Nitrogen-containing ecdysteroid derivatives vs. multi-drug resistance in cancer: Preparation and antitumor activity of oximes, oxime ethers and a lactam

17-Oxime ethers of oxidized ecdysteroid derivatives modulate oxidative stress in human brain endothelial cells and dose-dependently might protect or damage the blood-brain barrier

20-Hydroxyecdysone and several of its oxidized derivatives exert cytoprotective effect in mammals including humans. Inspired by this bioactivity of ecdysteroids, in the current study it was our aim to prepare a set of sidechain-modified derivatives and to evaluate their potential to protect the blood-brain barrier (BBB) from oxidative stress. Six novel ecdysteroids, including an oxime and five oxime ethers, were obtained through regioselective synthesis from a sidechain-cleaved calonysterone derivative 2 and fully characterized by comprehensive NMR techniques revealing their complete 1H and 13C signal assignments. Surprisingly, several compounds sensitized hCMEC/D3 brain microvascular endothelial cells to tert-butyl hydroperoxide (tBHP)-induced oxidative damage as recorded by impedance measurements. Compound 8, containing a benzyloxime ether moiety in its sidechain, was the only one that exerted a protective effect at a higher, 10 μM concentration, while at lower (10 nM- 1 μM) concentrations it promoted tBHP-induced cellular damage. Brain endothelial cells were protected from tBHP-induced barrier integrity decrease by treatment with 10 μM of compound 8, which also mitigated the intracellular reactive oxygen species production elevated by tBHP. Based on our results, 17-oxime ethers of oxidized ecdysteroids modulate oxidative stress of the BBB in a way that may point towards unexpected toxicity. Further studies are needed to evaluate any possible risk connected to dietary ecdysteroid consumption and CNS pathologies in which BBB damage plays an important role.

Research progress of Paris polyphylla in the treatment of digestive tract cancers

Cancer has become one of the most important causes of human death. In particular, the 5 year survival rate of patients with digestive tract cancer is low. Although chemotherapy drugs have a certain efficacy, they are highly toxic and prone to chemotherapy resistance. With the advancement of antitumor research, many natural drugs have gradually entered basic clinical research. They have low toxicity, few adverse reactions, and play an important synergistic role in the combined targeted therapy of radiotherapy and chemotherapy. A large number of studies have shown that the active components of Paris polyphylla (PPA), a common natural medicinal plant, can play an antitumor role in a variety of digestive tract cancers. In this paper, the main components of PPA such as polyphyllin, C21 steroids, sterols, and flavonoids, amongst others, are introduced, and the mechanisms of action and research progress of PPA and its active components in the treatment of various digestive tract cancers are reviewed and summarized. The main components of PPA have been thoroughly explored to provide more detailed references and innovative ideas for the further development and utilization of similar natural antitumor drugs.

Synthesis and DFT calculations of metal(II) oxime complexes bearing cysteine as coligand and investigation of their biological evolutions in vitro and in silico

New complexes with the formula of [ML(Cys)(H2O)2] were obtained as a result of the reaction between the oxime ligand [HL: 4-(4-bromophenylaminoisonitrosoacetyl)biphenyl], cysteine (Cys), and the metal(II) salts (Mn, Ni, Co, Zn, Cu). The newly synthesized compounds were characterized using conventional techniques such as molar conductance, magnetic measurements, elemental analysis, infrared spectroscopy, and thermal analysis (TGA/DTA). Based on the conductivity measurements in DMF, it was determined that the complexes were non-electrolytes. The TGA/DTA analysis was performed to examine the thermal stability and degradation behavior of all samples, and results demonstrated that metal oxides or sulfides formed as a result of the decompositions. In conjunction with other data obtained, the elemental analysis confirmed the octahedral coordination of the complexes with deprotonated oxime (O, O-donor) and amino acid (N, S-donor) ligands and two coordinated waters. The compounds' optimized geometries, molecular electrostatic potential diagrams, and frontier molecular orbitals were computed at the DFT/B3LYP level using the 6-311 G(d,p) and LANL2DZ basis sets. The antibacterial and DNA cleavage activities of all synthesized compounds were also screened, and molecular docking simulations were performed. According to the results of molecular docking studies conducted with three different proteins, the best interaction was found to be between HL-1HNJ with a binding energy of -9.5 kcal/mol. The stability of the HL-1HNJ complex was also verified by a molecular dynamics simulation performed for 50 ns.Communicated by Ramaswamy H. Sarma.

