Selective Cytotoxicity of Oxysterols through Structural Modulation on Rings A and B. Synthesis, in Vitro Evaluation, and SAR

Palladium catalysed cross coupling reactions on 2,3-isoxazol-17α-ethynyltestosterone, their anti-cancer activity, molecular docking studies and ADMET analysis

In the current study, the Sonogashira coupling reaction of danazol with aryl halides was carried out, yielding new aryl substituted danazol derivatives. The synthetic compounds were examined for anti-cancer potential on the HeLa human cervical cancer cell line, and they showed promising cytotoxic action. Synthesized compounds 2, 4 and 5 inhibited the growth of HeLa cervical cancer cells, potentially making them effective anti-cancer drugs in the future. Furthermore, molecular docking studies were performed to evaluate the inhibitory impact of danazol derivatives on the Human Papillomavirus (HPV) target protein (1F9F). The docking results showed a significant inhibitory action against the cervical cancer protein (1F9F). The binding energy (ΔG) values of 1, 2, 3, 4 and 5 against the protein 1F9F were -8.01, -8.70, -9.43, -9.58 and -9.75 kcal/mol, indicating a high affinity of the synthesized compounds to bind with the HPV target proteins compared to their parent compound danazol (1). ADMET analyses of all derivatives have also been carried out.

Antibacterial oxygenated ergostane-type steroids produced by the marine sponge-derived fungus Aspergillus sp

Two oxygenated ergostane-type steroids including one new compound, 3β-hydroxy-5α,6β-methoxyergosta-7,22-dien-15-one (1) along with a known analogue ergosta-6,22-dien-3β,5α,8α-triol (2) were isolated from the crude extracts of the marine sponge-derived fungus Aspergillus sp. Their structures were elucidated on the basis of combined NMR and MS spectroscopic methods. Compound 1 was a marine ergostane-type steroid with two methoxy groups at C-5 and C-6, respectively. These oxygenated ergostane-type steroids were evaluated for their antibacterial activities against human or aquatic pathogens. Among them, compound 1 exhibited antibacterial activity against Staphylococcus aureus.

Oxysterols as Biomarkers of Aging and Disease

Oxysterols derive from either enzymatic or non-enzymatic oxidation of cholesterol. Even though they are produced as intermediates of bile acid synthesis pathway, they are recognised as bioactive compounds in cellular processes. Therefore, their absence or accumulation have been shown to be associated with disease phenotypes. This chapter discusses the contribution of oxysterol to ageing, age-related diseases such as neurodegeneration and various disorders such as cancer, cardiovascular disease, diabetes, metabolic and ocular disorders. It is clear that oxysterols play a significant role in development and progression of these diseases. As a result, oxysterols are being investigated as suitable markers for disease diagnosis purposes and some drug targets are in development targeting oxysterol pathways. However, further research will be needed to confirm the suitability of these potentials.

The Structural Diversity and Biological Activity of Steroid Oximes

Steroids and their derivatives have been the subject of extensive research among investigators due to their wide range of pharmacological properties, in which steroidal oximes are included. Oximes are a chemical group with the general formula R1R2C=N-OH and they exist as colorless crystals and are poorly soluble in water. Oximes can be easily obtained through the condensation of aldehydes or ketones with various amine derivatives, making them a very interesting chemical group in medicinal chemistry for the design of drugs as potential treatments for several diseases. In this review, we will focus on the different biological activities displayed by steroidal oximes such as anticancer, anti-inflammatory, antibacterial, antifungal and antiviral, among others, as well as their respective mechanisms of action. An overview of the chemistry of oximes will also be reported, and several steroidal oximes that are in clinical trials or already used as drugs are described. An extensive literature search was performed on three main databases-PubMed, Web of Science, and Google Scholar.

Oxysterols in catfish skin secretions (Arius bilineatus, Val.) exhibit anti-cancer properties

The edible catfish Arius bilineatus, (Valenciennes) elaborates a proteinaceous gel-like material through its epidermis when threatened or injured. Our on-going studies on this gel have shown it to be a complex mixture of several biologically active molecules. Anti-cancer studies on lipid fractions isolated from the gel-like materials showed them to be active against several cancer cell lines. This prompted us to investigate further the lipid composition of the catfish epidermal gel secretions (EGS). Analysis of the lipid fraction of EGS resulted in identification of 12 oxysterols including cholesterol and 2 deoxygenated steroids i.e., 7α-hydroxy cholesterol, 7β-hydroxycholesterol, 5,6 epoxycholesterol, 3β-hydroxycholest-5-ene-7-one and cholesta-3,5-dien-7-one. Progesterone, cholest-3,5-diene, cholesta-2,4-diene, cholest-3,5,6-triol and 4-cholesten-3-one were found as minor components, and were identified through their MS, ¹HNMR and FTIR spectral data and were compared with those of the standards. Cholest-3,6-dione, cholesta-4,6-diene-3-one, cholesta-2,4-diene, and cholesta-5,20(22)-dien-3-ol were found only in trace amounts and were identified by GC/MS/MS spectral data. Since cholesterol is the major component of EGS, the identified oxysterols (OS) are presumably cholesterol oxidation products. Many of the identified OS are known important biological molecules that play vital physiological role in the producer and recipient organisms. We report herein the effects of these sterols on three human cancer cell lines in vitro, i.e., K-562 (CML cell line), MDA MB-231 (estrogen positive breast cancer cell line) and MCF-7 (estrogen negative breast cancer cell line). Interestingly significant (p < 0.05) dose differences were observed between tested OS on cell types used. The presence of these sterols in EGS may help explain some aspects of the physiological activities of fraction B (FB) prepared from EGS, such as enhanced wound and diabetic ulcer healing, anti-inflammatory action and cytotoxic activities reported in our previous studies. The anti-proliferative actions of some of these oxysterols especially the cholesterol 3,5,6-triol (#5) as established on selected cancer cell lines in this study support our previous studies and make them candidates for research for human application.

