Design, Synthesis, and Evaluation of a Series of Novel Super Long-Acting DPP-4 Inhibitors for the Treatment of Type 2 Diabetes.

In the present work, a novel series of trifluoromethyl-substituted tetrahydropyran derivatives were rationally designed and synthesized as potent DPP-4 inhibitors with significantly improved duration time of action over current commercially available DPP-4 inhibitors. The incorporation of the trifluoromethyl group on the 6-position of the tetrahydropyran ring of omarigliptin with the configuration of (2R,3S,5R,6S) not only significantly improves the overall pharmacokinetic profiles in mice but also maintains comparable DPP-4 inhibition activities. Further preclinical development of compound 2 exhibited its extraordinary efficacy in vivo and good safety profile. Clinical studies of compound 2 (Haisco HSK7653) are now ongoing in China, which revealed that inhibitor 2 could serve as an efficient candidate with a once-biweekly therapeutic regimen.

Salinomycin-loaded PLA nanoparticles: drug quantification by GPC and wave voltammetry and biological studies on osteosarcoma cancer stem cells.

A new straightforward gel permeation chromatography (GPC) method was developed to calculate the drug encapsulation efficiency and loading content of Poly(lactic acid) nanoparticles (PLA NPs) loaded with Salinomycin (Sal), exploiting the capability of this technique to separate a macromolecular/molecular mixture on the basis of the molecular weight of each component. The proposed GPC method allowed Sal detection until 1% of Sal content in PLA NPs, avoiding sample pre-treatments. The method was validated by wave voltammetry (SW) technique, using a slightly modified literature procedure, useful to detect Sal in the concentration range 0.4 ≤ C/µmol/L ≤ 12 (linear concentration range). PLA-based NPs were prepared by nanoprecipitation with either native and functionalized PLA. Specifically, folate-decorated PLA NPs (PLA-FA NPs) were obtained by CuAAC click functionalization of alkyne-grafted PLA with azide-folate. Sal-loaded NPs were characterized physicochemically and morphologically. They exhibited adequate physicochemical properties, good drug encapsulation efficiency (98 ± 0.5% and 99 ± 0.5%), and loading content (8.8 ± 0.1% and 8.9 ± 0.1% for PLA/Sal and PLA-FA/Sal NPs, respectively). The size of empty PLA NPs resulted smaller (90 ± 3.2 nm and 680 ± 15.3 nm, for PLA NPs and PLA-FA NPs respectively) than the correspondent drug-loaded NPs (110 ± 3.8 nm and 875 ± 20.5 nm, respectively). Their biological activity was assessed on osteosarcoma bulk cells MG63, healthy osteoblast cell line (hFOB1.19), and enriched osteosarcoma cancer stem cells (CSCs), showing cell-depending effect. Entrapped Sal maintained its cytotoxic effect on CSCs and MG63 cells, with a potency comparable to the free drug and no evident benefit was detected for folate-decorated PLA NPs respect to native PLA NPs. Graphical abstract.

Enhanced and Prolonged Antitumor Effect of Salinomycin-Loaded Gelatinase-Responsive Nanoparticles via Targeted Drug Delivery and Inhibition of Cervical Cancer Stem Cells.

