17β-Hydroxywithanolides as Sensitizers of Renal Carcinoma Cells to Tumor Necrosis Factor-α Related Apoptosis Inducing Ligand (TRAIL) Mediated Apoptosis: Structure-Activity Relationships

Pregnane C21-Steroids with Anti-Inflammatory Activity from the Roots of Cynanchum bungei

Five pregnane C21-steroids, including three 5,6-epoxy steroids (1-3) and two 8,14-seco-steroids (4 and 5), were isolated from the acid hydrolysate of Cynanchum bungei roots. Cynbungenins L-O (1-4) are previously undescribed compounds. Compound 3 with a 5α,6α-epoxy group represents the first example found in the Cynanchum plants. Their structures and absolute configurations were elucidated by a variety of spectroscopic analysis and theoretical ECD calculations. All compounds (1-5) were evaluated for their anti-inflammatory activity by inhibiting the lipopolysaccharide (LPS)-induced nitric oxide (NO) released in RAW264.7 cells. The results showed that they all possessed NO inhibitory activity at 50 µM, and compounds 3 and 4 exhibited stronger NO inhibitory activity than indomethacin.

Gintonin-Enriched Panax ginseng Extract Fraction Sensitizes Renal Carcinoma Cells to TRAIL-Induced Apoptosis through DR4/5 Upregulation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising chemotherapeutic agent because of its selective apoptotic action on cancer cells. However, resistance to TRAIL-induced apoptosis remains a challenge in many cancers. The gintonin-enriched Panax ginseng extract fraction (GEF) has diverse pharmacological benefits. We explored the combined efficacy of GEF and TRAIL in inducing apoptosis in human renal cell carcinoma (RCC) cells. The effect of GEF treatment on the viability, clonogenic potential, wound healing, and TRAIL-induced apoptotic signaling of RCC cells was studied in vitro. Our investigation revealed that GEF pre-treatment sensitized RCC cells to TRAIL-induced apoptosis, as evidenced by DNA fragmentation and cell proliferation, colony formation, and migration inhibition. This sensitization was linked to the upregulation of death receptors 4 and 5 and alterations in apoptotic protein expression, notably, the decreased expression of the Mu-2-related death-inducing gene, a novel anti-apoptotic protein. Our findings underscore the necessity of caspase activation for GEF/TRAIL-induced apoptosis using the pan-caspase inhibitor Z-VAD-FMK. This study demonstrates that GEF sensitizes human RCC cells to TRAIL-induced apoptosis by upregulating DR4/5 and modulating apoptotic protein expression. These findings suggest a promising strategy for overcoming TRAIL resistance in cancer therapy and highlight the potential of GEF as a valuable adjunct to TRAIL-based treatments.

Anti-tumor withanolides as signal transducers and activators of transcription 3 (STAT3)-inhibition from Withania obtusifolia

The Solanaceae family and the Withania genus specifically are rich sources of medicinal plants. Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS/MS) revealed a predominance of withanolides from an organic extract of Withania obtusifolia. A constructed molecular network uncovered the presence of potentially novel withanolides. A series of withanolides were then isolated and structurally characterized from the extract including two new withanolides (withafolia A and withafolia B) and seven previously reported metabolites. Of the isolated compounds, cytotoxicity of withanolide J, physaperuvin G, and a commercial STAT3 inhibitor (S3I-201) were assessed against a human leukemia HL-60 cell line resulting in IC50 values of 26, 29, and 120 μM, respectively. In silico molecular docking simulations indicate that withanolide J and physaperuvin G can bind as an inhibitor in the active site of STAT3 with docking scores comparable to the selective STAT3 inhibitor, S3I-201.

Novel small molecule inhibitors targeting renal cell carcinoma: Status, challenges, future directions

Renal cell carcinoma (RCC) is the most common renal malignancy with a rapidly increasing morbidity and mortality rate gradually. RCC has a high mortality rate and an extremely poor prognosis. Despite numerous treatment strategies, RCC is resistant to conventional radiotherapy and chemotherapy. In addition, the limited clinical efficacy and inevitable resistance of multiple agents suggest an unmet clinical need. Therefore, there is an urgent need to develop novel anti-RCC candidates. Nowadays many promising results have been achieved with the development of novel small molecule inhibitors against RCC. This paper reviews the recent research progress of novel small molecule inhibitors targeting RCC. It is focusing on the structural optimization process and conformational relationships of small molecule inhibitors, as well as the potential mechanisms and anticancer activities for the treatment of RCC. To provide a theoretical basis for promoting the clinical translation of novel small molecule inhibitors, we discussed their application prospects and future development directions. It could be capable of improving the clinical efficacy of RCC and improving the therapy resistance for RCC.