Oxysterols are potential physiological regulators of ageing

Delaying and even reversing ageing is a major public health challenge with a tremendous potential to postpone a plethora of diseases including cancer, metabolic syndromes and neurodegenerative disorders. A better understanding of ageing as well as the development of innovative anti-ageing strategies are therefore an increasingly important field of research. Several biological processes including inflammation, proteostasis, epigenetic, oxidative stress, stem cell exhaustion, senescence and stress adaptive response have been reported for their key role in ageing. In this review, we describe the relationships that have been established between cholesterol homeostasis, in particular at the level of oxysterols, and ageing. Initially considered as harmful pro-inflammatory and cytotoxic metabolites, oxysterols are currently emerging as an expanding family of fine regulators of various biological processes involved in ageing. Indeed, depending of their chemical structure and their concentration, oxysterols exhibit deleterious or beneficial effects on inflammation, oxidative stress and cell survival. In addition, stem cell differentiation, epigenetics, cellular senescence and proteostasis are also modulated by oxysterols. Altogether, these data support the fact that ageing is influenced by an oxysterol profile. Further studies are thus required to explore more deeply the impact of the "oxysterome" on ageing and therefore this cholesterol metabolic pathway constitutes a promising target for future anti-ageing interventions.

Design, synthesis, and antitumor activity evaluation of steroidal oximes

Steroidal compounds were proven to be efficient drugs against several types of cancer. Oximes are also chemical structures frequently associated with anticancer activity. The main goal of this work was to combine the two referred structures by synthesizing steroidal oximes and evaluating them in several cancer cell lines. Compounds (17E)-5α-androst-3-en-17-one oxime (3,4 - OLOX), (17E)-3α,4α-epoxy-5α-androstan-17-one oxime (3,4 - EPOX), (17E)-androst-4-en-17-one oxime (4,5 - OLOX) and (17E)-4α,5α-epoxyandrostan-17-one oxime (4,5 - EPOX) were synthesized and their cytotoxicity evaluated in four human cancer cell lines, namely colorectal adenocarcinoma (WiDr), non-small cell lung cancer (H1299), prostate cancer (PC3) and hepatocellular carcinoma (HepG2). A human non-tumour cell line, CCD841 CoN (normal colon cell line) was also used. MTT assay, flow cytometry, fluorescence and hemocompatibility techniques were performed to further analyse the cytotoxicity of the compounds. 3,4 - OLOX was the most effective compound in decreasing tumour cell proliferation in all cell lines, especially in WiDr (IC₅₀ = 9.1 μM) and PC3 (IC₅₀ = 13.8 μM). 4,5 - OLOX also showed promising results in the same cell lines (IC₅₀ = 16.1 μM in WiDr and IC₅₀ = 14.5 μM in PC3). Further studies also revealed that 3,4 - OLOX and 4,5 - OLOX induced a decrease in cell viability accompanied by an increase in cell death, mainly by apoptosis/necroptosis for 3,4 - OLOX in both cell lines and for 4,5 - OLOX in WiDr cells, and by necrosis for 4,5 - OLOX in PC3 cells. These compounds might also exert their cytotoxicity by ROS production and are not toxic for non-tumour CCD841 CoN cells. Additionally, both compounds did not induce haemoglobin release, proving to be safe for intravenous administration. 3,4 - OLOX and 4,5 - OLOX might be the starting point for an optimization program towards the discover of new steroidal oximes for anticancer treatment.

