Characterization of a novel curcumin analog P1 as potent inhibitor of the NF-κB signaling pathway with distinct mechanisms

Transcending frontiers in prostate cancer: the role of oncometabolites on epigenetic regulation, CSCs, and tumor microenvironment to identify new therapeutic strategies

Prostate cancer, as one of the most prevalent malignancies in males, exhibits an approximate 5-year survival rate of 95% in advanced stages. A myriad of molecular events and mutations, including the accumulation of oncometabolites, underpin the genesis and progression of this cancer type. Despite growing research demonstrating the pivotal role of oncometabolites in supporting various cancers, including prostate cancer, the root causes of their accumulation, especially in the absence of enzymatic mutations, remain elusive. Consequently, identifying a tangible therapeutic target poses a formidable challenge. In this review, we aim to delve deeper into the implications of oncometabolite accumulation in prostate cancer. We center our focus on the consequential epigenetic alterations and impacts on cancer stem cells, with the ultimate goal of outlining novel therapeutic strategies.

Anti-Cancer Stem-Cell-Targeted Therapies in Prostate Cancer

Prostate cancer (PCa) is the second-most commonly diagnosed cancer in men around the world. It is treated using a risk stratification approach in accordance with the National Comprehensive Cancer Network (NCCN) in the United States. The main treatment options for early PCa include external beam radiation therapy (EBRT), brachytherapy, radical prostatectomy, active surveillance, or a combination approach. In those with advanced disease, androgen deprivation therapy (ADT) is considered as a first-line therapy. However, the majority of cases eventually progress while receiving ADT, leading to castration-resistant prostate cancer (CRPC). The near inevitable progression to CRPC has spurred the recent development of many novel medical treatments using targeted therapies. In this review, we outline the current landscape of stem-cell-targeted therapies for PCa, summarize their mechanisms of action, and discuss avenues of future development.

Neurofibromatosis: Molecular Pathogenesis and Natural Compounds as Potential Treatments

The neurofibromatosis syndromes, including NF1, NF2, and schwannomatosis, are tumor suppressor syndromes characterized by multiple nervous system tumors, particularly Schwann cell neoplasms. NF-related tumors are mainly treated by surgery, and some of them have been treated by but are refractory to conventional chemotherapy. Recent advances in molecular genetics and genomics alongside the development of multiple animal models have provided a better understanding of NF tumor biology and facilitated target identification and therapeutic evaluation. Many targeted therapies have been evaluated in preclinical models and patients with limited success. One major advance is the FDA approval of the MEK inhibitor selumetinib for the treatment of NF1-associated plexiform neurofibroma. Due to their anti-neoplastic, antioxidant, and anti-inflammatory properties, selected natural compounds could be useful as a primary therapy or as an adjuvant therapy prior to or following surgery and/or radiation for patients with tumor predisposition syndromes, as patients often take them as dietary supplements and for health enhancement purposes. Here we review the natural compounds that have been evaluated in NF models. Some have demonstrated potent anti-tumor effects and may become viable treatments in the future.

Highly Oxygenated Triterpenoids and Diterpenoids from Fructus Rubi (Rubus chingii Hu) and Their NF-kappa B Inhibitory Effects

During a phytochemical investigation of the unripe fruits of Rubus chingii Hu (i.e., Fructus Rubi, a traditional Chinese medicine named "Fu-Pen-Zi"), a number of highly oxygenated terpenoids were isolated and characterized. These included nine ursane-type (1, 2, and 4-10), five oleanane-type (3, 11-14), and six cucurbitane-type (15-20) triterpenoids, together with five ent-kaurane-type diterpenoids (21-25). Among them, (4R,5R,8R,9R,10R,14S,17S,18S,19R,20R)-2,19α,23-trihydroxy-3-oxo-urs-1,12-dien-28-oic acid (rubusacid A, 1), (2R*,4S*,5R*,8R*,9R*,10R*,14S*,17S*, 18S*,19R*,20R*)-2α,19α,24-trihydroxy-3-oxo-urs-12-en-28-oic acid (rubusacid B, 2), (5R,8R,9R,10R, 14S,17R,18S,19S)-2,19α-dihydroxy-olean-1,12-dien-28-oic acid (rubusacid C, 3), and (3S,5S,8S,9R, 10S,13R,16R)-3α,16α,17-trihydroxy-ent-kaur-2-one (rubusone, 21) were previously undescribed. Their chemical structures and absolute configurations were elucidated on the basis of spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds 1 and 3 are rare naturally occurring pentacyclic triterpenoids featuring a special α,β-unsaturated keto-enol (diosphenol) unit in ring A. Cucurbitacin B (15), cucurbitacin D (16), and 3α,16α,20(R),25-tetrahydroxy-cucurbita-5,23- dien-2,11,22-trione (17) were found to have remarkable inhibitory effects against NF-κB, with IC50 values of 0.08, 0.61, and 1.60 μM, respectively.

