, and alA adrenoceptor antagonists is carried out, and the results could give some insight into multi-target drug design.