AmAT19, an acetyltransferase from Astragalus membranaceus, catalyses specific 6α-OH acetylation for tetracyclic triterpenes and steroids

Tetracyclic triterpenes and steroids are pharmacologically important molecules, and acetylation could improve their bioactivities. In this study, a highly regio- and stereo-specific acetyltransferase, AmAT19, was discovered from Astragalus membranaceus. AmAT19 could selectively catalyze the 6α-OH acetylation of four tetracyclic triterpenes and steroids. The strict selectivity is associated with different orientations of the 6α/β-OH as indicated by molecular docking. Acetylated products 1a, 3a and 4a remarkably increased the inhibitory activity against the 3-chymotrypsin-like protease (3CL^pro) of SARS-CoV-2, compared to 1, 3, and 4. AmAT19 could be a promising catalyst for specific 6α-OH acetylation to expand the molecular diversity of triterpenes and steroids.

Cholesterol homeostasis in the vertebrate retina: biology and pathobiology

Cholesterol is a quantitatively and biologically significant constituent of all mammalian cell membrane, including those that comprise the retina. Retinal cholesterol homeostasis entails the interplay between de novo synthesis, uptake, intraretinal sterol transport, metabolism, and efflux. Defects in these complex processes are associated with several congenital and age-related disorders of the visual system. Herein, we provide an overview of the following topics: (a) cholesterol synthesis in the neural retina; (b) lipoprotein uptake and intraretinal sterol transport in the neural retina and the retinal pigment epithelium (RPE); (c) cholesterol efflux from the neural retina and the RPE; and (d) biology and pathobiology of defects in sterol synthesis and sterol oxidation in the neural retina and the RPE. We focus, in particular, on studies involving animal models of monogenic disorders pertinent to the above topics, as well as in vitro models using biochemical, metabolic, and omic approaches. We also identify current knowledge gaps and opportunities in the field that beg further research in this topic area.

Chemical Compositional Changes in Over-Oxidized Fish Oils

A recent study has reported that the administration during gestation of a highly rancid hoki liver oil, obtained by oxidation through sustained exposure to oxygen gas and incident light for 30 days, causes newborn mortality in rats. This effect was attributed to lipid hydroperoxides formed in the omega-3 long-chain polyunsaturated fatty acid-rich oil, while other chemical changes in the damaged oil were overlooked. In the present study, the oxidation condition employed to damage the hoki liver oil was replicated, and the extreme rancidity was confirmed. A detailed analysis of temporal chemical changes resulting from the sustained oxidative challenge involved measures of eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) omega-3 oil oxidative quality (peroxide value, para-anisidine value, total oxidation number, acid value, oligomers, antioxidant content, and induction time) as well as changes in fatty acid content, volatiles, isoprostanoids, and oxysterols. The chemical description was extended to refined anchovy oil, which is a more representative ingredient oil used in omega-3 finished products. The present study also analyzed the effects of a different oxidation method involving thermal exposure in the dark in contact with air, which is an oxidation condition that is more relevant to retail products. The two oils had different susceptibility to the oxidation conditions, resulting in distinct chemical oxidation signatures that were determined primarily by antioxidant protection as well as specific methodological aspects of the applied oxidative conditions. Unique isoprostanoids and oxysterols were formed in the over-oxidized fish oils, which are discussed in light of their potential biological activities.

Oxysterols in cancer management: From therapy to biomarkers

Oxysterols are oxidized derivatives of cholesterol, both endogenous and exogenous. They have been implicated in numerous pathologies, including cancer. In addition to their roles in carcinogenesis, proliferation, migration, apoptosis, and multiple signalling pathways, they have been shown to modulate cancer therapy. They are known to affect therapy of hormonally positive breast cancer through modulating oestrogen receptor activity. Oxysterols have also been shown in various in vitro models to influence efficacy of chemotherapeutics, such as doxorubicin, vincristine, cisplatin, 5-fluorouracil, and others. Their effects on the immune system should also be considered in immunotherapy. Selective anti-cancer cytotoxic properties of some oxysterols make them candidates for new therapeutic molecules. Finally, differences in oxysterol levels in blood of cancer patients in different stages or versus healthy controls, and in tumour versus non-tumour tissues, show potential of oxysterols as biomarkers for cancer management and patient stratification for optimization of therapy. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Polyhydroxylated steroid derivatives from the starfish Pentaceraster regulus

A new polyhydroxysteroid glycoside, regulusoside D (1), and a new polyhydroxylated steroid, (24S)-cholestane-3β,5,6β,8,15α,24-hexol (2), together with seven known compounds were purified from the starfish Pentaceraster regulus collected near Con Co Islands, Vietnam. The structure elucidation was confirmed by extensive analysis of their NMR and HR-QTOF mass experiments. Among isolated compounds, regulusoside D (1), (24S)-cholestane-3β,5,6β,8,15α,24-hexol (2), granulatoside A (4), 5α-cholestane-3β,6β,7α,15α,16β,26-hexol (6), 5α-cholestane-3β,6β,7α,8β,15α,16β,26-heptol (7) and 5α-cholestane-3β,6α,8,15α,16β,26-hexol (8) exhibited strong inhibitory effects on LPS-induced NO production in RAW264.7 cells with IC₅₀ values of 9.13 ± 1.17, 9.19 ± 0.77, 8.63 ± 3.31, 12.61 ± 0.51, 14.83 ± 3.02 and 10.98 ± 1.22 µM, respectively.

