Oxidative stress is a redox imbalance in the body, which is one of the important factors leading to tissue damage and diseases. The nuclear factor E2-related factor 2 (Nrf2)-Kelch like ECH-associated protein 1 (Keap1) signaling pathway is not only an important defense system against oxidative damage, but also one of the key signaling pathways of the antioxidant capacity. Numerous studies have shown that targeting the Keap1-Nrf2 signaling pathway to activate Nrf2 has become an effective strategy for the treatment of oxidative stress and related diseases. Using small molecules to directly block the Keap1-Nrf2 protein-protein interaction (PPI) is one of the important directions for activating Nrf2 and exerting the cytoprotective effect, which can avoid the potential side effects of covalent modification of Nrf2. On the other hand, the Keap1 is an efficient E3 ubiquitin ligase that has been used in the design of proteolysis targeting chimeras (PROTACs). This review summarizes the research progresses of Keap1-Nrf2 protein interaction inhibitors and degraders based on the Keap1 E3 ubiquitination system in recent years.

The UHPLC-LTQ-orbitrap-MS metabolomics technique was used to determine the effect of deapio-platycodin D (DPD) on endogenous metabolites in lung tissues of mice with ammonia-induced cough, and to identify the metabolic regulatory pathways of DPD in its antitussive and expectorant activities. This work was approved by the Animal Ethics Committee of Jiangxi University of Chinese Medicine (Approval No. JZLLSC-20190235). Metabolites were identified by UHPLC-LTQ-orbitrap-MS method and the metabolic pathways related to differentially-expressed metabolites were analyzed by the MetaboAnalyst platform. DPD significantly prolonged (P < 0.05) cough latency, reduced the number of coughs, and significantly increased (P < 0.05) phenol red excretion in ammonia-induced cough mice. Twenty-five metabolites related to cough and 38 metabolites related to sputum excretion were identified by UHPLC-LTQ-orbitrap-MS. Changes in the metabolism of linoleic acid, arachidonic acid, glycerophospholipid, alanine, aspartic acid and glutamic acid, pentose and glucuronate interconversions, and lysine degradation were evident with DPD treatment of ammonia-induced cough mice. Changes in the metabolism of linoleic acid, taurine and hypotaurine, glycerophospholipid, purines and pyrimidines, arachidonic acid and the biosynthesis of unsaturated fatty acids after DPD treatment were related to phenol red excretion. Linoleic acid metabolism, arachidonic acid metabolism and glycerophospholipid metabolism are common regulatory pathways by which DPD appears to exert its antitussive and expectorant activity. These metabolic pathways are closely related to anti-inflammatory pathways, immune function regulation, neurotransmitter release, cell signal transduction, energy metabolism and apoptosis. This study clarifies the antitussive and expectorant activity and mechanism of DPD.

Hepatitis B virus (HBV) infection is a serious global public health problem. Chronic hepatitis B virus infection can cause health problems such as cirrhosis, liver metabolism disorders and hepatocellular carcinoma. Nucloes(t)ide analogues and interferon drugs used to treat chronic HBV infection do not completely eradicate covalently closed circular DNA (cccDNA) and integrated genome of HBV DNA, so that they cannot achieve the functional cure of chronic HBV infection. Currently, a series of drugs targeting the phases of HBV lifecycle and immunomodulators have entered clinical trials. Here, we review the current status of the therapeutic drugs as well as the recent advance of direct antiviral agents.

We developed an in-vitro bioassay for determining the bioactivity of human insulin by homogeneous time-resolved fluorescence immunoassay. CHO-INSR B1284 transgenic cells were used as target cells. Key assay parameters, including the cell density, the range of working concentrations, and the stimulation time were optimized. The specificity, relative accuracy, intermediate precision, linearity, and range of the method were validated, as well as the passage stability of the CHO-INSR B1284 cell line. The national standard of recombinant human insulin was used as the benchmark to evaluate the relative potency of insulin analogues and drugs. The drugs and the reference human insulin showed a dose-response relationship, R² > 0.995, which conforms to the four-parameter equation: y = (A - D) / [1 + (x/C)^B] + D. Specificity of the method was good. The geometric mean, relative bias, and geometric coefficient of variation (GCV, %) of the five concentrations (n = 8, 64%, 80%, 100%, 125% and 156%) met the requirements of the General Rules of Chinese Pharmacopoeia, 2020 edition, Volume IV (9401). In summary, a bioassay for determining the in vitro bioactivity of human insulin based on a homogeneous time-resolved fluorescence technique was established; the method was simple, time-saving, accurate and precise, and could be used for the evaluation of biological activity and quality.