BACKGROUND: Cervical cancer stem cells (CCSCs) represent a subpopulation of tumor cells that possess self-renewal capacity and numerous intrinsic mechanisms of resistance to conventional chemotherapy and radiotherapy. These cells play a crucial role in relapse and metastasis of cervical cancer. Therefore, eradication of CCSCs is the primary objective in cervical cancer therapy. Salinomycin (Sal) is an agent used for the elimination of cancer stem cells (CSCs); however, the occurrence of several side effects hinders its application. Nanoscale drug-delivery systems offer great promise for the diagnosis and treatment of tumors. These systems can be used to reduce the side effects of Sal and improve clinical benefit. METHODS: Sal-loaded polyethylene glycol-peptide-polycaprolactone nanoparticles (Sal NPs) were fabricated under mild and non-toxic conditions. The real-time biodistribution of Sal NPs was investigated through non-invasive near-infrared fluorescent imaging. The efficacy of tumor growth inhibition by Sal NPs was evaluated using tumor xenografts in nude mice. Flow cytometry, immunohistochemistry, and Western blotting were used to detect the apoptosis of CSCs after treatment with Sal NPs. Immunohistochemistry and Western blotting were used to examine epithelial-mesenchymal transition (epithelial interstitial transformation) signal-related molecules. RESULTS: Sal NPs exhibited antitumor efficacy against cervical cancers by inducing apoptosis of CCSCs and inhibiting the epithelial-mesenchymal transition pathway. Besides, tumor pieces resected from Sal NP-treated mice showed decreased reseeding ability and growth speed, further demonstrating the significant inhibitory ability of Sal NPs against CSCs. Moreover, owing to targeted delivery based on the gelatinase-responsive strategy, Sal NPs was more effective and tolerable than free Sal. CONCLUSION: To the best of our knowledge, this is the first study to show that CCSC-targeted Sal NPs provide a potential approach to selectively target and efficiently eradicate CCSCs. This renders them a promising strategy to improve the therapeutic effect against cervical cancer.

Facile fabrication of a novel 3D rose like lanthanum doped zirconia decorated reduced graphene oxide nanosheets: An efficient electro-catalyst for electrochemical reduction of futuristic anti-cancer drug salinomycin during pharmacokinetic study.

An innovative electrochemical nanoprobe, for analysis of salinomycin (SAL), was proposed. The nanoprobe based on decoration of glassy carbon electrode (GCE) with 3D rose like La3+@ ZrO2 supported on reduced graphene oxide (RGO) nanosheets. The 3D rose like La3+@ ZrO2 was synthesized via sintering process. The successful decoration of 3D rose like La3+@ ZrO2 on the surface of RGO was characterized using different spectroscopic and analytical techniques. The obtained voltammetric results confirmed the good electrochemical performance of 3D rose like La3+@ ZrO2 in terms of lower peak potential (Epc) and higher cathodic current (Ipc). Moreover, the modified nanoprobe showed wide linearity range (0.34-115 × 10-8 M), lower detection limit (0.11 × 10-8 M) and higher selectivity. Besides, the nanocomposite showed good applicability for analysis of SAL in biological fluids and during pharmacokinetic evaluation in rabbit plasma. The obtained results opens a new venue for the determination of futuristic drug, SAL, during pharmacokinetic and pharmacodynamics studies.

The Discovery of 7-Methyl-2-[(7-methyl[1,2,4]triazolo[1,5-a]pyridin-6-yl)amino]-9-(tetrahydro-2H-pyran-4-yl)-7,9-dihydro-8H-purin-8-one (AZD7648), a Potent and Selective DNA-Dependent Protein Kinase (DNA-PK) Inhibitor.

DNA-PK is a key component within the DNA damage response, as it is responsible for recognizing and repairing double-strand DNA breaks (DSBs) via non-homologous end joining. Historically it has been challenging to identify inhibitors of the DNA-PK catalytic subunit (DNA-PKcs) with good selectivity versus the structurally related PI3 (lipid) and PI3K-related protein kinases. We screened our corporate collection for DNA-PKcs inhibitors with good PI3 kinase selectivity, identifying compound 1. Optimization focused on further improving selectivity while improving physical and pharmacokinetic properties, notably co-optimization of permeability and metabolic stability, to identify compound 16 (AZD7648). Compound 16 had no significant off-target activity in the protein kinome and only weak activity versus PI3Kα/γ lipid kinases. Monotherapy activity in murine xenograft models was observed, and regressions were observed when combined with inducers of DSBs (doxorubicin or irradiation) or PARP inhibition (olaparib). These data support progression into clinical studies (NCT03907969).