Significance of TRAIL/Apo-2 ligand and its death receptors in apoptosis and necroptosis signalling: Implications for cancer-targeted therapeutics

The human immune defensesystem routinely expresses the tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), which is the most prevalent element for antitumor immunity. TRAIL associates with its death receptors (DRs), DR4 (TRAIL-R1), and DR5 (TRAIL-R2), in cancer cells to initiate the intracellular apoptosis cascade. Accordingly, numerous academic institutions and pharmaceutical companies havetried to exploreTRAIL's capacity to kill tumourcells by producing recombinant versions of it (rhTRAIL) or TRAIL receptor agonists (TRAs) [monoclonal antibody (mAb), synthetic and natural compounds, etc.] and molecules that sensitize TRAIL signalling pathway for therapeutic applications. Recently, several microRNAs (miRs) have been found to activate or inhibit death receptor signalling. Therefore, pharmacological regulation of these miRs may activate or resensitize the TRAIL DRs signal, and this is a novel approach for developing anticancer therapeutics. In this article, we will discuss TRAIL and its receptors and molecular pathways by which it induces various cell death events. We will unravel potential innovative applications of TRAIL-based therapeutics, and other investigated therapeutics targeting TRAIL-DRs and summarize the current preclinical pharmacological studies and clinical trials. Moreover, we will also emphasizea few situations where future efforts may be addressed to modulate the TRAIL signalling pathway.

Bortezomib in Combination with Physachenolide C Reduces the Tumorigenic Properties of KRASmut/P53mut Lung Cancer Cells by Inhibiting c-FLIP

BACKGROUND

Defects in apoptosis regulation are one of the classical features of cancer cells, often associated with more aggressiveness and failure to therapeutic options. We investigated the combinatorial antitumor effects of a natural product, physachenolide C (PCC) and bortezomib, in KRASmut/P53mut lung cancer cells and xenograft mice models.

METHODS

The in vitro anticancer effects of the bortezomib and PCC combination were investigated using cell viability, migration, and invasion assays in 344SQ, H23, and H358 cell lines. Furthermore, the effects of combination treatment on the critical parameters of cellular metabolism, including extracellular acidification rate (ECAR) and mitochondrial oxidative phosphorylation based on the oxygen consumption rate of cancer cells were assessed using Seahorse assay. Finally, the antitumor effect of the bortezomib (1 mg/kg) and PCC (10 mg/kg) combination was evaluated using xenograft mice models.

RESULTS

Our data showed that the bortezomib-PCC combination was more effective in reducing the viability of lung cancer cells in comparison with the individual treatments. Similarly, the combination treatment showed a significant inhibition of cell migration and invasion of cancer cells. Additionally, the key anti-apoptotic protein c-FLIP was significantly inhibited along with a substantial reduction in the key parameters of cellular metabolism in cancer cells. Notably, the bortezomib or PCC inhibited the tumor growth compared to the control group, the tumor growth inhibition was much more effective when bortezomib was combined with PCC in tumor xenograft mice models.

CONCLUSION

These findings demonstrate that PCC sensitizes cancer cells to bortezomib, potentially improving the antitumor effects against KRASmut/P53mut lung cancer cells, with an enhanced efficacy of combination treatments without causing significant side effects.

Hydrolytic Metabolism of Withangulatin A Mediated by Serum Albumin Instead of Common Esterases in Plasma

BACKGROUND AND OBJECTIVES

The oral bioavailability of withangulatin A (WA) is low and may undergo first-pass metabolism because of the presence of two esters bonds. This study aimed to identify the hydrolysis behavior and mechanism of WA, thus enriching its structure-pharmacokinetic relationship.