The 5,6-epoxycholesterol metabolic pathway in breast cancer: Emergence of new pharmacological targets

Metabolic pathways have emerged as cornerstones in carcinogenic deregulation providing new therapeutic strategies for cancer management. Recently, a new branch of cholesterol metabolism has been discovered involving the biochemical transformation of 5,6-epoxycholesterols (5,6-ECs). The 5,6-ECs are metabolized in breast cancers to the tumour promoter oncosterone whereas, in normal breast tissue, they are metabolized to the tumour suppressor metabolite, dendrogenin A (DDA). Blocking the mitogenic and invasive potential of oncosterone will present new opportunities for breast cancer treatment. The reactivation of DDA biosynthesis, or its use as a drug, represents promising therapeutic approaches such as DDA-deficiency complementation, activation of breast cancer cell re-differentiation and breast cancer chemoprevention. This review presents current knowledge of the 5,6-EC metabolic pathway in breast cancer, focusing on the 5,6-EC metabolic enzymes ChEH and HSD11B2 and on 5,6-EC metabolite targets, the oxysterol receptor (LXRβ) and the glucocorticoid receptor. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Regio- and Stereoselective Addition of HO/OOH to Allylic Alcohols

A range of allylic alcohols are shown to readily react with ethereal H₂O₂ in the presence of catalytic amounts of Na₂MoO₄-gly or MoO₂(acac)₂, affording the C═C trans hydroxylation-hydroperoxylation products in good yields with high regio- and stereoselectivity. Use of enantiomers of cyclic substrates resulted in corresponding enantiopure diol-tert-hydroperoxides. The possibility of further conversion of the diol-tert-hydroperoxides into triols or linear building blocks with an isolated tert-peroxy group containing a quaternary center is also exemplified.

Sinulasterols A-C, three new bioactive oxygenated steroids from the South China Sea soft coral Sinularia depressa

Three new oxygenated steroids, sinulasterols A-C (1-3), along with seven known related steroids 4-10, were isolated from the Chinese soft coral Sinularia depressa. The structures of the new compounds were established from extensive spectroscopic data analyses and by comparison of their spectral data with those reported in the literature. Among the new compounds, metabolites 1 and 2 featured on unusual C-18 oxygenated pattern. In the TNF-α bioassay, compound 4 exhibited a potent inhibitory activity (IC₅₀ = 12.1 μM), which was analogous to the positive control dexamethasone (IC₅₀ = 8.7 μM), metabolites 1 and 2 displayed a moderate inhibitory activity (IC₅₀ 51.1 μM and 22.7 μM respectively).

Synthesis and antiproliferative evaluation of novel steroid-benzisoselenazolone hybrids

The two different types of steroidal benzisoselenazolone hybrids were synthesized by incorporating benzisoselenazolone scaffold into dehydroepiandrosterone and B-norcholesterol. The antiproliferative activity of the synthesized compounds against some carcinoma cell lines were investigated. The results showed that some of these compounds have better inhibitory activity than abiraterone on the proliferation of tumor cells associated with human growth hormone, and have less cytotoxicity on normal human cells. In particular, the IC₅₀ values of the compound 8a and 8f are 5.4 and 6.5 µmol/L against human ovarian carcinoma (SKOV3) cell line, and possess SI values of 13.9 and 10.5, respectively. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.

7-Ketocholesterol Promotes Oxiapoptophagy in Bone Marrow Mesenchymal Stem Cell from Patients with Acute Myeloid Leukemia

7-Ketocholesterol (7-KC) is a cholesterol oxidation product with several biological functions. 7-KC has the capacity to cause cell death depending on the concentration and specific cell type. Mesenchymal stem cells (MSCs) are multipotent cells with the ability to differentiate into various types of cells, such as osteoblasts and adipocytes, among others. MSCs contribute to the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases, such as leukemia, to a yet unknown extent. Here, we describe the effect of 7-KC on the death of bone marrow MSCs from patients with acute myeloid leukemia (LMSCs). LMSCs were less susceptible to the death-promoting effect of 7-KC than other cell types. 7-KC exposure triggered the extrinsic pathway of apoptosis with an increase in activated caspase-8 and caspase-3 activity. Mechanisms other than caspase-dependent pathways were involved. 7-KC increased ROS generation by LMSCs, which was related to decreased cell viability. 7-KC also led to disruption of the cytoskeleton of LMSCs, increased the number of cells in S phase, and decreased the number of cells in the G1/S transition. Autophagosome accumulation was also observed. 7-KC downregulated the SHh protein in LMSCs but did not change the expression of SMO. In conclusion, oxiapoptophagy (OXIdative stress + APOPTOsis + autophagy) seems to be activated by 7-KC in LMSCs. More studies are needed to better understand the role of 7-KC in the death of LMSCs and the possible effects on the SHh pathway.