A new tripodal kojic acid derivative for iron sequestration: Synthesis, protonation, complex formation studies with Fe3+, Al3+, Cu2+ and Zn2+, and in vivo bioassays.

This work presents the simple and low cost synthesis of a new tripodal ligand, in which three units of kojic acid are coupled to a tris(2-aminoethyl)amine (tren) backbone molecule. The protonation equilibria, together with the complex formation equilibria of this ligand with Fe3+, Al3+, Cu2+ and Zn2+ ions were studied. The complementary use of potentiometric, spectrophotometric and NMR techniques, and of Density Functional Theory (DFT) calculations, has allowed a thorough characterization of the different species involved in equilibrium. The stability of the formed complexes with Fe3+ and Al3+ are high enough to consider the new ligand for further studies for its clinical applications as a chelating agent. Biodistribution studies were carried out to assess the capacity the ligand for mobilization of gallium in 67Ga-citrate injected mice. These studies demonstrated that this ligand efficiently chelates the radiometal in our animal model, which suggests that it can be a promising candidate as sequestering agent of iron and other hard trivalent metal ions. Furthermore, the good zinc complexation capacity appears as a stimulating result taking into a potential use of this new ligand in analytical chemistry as well as in agricultural and environmental applications.

Co-Delivery of Docetaxel and Salinomycin to Target Both Breast Cancer Cells and Stem Cells by PLGA/TPGS Nanoparticles.

PURPOSE: Conventional chemotherapy is hampered by the presence of breast cancer stem cells (BCSCs). It is crucial to eradicating both the bulky breast cancer cells and BCSCs, using a combination of conventional chemotherapy and anti-CSCs drugs. However, the synergistic ratio of drug combinations cannot be easily maintained in vivo. In our previous studies, we demonstrated that the simultaneous delivery of two drugs via nanoliposomes could maintain the synergistic drug ratio for 12 h in vivo. However, nanoliposomes have the disadvantage of quick drug release, which makes it difficult to maintain the synergistic drug ratio for a long time. Herein, we developed a co-delivery system for docetaxel (DTX)-a first-line chemotherapy drug for breast cancer-and salinomycin (SAL)-an anti-BCSCs drug-in rigid nanoparticles constituted of polylactide-co-glycolide/D-alpha-tocopherol polyethylene glycol 1000 succinate (PLGA/TPGS). METHODS: Nanoparticles loaded with SAL and DTX at the optimized ratio (NSD) were prepared by the nanoprecipitation method. The characterization, cellular uptake, and cytotoxicity of nanoparticles were investigated in vitro, and the pharmacokinetics, tissue distribution, antitumor and anti-CSCs activity of nanoparticles were evaluated in vivo. RESULTS: We demonstrated that a SAL/DTX molar ratio of 1:1 was synergistic in MCF-7 cells and MCF-7-MS. Moreover, the enhanced internalization of nanoparticles was observed in MCF-7 cells and MCF-7-MS. Furthermore, the cytotoxicity of NSD against both MCF-7 cells and MCF-7-MS was stronger than the cytotoxicity of any single treatment in vitro. Significantly, NSD could prolong the circulation time and maintain the synergistic ratio of SAL to DTX in vivo for 24 h, thus exhibiting superior tumor targeting and anti-tumor activity compared to other treatments. CONCLUSION: Co-encapsulation of SAL and DTX in PLGA/TPGS nanoparticles could maintain the synergistic ratio of drugs in vivo in a better manner; thus, providing a promising strategy for synergistic inhibition of breast cancer.

Design, synthesis and biological evaluation of fused naphthofuro[3,2-c] quinoline-6,7,12-triones and pyrano[3,2-c]quinoline-6,7,8,13-tetraones derivatives as ERK inhibitors with efficacy in BRAF-mutant melanoma.