A Review of Biologically Active Oxime Ethers

Oxime ethers are a class of compounds containing the >C=N-O-R moiety. The presence of this moiety affects the biological activity of the compounds. In this review, the structures of oxime ethers with specific biological activity have been collected and presented, and bactericidal, fungicidal, antidepressant, anticancer and herbicidal activities, among others, are described. The review includes both those substances that are currently used as drugs (e.g., fluvoxamine, mayzent, ridogrel, oxiconazole), as well as non-drug structures for which various biological activity studies have been conducted. To the best of our knowledge, this is the first review of the biological activity of compounds containing such a moiety. The authors hope that this review will inspire scientists to take a greater interest in this group of compounds, as it constitutes an interesting research area.

20-Hydroxyecdysone Confers Antioxidant and Antineoplastic Properties in Human Non-Small Cell Lung Cancer Cells

20-Hydroxyecdysone (20E) is an arthropod hormone which is synthesized by some plants as part of their defense mechanism. In humans, 20E has no hormonal activity but possesses a number of beneficial pharmacological properties including anabolic, adaptogenic, hypoglycemic, and antioxidant properties, as well as cardio-, hepato-, and neuroprotective features. Recent studies have shown that 20E may also possess antineoplastic activity. In the present study, we reveal the anticancer properties of 20E in Non-Small Cell Lung Cancer (NSCLC) cell lines. 20E displayed significant antioxidant capacities and induced the expression of antioxidative stress response genes. The RNA-seq analysis of 20E-treated lung cancer cells revealed the attenuation of genes involved in different metabolic processes. Indeed, 20E suppressed several enzymes of glycolysis and one-carbon metabolism, as well as their key transcriptional regulators-c-Myc and ATF4, respectively. Accordingly, using the SeaHorse energy profiling approach, we observed the inhibition of glycolysis and respiration mediated by 20E treatment. Furthermore, 20E sensibilized lung cancer cells to metabolic inhibitors and markedly suppressed the expression of Cancer Stem Cells (CSCs) markers. Thus, in addition to the known beneficial pharmacological activities of 20E, our data uncovered novel antineoplastic properties of 20E in NSCLC cells.

Discovery of novel benzenesulfonamides incorporating 1,2,3-triazole scaffold as carbonic anhydrase I, II, IX, and XII inhibitors

Sulfonamides are among the most promising potential inhibitors for carbonic anhydrases (CAs), which are pharmaceutically relevant targets for treating several disease conditions. Herein, a series of benzenesulfonamides bearing 1,2,3-triazole moiety as inhibitors of human (h) α-CAs (hCAs) were designed using the tail approach. The design method combines a benzenesulfonamide moiety with a tail of oxime and a zinc-binding group on a 1,2,3-triazole scaffold. Among the synthesized derivatives, the naphthyl (6m, K_I of 68.6 nM, S_I of 10.3), and methyl (6a, K_I of 56.3 nM, S_I of 11.7) derivatives (over hCA IX) and propyl (6c, K_I of 95.6 nM, S_I of 2.7), and pentyl (6d, K_I of 51.1 nM, S_I of 6.6) derivatives (over hCA XII) displayed a noticeable selectivity for isoforms hCA I and II, respectively. Meanwhile, derivative 6e displayed a potent inhibitory effect versus the cytosolic isoform hCA I (K_I of 47.8 nM) and tumor-associated isoforms hCA IX and XII (K_Is of 195.9 and 116.9 nM, respectively) compared with the reference drug acetazolamide (AAZ, K_Is of 451.8, 437.2, and 338.9 nM, respectively). Derivative 6b showed higher potency (K_I of 33.2 nM) than AAZ (K_I of 327.3 nM) towards another cytosolic isoform hCA II. Nevertheless, substituting the lipophilic large naphthyl tail to the 1,2,3-triazole linked benzenesulfonamides (6a-n) raised inhibitory effect versus hCA I and XII and selectivity towards hCA I and II isoforms over hCA IX. Evaluation of the cytotoxic potential of the synthesized derivatives was conducted in L929, MCF-7, and Hep-3B cell lines. Several compounds in the series demonstrated significant antiproliferative activity and minimal cytotoxicity. In the molecular docking study, the sulfonamide moiety interacted with the zinc-ion and neatly fit into the hCAs active sites. The extension of the tail was found to participate in diverse hydrophilic and hydrophobic interactions with adjacent amino acids, ultimately influencing the effectiveness and specificity of the derivatives.