7-Ketocholesterol and cholestane-triol increase expression of SMO and LXRα signaling pathways in a human breast cancer cell line

Oxysterols are 27-carbon oxidation products of cholesterol metabolism. Oxysterols possess several biological actions, including the promotion of cell death. Here, we examined the ability of 7-ketocholesterol (7-KC), cholestane-3β-5α-6β-triol (triol), and a mixture of 5α-cholestane-3β,6β-diol and 5α-cholestane-3β,6α-diol (diol) to promote cell death in a human breast cancer cell line (MDA-MB-231). We determined cell viability, after 24-h incubation with oxysterols. These oxysterols promoted apoptosis. At least part of the observed effects promoted by 7-KC and triol arose from an increase in the expression of the sonic hedgehog pathway mediator, smoothened. However, this increased expression was apparently independent of sonic hedgehog expression, which did not change. Moreover, these oxysterols led to increased expression of LXRα, which is involved in cellular cholesterol efflux, and the ATP-binding cassette transporters, ABCA1 and ABCG1. Diols did not affect these pathways. These results suggested that the sonic hedgehog and LXRα pathways might be involved in the apoptotic process promoted by 7-KC and triol.

Complex formation equilibria between cholesterol and diosgenin analogues in monolayers determined by the Langmuir method

The purpose of this study was to investigate the interaction between diosgenin analogues [DioA: diosgenin acetate (DAc) and (25R)-5α,6β-dihydroxyspirostan-3β-ol acetate (DSol)] and cholesterol (Ch) monolayers at the air/water interface. The surface tension of pure and mixed lipid monolayers at 22 °C was measured by using the Langmuir method with a Teflon trough and a Nima 9002 tensiometer. The surface tension values were used to calculate the π-A isotherms and to determine the molecular surface areas. The interactions between Ch and each DioA resulted in significant deviations from the additivity rule. The theory described in this work was used to determine the stability constants, the areas occupied by one molecule of Ch-DAc or Ch-DSol, and the complex formation energy (Gibbs free energy) values.

Chemistry, biochemistry, metabolic fate and mechanism of action of 6-oxo-cholestan-3β,5α-diol (OCDO), a tumor promoter and cholesterol metabolite

Oxygenation products of cholesterol, named oxysterols, were suspected since the 20th century to be involved in carcinogenesis. Among the family of oxysterol molecules, cholesterol-5,6-epoxides (5,6-EC) retained the attention of scientists because they contain a putative alkylating epoxide group. However, studies failed into demonstrating that 5,6-EC were direct carcinogens and revealed a surprising chemical stability and unreactivity towards nucleophiles in standard conditions. Analyses of 5,6-EC metabolism in normal cells showed that they were extensively transformed into cholestane-3β,5α,6β-triol (CT) by the cholesterol-5,6-epoxide hydrolase (ChEH). Studies performed in cancer cells showed that CT was additionally metabolized into an oxysterol identified as the 6-oxo-cholestan-3β,5α-diol (OCDO), by the 11β-hydroxysteroid dehydrogenase of type 2 (HSD2), the enzyme which inactivates cortisol into cortisone. Importantly, OCDO was shown to display tumor promoter properties in breast cancers, by binding to the glucocorticoid receptor, and independently of their estrogen receptor status, revealing the existence of a new tumorigenic pathway centered on 5,6-EC. In breast tumors from patients, OCDO production as well as the expression of the enzymes involved in the pathway producing OCDO, namely ChEH subunits and HSD2, were higher compared to normal tissues, and overexpression of these enzymes correlate with a higher risk of patient death, indicating that this onco-metabolism is of major importance to breast cancer pathology. Herein, we will review the actual knowledge and the future trends in OCDO chemistry, biochemistry, metabolism and mechanism of action and will discuss the impact of OCDO discovery on new anticancer therapeutic strategies.

Hybrid pharmacophore approach for bio-relevant di-imines based homobimetallic complexes incorporating functionalized dicarboxylates as co-ligands: Synthesis, spectral and structural activity dependent biological insights (in-vitro DNA and HSA binding, antioxidant and cytotoxicity)