The therapeutic efficacy of water-soluble coenzyme Q10 in an experimental model of tacrolimus-induced diabetes mellitus

BACKGROUND/AIMS

Coenzyme Q10 (CoQ10) has antioxidant effects and is commercially available and marketed extensively. However, due to its low bioavailability, its effects are still controversial. We developed a water-soluble CoQ10-based micelle formulation (CoQ10-W) and tested it in an experimental model of tacrolimus (TAC)-induced diabetes mellitus (DM).

METHODS

We developed CoQ10-W from a glycyrrhizic-carnitine mixed layer CoQ10 micelle preparation based on acyltransferases. TAC-induced DM rats were treated with either lipid-soluble CoQ10 (CoQ10-L) or CoQ10-W for 4 weeks. Their plasma and pancreatic CoQ10 concentrations were measured using liquid chromatography- tandem mass spectrometry. The therapeutic efficacies of CoQ10-W and CoQ10-L on TAC-induced DM were compared using functional and morphological parameters and their effects on cell viability and reactive oxygen species (ROS) production were also evaluated in cultured rat insulinoma cells.

RESULTS

The plasma CoQ10 level was significantly increased in the CoQ10-W group compared to that in the CoQ10-L group. Intraperitoneal glucose tolerance tests and glucose-stimulated insulin secretion revealed that CoQ10-W controlled hyperglycemia and restored insulin secretion significantly better than CoQ10-L. The TAC-mediated decrease in pancreatic islet size was significantly attenuated by CoQ10-W but not by CoQ10-L. TAC-induced oxidative stress and apoptosis were significantly more reduced by CoQ10-W than CoQ10-L. Electron microscopy revealed that CoQ10-W restored TAC-induced attenuation in the number of insulin granules and the average mitochondrial area, unlike CoQ10-L. In vitro studies showed that CoQ10-L and CoQ10-W both improved cell viability and reduced ROS production in TAC-treated islet cells to a similar extent.

CONCLUSION

CoQ10-W has better therapeutic efficacy than CoQ10-L in TAC-induced DM.

Alkaloid Constituents of Ficus hispida and Their Antiinflammatory Activity

Four new alkaloids, ficuhismines A-D (1-4), together with three known ones, were isolated from Ficus hispida. Their structures were elucidated by spectroscopic analysis and chemical method. The new compounds represent the first amine alkaloids with a rhamnosyl moiety (1-2) or with a N-oxide motif (2-4) from the genus Ficus. Compound 2 showed potent inhibitory effect in nuclear factor-κB (NF-κB) pathway luciferase assay with IC₅₀ value of 0.52 ± 0.11 μM.