Approximately 60% of human cancers exhibit enhanced activity of ERK1 and ERK2, reflecting their multiple roles in tumor initiation and progression. Acquired drug resistance, especially mechanisms associated with the reactivation of the MAPK (RAF/MEK/ERK) pathway represent a major challenge to current treatments of melanoma and several other cancers. Recently, targeting ERK has evolved as a potentially attractive strategy to overcome this resistance. Herein, we report the design and synthesis of novel series of fused naphthofuro[3,2-c]quinoline-6,7,12-triones 3a-f and pyrano[3,2-c]quinoline-6,7,8,13-tetraones 5a,b and 6, as potential ERK inhibitors. New inhibitors were synthesized and identified by different spectroscopic techniques and X-ray crystallography. They were evaluated for their ability to inhibit ERK1/2 in an in vitro radioactive kinase assay. 3b and 6 inhibited ERK1 with IC50s of 0.5 and 0.19 µM, and inhibited ERK2 with IC50s of 0.6 and 0.16 µM respectively. Kinetic mechanism studies revealed that the inhibitors are ATP-competitive inhibitors where 6 inhibited ERK2 with a Ki of 0.09 µM. Six of the new inhibitors were tested for their in vitro anticancer activity against the NCI-60 panel of tumor cell lines. Compound 3b and 6 were the most potent against most of the human tumor cell lines tested. Moreover, 3b and 6 inhibited the proliferation of the BRAF mutant A375 melanoma cells with IC50s of 3.7 and 0.13 µM, respectively. In addition, they suppressed anchorage-dependent colony formation. Treatment of the A375 cell line with 3b and 6 inhibited the phosphorylation of ERK substrates p-90RSK and ELK-1 and induced apoptosis in a dose dependent manner. Finally, a molecular docking study showed the potential binding mode of 3b and 6 within the ATP catalytic binding site of ERK2.

Effects of D-α-tocopherol polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles on the absorption, pharmacokinetics, and pharmacodynamics of salinomycin sodium.

Although salinomycin sodium (SS) has shown in-vitro potential to inhibit cancer stem cell growth and development, its low water solubility makes it a poor candidate as an oral chemotherapeutic agent. To improve the bioavailability of SS, SS was encapsulated here using D-α-tocopherol polyethylene glycol succinate (TPGS)-emulsified poly(lactic-co-glycolic acid) (PLGA) nanoparticles and compared with its parent SS in terms of absorption, pharmacokinetics, and efficacy in suppressing nasopharyngeal carcinomas stem cells. The pharmacokinetics of SS and salinomycin sodium-loaded D-α-tocopherol polyethylene glycol succinate-emulsified poly(lactic-co-glycolic acid) nanoparticles (SLN) prepared by nanoprecipitation were analyzed in-vivo by timed-interval blood sampling and oral administration of SS and SLN to rats. Sensitive liquid chromatography-mass spectrometry (LC-MS) was developed to quantify plasma drug concentrations. SS and SLN transport in Caco-2 cells was also investigated. The therapeutic efficacy of SS and SLN against cancer stem cells was determined by orally administering the drugs to mice bearing CNE1 and CNE2 nasopharyngeal carcinoma xenografts and then evaluating CD133 cell proportions and tumorsphere formation. The in-vivo trial with rats showed that the Cmax, AUC(0-t), and Tmax for orally administered SLN were all significantly higher than those for SS (P<0.05). These findings were corroborated by a Caco-2 cell Transwell assay showing that relative SLN absorption was greater than that of SS on the basis of their apparent permeability coefficients (Papp). Significantly, therapeutic SLN efficacy against nasopharyngeal carcinoma stem cells was superior to that of SS. TPGS-emulsified PLGA nanoparticles effectively increase SS solubility and bioavailability. SLN is, therefore, promising as an oral chemotherapeutic agent against cancer stem cells.

Discovery of 4-(((4-(5-chloro-2-(((1s,4s)-4-((2-methoxyethyl)amino)cyclohexyl)amino)pyridin-4-yl)thiazol-2-yl)amino)methyl)tetrahydro-2H-pyran-4-carbonitrile (JSH-150) as a novel highly selective and potent CDK9 kinase inhibitor.

