Novel N-substituted sophoridinol derivatives as anticancer agents

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.

Matrine-Family Alkaloids: Versatile Precursors for Bioactive Modifications

Matrine-family alkaloids as tetracycloquinolizindine analogues from Traditional Chinese Medicine Sophora flavescens Ait, Sophora subprostrata and Sophora alopecuroides L possess various pharmacological activities and have aroused great interests over the past decades. Especially, a lot of matrine derivatives have been designed and synthesized and their biological activities investigated, and encouraging results have continuously been achieved in recent several years. These studies are helpful to develop more potent candidates or therapeutic agents and disclose their molecular targets and mechanisms. This paper reviews recent advances in the bioactive modifications of matrine-family alkaloids from derivatization of the C-13, C-14 or C-15 position, opening D ring, fusing D ring and structural simplification.

Structure-activity relationship and hypoglycemic activity of tricyclic matrines with advantage of treating diabetic nephropathy

Forty-three tricyclic matrinic derivatives with a unique scaffold were prepared and evaluated for their stimulation effects on glucose consumption in HepG2 cells. The structure-activity relationship was systematically elucidated for the first time. Among them, compound 17a exhibited the most promising potency, and dose-dependently increased glucose consumption in L6 myotubes. It significantly lowered blood glucose, glucosylated haemoglobin and AGE level, and improved glucose tolerance and insulin resistance in KK-Ay mice as well. More importantly, 17a effectively ameliorated diabetic nephropathy (DN), as indicated by the improvement of renal function and pathological changes, and decrease of urinary protein. Furthermore, 17a could induce glycolysis but suppressed aerobic oxidation of glucose, in a similar mechanism to Metform. Our results indicated that in addition to hyperglycemia, 17a may be developed to treat diabetic complication such as DN.

Preparation of Matrinic/Oxymatrinic Amide Derivatives as Insecticidal/Acaricidal Agents and Study on the Mechanisms of Action against Tetranychus cinnabarinus

In continuation of our program to develop natural-product-based pesticidal candidates, matrinic/oxymatrinic amides were obtained through structural optimization of matrine. N'-(4-Fluoro)phenyl-N-(4-bromo)phenylsulfonyloxymatrinic amide (IIm) showed potent insecticidal activity against Mythimna separata. N-(Un)substituted phenylsulfonylmatrinic acids (3a-c) exhibited promising acaricidal activity against Tetranychus cinnabarinus. By qRT-PCR analysis of nAChR subunits and AChE genes and determination of AChE activity of (un)treated T. cinnabarinus, it suggested that the open lactam ring of matrine and carboxyl group and (4-methyl)phenylsulfonyl of N-(4-methyl)phenylsulfonylmatrinic acid (3b) were necessary for action with α2, α4, α5, and β3 nAChR subunits; compound 3b was an inhibitor of AChE in T. cinnabarinus, and AChE was one possible target of action in T. cinnabarinus against 3b; and compound 3b may be an antagonist of nAChR and AChE in T. cinnabarinus.

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.

IMB-6G induces endoplasmic reticulum stress-mediated apoptosis in human nasopharyngeal carcinoma cells

IMB-6G is a novel N-substituted sophoridine acid that has been reported to have anticancer effects. The purpose of the present study was to investigate the effect and underlying mechanism of IMB-6G on human nasopharyngeal carcinoma (NPC) cells. The NPC cell line C666-1 was used in the present study and treated with different concentrations of IMB-6G (0, 1, 2 and 5 µM) for 24 h. Subsequently, cell viability was determined using the Cell Counting kit-8 assay and cell apoptosis was analyzed by performing flow cytometry. The expression levels of genes and proteins in the current study were determined using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Results indicated that IMB-6G dose-dependently inhibited C666-1 cell viability and induced apoptosis. It was also revealed that IMB-6G induced apoptosis via inducing endoplasmic reticulum (ER) stress activation. Notably, IMB-6G administration enhanced the expression levels of Binding immunoglobulin protein and CCAAT-enhancer-binding protein homologous protein in C666-1 cells. Further analysis suggested that IMB-6G treatment activated inositol-requiring enzyme 1α (IRE1α) and PKR-like ER kinase (PERK) signaling pathways in C666-1 cells. In addition, silencing of IRE1α and PERK significantly reversed IMB-6G-induced cell growth inhibition and apoptosis. In conclusion, the present findings indicated that IMB-6G induced ER stress-mediated apoptosis through activating IRE1α and PERK signaling pathways. The present study suggests that IMB-6G may be a promising agent for NPC treatment.

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.

Synthesis and biological evaluation of novel tricyclic matrinic derivatives as potential anti-filovirus agents

Twenty-six novel tricyclic sophoridinic and matrinic derivatives containing a common chlorinated benzene fragment were designed, synthesized and evaluated for their anti-ebolavirus (EBOV) activities. Structure-activity relationship analysis indicated: (i) 12N-dichlorobenzyl motif was beneficial for the activity; (ii) the chiral configuration at C5 atom might not affect the activity much. Among the target compounds, compound 7d exhibited the most potent potency against EBOV with an IC₅₀ value of 5.29 μmol/L and an SI value of over 37.8. Further in vivo anti-EBOV assay of 7d identified its high effectiveness, and in vivo anti-MARV assay of 7d suggested its inspiring broad-spectrum anti-filovirus activity. The results provided powerful information on further strategic optimization and development of this kind of compounds against filoviruses.