Copper(I)-Catalyzed Late-Stage Introduction of Oxime Ethers into Peptides at the Carboxylic Acid Site

We have developed a method of introducing biological oxime ether fragments into peptides by CuI-catalyzed late-stage modification and functionalization of peptides, utilizing their acid moiety and varied 2H-azirines. As a result of its mild conditions, high atom economy, moderate yield, and excellent functional-group tolerance, the method can provide access to late-stage peptide modification and functionalization at their acid sites both in the homogeneous phase and on resins in SPPS, providing a new tool kit for peptide functionalization, diversification, and fluorescent labeling.

Semi-Synthetic Ecdysteroid 6-Oxime Derivatives of 20-Hydroxyecdysone Possess Anti-Cryptococcal Activity

Cryptococcosis, a life-threatening fungal infection, frequently occurs in patients suffering from AIDS. The treatment of the disease is hampered by the limited number of the effective drugs and the increasing resistance; therefore, to find new active substances is needed. As meningitis is the most serious infection affecting the AIDS patients, effective drugs have to be capable of entering to the central nervous system. Ecdysteroids are natural bioactive molecules with considerable anabolic activity and without toxic side effects on humans. The aim of this work was to study the anti-cryptococcal activity of a natural ecdysteroid, 20E, and its three semi-synthetic derivatives obtained by structural modification of the original molecule. We established the minimum inhibitory concentration of the compounds with microdilution method and demonstrated their fungicidal activity by flow cytometry and cultivation of the drug-treated cells. The interaction of the compounds with each other and efflux transporter inhibitors was assessed by checkerboard titration method. Two derivatives, 20E-EOx and 20E-ZOx, inhibited the growth of Cryptococcus neoformans with minimum inhibitory concentration 2 mg/mL and 1 mg/mL, respectively; both compounds possess fungicidal effect. A combination of the ecdysteroids with each other and verapamil resulted in additive interaction. This study confirmed that structural modification of an originally non-antimicrobial molecule can enhance its effectiveness.

Phytoecdysteroids: Distribution, Structural Diversity, Biosynthesis, Activity, and Crosstalk with Phytohormones

Phytoecdysteroids (PEs) are naturally occurring polyhydroxylated compounds with a structure similar to that of insect molting hormone and the plant hormone brassinosteroids. PEs have a four-ringed skeleton composed of 27, 28, 29, or 30 carbon atoms (derived from plant sterols). The carbon skeleton of ecdysteroid is known as cyclopentanoperhydrophenanthrene and has a β-sidechain on C-17. Plants produce PEs via the mevalonate pathway with the help of the precursor acetyl-CoA. PEs are found in algae, fungi, ferns, gymnosperms, and angiosperms; more than 500 different PEs are found in over 100 terrestrial plants. 20-hydroxyecdysone is the most common PE. PEs exhibit versatile biological roles in plants, invertebrates, and mammals. These compounds contribute to mitigating biotic and abiotic stresses. In plants, PEs play a potent role in enhancing tolerance against insects and nematodes via their allelochemical activity, which increases plant biological and metabolic responses. PEs promote enzymatic and non-enzymatic antioxidant defense systems, which decrease reactive oxygen species in the form of superoxide radicals and hydroxyl radicals and reduce malondialdehyde content. PEs also induce protein biosynthesis and modulate carbohydrate and lipid synthesis. In humans, PEs display biological, pharmacological, and medicinal properties, such as anti-diabetic, antioxidant, anti-microbial, hepatoprotective, hypoglycemic, anti-cancer, anti-inflammatory, antidepressant, and tissue differentiation activity.