Synthesis of bio-efficient homobimetallic complexes, [Cu₂(L¹)₂(dipic)](NO₃)₂.3H₂O (1), [Zn₂(L¹)₂(dipic)](NO₃)₂.4H₂O (2), [Cu₂(L²)₂(oxa)](NO₃)₂.4H₂O (3) and [Zn₂(L²)₂(oxa)] (NO₃)₂.5H₂O (4) was carried out using Schiff bases [(N¹E,N²E)-N¹,N²-bis(5-chlorothiophen-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L¹] and [(N¹E,N²E)-N¹,N²-bis(5-chlorofuran-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L²] as main ligands and dicarboxylate moieties of 2,6-pyridine dicarboxylic acid (H₂-dipic) and oxalic acid (H₂-oxa) as co-ligands, respectively in order to apprehend their structure activity relationships on the basis of pharmacophore hybrid approach. The stoichiometry, geometry, thermal stability, morphology and crystallite size of the compounds were inferred by analytical, spectral (FT-IR, ¹H NMR and ¹³C NMR and Mass), thermal (TGA/DTA), SEM and XRD studies. In-vitro DNA and HSA binding profiles of complexes were analysed by different biophysical measurements. The absorption study divulged that the observed alterations in the physico-chemical properties of complexes upon binding with DNA connoted their intercalative binding mode while fluorescence quenching mechanism was quantified by using Stern Volmer constant (K_SV)_; 1.73×10⁴ (1), 1.47×10⁴ (2), 5.65×10³ (3) and 3.60×10³M^-1 (4) which discerned that hybrid pharmacophore active metal complexes (1 and 2) exhibited efficient quenching effect with Ct-DNA in comparison to complexes (3 and 4) due to greater planarity and extent of conjugation (π-π interactions). The intercalative binding mode of complexes is further supported by competitive displacement assay by using fluorogenic dyes (EtBr and Hoechst 33258). The results of HSA fluorescence study divulged static quenching of the complexes (1-4) with K_SV values of 7.24×10⁴ (1), 6.03×10⁴ (2), 5.06×10⁴ (3) and 2.85×10⁴ (4) while K_b values; 1.16×10⁵ (1), 2.01×10⁴ (2), 5.84×10³ (3) and 8.60×10² (4) suggested them potent avid binder of HSA. Additionally, comparative estimation of scavenging properties using DPPH, superoxide(O₂^.-), hydroxyl (OH^-) and ABTS method and in-vitro cytotoxicity against different cell lines (MCF-7, HeLa and Hep G2) brought out distinct biopotency of complexes due to diverse structural features and chelation effect.

Oxysterols in adipose tissue-derived mesenchymal stem cell proliferation and death

Mesenchymal stem cells (MSCs) are multipotent cells characterized by self-renewal and cellular differentiation capabilities. Oxysterols comprise a very heterogeneous group derived from cholesterol through enzymatic and non-enzymatic oxidation. Potent effects in cell death processes, including cytoxicity and apoptosis induction, were described in several cell lines. Very little is known about the effects of oxysterols in MSCs. 7-ketocholesterol (7-KC), one of the most important oxysterols, was shown to be cytotoxic to human adipose tissue-derived MSCs. Here, we describe the short-term (24h) cytotoxic effects of cholestan-3α-5β-6α-triol, 3,5 cholestan-7-one, (3α-5β-6α)- cholestane-3,6-diol, 7-oxocholest-5-en-3β-yl acetate, and 5β-6β epoxy-cholesterol, on MSCs derived from human adipose tissue. MSCs were isolated from adipose tissue obtained from three young, healthy women. Oxysterols, with the exception of 3,5 cholestan-7-one and 7-oxocholest-5-en-3β-yl acetate, led to a complex mode of cell death that include apoptosis, necrosis and autophagy, depending on the type of oxysterol and concentration, being cholestan-3α-5β-6α-triol the most effective. Inhibition of proliferation was also promoted by these oxysterols, but no changes in cell cycle were observed.

Pharmacophore hybrid approach of new modulated bis-diimine Cu(II)/Zn(II) complexes based on 5-chloro Isatin Schiff base derivatives: Synthesis, spectral studies and comparative biological assessment

Novel bioactive 5-chloro isatin based Schiff base ligands, (N,N'E,N,N'Z)-N,N'-(5-chloroindoline-2,3-diylidene)bis(5-nitrobenzo [d]thiazol-2-amine), L(1) and (N,N'E,N,N'Z)-N,N'-(5-chloroindoline-2,3-diylidene)bis(5-nitrothiazol-2-amine), L(2) derived from 2-amino 5-nitrobenzothiazole and 2-amino 5-nitrothiazole and their metal complexes, [Cu(L(1))2]Cl2;1, [Zn(L(1))2(H2O)2]Cl2;2, [Cu(L(2))2]Cl2;3 and [Zn(L(2))2(H2O)2]Cl2;4 have been synthesized. The composition, stoichiometry and geometry of the proposed ligands and their complexes have been envisaged by the results of elemental analyses and spectroscopic data (FT-IR, (1)H NMR and (13)C NMR, Mass and EPR). The molar conductivity values of the metal complexes revealed their ionic nature. The thermal stability of metal complexes was demonstrated by TGA/DTA studies while the crystalline nature of the complexes has been ascertained by XRD. Furthermore, a comparative account of in vitro antibacterial study against different bacterial strains with respect to standard antibiotic and scavenging activity against standard control at different concenterations unfolded pronounced antibacterial and radical scavenging potencies of the metal complexes as compared to free ligands. In addition, in vitro cytotoxicity of ligands and its metal complexes was also screened on MCF7 (Human breast adenocarcinoma), HeLa (Human cervical carcinoma) and HepG2 (Human Hepatocellular carcinoma), cell lines and normal cells (PBMC). The antiproliferative outcomes revealed that metal complexes exhibit superior activity in general as compared to free ligands (L(1) and L(2)) where metal complexes (1 and 2) of 5-chloro isatin linked benzothiazole motif (L(1)) are found to have better prospect of acting as chemotherapeutic agents which can be explained in terms of greater biopotency, planarity and conjugation against all the tested cancer cell lines with IC50<2.80 μM.