Through a structure-guided rational drug design approach, we have discovered a highly selective inhibitor compound 40 (JSH-150), which exhibited an IC50 of 1 nM against CDK9 kinase in the biochemical assay and achieved around 300-10000-fold selectivity over other CDK kinase family members. In addition, it also displayed high selectivity over other 468 kinases/mutants (KINOMEscan S score(1) = 0.01). Compound 40 displayed potent antiproliferative effects against melanoma, neuroblastoma, hepatoma, colon cancer, lung cancer as well as leukemia cell lines. It could dose-dependently inhibit the phosphorylation of RNA Pol II, suppress the expression of MCL-1 and c-Myc, arrest the cell cycle and induce the apoptosis in the leukemia cells. In the MV4-11 cell-inoculated xenograft mouse model, 10 mg/kg dosage of 40 could almost completely suppress the tumor progression. The high selectivity and good in vivo PK/PD profile suggested that 40 would be a good pharmacological tool to study CDK9-mediated physiology and pathology as well as a potential drug candidate for leukemia and other cancers.

In vitro bioaccessibility of the marine biotoxins okadaic acid, dinophysistoxin-2 and their 7-O-acyl fatty acid ester derivatives in raw and steamed shellfish.

Okadaic acid (OA), Dinophysistoxins (DTX1 and DTX2) and their acyl-derivatives (DTX3) are marine toxins responsible for the human diarrhetic shellfish poisoning. To date the amount of toxins ingested from consumption of shellfish has been considered equal to the amount of toxins available for uptake by the human body. The aim of this study is to assess the OA, DTX2 and DTX3 fractions released from raw and steamed mussels and cockles into the digestive fluids (bioaccessibility) using a static in vitro digestion model. Higher bioaccessibility was found in mussels (86 ± 4%) than in cockles (59 ± 9%). A significant reduction of ester derivatives of OA and an increase of OA were observed in the bioaccessible fraction of mussel samples, suggesting that DTX3 undergo conversion into their more toxic parent compounds during human digestion. However, similar increase of DTX2 and reduction of the respective acyl derivatives was not observed. Steaming lead to significant reduction of OA and analogues bioaccessibility in both species even though increased concentrations of toxins are obtained after this treatment. Risk assessment based solely on DSP toxins occurrence in seafood can conduct to an overestimation of the exposure and lead to more conservative regulatory measures.

An iTEP-salinomycin nanoparticle that specifically and effectively inhibits metastases of 4T1 orthotopic breast tumors.

Cancer stem cell (CSC) inhibitors are a new category of investigational drugs to treat metastasis. Salinomycin (Sali) is one of most studied CSC inhibitors and has reached clinical tests. Several drug carriers have been developed to improve efficacy of Sali. However, Sali has not been shown to inhibit metastasis from orthotopic tumors, the gold standard for metastasis. To fill this gap, we developed an immune-tolerant, elastin-like polypeptide (iTEP)-based nanoparticle (iTEP-Sali-ABA NP) that released 4-(aminomethyl)benzaldehyde-modified Sali (Sali-ABA) under acidic conditions. We found that the NP increased the area under the curve (AUC) of Sali-ABA by 30-fold and the tumor accumulation by 3.4-fold. Furthermore, no metastasis was detected in any of the mice given the NP. However, all the mice died of primary tumor burdens. To overcome primary tumor growth and improve the overall survival, we applied a combination therapy consisting of the iTEP-Sali-ABA NP and iTEP NP-delivered paclitaxel. This therapy effectively retarded primary tumor growth, and most importantly, improved the overall survival. In conclusion, delivery of Sali-ABA by the NP, alone or in combination with paclitaxel, was more effective than free Sali-ABA in decreasing metastasis and increasing survival. This iTEP-Sali-ABA NP represents a novel and clinically promising therapy to combat metastasis.

Structure-activity-relationship of amide and sulfonamide analogs of omarigliptin.

