Synthesis, structure-activity relationship and biological evaluation of anticancer activity for novel N-substituted sophoridinic acid derivatives

QSAR prediction, synthesis, anticancer evaluation, and mechanistic investigations of novel sophoridine derivatives as topoisomerase I inhibitors

Sophoridine, which is derived from the Leguminous plant Sophora alopecuroides L., has certain pharmacological activity as a new anticancer drug. Herein, a series of novel N-substituted sophoridine derivatives was designed, synthesized and evaluated with anticancer activity. Through QSAR prediction models, it was discovered that the introduction of a benzene ring as a main pharmacophore and reintroduced into a benzene in para position on the phenyl ring in the novel sophoridine derivatives improved the anticancer activity effectively. In vitro, 28 novel compounds were evaluated for anticancer activity against four human tumor cell lines (A549, CNE-2, HepG-2, and HEC-1-B). In particular, Compound 26 exhibited remarkable inhibitory effects, with an IC50 value of 15.6 μM against HepG-2 cells, surpassing cis-Dichlorodiamineplatinum (II). Molecular docking studies verified that the derivatives exhibit stronger binding affinity with DNA topoisomerase I compared to sophoridine. In addition, 26 demonstrated significant inhibition of DNA Topoisomerase I and could arrest cells in G0/G1 phase. This study provides valuable insights into the design and synthesis of N-substituted sophoridine derivatives with anticancer activity.

Exploring Derivatives of Quinolizidine Alkaloid Sophoridine in the Design and Biological Mechanistic Evaluation of Histone Deacetylase Inhibitors against Triple-Negative Breast Cancer

As a critical epigenetic modulator of gene expression, histone deacetylases (HDACs) have been involved in the pathogenesis and therapeutic investigation of cancer. Quinolizidine alkaloid sophoridine is known to have anticancer efficacy but with limited indication. By incorporating the pharmacophore of the HDAC inhibitor into the ring-opened sophoridine core, a new series of sophoridine hydroxamic acid derivatives were synthesized. After structure-activity studies, a selected compound was found to exert significant cytotoxicity in triple-negative breast cancer CAL-51 cells (IC50 1.17 μM), and demonstrated low nanomolar inhibitory potency toward HDAC1/3/6. Cellular functional assays indicated that this compound was able to induce apoptosis and cause accumulation of cells in the S phase of the cell cycle. Western blot analysis revealed it to decrease the expression of DNMT1, DNMT3a and DNMT3b by down-regulating phosphor-ERK1/2. Furthermore, treatment with this compound proved to block the PI3K/AKT/mTOR signaling in the PI3KCA and PTEN-mutant CAL-51 cells. Collectively, this work provides a novel lead compound for the development of potential therapeutics against triple-negative breast cancers, possibly mesenchymal-like subtype.

Research Progress in the Pharmacological Activities, Toxicities, and Pharmacokinetics of Sophoridine and Its Derivatives

Sophoridine is a natural quinolizidine alkaloid and a bioactive ingredient that can be isolated and identified from certain herbs, including Sophora flavescens Alt, Sophora alopecuroides L, and Sophora viciifolia Hance. In recent years, this quinolizidine alkaloid has gained widespread attention because of its unique structure and minimal side effects. Modern pharmacological investigations have uncovered sophoridine's multiple wide range biological activities, such as anti-cancer, anti-inflammatory, anti-viral, anti-arrhythmia, and analgesic functions, among others. These pharmacological activities and beneficial effects point to sophoridine as a strong potential therapeutic candidate for the treatment of various diseases, including several cancer types, hepatitis B virus, enterovirus 71, coxsackievirus B3, cerebral edema, cancer pain, heart failure, acute myocardial ischemia, arrhythmia, inflammation, acute lung injury, and osteoporosis. The data showed that sophoridine had adverse reactions, including hepatotoxicity and neurotoxicity. Additionally, analyses of sophoridine's safety, bioavailability, and pharmacokinetic parameters in animal models of research have been limited, especially in the clinic, as have been investigations on its structure-activity relationship. In this article, we comprehensively summarize the biological activities, toxicity, and pharmacokinetic characteristics of sophoridine and its derivatives, as currently reported in publications, as we attempt to provide an overall perspective on sophoridine analogs and the prospects of its application clinically.