IMB-6G, a novel N-substituted sophoridinic acid derivative, induces endoplasmic reticulum stress-mediated apoptosis via activation of IRE1α and PERK signaling

Sophoridinic acid derivatives have received considerable attentions for their potencies in cancer therapy. IMB-6G is a novel N-substituted sophoridinic acid derivative with potent cytotoxicity against tumor cells. In the present study, we explored the antitumor abilities of IMB-6G in human hepatocellular carcinoma (HCC) cells and investigated the underlying mechanisms. We found that IMB-6G inhibited cell growth and induced mitochondrial-dependent apoptosis in HepG2 and SMMC7721 cells. Analyses of the molecular mechanism of IMB-6G-induced apoptosis indicated IMB-6G induced endoplasmic reticulum (ER) stress activation. Incubation of HCC cells with IMB-6G induced increase in Bip and CHOP levels, which precede induction of apoptosis. Further study showed IMB-6G activated IRE1α and PERK pathways but did not stimulated ATF6 pathway in HCC cells. Moreover, silencing of IRE1α dramatically abrogated IMB-6G-induced pro-apoptotic ASK1-JNK signaling. Importantly, interruption of CHOP rendered HCC cells sensitive to IMB-6G-induced apoptosis via inactivation of Bim, PUMA and Bax. Thus, the IRE1α-ASK1 and PERK-CHOP pathways may be a novel molecular mechanism of IMB-6G-induced apoptosis. Collectively, our study demonstrates that IMB-6G induces ER stress-mediated apoptosis by activating IRE1α and PERK pathways. Our findings provide a rationale for the potential application of IMB-6G in HCC therapy.

Synthesis, Biological Evaluation, and Autophagy Mechanism of 12N-Substituted Sophoridinamines as Novel Anticancer Agents

A series of 12N-substituted sophoridinamine derivatives were synthesized and evaluated for their cytotoxic activities in human HepG2 hepatoma cells. Structure-activity relationship revealed that introduction of a suitable arylidene or arylethyl at the N'-end could greatly enhance antiproliferation potency. Among them, compound 6b possessing a N'-trimethoxyphenyl methylene exhibited potent antiproliferation effect against three human tumor cell lines including HepG2, leukemia (K562), and breast cancer (HMLE), with IC₅₀ between 0.55 and 1.7 μM. The underlying mechanism of 6b against tumor cells is to block autophagic flux, mainly through neutralizing lysosomal acidity. Our results indicated that compound 6b is a potent lysosomal deacidification agent and is accordingly able to block autophagic flux and inhibit tumor cell growth.

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.

Sophoridinol derivative 05D induces tumor cells apoptosis by topoisomerase1-mediated DNA breakage

Sophoridine is a quinolizidine natural product of Sophora alopecuroides and has been applied for treatment of malignant trophoblastic tumors. Although characterized by low toxicity, the limited-spectrum antitumor activity hinders its further applications. 05D, a derivative of sophoridine, exhibits a better anticancer activity on diverse cancer cells, including solid tumors, and hematologic malignancy. It could inhibit topoisomerase 1 (top1) activity by stabilizing DNA-top1 complex and induce mitochondria-mediated apoptosis by promoting DNA single- and double-strand breakage mediated by top1. Also, 05D induced HCT116 cells arrest at G1 phase by inactivating CDK2/CDK4-Rb-E2F and cyclinD1-CDK4-p21 checkpoint signal pathways. 05D suppressed the ataxia telangiectasia mutated (ATM) and ATM and Rad3-related (ATR) activation and decreased 53BP level, which contributed to DNA damage repair, suggesting that the novel compound 05D might be helpful to improve the antitumor activity of DNA damaging agent by repressing ATM and ATR activation and 53BP level. In addition, the priorities in molecular traits and druggability, such as a simple structure and formulation for oral administration, further prove 05D to be a promising targeting topoisomerase agent.

Synthesis and biological evaluation of 12-N-p-chlorobenzyl sophoridinol derivatives as a novel family of anticancer agents

Taking 12-N-p-chlorobenzyl sophoridinol 2 as a lead, a series of novel sophoridinic derivatives with various 3'-substituents at the 11-side chain were synthesized and evaluated for their anticancer activity from sophoridine (1), a natural antitumor medicine. Among them, the sophoridinic ketones 5a-b, alkenes 7a-b and sophoridinic amines 14a-b displayed reasonable antiproliferative activity with IC50 values ranging from 3.8 to 5.4 μmol/L. Especially, compounds 5a and 7b exhibited an equipotency in both adriamycin (AMD)-susceptible and resistant MCF-7 breast carcinoma cells, indicating a different mechanism from AMD. The primary mechanism of action of 5a was to arrest the cell cycle at the G0/G1 phase, consistent with that of parent compound 1. Thus, we consider 12-chlorobenzyl sophoridinic derivatives with a tricyclic scaffold to be a new class of promising antitumor agents with an advantage of inhibiting drug-resistant cancer cells.

SAR evolution and discovery of benzenesulfonyl matrinanes as a novel class of potential coxsakievirus inhibitors

Materials & methods: Fifty-one novel 12N-substituted matrinic acid derivatives were synthesized and evaluated for their anti-coxsackievirus B3 activities. Results: Structure–activity relationship studies revealed that the 11-side chain could be determinant for the selectivity index by adjusting overall lipophilicity, and 11-butane was the best one for both potency and druggability. The optimized 35d showed the broad-spectrum anti-coxsackieviruse effects, an excellent pharmacokinetics and a good safety profile. More importantly, it displayed a potential effect for the pleconaril-resistant coxsackievirus B3 as well. Its mode of action is targeting on the viral transcription and translation stage, a different mechanism from that of pleconaril. Conclusion: Thus, we considered that 35d is a promising anti-enteroviral candidate for the treatment of various diseases infected with coxsackieviruses.

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.