METHODS

The in vivo pharmacokinetic studies of WA in rats were first investigated, followed by in vitro assays including metabolic stability, phenotyping identification and metabolic kinetics assays. After screening out the responsible enzymes with higher catalytic capacity, molecular docking study was performed to demonstrate the interaction mode between WA and metabolic enzymes. Then, metabolites in human serum albumin (HSA) were identified by LC-TOF-MS/MS.

RESULTS

In rats, the oral bioavailability of WA was only 2.83%. In vitro, WA was hydrolyzed in both rat and human plasma and could not be inhibited by selective esterase inhibitors. Physiologic concentration of HSA not recombinant human carboxylesterases (rhCES) could significantly hydrolyze WA, and it had a similar hydrolytic capacity with human plasma to WA. Furthermore, WA could stably bind to HSA by forming hydrogen bonds with Lys199 and Arg410, accompanied by the metabolic reaction of the lactone ring opening.

CONCLUSION

The study showed that WA underwent obvious hydrolysis in rat and human plasma, which implied a strong first-pass effect. Serum albumin rather than common esterases primarily contributed to the hydrolytic metabolism of WA in plasma.

Five New C21 -Steroidal Sapogenins from the Acid Hydrolysate of Cynanchum otophyllum Roots

Five new C₂₁ -steroidal sapogenins (1-5) named cynotogenins J-N, were isolated from the acid hydrolysate of Cynanchum otophyllum roots. Their structures were established by extensive spectroscopic analysis (UV, IR, HR-ESI-MS, and NMR). Most notably, compounds 1-3 harboring a rare 5β,6β-epoxy group in the C₂₁ -steroidal skeleton of Cynanchum plants. All compounds were evaluated for their cytotoxicities against multiple cancer cell lines, in which compounds 5 showed weak cytotoxicity against HepG2 cancer cells with IC₅₀ values of 44.90 μM.

Physachenolide C is a Potent, Selective BET Inhibitor

A pulldown using a biotinylated natural product of interest in the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), identified the bromodomain and extra-terminal domain (BET) family of proteins (BRD2, BRD3, and BRD4), readers of acetyl-lysine modifications and regulators of gene transcription, as potential cellular targets. BROMOscan bromodomain profiling and biochemical assays support PCC as a BET inhibitor with increased selectivity for bromodomain (BD)-1 of BRD3 and BRD4, and X-ray crystallography and NMR studies uncovered specific contacts that underlie the potency and selectivity of PCC toward BRD3-BD1 over BRD3-BD2. PCC also displays characteristics of a molecular glue, facilitating proteasome-mediated degradation of BRD3 and BRD4. Finally, PCC is more potent than other withanolide analogues and gold-standard pan-BET inhibitor (+)-JQ1 in cytotoxicity assays across five prostate cancer (PC) cell lines regardless of androgen receptor (AR)-signaling status.

Withania somnifera - a magic plant targeting multiple pathways in cancer related inflammation

BACKGROUND

Deregulated inflammatory responses are known to play a pivotal role in cancer initiation and progression. Tumor microenvironment is associated with the presence of a diverse array of inflammatory reactions, which further help tumor growth, metastasis and drug resistance. Withania somnifera is known to curb proliferation of cancer cells and lower inflammatory responses.

PURPOSE

In order to minimize the inflammation, cancer treatments often include immunomodulatory drugs. However, given the side effects of both of the cytotoxic cancer drugs and synthetic immunomodulatory agents, there is a need to develop novel anti-inflammatory agents for improved cancer therapy. A number of reports indicate that bioactive phytochemicals derived from W. somnifera exhibit anti-inflammatory capabilities in cancer. A deeper look into the underlying molecular mechanisms implicated in W. somnifera mediated anti inflammation is lacking, which is essential to fully understand the potential of this magical plant in cancer. Therefore, in the present review we are summarizing various reports, which describe mechanistic understanding of W. somnifera in cancer related inflammation.

STUDY DESIGN AND METHODOLOGY

In order to gather information on the molecular pathways affected by W. somnifera in cancer related inflammation, 'PubMed' and 'Science Direct' databases were searched using keywords Withania, cancer inflammation, and Withaferin A. Selected literature was analyzed to cover the role of inflammation in cancer, usage and side effects of anti-inflammatory drugs, W. somnifera as an immunomodulatory agent in cancer, molecular pathways modulated by W. somnifera in various preclinical models, and clinical trials using W. somnifera as an anti-inflammatory agent.