Phytochemical and biological studies on rare and endangered plants endemic to China. Part XV. Structurally diverse diterpenoids and sesquiterpenoids from the vulnerable conifer Pseudotsuga sinensis

An extensive phytochemical investigation on the chemical constituents from the needles and twigs of the vulnerable conifer Pseudotsuga sinensis yielded 19 diterpenoids and 21 sesquiterpenoids with various carbocyclic skeletons. Among them, 13 (named pseudosinins A-M, resp.) were undescribed compounds. Their structures with absolute configurations were characterized by a combination of spectroscopic methods, calculated and experimental electronic circular dichroism (ECD) data, quantum chemical calculations of the chemical shifts, and single crystal X-ray diffraction analyses. In particular, an array of labdane-derived norditerpenoids with C₁₉-, C₁₈-, and C₁₆-skeletons, and related drimane-type sesquitepenoids with C₁₅- and C₁₃-skeletons were found in the title plant. The possible biogenetic relationships of these degraded terpenoids were briefly discussed. Among the isolates, pseudosinin D, cis-communic acid, and 4β,15-dihydroxy-19-norabieta-8,11,13-trien-7-one showed moderate inhibitory activities against the enzyme ATP-citrate lyase (ACL), a potential drug target for the treatment of hyperlipidemia and hypercholesterolemia.

Stewartiacids A–N, C-23 carboxylated triterpenoids from Chinese Stewartia and their inhibitory effects against ATP-citrate lyase and NF-κB

Fourteen previously undescribed naturally occurring C-23 carboxylated triterpenoids, stewartiacids A–N (1–14), were isolated and characterized from the twigs and leaves of the ornamental and medicinal plant Stewartia sinensis (Chinese Stewartia), a ‘vulnerable’ species endemic to China. The new structures were elucidated on the basis of spectroscopic data, single crystal X-ray diffraction, and electronic circular dichroism (ECD) analyses. Stewartiacids A (1) and B (2) are isoursenol derivatives. Stewartiacid C (3) is a 12-oxo-γ-amyrin analogue. Both isoursenol and γ-amyrin derivatives are quite rare in nature. Stewartiacids D (4) and E (5) are 13,27-cycloursane-type compounds. Stewartiacids K (11) and L (12) are ursane-type triterpene and phenylpropanol adducts built through a 1,4-dioxane ring, which are also seldom reported in the literature. The rest are common C-23 carboxylated ursane-type (6–10) and oleanane-type (13, 14) pentacyclic triterpenoids. Stewartiacids G (7), K (11), and L (12) showed moderate inhibitory effects against ATP-citrate lyase (ACL), with IC₅₀ values of 12.5, 2.8, and 10.6 μM, respectively. Stewartiacid K (11) also exhibited moderate inhibition (IC₅₀: 16.8 μM) of NF-κB.

Fourteen new C-23 carboxylated triterpenoids (stewartiacids A–N, 1–14) were obtained from the ‘vulnerable’ plant Stewartia sinensis. 11 and 12 showed inhibitory effects against ACL.

The Therapeutic and Preventive Efficacy of Curcumin and Its Derivatives in Esophageal Cancer

Esophageal cancer is the eighth most common occurring cancer type worldwide and 6th most common among the cancer related deaths of which the most common type is squamous cell carcinoma which comprise about 90% of esophageal cancer cases. The standard of care for esophageal cancer is neoadjuvant concurrent chemotherapy and radiation (NACRT) followed by surgery however the prognosis remains dismal with 5 year survival a meager 10-15%. The treatment modalities for esophageal cancer is associated with both long term and short term toxicities. Curcumin has been explored as a therapeutic modality as a chemo adjuvant in different cancers due to its low toxicity profile and potent anticancer effect however despite lot of promising preclinical data it has not progressed from bench side to bed side. The primary reason that has obstructed its application in clinic has been its low bioavailability which was seen in different clinical trials but there has been tremendous progress in developing formulations of curcumin which have significantly increased its bioavailability and are being tested in clinical trials. Esophageal cancer is associated with inflammation that’s why curcumin being a natural antioxidant offer a potential avenue to reduce toxicity of current therapeutic modalities in a chemo adjuvant setting while simultaneously targeting different pro oncogenic pathways. The present review tries to cover in depth different aspects of curcumin application in treatment of esophageal cancer and progress of this potent anticancer agent in its treatment and prevention.