A series of novel substituted-[(3R)-amino-2-(2,5-difluorophenyl)]tetrahydro-2H-pyran analogs have been prepared and evaluated as potent, selective and orally active DPP-4 inhibitors. These efforts lead to the discovery of a long acting DPP-4 inhibitor, omarigliptin (MK-3102), which recently completed phase III clinical development and has been approved in Japan.

Preclinical drug metabolism and pharmacokinetics of salinomycin, a potential candidate for targeting human cancer stem cells.

There has been a search for new anticancer agents to treat cancer resistance throughout the globe. Salinomycin (SAL), a broad spectrum antibiotic and a coccidiostat has been found to counter tumour resistance and kill cancer stem cells with better efficacy than the existing chemotherapeutic agents; paclitaxel and doxorubicin. This refocused its importance for treatment of human cancers. In this study, we studied the in vitro drug metabolism and pharmacokinetic parameters of SAL. SAL undergoes rapid metabolism in liver microsomes and has a high intrinsic clearance. SAL metabolism is mainly mediated by CYP enzymes; CYP3A4 the major enzyme metabolising SAL. The percent plasma protein binding of SAL in human was significantly lower as compared to mouse and rat plasma. CYP inhibition was carried out by chemical inhibition and recombinant enzyme studies. SAL was found to be a moderate inhibitor of CYP2D6 as well as CYP3A4. As CYP3A4 was the major enzyme responsible for metabolism of SAL, in vivo pharmacokinetic study in rats was done to check the effect of concomitant administration of Ketoconazole (KTC) on SAL pharmacokinetics. KTC, being a selective CYP3A4 inhibitor increased the systemic exposure of SAL significantly to 7-fold in AUC0-α and 3-fold increase in Cmax of SAL in rats with concomitant KTC administration.

Polymeric Micelles of PEG-PLA Copolymer as a Carrier for Salinomycin Against Gemcitabine-Resistant Pancreatic Cancer.

PURPOSE: Resistance to gemcitabine in pancreatic cancer (PC) may account for the failure of conventional treatments. Recently, salinomycin (SAL) has been identified as selective inhibitor of cancer stem cells (CSCs). In our study, we aimed to deliver SAL to gemcitabine-resistant PC by the aid of poly ethylene glycol-b-poly lactic acid (PEG-b-PLA) polymeric micelles (PMs). METHODS: SAL-loaded PMs were prepared and investigated in terms of pharmaceutical properties. MTT and Annexin V/PI assays were used to study cell proliferation and apoptosis in AsPC-1 cells in response to treatment with SAL micellar formulations. Alterations in CSC phenotype, invasion strength, and mRNA expression of epithelial mesenchymal transition (EMT) markers were also determined in the treated cells. In vivo antitumor study was performed in Balb/c AsPC-1 xenograft mice. RESULTS: PM formulations of SAL were prepared in suitable size and loading traits. In gemcitabine-resistant AsPC-1 cells, SAL was found to significantly increase cell mortality and apoptosis. It was also observed that SAL micellar formulations inhibited invasion and harnessed EMT in spite of induced expression of Snail. The in vivo antitumor experiment showed significant tumor eradication and the highest survival probability in mice treated with SAL PMs. CONCLUSIONS: The obtained results showed the efficacy of SAL nano-formulation against PC tumor cells.

Poly(lactic-co-glycolic acid) nanoparticles conjugated with CD133 aptamers for targeted salinomycin delivery to CD133+ osteosarcoma cancer stem cells.