RESULTS

Upon literature survey we found that both W. somnifera extracts and Withaferin-A, exhibit anti inflammatory activities in various preclinical cancer models. W. somnifera modulates a number of signaling pathways such as NF-kB, JAK-STAT and AP1 to reduce cancer related inflammation. Anti inflammatory properties of W. somnifera might be effective in the treatment of drug resistance in cancers. Based on its promising effects against cancer associated inflammation in preclinical studies, W. somnifera derived products are being tested in clinical trials.

CONCLUSION

Several preclinical studies demonstrated anti-inflammatory potential of W. somnifera in a variety of cancers. While a few clinical trials are investigating the role of W. somnifera in various diseases, focused studies on its role in cancer related inflammation are lacking. Additionally, its anti-inflammatory effects offer targeting of senescence associated secretory phenotype (SASP), which is speculated to play a critical role in chemoresistance. Apart from targeting cancer cell proliferation, anti-inflammatory effects of Withania provide double advantage in cancer management. Therefore, clinical trials to target cancer related inflammation using W. somnifera as a drug, should be performed to validate its advantages in cancer therapy.

Therapeutic Potential of Natural Products in the Treatment of Renal Cell Carcinoma: A Review

Renal cell carcinoma (RCC) is a common cancer of the urinary system. The potential therapeutic effects of certain natural products against renal cell carcinoma have been reported both in vivo and in vitro, but no reviews have been published classifying and summarizing the mechanisms of action of various natural products. In this study, we used PubMed and Google Scholar to collect and screen the recent literature on natural products with anti-renal-cancer effects. The main mechanisms of action of these products include the induction of apoptosis, inhibition of angiogenesis, inhibition of metastasis and reduction of drug resistance. In total, we examined more than 30 natural products, which include kahweol acetate, honokiol, englerin A and epigallocatechin-3-gallate, among others, have demonstrated a variety of anti-renal-cancer effects. In conclusion, natural products may have a wider application in kidney cancer than previously believed and are potential candidates for treatment in RCC.

Withania somnifera (L.) Dunal: Phytochemistry, structure-activity relationship, and anticancer potential

BACKGROUND

Ayurveda is a highly recognized, well-documented, and well-accepted traditional medicine system. This system utilizes many natural products in various forms for therapeutic purposes. Thousands of plants mentioned in the Ayurvedic system are useful in disease mitigation and health preservation. One potential plant of the Ayurvedic system is "Ashwagandha" [Withania somnifera (L.) Dunal], commonly regarded as Indian Ginseng. It possesses various therapeutic activities, such as neuroprotective, hypoglycemic, hepatoprotective, antiarthritic, and anticancer effects.

PURPOSE

Here we present a comprehensive insight on the anticancer effects of W. somnifera and mechanistic attributes of its bioactive phytocompounds. This review also provides updated information on the clinical studies pertaining to cancer, safety evaluation and opportunities for chemical modifications of withanolides, a group of specialized phytochemicals of W. somnifera.

METHODS

The present study was performed in accordance with the guidelines of the Preferred Reporting Items for Systemic Reviews and Meta-Analysis. Various scientific databases, such as PubMed, Science Direct, Scopus, Google Scholar, were explored for related studies published up to May 2021.

RESULTS

An updated review on the anticancer potential and mechanisms of action of the major bioactive components of W. somnifera, including withanolides, withaferin A and withanone, is presented. Comprehensive information on clinical attributes of W. somnifera and its active components are presented with the structure-activity relationship (SAR) and toxicity evaluation.

CONCLUSION

The outcome of the work clearly indicates that W. somnifera has a significant potential for cancer therapy. The SAR revealed that various withanolides in general and withaferin A in particular have binding energies against various proteins and tremendous potential to serve as the lead for new chemical entities. Nevertheless, additional studies, particularly well-designed clinical trials are required before therapeutic application of withanolides for cancer treatment.