Septosones A-C, in Vivo Anti-inflammatory Meroterpenoids with Rearranged Carbon Skeletons from the Marine Sponge Dysidea septosa

Three unusual meroterpenoids, septosones A-C (1-3), were isolated from the marine sponge Dysidea septosa. The structures were determined by analysis of spectroscopic data combined with single-crystal X-ray diffraction and ECD calculations. Septosone A (1) features an unprecedented "septosane" carbon skeleton, whereas septosones B (2) and C (3) share a rare spiro[4.5]decane motif. Septosone A showed in vivo anti-inflammatory activity in CuSO₄-induced transgenic fluorescent zebrafish likely through inactivation of the NF-κB signaling pathway.

Effect of Conversion to CTLA4Ig on Tacrolimus-Induced Diabetic Rats

BACKGROUND

The effect of conversion to cytotoxic T lymphocyte-associated protein 4 immunoglobulin (CTLA4Ig) treatment on tacrolimus (TAC)-induced renal dysfunction is well known, but its effect on TAC-induced diabetes mellitus (DM) is still undetermined. In the present study, we tested the diabetogenicity of CTLA4Ig and evaluated the effect of conversion to CTLA4Ig treatment on TAC-induced diabetic rats.

METHODS

We tested diabetogenicity of CTLA4Ig by escalating doses (0.25, 0.5, 1, 2, and 4 mg/kg weekly) for 4 weeks. In the conversion study, we administered TAC (1.5 mg/kg) for 3 weeks and confirmed TAC-induced DM by intraperitoneal glucose tolerance test. Thereafter, TAC administration was continued, withdrawn, or replaced by CTLA4Ig treatment (1 or 2 mg/kg) for additional 3 weeks. The effect of CTLA4Ig on TAC-induced DM in vivo and in vitro was evaluated by assessing pancreatic islet function, histopathology, oxidative stress, apoptosis, and macrophage infiltration.

RESULTS

Intraperitoneal glucose tolerance test in the CTLA4Ig groups did not differ from the control group. In addition, plasma insulin level, glucose-induced insulin secretion, and islet viability were not different between the CTLA4Ig and control groups. In the conversion study, TAC withdrawal ameliorated pancreatic islet dysfunction compared with the TAC group, and conversion to CTLA4Ig further improved pancreatic islet function compared with the TAC withdrawal group. TAC-induced oxidative stress, apoptotic cell death, and infiltration of macrophages decreased with TAC withdrawal, and CTLA4Ig conversion further reduced those values. In the in vitro study, CTLA4Ig decreased TAC-induced pancreatic islet cell death and reactive oxygen species production.

CONCLUSIONS

CTLA4Ig was not diabetogenic, and conversion to CTLA4Ig reduced TAC-induced pancreatic islet injury.

Effect of Empagliflozin on Tacrolimus-Induced Pancreas Islet Dysfunction and Renal Injury

An inhibitor of sodium glucose co-transporter type 2 (SGLT-2) is recommended in type 2 diabetes mellitus (DM) but its use is still undetermined in tacrolimus (TAC)-induced DM. We evaluated the effect of empagliflozin (Em) on TAC-induced pancreatic islet dysfunction and renal injury in an experimental model of TAC-induced DM and in vitro. TAC induced a twofold increase in SGLT-2 expression, while Em decreased SGLT-2 expression and further increased urinary glucose excretion compared to the TAC group. Em reduced hyperglycemia and increased plasma insulin level, pancreatic islet size, and glucose-stimulated insulin secretion compared to the TAC group. In kidney, Em alleviated TAC-induced renal dysfunction and decreased albumin excretion and histological injury compared with the TAC group. Increased oxidative stress and apoptotic cell death by TAC was remarkably decreased with Em in serum and pancreatic and renal tissues. In in vitro study, TAC decreased cell viability and increased reactive oxygen species (ROS) production in both insulin-secreting beta-cell derived (INS-1) and human kidney-2 (HK-2) cell lines. Addition of Em increased cell viability and decreased ROS production in HK-2 but not in INS-1 cell lines. This suggests that Em is effective in controlling TAC-induced hyperglycemia and has direct protective effect on TAC-induced renal injury.