Sophoridine Derivatives Induce Apoptosis and Autophagy to Suppress the Growth of Triple-Negative Breast Cancer through Inhibition of mTOR Signaling

In order to improve the antitumor potency and therapeutic margins of natural product sophoridine, its novel nitrogen mustard carbamate derivatives were designed and synthesized. In screening their in vitro activity, we found all the tested compounds were more potent against the highly aggressive triple-negative breast cancer cell line MDA-MB-231. Cellular functional assays showed that representative compounds could induce G1-phase arrest and trigger apoptosis, evidenced by the alteration of Bax, Bcl-2, caspase-3 and PARP levels. Furthermore, these compounds significantly enhanced the autophagic flux with increased expression of LC3-II and Beclin-1, as well as decreased level of p62, which may attribute to simultaneously inhibition of the phosphorylation of p70S6K, 4E-BP1 and AKT, the key substrates of the mTOR signaling pathway. In vivo, two compounds revealed potent antitumor activity in mice bearing MDA-MB-231. Altogether, our work describes novel leads to yield more potent chemotherapeutics against triple-negative breast cancers, possibly mesenchymal stem-like subtype.

Anti-cancer potential of sophoridine and its derivatives: Recent progress and future perspectives

Cancer is the second leading cause of mortality and has resulted in about 9.6 million deaths around the world in 2018. Cancer-caused deaths are expected to be 11.5 million by 2030 all over the world. Because of the fatal nature of cancer, substantial efforts are made all over the world to combat it. Phytoconstituents such as certain alkaloids, saponins, tannins, polyphenols, and terpenoids exhibit anticancer effects. Sophoridine is a tetracyclic quinolizidine alkaloid isolated from the stem and leaves of medicinal plants Sophora alopecuroides L., and Euchresta japonica Benth, and roots of Sophora alopecuroides Ait. Chinese Food and Drug Administration (CFDA) approved sophoridine as an antitumor agent in 2005. This review covers the antitumor activities of sophoridine and its derivatives. The efficacy of sophoridine analogs is expressed with respect to their half-maximal inhibitory concentration (IC₅₀ values). Structure-activity relationship (SAR) study for most of the sophoridine derivatives has been explained. Moreover, the current market of anticancer drugs and its expected growth are discussed. Prospects provide suggestions and clues for novel sophoridine-based anticancer agents with enhanced expected efficacy and minimum toxicity.

Anti-Tumor Activities of Bioactive Phytochemicals in Sophora flavescens for Breast Cancer

Patients with breast cancer and breast cancer survivors are frequent users of botanicals and their bioactive phytochemicals. In China, active ingredients in Sophora flavescens like matrine (MT), oxymatrine (OMT), other Sophora flavescens alkaloids and Compound Kushen Injection (CKI) are extensively used for multiple malignant tumors. In vivo and in vitro studies have confirmed that these activities or injection have significant effects on relieving symptoms, alleviating side effects after chemotherapy and improving the quality of life of breast cancer patients, where there is evidence for efficacy. A large number of experimental studies have also revealed that they can inhibit the proliferation, invasion and migration of breast cancer cells according to different mechanisms. This provides promising valuable supportive therapies for prevention, treatment and postoperative recovery of breast cancer. Rigorous clinical research and experimental studies reflect integrative care as it is used in hospital is needed to responsibly move this field forward. This review summarizes an up to date knowledge of the available bioactive phytochemicals, their discovery, current clinical and experimental status.

Research advances on anticancer activities of matrine and its derivatives: An updated overview

Cancer is the second leading cause of mortality, only overcome by cardiovascular diseases, and has caused more than 8.7 million deaths in 2015 all over the world. This figure is expected to rise to about 13.1 million by 2030. In order to prevent or cure this fatal illness, substantial efforts have been devoted to develop and discover new anticancer drugs with same or better antitumor activity but lesser toxicity. Matrine is an alkaloid isolated from Sophora flavescens Ait. For decades, matrine and its derivatives have been studied as antineoplastic agents which predominantly work by inhibiting proliferation and inducing apoptosis of cancer cells. The mechanism responsible for the anticancer activity of matrine can be recognized via up-regulating or down-regulating expression of the cancer related molecules, eventually causing tumor cell death. This review summarizes research developments of matrine and its derivatives as anticancer agents. A few possible research directions, suggestions and clues for future work on the development of novel matrine-based anticancer agents with improved expected activities and lesser toxicity have also been provided.