Diversity-Oriented Synthesis Catalyzed by Diethylaminosulfur-Trifluoride-Preparation of New Antitumor Ecdysteroid Derivatives

Fluorine represents a privileged building block in pharmaceutical chemistry. Diethylaminosulfur-trifluoride (DAST) is a reagent commonly used for replacement of alcoholic hydroxyl groups with fluorine and is also known to catalyze water elimination and cyclic Beckmann-rearrangement type reactions. In this work we aimed to use DAST for diversity-oriented semisynthetic transformation of natural products bearing multiple hydroxyl groups to prepare new bioactive compounds. Four ecdysteroids, including a new constituent of Cyanotis arachnoidea, were selected as starting materials for DAST-catalyzed transformations. The newly prepared compounds represented combinations of various structural changes DAST was known to catalyze, and a unique cyclopropane ring closure that was found for the first time. Several compounds demonstrated in vitro antitumor properties. A new 17-N-acetylecdysteroid (13) exerted potent antiproliferative activity and no cytotoxicity on drug susceptible and multi-drug resistant mouse T-cell lymphoma cells. Further, compound 13 acted in significant synergism with doxorubicin without detectable direct ABCB1 inhibition. Our results demonstrate that DAST is a versatile tool for diversity-oriented synthesis to expand chemical space towards new bioactive compounds.

BK002 Induces miR-192-5p-Mediated Apoptosis in Castration-Resistant Prostate Cancer Cells via Modulation of PI3K/CHOP

BK002 consists of Achyranthes japonica Nakai (AJN) and Melandrium firmum Rohrbach (MFR) that have been used as herbal medicines in China and Korea. AJN and MFR have been reported to have anti-inflammatory, anti-oxidative, and anti-cancer activities, although the synergistic targeting multiple anti-cancer mechanism in castration-resistant prostate cancer (CRPC) has not been well reported. However, the drug resistance and transition to the androgen-independent state of prostate cancer contributing to CRPC is not well studied. Here, we reported that BK002 exerted cytotoxicity and apoptosis in CRPC PC3 cell lines and prostate cancer DU145 cell lines examined by cytotoxicity, western blot, a LIVE/DEAD cell imaging assay, reactive oxygen species (ROS) detection, quantitative real-time polymerase chain reaction (RT-PCR), and transfection assays. The results from our investigation found that BK002 showed more cellular cytotoxicity than AJN and MFR alone, suggesting that BK002 exhibited potential cytotoxic properties. Consistently, BK002 increased DNA damage, and activated p-γH2A.X and depletion of survivin-activated ubiquitination of pro-PARP, caspase9, and caspase3. Notably, live cell imaging using confocal microscopy found that BK002 effectively increased DNA-binding red fluorescent intensity in PC3 and DU145 cells. Also, BK002 increased the anti-proliferative effect with activation of the C/EBP homologous protein (CHOP) and significantly attenuated PI3K/AKT expression. Notably, BK002-treated cells increased ROS generation and co-treatment of N-Acetyl-L-cysteine (NAC), an ROS inhibitor, significantly preventing ROS production and cellular cytotoxicity, suggesting that ROS production is essential for initiating apoptosis in PC3 and DU145 cells. In addition, we found that BK002 significantly enhanced miR-192-5p expression, and co-treatment with BK002 and miR-192-5p inhibitor significantly reduced miR-192-5p expression and cellular viability in PC3 and DU145 cells, indicating modulation of miR-192-5p mediated apoptosis. Finally, we found that BK002-mediated CHOP upregulation and PI3K downregulation were significantly reduced and restrained by miR-192-5p inhibitor respectively, suggesting that the anti-cancer effect of BK002 is associated with the miR-192-5p/PI3K/CHOP pathway. Therefore, our study reveals that a combination of AJN and MFR might be more effective than single treatment against apoptotic activities of both CRPC cells and prostate cancer cells.