Identification of Biologically Active Pyrimido[5,4-b]indoles That Prolong NF-κB Activation without Intrinsic Activity

Most vaccine adjuvants directly stimulate and activate antigen presenting cells but do not sustain immunostimulation of these cells. A high throughput screening (HTS) strategy was designed to identify compounds that would sustain NF-κB activation by a stimulus from the Toll-like receptor (TLR)4 ligand, lipopolysaccharide (LPS). Several pilot studies optimized the parameters and conditions for a cell based NF-κB reporter assay in human monocytic THP-1 cells. The final assay evaluated prolongation of LPS induced NF-κB activation at 12 h. The dynamic range of the assay was confirmed in a pilot screen of 14 631 compounds and subsequently in a main extensive screen with 166 304 compounds. Hit compounds were identified using an enrichment strategy based on unsupervised chemoinformatic clustering, and also by a naı̈ve "Top X" approach. A total of 2011 compounds were then rescreened for levels of coactivation with LPS at 5 h and 12 h, which provided kinetic profiles. Of the 407 confirmed hits, compounds that showed correlation of the kinetic profiles with the structural similarities led to identification of four chemotypes: pyrimido[5,4-b]indoles, 4H-chromene-3-carbonitriles, benzo[d][1,3]dioxol-2-ylureas, and tetrahydrothieno[2,3-c]pyridines, which were segregated by 5 h and 12 h kinetic characteristics. Unlike the TLR4 agonistic pyrimidoindoles identified in previous studies, the revealed pyrimidoindoles in the present work did not intrinsically stimulate TLR4 nor induce NF-κB but rather prolonged NF-κB signaling induced by LPS. A 42-member combinatorial library was synthesized which led to identification of potent N3-alkyl substituted pyrimidoindoles that were not only active in vitro but also enhanced antibody responses in vivo when used as a coadjuvant. The novel HTS strategy led to identification of compounds that are intrinsically quiescent but functionally prolong stimulation by a TLR4 ligand and thereby potentiate vaccine efficacy.

Cephalotanins A-D, Four Norditerpenoids Represent Three Highly Rigid Carbon Skeletons from Cephalotaxus sinensis

Four polycyclic norditerpenoids, cephalotanins A-D (1-4) representing three unprecedented carbon skeletons with highly rigid ring systems, were isolated from Cephalotaxus sinensis and structurally characterized by a combination of various methods. Compounds 1 and 2 are new skeletal norditerpenoid trilactones, while 3 and 4 are two norditerpenoids featuring different new carbon skeletons. Biosynthetic pathways for 1-4 were proposed by involving diverse and very fascinating chemical events with the coexisting cephalotane troponoids as the precursors. Compound 1 exhibited good NF-κB inhibition with an IC50 value of 4.12±0.61 μΜ.

Effects of addition of a dipeptidyl peptidase IV inhibitor to metformin on sirolimus-induced diabetes mellitus

The guideline for the management of new-onset diabetes after transplantation recommends metformin (MET) as a first-line drug, and addition of a second-line drug is needed to better control of hyperglycemia. We tested the effect of addition of a dipeptidyl peptidase IV (DPP IV) inhibitor to MET on sirolimus (SRL)-induced diabetes mellitus (DM). In animal model of SRL-induced DM, MET treatment improved pancreatic islet function (blood glucose level and insulin secretion) and attenuated oxidative stress and apoptotic cell death. Addition of a DPP IV inhibitor to MET improved these parameters more than MET alone. An in vitro study showed that SRL treatment increased pancreas beta cell death and production of reactive oxygen species (ROS), and pretreatment of ROS inhibitor, or p38MAPK inhibitor effectively decreased SRL-induced islet cell death. Exendin-4 (EXD), a substrate of DPP IV or MET significantly improved cell viability and decreased ROS production compared with SRL treatment, and combined treatment with the 2 drugs improved both parameters. At the subcellular level, impaired mitochondrial respiration by SRL were partially improved by MET or EXD and much improved further after addition of EXD to MET. Our data suggest that addition of a DPP IV inhibitor to MET decreases SRL-induced oxidative stress and improves mitochondrial respiration. This finding provides a rationale for the combined use of a DPP IV inhibitor and MET in treating SRL-induced DM.