At present, majority of the small molecular drugs used in clinics target proteins, they exert the efficacy through the binding to specific sites on the target protein. However, the "druggable" protein targets account for a small portion of the total number of proteins, and "non-druggable" proteins account for 80%, because of not having suitable drug binding sites. In the central rule, RNA is located in the upstream of proteins and controls the transcription of proteins. The research of small molecule drugs targeting RNA can solve the problem of protein "undruggable proteins" in some extent. This review summarizes the representative research achievements of small molecular drugs targeting RNA in recent years, and the screening methods applied to this field, with the focuses on the latest progress of small molecular drugs targeting novel coronavirus RNA.

Lysine-specific demethylase 1 (LSD1) plays vital roles in cell stemness, differentiation, cell motility, metabolic control and epithelial-mesenchymal transition, which is closely associated with tumorigenesis processes including cell proliferation, invasive, metastasis and poor prognosis. Besides, LSD1 also contributes to the occurrence of other diseases such as neurodegenerative diseases and viral infections. Since 2013, the irreversible inhibitors including tranylcypromine, ORY-1001, ORY-2001, GSK-2879552, IMG-7289, INCB059872, TAK-418, LH-1802 and reversible inhibitors including CC-90011 and SP-2577 have been approved for clinical assessment. This review comprehensively summarizes the clinical research of LSD1 drug candidates and briefly discusses the prospects, opportunities and challenges of LSD1-targeted drug discovery, aiming to provide a landscape for the related drug development.

The overexpression of doublecortin-like kinase 1 (DCLK1) is closely related to the occurrence and development of various malignant tumors. Discovery of novel anti-tumor agents targeting DCLK1 represents a hot spot in this field. So far, several DCLK1 small molecule inhibitors with excellent anti-tumor activity in vitro and in vivo have been designed and synthesized, which is expected to provide a new strategy for tumor therapy. This article reviews the research progress in the discovery, structure type, structural optimization, biological activity and mechanism of action of DCLK1 small molecule inhibitors, and provides research basis for the development of new anti-tumor small molecule inhibitors targeting DCLK1.

Bitter almonds (Semen Armeniacae Amarum) are prone to oil deterioration during storage, so they often require mashing prior to clinical use. To confirm the medical value of bitter almonds "being mashed when used" and to determine the optimal storage conditions for bitter almonds, UPLC-MS/MS was used to perform a comparative study of the chemical composition of bitter almonds in different storage states (mashed and unmashed), storage times (0, 2 and 4 weeks), and storage temperatures (25 ℃ and 4 ℃). A total of 58 substances were identified in bitter almond extracts through literature review, this group's previous work, and a Compound Discoverer software search. Statistically significant differences were found in the chemical composition and content of bitter almonds in different storage states, storage times, and storage temperatures. The results show that the chemical composition of bitter almonds stored unmashed was more stable than that of bitter almonds stored mashed; the chemical composition of bitter almonds stored at 4 ℃ was more stable than that of bitter almonds stored at 25 ℃; and the shorter the storage time, the less the chemical composition changed. Amygdalin, the main medicinal component of bitter almonds, showed statistically significant differences in content under the above three storage conditions, which can be used as a potential quality marker for bitter almonds.

New drug research and development is a technology-intensive industry with high investment, high cycle and high risk. In recent years, with the rapid development of modern disciplines such as omics technology, bioinformatics, high-throughput and high-content screening, and artificial intelligence, the research and development of small-molecule drugs has presented a new paradigm characterized by "integrated medicinal chemistry". This review summarizes new enabling drug discovery technologies, the emergence of new subfields formed through integration innovations and practical chemistry toolbox in the field of medicinal chemistry.

Autoimmune diseases (AID) are characterized by autoimmune disorder, as autologous tissue is attacked by the autoimmune system. It is reported that the imbalance of autoimmune tolerance and ingrained inflammatory response are the core events of AID undoubtedly. Peroxisome proliferator-activated receptor γ (PPARγ) which belongs to the nuclear hormone receptor superfamily is a ligand activated transcription factor. PPARγ combines with retinoid X receptor (RXR) to form heterodimer. When PPARγ is activated, the complex regulates gene expression by binding to a specific peroxisome proliferator response element (PPRE). In addition, PPARγ has diversified biological functions, playing important roles in regulating metabolism, controling inflammation, modulating glucose and lipid metabolism, ameliorating atherosclerosis, anti-tumor, and regulating immune response. However, recently researches indicate that PPARγ participates in the pathogenesis of AID. PPARγ plays key roles in regulating activation and polarization of macrophages, function of dendritic cells, proliferation and differentiation of T cells, and modulation of the function of related stromal cells. This article summarizes the biological functions and signal transduction pathways of PPARγ and the protective effects of agonists of PPARγ on AID, aiming to provide theoretical support for the research of mechanism and prevention and treatment of AID.