Copper-catalyzed selective oxidation of hydrazones through C(sp3)-H functionalization

A simple and mild protocol for copper-catalyzed oxidation of hydrazones at the α-position has been reported. Various substrates are compatible, providing the corresponding products in moderate to good yields. This strategy provides an efficient and convenient solution for the synthesis of carbonyl hydrazone. A free radical pathway mechanism is suggested for the transformation.

A Commercial Extract of Cyanotis arachnoidea Roots as a Source of Unusual Ecdysteroid Derivatives with Insect Hormone Receptor Binding Activity

Ecdysteroids act as molting hormones in insects and as nonhormonal anabolic agents and adaptogens in mammals. A wide range of ecdysteroid-containing herbal extracts are available worldwide as food supplements. The aim of this work was to study such an extract as a possible industrial source of new bioactive ecdysteroids. A large-scale chromatographic isolation was performed from an extract of Cyanotis arachnoidea roots. Ten ecdysteroids (1-10) including eight new compounds were isolated and characterized by extensive nuclear magnetic resonance studies. Highly unusual structures were identified, including a H-14β (1, 2, 4, and 10) moiety, among which a 14β(H)17β(H) phytosteroid (1) is reported for the first time. Compounds with an intact side chain (4-10) and 11 other natural or semisynthetic ecdysteroids (11-21) were tested for insect ecdysteroid receptor (EcR) binding activity. Two new compounds, i.e., 14-deoxydacryhainansterone (5) and 22-oxodacryhainansterone (6), showed strong EcR binding activity (IC50 = 41.7 and 380 nM, respectively). Six compounds were identified as EcR agonists and another two as antagonists using a transgenic ecdysteroid reporter gene assay. The present results demonstrate that commercial C. arachnoidea extracts are rich in new, unusual bioactive ecdysteroids. Because of the lack of an authentic plant material, the truly biosynthetic or artifactual nature of these compounds cannot be confirmed.

Novel penta-1,4-diene-3-one derivatives containing quinazoline and oxime ether fragments: Design, synthesis and bioactivity

A series of novel penta-1,4-diene-3-one derivatives containing quinazoline and oxime ether moieties were designed and synthesized. Their anticancer activities were evaluated by MTT assay, the results showed that most compounds exhibited extremely inhibitory effects against hepatoma SMMC-7721 cells. In particular, compounds Q2 and Q8 displayed the more potent inhibitory activity with IC₅₀ values of 0.64 and 0.63 μM, which were better than that of gemcitabine (1.40 μM). Further mechanism studies indicated that compounds Q2, Q8, Q13 and Q19 could control the migration of SMMC-7721 cells effectively, and inhibit the proliferation of cancer cells by inhibiting the DNA replication. Western-blot results showed that compounds Q2 and Q8 induced irreversible apoptosis of SMMC-7721 cells by regulating the expression level of apoptose-related proteins. Those studies demonstrated that the penta-1,4-diene-3-one derivatives containing quinazoline and oxime ether fragments merited further research as potential anticancer agents.

In vitro adjuvant antitumor activity of various classes of semi-synthetic poststerone derivatives

Various classes of semi-synthetic analogs of poststerone, the product of oxidative cleavage of the C20-C22 bond in the side chain of the phytoecdysteroid 20-hydroxyecdysone, were synthesized. The analogs were obtained by reductive transformations using L-Selectride and H₂-Pd/C, by molecular abeo-rearrangements using the DAST reagent or ultrasonic treatment in the NaI-Zn-DMF system, and by acid-catalyzed reactions of poststerone derivatives with various aldehydes (o-FC₆H₄CHO, m-CF₃C₆H₄CHO, CO₂Me(CH₂)₈CHO). The products were tested on a mouse lymphoma cell line pair, L5178 and its ABCB1-transfected multi-drug resistant counterpart, L5178_MDR, for their in vitro activity alone and in combination with doxorubicin, and for the ability to inhibit the ABCB1 transporter. Among the tested compounds, new 2,3-dioxolane derivatives of the pregnane ecdysteroid were found to have a pronounced chemosensitizing activity towards doxorubicin and could be considered as promising candidates for further structure optimization for the development of effective chemosensitizing agents.