Production and Structural Diversification of Withanolides by Aeroponic Cultivation of Plants of Solanaceae: Cytotoxic and Other Withanolides from Aeroponically Grown Physalis coztomatl

Withanolides constitute one of the most interesting classes of natural products due to their diversity of structures and biological activities. Our recent studies on withanolides obtained from plants of Solanaceae including Withania somnifera and a number of Physalis species grown under environmentally controlled aeroponic conditions suggested that this technique is a convenient, reproducible, and superior method for their production and structural diversification. Investigation of aeroponically grown Physalis coztomatl afforded 29 withanolides compared to a total of 13 obtained previously from the wild-crafted plant and included 12 new withanolides, physacoztolides I−M (9–13), 15α-acetoxy-28-hydroxyphysachenolide C (14), 28-oxophysachenolide C (15), and 28-hydroxyphysachenolide C (16), 5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (17), 15α-acetoxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (18), 28-hydroxy-5α-chloro-6β-hydroxy-5,6-dihydrophysachenolide D (19), physachenolide A-5-methyl ether (20), and 17 known withanolides 3–5, 8, and 21–33. The structures of 9–20 were elucidated by the analysis of their spectroscopic data and the known withanolides 3–5, 8, and 21–33 were identified by comparison of their spectroscopic data with those reported. Evaluation against a panel of prostate cancer (LNCaP, VCaP, DU-145, and PC-3) and renal carcinoma (ACHN) cell lines, and normal human foreskin fibroblast (WI-38) cells revealed that 8, 13, 15, and 17–19 had potent and selective activity for prostate cancer cell lines. Facile conversion of the 5,6-chlorohydrin 17 to its 5,6-epoxide 8 in cell culture medium used for the bioassay suggested that the cytotoxic activities observed for 17–19 may be due to in situ formation of their corresponding 5β,6β-epoxides, 8, 27, and 28.

Ring A/B-Modified 17β-Hydroxywithanolide Analogues as Antiproliferative Agents for Prostate Cancer and Potentiators of Immunotherapy for Renal Carcinoma and Melanoma

Physachenolide C (1) is a 17β-hydroxywithanolide natural product with a unique anticancer potential, as it exhibits potent and selective in vitro antiproliferative activity against prostate cancer (PC) cells and promotes TRAIL-induced apoptosis of renal carcinoma (RC) and poly I:C-induced apoptosis of melanoma cells. To explore the effect of ring A/B modifications of physachenolide C (1) on these biological activities, 23 of its natural and semisynthetic analogues were evaluated. Analogues 4-23 were prepared by chemical transformations of a readily accessible compound, physachenolide D (2). Compound 1 and its analogues 2-23 were evaluated for their antiproliferative activity against PC (LNCaP and 22Rv1), RC (ACHN), and melanoma (M14 and SK-MEL-28) cell lines and normal human foreskin fibroblast (HFF) cells. Most of the active analogues had selective and potent activity in reducing cell number for PC cell lines, some showing selectivity for androgen-independent and enzalutamide-resistant 22Rv1 cells compared to androgen-dependent LNCaP cells. Analogues with IC₅₀s below 5.0 μM against ACHN cells, when tested in the presence of TRAIL, showed a significantly increased ability to reduce cell number, and those analogues active against the M14 and SK-MEL-28 cell lines exhibited enhanced activity when combined with poly I:C. These data provide additional structure-activity relationship information for 17β-hydroxywithanolides and suggest that selective activities of some analogues may be exploited to develop natural products-based tumor-specific agents for cancer chemotherapy.

Physachenolide C induces complete regression of established murine melanoma tumors via apoptosis and cell cycle arrest

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PCC and LG-134 had direct cytotoxicity in murine melanoma cell lines (IC₅₀ values ranged from 0.19–1.8 µM).

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PCC treatment induced apoptosis of tumor cells both in vitro and in vivo.

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PCC treatment induced G0-G1 cell cycle arrest of melanoma cells.

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PCC treatment caused complete regression of established melanoma tumors in all mice.

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17β-hydroxywithanolides have the potential to improve melanoma therapeutic outcome.