Synthesis and characterization of steroidal heterocyclic compounds, DNA condensation and molecular docking studies and their in vitro anticancer and acetylcholinesterase inhibition activities

A facile and efficient approach for the synthesis of steroidal heterocyclic compounds (4–12) has been performed. Furthermore, these newly synthesized compounds were evaluated for their various biological activities.

Polyoxygenated steroids from the octocoral Leptogorgia punicea and in vitro evaluation of their cytotoxic activity

Five new polyoxygenated marine steroids-punicinols A-E (1-5)-were isolated from the gorgonian Leptogorgia punicea and characterized by spectroscopic methods (IR, MS, 1H, 13C and 2-D NMR). The five compounds induced in vitro cytotoxic effects against lung cancer A549 cells, while punicinols A and B were the most active, with IC50 values of 9.7 μM and 9.6 μM, respectively. The synergistic effects of these compounds with paclitaxel, as well as their effects on cell cycle distribution and their performance in the clonogenic assay, were also evaluated. Both compounds demonstrated significant synergistic effects with paclitaxel.

The NADPH oxidase inhibitor imipramine-blue in the treatment of Burkitt lymphoma

Burkitt lymphoma is a rare malignancy arising from B cells. Current chemotherapeutic regimens achieve excellent overall survival rates in children, but less impressive rates in adults. There are cases with poor outcome caused by toxic effects of the therapy, tumor lysis syndrome, or metastatic spread of lymphomas to the central nervous system. Modulators of reactive oxygen species are currently discussed as potential drugs for the treatment of cancer. The NADPH oxidase 4 inhibitor imipramine-blue might satisfy the aforementioned requirements, and was studied here. We used MTT assay, crystal violet assay, and thymidine 3H-incorporation assay to analyze the effects of imipramine-blue on Burkitt lymphoma (BL2, BL2B95, BL30B95, BL41B95), neuroblastoma (KELLY, SH-SY5Y, SMS-KAN), cervix carcinoma (HeLa), breast cancer (MDA-MB231), angiosarcoma (AS-M), human embryonic kidney (HEK293WT), and nonmalignant (FLP1) cell lines. The effects of imipramine-blue on BL2B95 cells in vivo were investigated in xenografts on the chick chorioallantoic membrane (CAM). We report that imipramine-blue is a potent growth inhibitor for several cancer cell lines in vitro with IC(50) values comparable to those of doxorubicin (0.16-7.7 μmol/L). Tumor size of BL2B95 cells inoculated in the CAM was reduced significantly (P < 0.05) after treatment with 10 μmol/L imipramine-blue. Lymphogenic dissemination of BL2B95 and the formation of blood and lymphatic vessels in experimental tumors were not affected. We show that imipramine-blue can be used to decrease the viability of cancer cell lines in vitro and in vivo. Imipramine-blue reduces the size of experimental Burkitt lymphoma significantly but does not affect the dissemination of BL2B95 cells, angiogenesis, and lymphangiogenesis.

Synthesis and anti-tumor evaluation of B-ring substituted steroidal pyrazoline derivatives

The synthesis and anti-tumor activity screening of new steroidal derivatives (4-18) containing pharmacologically attractive pyrazoline moieties are performed. During in vitro anticancer evaluation, the newly synthesized compounds displayed moderate to good cytotoxicity on cervical and leukemia cancer cell lines. In addition these compounds were found to be nontoxic to normal cell (PBMCs) (IC50>50 μM). The structure-activity relationship is also discussed. The most effective anticancer compound 9 was found to be active with IC50 value of 10.6 μM. It demonstrated significant antiproliferative influence on Jurkat cell lines. The morphological changes and growth characteristics of HeLa cells treated with compound 4 were analyzed by means of SEM.

Tumor cell growth inhibitory activity and structure-activity relationship of polyoxygenated steroids from the gorgonian Menella kanisa

Fourteen new polyoxygenated steroids (6, 9, 14-18, 20-23, 25-27) having carbon skeletons of cholestane, ergostane, and 24-norcholestane, were isolated together with thirteen known analogues (1-5, 7, 8, 10-13, 19, 24) from the South China Sea gorgonian Menella kanisa. The structures of the new compounds were elucidated by detailed analysis of spectroscopic data and comparisons with reported data. This is the first report of chemical investigation on the title gorgonian. Compounds 12 and 13 were reported for the first time from natural sources. These compounds exhibited different levels of growth inhibition activity against A549 and MG-63 cell lines in bioassay in vitro. Preliminary structure-activity analysis revealed an important role of side chain in the activity. A substitution of a 5α-hydroxy or an oxidation of 6β-hydroxy to a ketone carbonyl group may decrease the activity whereas the contribution of the 1-ketone group remains uncertain.