A novel targeted delivery system for drug-resistant hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is a severe malignant disease threatening human life. Current chemotherapy methods usually result in poor prognosis with low treatment efficacy and high side effects because of weak targeting specificity and fast acquisition of multidrug resistance (MDR). HCSP4 is a 12-aa peptide previously identified to specifically and sensitively bind to HCC cells and tissues. In this study, a novel class of HCC-targeting doxorubicin (DOX) delivery system, named HCSP4-Lipo-DOX-miR101, was synthesized and investigated for anticancer activity. HCSP4-Lipo-DOX-miR101 exhibited specific HCC targeting characteristics and satisfactory anticancer potency against HepG2 and HepG2/ADR cells, particularly HepG2/ADR cells. Moreover, the expression levels of genes closely related to membrane transport and cancer growth were significantly suppressed. This finding suggests that HCSP4-Lipo-DOX-miR101 can cause DOX-resistant HCC cell death and growth inhibition based on the targeting of MDR-related genes by miR-101. In conclusion, the findings of this study suggest that HCSP4-Lipo-DOX-miR101 may serve as a promising novel targeted delivery system for improving the therapeutic efficiency of drug-resistant hepatocellular carcinoma.

Cell Type-Dependent Specificity and Anti-Inflammatory Effects of Charge-Reversible MSNs-COS-CMC for Targeted Drug Delivery in Cervical Carcinoma

The surface charge of nanocarriers inevitably affects drug delivery efficiency; however, the cancer cell specificity, anti-inflammatory effects, and charge-reversal points remain to be further addressed in biomedical applications. The aim of this study was to comprehensively assess the cancer cell specificity of DOX-loaded mesoporous silica-chitosan oligosaccharide-carboxymethyl chitosan nanoparticles (DOX@MSNs-COS-CMC) in MCF-7 and HeLa cells, inhibit the production of inflammatory cytokines, and improve the drug accumulation in the tumor site. Intracellular results reveal that the retention time prolonged to 48 h in both HeLa and MCF-7 cells at pH 7.4. However, DOX@MSNs-COS-CMC exhibited a cell type-dependent cytotoxicity and enhanced intracellular uptake in HeLa cells at pH 6.5, due to the clathrin-mediated endocytosis and macropinocytosis in HeLa cells in comparison with the vesicular transport in MCF-7 cells. Moreover, Pearson's correlation coefficient value significantly decreased to 0.25 after 8 h, prompting endosomal escape and drug delivery into the HeLa nucleus. After the treatment of MSNs-COS-CMC at 200 μg/mL, the inflammatory cytokines IL-6 and TNF-α level decreased by 70% and 80%, respectively. Tumor inhibition of DOX@MSNs-COS-CMC was 0.4 times higher than free DOX, alleviating cardiotoxicity and inflammation in the HeLa xenograft tumor model. Charge-reversible DOX@MSNs-COS-CMC could be a possible candidate for clinical therapy of cervical carcinoma.

Synthesis and evaluation of novel coumarin-oxime ethers as potential anti-tubercular agents: Their DNA cleavage ability and BSA interaction study

As a contribution to the development of novel coumarin-oxime ether conjugates with therapeutically interesting properties, a series of coumarin-oxime ether (1a-1j) was synthesised using S_N2 reaction of bromomethyl coumarins with butane-2,3-dione monoxime. Invitro anti-tuberculosis activityagainstMTBH₃₇Rv strain was established for the coumarin-oxime ether (1a-1j). Most of the compounds exhibited significant activity with minimum inhibitory concentration (MIC)in the range of 0.04-3.12 μg mL^-1. Compound (1h) was identified as a hit candidate exhibiting MIC of 0.04 μg mL^-1, closer to the MIC value of Isoniazid (0.02 μg mL^-1), a commercially available drug for the treatment of tuberculosis. Compound 1h also displayed a low level of toxicity in Vero cells along with a good safety profile in vitro. Compounds that showed potent anti-tubercular activity were also found to cleave DNA more efficiently and thereby exhibit nuclease activity. The most active compound (1h) was further studied to deduce the mode of interaction with model serum protein, bovine serum albumin (BSA).