Melanoma is an aggressive skin cancer that metastasizes to other organs. While immune checkpoint blockade with anti-PD-1 has transformed the treatment of advanced melanoma, many melanoma patients fail to respond to anti-PD-1 therapy or develop acquired resistance. Thus, effective treatment of melanoma still represents an unmet clinical need. Our prior studies support the anti-cancer activity of the 17β-hydroxywithanolide class of natural products, including physachenolide C (PCC). As single agents, PCC and its semi-synthetic analog demonstrated direct cytotoxicity in a panel of murine melanoma cell lines, which share common driver mutations with human melanoma; the IC₅₀ values ranged from 0.19–1.8 µM. PCC treatment induced apoptosis of tumor cells both in vitro and in vivo. In vivo treatment with PCC alone caused the complete regression of established melanoma tumors in all mice, with a durable response in 33% of mice after discontinuation of treatment. T cell-mediated immunity did not contribute to the therapeutic efficacy of PCC or prevent tumor recurrence in YUMM2.1 melanoma model. In addition to apoptosis, PCC treatment induced G0-G1 cell cycle arrest of melanoma cells, which upon removal of PCC, re-entered the cell cycle. PCC-induced cycle cell arrest likely contributed to the in vivo tumor recurrence in a portion of mice after discontinuation of treatment. Thus, 17β-hydroxywithanolides have the potential to improve the therapeutic outcome for patients with advanced melanoma.

Structure-Activity Relationships of Withanolides as Antiproliferative Agents for Multiple Myeloma: Comparison of Activity in 2D Models and a 3D Coculture Model

Multiple myeloma (MM) is a hematological cancer in which relapse and resistance are highly frequent. Therefore, alternatives to conventional treatments are necessary. Withaferin A, a withanolide isolated from Withania somnifera, has previously shown promising activity against various MM models. In the present study, structure-activity relationships (SARs) were evaluated using 56 withanolides. The antiproliferative activity was assessed in three MM cell lines and in a 3D MM coculture model to understand the in vitro activity of compounds in models of various complexity. While the results obtained in 2D allowed a quick and simple evaluation of cytotoxicity used for a first selection, the use of the 3D MM coculture model allowed filtering compounds that perform better in a more complex setup. This study shows the importance of the last model as a bridge between 2D and in vivo studies to select the most active compounds and ultimately lead to a reduction of animal use for more sustained in vivo studies. NF-κB inhibition was determined to evaluate if this could be one of the targeted pathways. The most active compounds, withanolide D (2) and 38, should be further evaluated in vivo.

Small-Molecule Natural Product Physachenolide C Potentiates Immunotherapy Efficacy by Targeting BET Proteins

Screening for sensitizers of cancer cells to TRAIL-mediated apoptosis identified a natural product of the 17β-hydroxywithanolide (17-BHW) class, physachenolide C (PCC), as a promising hit. In this study, we show that PCC was also able to sensitize melanoma and renal carcinoma cells to apoptosis in response not only to TRAIL, but also to the synthetic polynucleotide poly I:C, a viral mimetic and immune activator, by reducing levels of antiapoptotic proteins cFLIP and Livin. Both death receptor and TLR3 signaling elicited subsequent increased assembly of a proapoptotic ripoptosome signaling complex. Administration of a combination of PCC and poly I:C in human M14 melanoma xenograft and a syngeneic B16 melanoma model provided significant therapeutic benefit as compared with individual agents. In addition, PCC enhanced melanoma cell death in response to activated human T cells in vitro and in vivo in a death ligand-dependent manner. Biochemical mechanism-of-action studies established bromo and extraterminal domain (BET) proteins as major cellular targets of PCC. Thus, by targeting of BET proteins to reduce antiapoptotic proteins and enhance caspase-8-dependent apoptosis of cancer cells, PCC represents a unique agent that can potentially be used in combination with various immunotherapeutic approaches to promote tumor regression and improve outcome. SIGNIFICANCE: These findings demonstrate that PCC selectively sensitizes cancer cells to immune-mediated cell death, potentially improving the efficacy of cancer immunotherapies. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3374/F1.large.jpg.

The synthesis and cytotoxic activity of derivatives of 4β-hydroxywithanolide E

4β-Hydroxywithanolide E, which can be obtained in large amounts from the Physalis genus, possessed anti-proliferative effects on a variety of human cancer cell lines. For discussing its anti-tumor structure-activity relationship, a series of 4β-hydroxywithanolide E derivatives (1-17) were synthesized and evaluated for their antitumor activity in vitro towards acute promyelocytic leukemia NB4 cell line by the Alarma blue assay. Cytotoxicity data revealed that the enone structure and C-4 hydroxyl substituents of ring A, together with the side chain (C-20-C-28) play an important effect on the cytotoxicity.