Design, synthesis, biological evaluation and structure-activity relationship of sophoridine derivatives bearing pyrrole or indole scaffold as potential antitumor agents

Taking sophoridine as a lead compound, 58 sophoridine derivatives were designed, synthesized and evaluated for their antiproliferative activity in the HepG2 cancer cell line. Among the 58 compounds, 33 compounds showed potent antiproliferative activity with IC₅₀ less than 10 μM. Compound 5w showed the most potent anti-proliferative activity in the HepG2 cancer cell line. Thus, we further extended our characterization of the antiproliferative activity of 5w in six cancer cell lines (HepG2, SMMC-7721, Hela, CNE1, CNE2 and MCF7). The representative compound 5w displayed robust anti-proliferative activities in all the tested cell lines with IC₅₀ values in range of 0.93-1.89 μM which were much lower than that of sophoridine. Here, we report the structure-activity relationships (SAR) in a sophoridine series of compounds, which indicated that introduction of N-benzyl indole group on the 14-carbon atom of sophoridine can significantly enhance the antiproliferative activity. By molecular docking and enzymatic assay, compound 5w was found to be able to inhibit the activity of DNA Topo I. Furthermore, apoptosis assay displayed that compound 5w could significantly induce the apoptosis of HepG2 cells in a dose-dependent manner by activating caspase-3, increasing expression of cleaved caspase-3 and reducing the ratio of Bcl-2/Bax. The in vivo antitumor assay demonstrated that 5w suppressed the growth of HepG2 xenografts in nude mice without any obvious side effects.

Novel Sophoridine Derivatives Bearing Phosphoramide Mustard Moiety Exhibit Potent Antitumor Activities In Vitro and In Vivo

Novel mustard functionalized sophoridine derivatives were synthesized and evaluated for their cytotoxicity against of a panel of various cancer cell lines. They were shown to be more sensitive to S180 and H22 tumor cells with IC₅₀ values ranging from 1.01–3.65 μM, and distinctly were more cytotoxic to cancer cells than normal cell L929. In addition, compounds 7a, 7c, and 7e displayed moderate tumor suppression without apparent organ toxicity in vivo against mice bearing H22 liver tumors. Furthermore, they arrested tumor cells in the G1 phase and induced cellular apoptosis. Their potential binding modes with DNA-Top I complex have also been investigated.

Design, synthesis and evaluation of novel sophoridinic imine derivatives containing conjugated planar structure as potent anticancer agents

Based on our previous study and the binding mode of camptothecin with Topo I, a series of novel sophoridine imine derivatives containing conjugated planar structure were designed, synthesized and tested for their in vitro anticancer activity. The results showed that most of the derivatives displayed potent activity. In particular, compounds 10b exhibited excellent anti-proliferative activities with IC₅₀ 5.7 µM and 8.5 µM against HepG-2 and HeLa cell lines, respectively. Molecular docking studies revealed that the introduction of conjugated planar structure could form π-π stacking interaction with DNA, leading to the improvement of biological activity. Its mode of action was to inhibit the activity of DNA Topo I, followed by the G0/G1 phase arrest. This work provides a theoretical basis for structural optimizations and exploring anticancer pathways of this kind of compound and 10b could emerge as promising lead compounds for the development of novel Topo I inhibitors.

Novel α, β-Unsaturated Sophoridinic Derivatives: Design, Synthesis, Molecular Docking and Anti-Cancer Activities

Using sophoridine 1 and chalcone 3 as the lead compounds, a series of novel α, β-unsaturated sophoridinic derivatives were designed, synthesized, and evaluated for their in vitro cytotoxicity. Structure-activity relationship (SAR) analysis indicated that introduction of α, β-unsaturated ketone moiety and heterocyclic group might significantly enhance anticancer activity. Among the compounds, 2f and 2m exhibited potential effects against HepG-2 and CNE-2 human cancer cell lines. Furthermore, molecular docking studies were performed to understand possible docking sites of the molecules on the target proteins and the mode of binding. This work provides a theoretical basis for structural optimizations and exploring anticancer pathways of this kind of compound.

Lysosomal dysfunction and autophagy blockade contribute to IMB-6G-induced apoptosis in pancreatic cancer cells