Anticancer steroids: linking natural and semi-synthetic compounds

Steroids, a widespread class of natural organic compounds occurring in animals, plants and fungi, have shown great therapeutic value for a broad array of pathologies. The present overview is focused on the anticancer activity of steroids, which is very representative of a rich structural molecular diversity and ability to interact with various biological targets and pathways. This review encompasses the most relevant discoveries on steroid anticancer drugs and leads through the last decade and comprises 668 references.

Similar pyruvate kinase modifications in glioblastoma cells by 7β-hydroxycholesterol and glutamine withdrawal

Oxysterols possess anti-proliferative properties that may be used with much effect in the treatment of cancer. We have demonstrated previously that 7 beta-hydroxycholesterol (7b-HC) provokes both metabolic stress, as witnessed by AMPK activation, and changes in lipid raft composition in C6 glioblastoma cells. These observations suggested that glycolysis might have been changed. Here we will show that 7b-HC increases cell cycle time and that it changes the affinity of pyruvate kinase to its substrate, phosphoenol pyruvate. The latter effect is mimicked by glutamine withdrawal.

Oxysterols in cancer cell proliferation and death

Oxysterols have been shown to interfere with proliferation and cause the death of many cancer cell types, such as leukaemia, glioblastoma, colon, breast and prostate cancer cells, while they have little or no effect on senescent cells. The mechanisms by which oxysterols may influence proliferation are manifold: they control the transcription and the turnover of the key enzyme in cholesterol synthesis, 3-hydroxy-3-methylglutaryl CoA reductase, by binding to Insig-1, Insig-2 and liver X receptors. Oxysterols are thought to be generated in proportion to the rate of cholesterol synthesis. Although there is no consensus about the mechanism by which these oxysterols are generated in vivo, it clearly has to be ubiquitous. The 25- and the 27-cholesterol hydroxylases, present in almost all tissues, are possible candidates. Cholesterol uptake from lipoproteins, intracellular vesicle transport and lipid transfer are also modified by oxysterols. Oxysterols interfere with ERK, hedgehog and wnt pathways of proliferation and differentiation. When administered in vitro to cancer cell lines, oxysterols invariably both slow down proliferation and provoke cell death. Perhaps is it sufficient to stop proliferation of a cancer to provoke its eradication. Therefore, the two facets of oxysterol action that seem important for cancer treatment, cytostaticity and cytotoxicity, will be discussed.

3β,5α,6β-Oxygenated sterols from the South China Sea gorgonian Muriceopsis flavida and their tumor cell growth inhibitory activity and apoptosis-inducing function

Three new polyhydroxysterols, named muriflasteroids A-C (1-3) were isolated from the South China Sea gorgonian Muriceopsis flavida, together with sixteen known analogs, cholest-3β,5α,6β-triol,3β-acetate (4), 5α-methoxycholest-3β,6β-diol (5), (22E)-cholest-22-en-3β,5α,6β-triol (6), cholest-3β,5α,6β-triol (7), (22E)-24-norcholest-22-en-3β,5α,6β-triol (8), (22E,24S)-ergost-22-en-3β,5α,6β-triol (9), ergost-24(28)-en-3β,5α,6β-triol (10), (22E)-cholest-7,22-dien-3β,5α,6β-triol (11), cholest-7-en-3β,5α,6β-triol (12), (22E)-24-norcholest-7,22-dien-3β,5α,6β-triol (13), ergost-7,24(28)-dien-3β,5α,6β-triol (14), (22E,24R)-ergost-7,22-dien-3β,5α,6β-triol (15), (22E)-cholest-22-en-1β,3β,5α,6β-tetrol (16), (22E)-24-norcholest-22-en-1β,3β,5α,6β-tetrol (17), cholest-1β,3β,5α,6β-tetrol (18), and (24ξ)-ergost-1β,3β,5α,6β-tetrol (19). The structures of the new compounds were elucidated by detailed spectroscopic analysis in combination with comparison of reported data. All the compounds are reported for the first time from the animal. In the bioassay in vitro, these compounds exhibited different levels of growth inhibition activity against A549 and MG63 cell lines. In particular, compound 18 displayed a considerable activity, being similar as that of positive control adriamycin. An annexin V analysis indicated that compounds 7 and 18 can significantly induce apoptosis in A549 cell, and compound 7 is more potent in the induction of apoptosis. Preliminary structure-activity analysis suggests that the acetylation on 3-OH and appearance of Δ⁷ may decrease the activity while substitution of 1-OH and the nature of side chain may also play an important role in the activity. Methylation of 5-OH contributed a little to the activity.