Dysiherbols A-C and Dysideanone E, Cytotoxic and NF-κB Inhibitory Tetracyclic Meroterpenes from a Dysidea sp. Marine Sponge

Four new tetracyclic meroterpnes, dysiherbols A-C (1-3) and dysideanone E (4), were isolated from a Dysidea sp. marine sponge collected from the South China Sea. Their complete structures and absolute configurations were unambiguously determined by a combination of NMR spectroscopic data, ECD calculations, and single-crystal X-ray diffraction analysis. Within the sesquiterpene quinol structures, dysiherbols A-C possess an intriguing 6/6/5/6-fused tetracyclic carbon skeleton. The NF-κB inhibitory and cytotoxic activity evaluation disclosed that dysiherbol A (1) showed potent activity with respective IC50 values of 0.49 and 0.58 μM, which were about 10-fold and 20-fold more potent than those of dysiherbols B (2) and C (3), which feature hydroxy and ketone carbonyl groups at the C-3 position.

Bioactive isoquinolinequinone alkaloids from the South China Sea nudibranch Jorunna funebris and its sponge-prey Xestospongia sp

Background: Nudibranchs are slug-like invertebrates, well known as rich sources of biologically active secondary metabolites with highly chemical diversity and complexity. The production of such interesting metabolites was possibly influenced by their diet relationship with sponges such as Xestospongia. Results: Our continuous investigation of South China Sea nudibranch Jorunna funebris and its sponge-prey Xestospongia sp. led to the isolation of two new and eight known metabolites (1–10). The absolute configurations were determined by time-dependent density functional theory (TDDFT) electronic circular dichroism (ECD) method and by the comparison of ECD spectra. In bioassays, 1–4 and 7 showed strong NF-κB inhibitory activity, 4–6 exhibited considerable cytotoxicity against A549 and HL-60 tumor cell lines. Conclusion: Five unusual isoquinolinequinones (3, 7–10) were discovered from both two animals, further confirmed their predator–prey relationship. Preliminary bioassay results and structure–activity relationship studies suggested that several isolated compounds were potential to be drug leads.

New alkaloids from Daphniphyllum himalense

A series ofDaphniphyllumalkaloids with selective kinase inhibitory activity were isolated and structurally characterized fromDaphniphyllum himalense.

Hydroxylated Daphniphyllum Alkaloids from Daphniphyllum himalense

Thirteen new hydroxylated calyciphylline A-type Daphniphyllum alkaloids (1-13) were isolated from an ethanolic extract of Daphniphyllum himalense. These structures were characterized on the basis of spectroscopic data analysis, especially from their 2D NMR spectra. Oxidation at the C-3, C-9, C-11, and C-12 positions is reported for the first time for this class of compounds. Selective compounds showed low inhibitory rates against three kinase enzymes, PTP1B, aurora A, and IKK-β, at a concentration of 20 μg/mL.

Bioactive sesquiterpene quinols and quinones from the marine sponge Dysidea avara

Reports the isolation, structure determination, and cytotoxic and NF-κB inhibitory activities of eight sesquiterpene quinols and quinones from Dysidea avara.

Eurifoloids A-R, structurally diverse diterpenoids from Euphorbia neriifolia

Eighteen new diterpenoids, named eurifoloids A-R (1-18), including ingenane (1 and 2), abietane (3-7), isopimarane (8-12), and ent-atisane (13-18) types, along with four known analogues were isolated from Euphorbia neriifolia. Eurifoloid M (13) represents a rare class of ent-atisane-type norditerpenoid. Eurifoloids E (5) and F (6) exhibited significant anti-HIV activities, with EC50 values of 3.58 ± 0.31 (SI = 8.6) and 7.40 ± 0.94 μM (SI = 10.3), respectively.

Dysidaminones A–M, cytotoxic and NF-κB inhibitory sesquiterpene aminoquinones from the South China Sea sponge Dysidea fragilis

Structural determination, absolute configuration assignments, and biological activities of new sesquiterpene aminoquinones from Dysidea fragilis.