New C21-steroidal aglycones from the roots of Cynanchum otophyllum and their anticancer activity

Naturally occurring C₂₁-steroidal aglycones from Cynanchum exhibit significant antitumor effects. To expand the chemical diversity and get large scale C₂₁-steroidal aglycones, the extracts of the roots of Cynanchum otophyllum were treated with 5% HCl in aqueous and the resulting hydrolysate was investigated. Nine new C₂₁-steroidal aglycones (1-9) namely cynotogenins A-I, along with seventeen known analogous (10-26), were isolated from the hydrolysate. The structures of compounds 1-9 were elucidated by spectroscopic analysis (IR, HR-ESI-MS, 1D and 2D NMR) and comparison of observed spectroscopic data with those of reported in the literature. Aglycones 2-5 with rare cis-cinnamoyl group as well as 8 and 9 with 5β,6β-epoxy group were found from the genus of Cynanchum for the first time. The cytotoxicities of compounds 1-26 toward human cancer HeLa, H1299, HepG2, and MCF-7 cells were evaluated and preliminary structure-activity relationship (SAR) was discussed. Moreover, compound 20 inhibits HepG2 cell apoptosis and induces of G0/G1 phase arrest in a dose dependent manner.

Impact of inflammation and immunotherapy in renal cell carcinoma

Substantial research attention has been directed at exploring the mechanisms and treatment of renal cell carcinoma (RCC). Indeed, the association between inflammation and tumor phenotypes has been at the center of cancer research. Concomitant with research on the inflammation response and inflammatory molecules involved in RCC, new breakthroughs have emerged. A large body of knowledge now shows that treatments targeting inflammation and immunity in RCC provide substantial clinical benefits. Adequate analysis and a better understanding of the mechanisms of inflammatory factors in the occurrence and progression of RCC are highly desirable. Currently, numerous RCC treatments targeted at inflammation and immunotherapy are available. The current review describes in detail the link between inflammation and RCC.

Discovery and optimization of withangulatin A derivatives as novel glutaminase 1 inhibitors for the treatment of triple-negative breast cancer

To develop novel GLS1 inhibitors as effective therapeutic agents for triple-negative breast cancer (TNBC), 25 derivatives were synthesized from the natural inhibitor withangulatin A (IC₅₀ = 18.2 μM). Bioassay optimization identified a novel and selective GLS1 inhibitor 7 (IC₅₀ = 1.08 μM). In MDA-MB-231 cells, 7 diminished cellular glutamate levels by blocking glutaminolysis pathway, further triggering the generation of reactive oxygen species to induce caspase-dependent apoptosis. Molecular docking indicated that 7 interacted with a new reacting site of allosteric binding pocket by forming various interactions in GLS1. The intraperitoneal administration of 7 at a dose of 50 mg/kg exhibited remarkable therapeutic effects and no apparent toxicity in the MDA-MB-231 xenograft model, indicating its potential as a novel GLS1 inhibitor for treatment of TNBC.

Creating and screening natural product libraries

Covering: up to 2020The National Cancer Institute of the United States (NCI) has initiated a Cancer Moonshot program entitled the NCI Program for Natural Product Discovery. As part of this effort, the NCI is producing a library of 1 000 000 partially purified natural product fractions which are being plated into 384-well plates and provided to the research community free of charge. As the first 326 000 of these fractions have now been made available, this review seeks to describe the general methods used to collect organisms, extract those organisms, and create a prefractionated library. Importantly, this review also details both cell-based and cell-free bioassay methods and the adaptations necessary to those methods to productively screen natural product libraries. Finally, this review briefly describes post-screen dereplication and compound purification and scale up procedures which can efficiently identify active compounds and produce sufficient quantities of natural products for further pre-clinical development.

Cellular target identification of Withangulatin A using fluorescent analogues and subsequent chemical proteomics

Find the target of Withangulatin A with the combination of fluorescent probes and chemical proteomics.