Targeting the autophagic pathway is currently regarded as an attractive strategy for cancer drug discovery. Our previous work showed that IMB-6G is a novel N-substituted sophoridinic acid derivative with potent cytotoxicity against tumor cells, yet the effect of IMB-6G on autophagy and pancreatic cancer cell death remains unknown. Here, we show that IMB-6G inhibits the growth of MiaPaCa-2 and HupT-3 pancreatic cancer cells and induces caspase-mediated apoptosis, which is correlated with an accumulation of autophagic vacuoles. IMB-6G promotes autophagosome accumulation from the early stage of treatment but blocks autophagic flux in the degradation stage, mainly through attenuation of lysosomal cathepsin activity in pancreatic cancer cells. Moreover, IMB-6G triggers lysosomal membrane permeabilization (LMP), followed by cathepsin B/CTSB and cathepsin D/CTSD release from lysosomes into the cytoplasm. Inhibition of autophagosome formation with siRNA against autophagy protein 5 (Atg5) attenuates IMB-6G-induced LMP and apoptosis. Furthermore, cathepsin inhibitors relieve IMB-6G-induced apoptosis as well. Altogether, our findings demonstrate that IMB-6G is a novel autophagy inhibitor, which induces autophagy-dependent apoptosis through autophagosomal-cathepsin axis in pancreatic cancer cells and indicate the potential value of IMB-6G as a novel antitumor drug candidate.

Alkaloids from Oxytropis ochrocephala and antiproliferative activity of sophoridine derivatives against cancer cell lines

Ten alkaloids (1-10), with sophoridine (1) as the most abundant component, were obtained from the whole plants of Oxytropis ochrocephala Bunge. Furthermore, eight new sophoridine derivatives (11-16, 20, 21), with modification on the C-14 position of 1 were synthesized. All compounds (1-16, 20, 21) were evaluated for antiproliferative activity against five human tumor cell lines. Among them, the newly synthesized derivative 20 exhibited the best inhibitory activity against the tested cell lines. Its activity was increased by more than fourfold as compared with parent compound 1.

1,5-Benzodiazepine derivatives as potential antimicrobial agents: design, synthesis, biological evaluation, and structure–activity relationships

36 novel 1,5-benzodiazepine derivatives were synthesized and evaluated for their in vitro antimicrobial activity. The results revealed that most of the 1,5-benzodiazepine derivatives exhibited considerable potency against all of the tested strains.

Synthesis and biological evaluation of sophoridinol derivatives as a novel family of potential anticancer agents

New N-substituted sophoridinic acid/ester and sophoridinol derivatives were synthesized and evaluated for their cytotoxic activity in human HepG2 hepatoma cells from the lead sophoridine (1). Among the newly synthesized compounds, sophoridinol 7i displayed a potential antiproliferative activity with an IC50 of 3.1 μM. Importantly, it exerted an almost equipotent effect against both wild MCF-7 and adriamycin (AMD)-resistant MCF-7 (MCF-7/AMD) breast carcinoma cell lines. Its mode of action was to arrest the cell cycle at the G0/G1 phase, consistent with that of the parent 1. In addition, compound 7i also showed a reasonable ClogP value and favorable pharmacokinetic property with an area under the concentration-time curve (AUC) of 10.3 μM·h in rats, indicating an ideal druggable characteristic. We consider sophoridinol derivatives to be a novel family of promising antitumor agents with an advantage of inhibiting drug-resistant cancer cells.

Synthesis and biological evaluation of sophocarpinic acid derivatives as anti-HCV agents

Chronic hepatitis C virus (HCV) infection has become a major public health burden worldwide. Twenty-two sophocarpinic acid or matrine derivatives were synthesized and their anti-HCV activities were evaluated in vitro. The structure-activity analysis revealed that (i) sophocarpinic acids with a D-seco 3-ring structure scaffold were more favorable than matrines with a 4-ring scaffold; (ii) the introduction of an electron-withdrawing group on the phenyl ring in 12-N-benzenesulfonyl Δ (βγ) sophocarpinic acids was beneficial for the antiviral activity against HCV. Among them, compounds 9h and 9j exhibited the most potent inhibitory activities on HCV replication with selectivity indies of 70.3 and 30.9, respectively. Therefore, both were selected as antiviral candidates for further investigation.

Novel N-substituted sophoridinol derivatives as anticancer agents

Using sophoridine (1) as the lead compound, a series of new N-substituted sophoridinic acid derivatives were designed, synthesized and evaluated for their cytotoxicity. SAR analysis indicated that introduction of a chlorobenzyl on the 12-nitrogen atom of sophoridinol might significantly enhance the antiproliferative activity. Of the newly synthesized compounds, sophoridinol analogue 9k exhibited a potent effect against six human tumor cell lines (liver, colon, breast, lung, glioma and nasopharyngeal). The mode of action of 9k was to inhibit the DNA topoisomerase I activity, followed by the G0/G1 phase arrest. It also showed a moderate oral bioavailability and good safety in vivo. Therefore, compound 9k has been selected as a novel-scaffold lead for further structural optimizations or as a chemical probe for exploring anticancer pathways of this kinds of compounds.