BACKGROUND: Cancer stem cells (CSCs) possess the characteristics associated with normal stem cells and are responsible for cancer initiation, recurrence, and metastasis. CD133 is regarded as a CSCs marker of osteosarcoma, which is the most common primary bone malignancy in childhood and adolescence. Salinomycin, a polyether ionophore antibiotic, has been shown to kill various CSCs, including osteosarcoma CSCs. However, salinomycin displayed poor aqueous solubility that hinders its clinical application. The objective of this study was to develop salinomycin-loaded nanoparticles to eliminate CD133(+) osteosarcoma CSCs. METHODS: The salinomycin-loaded PEGylated poly(lactic-co-glycolic acid) nanoparticles (SAL-NP) conjugated with CD133 aptamers (Ap-SAL-NP) were developed by an emulsion/solvent evaporation method, and the targeting and cytotoxicity of Ap-SAL-NP to CD133(+) osteosarcoma CSCs were evaluated. RESULTS: The nanoparticles are of desired particle size (~150 nm), drug encapsulation efficiency (~50%), and drug release profile. After 48 hours treatment of the Saos-2 CD133(+) osteosarcoma cells with drugs formulated in Ap-SAL-NP, SAL-NP, and salinomycin, the concentrations needed to kill 50% of the incubated cells were found to be 2.18, 10.72, and 5.07 µg/mL, respectively, suggesting that Ap-SAL-NP could be 4.92 or 2.33 fold more effective than SAL-NP or salinomycin, respectively. In contrast, Ap-SAL-NP was as effective as SAL-NP, and less effective than salinomycin in Saos-2 CD133(-) cells, suggesting that Ap-SAL-NP possess specific cytotoxicity toward Saos-2 CD133(+) cells. Ap-SAL-NP showed the best therapeutic effect in Saos-2 osteosarcoma xenograft mice, compared with SAL-NP or salinomycin. Significantly, Ap-SAL-NP could selectively kill CD133(+) osteosarcoma CSCs both in vitro and in vivo, as reflected by the tumorsphere formation and proportion of Saos-2 CD133(+) cells. CONCLUSION: Our results suggest that CD133 is a potential target for drug delivery to osteosarcoma CSCs and that it is possible to significantly inhibit the osteosarcoma growth by killing CD133(+) osteosarcoma CSCs. We demonstrated that Ap-SAL-NP have the potential to target and kill CD133(+) osteosarcoma CSCs.

iTEP nanoparticle-delivered salinomycin displays an enhanced toxicity to cancer stem cells in orthotopic breast tumors.

Salinomycin (Sali) has selective toxicity to cancer stem cells (CSCs), a subpopulation of cancer cells that have been recently linked with tumor multidrug resistance (MDR). To utilize its selective toxicity for cancer therapy, we sought to devise a nanoparticle (NP) carrier to deliver Sali to solid tumors through the enhanced permeability and retention effect and, hence, to increase its exposure to CSCs. First, hydrophobic Sali was conjugated to a hydrophilic, immune-tolerant, elastin-like polypeptide (iTEP); the amphiphilic iTEP-Sali conjugates self-assemble into NPs. Next, free Sali was encapsulated into the NPs alone or with two additives, N,N-dimethylhexylamine (DMHA) and α-tocopherol. The coencapsulation significantly improved the loading efficiency and release profile of Sali. The resulting NPs of the coencapsulation, termed as iTEP-Sali NP3s, have an in vitro release half-life of 4.1 h, four times longer than iTEP-Sali NP2s, the NPs that have encapsulated Sali only. Further, the NP3 formulation increases the plasma area under curve and the tumor accumulation of Sali by 10 and 2.4 times, respectively. Lastly, these improved pharmacokinetic and tumor accumulation profiles are consistent with a boost of CSC-elimination effect of Sali in vivo. In NP3-treated 4T1 orthotopic tumors, the mean CSC frequency is 55.62%, a significant reduction from the mean frequencies of untreated tumors, 75.00%, or free Sali-treated tumors, 64.32%. The CSC-elimination effect of the NP3 can further translate to a delay of tumor growth. Given the role of CSCs in driving tumor MDR and recurrence, it could be a promising strategy to add the NP3 to conventional cancer chemotherapies to prevent or reverse the MDR.

Discovery of 7-tetrahydropyran-2-yl chromans: ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitors that reduce amyloid ß-protein (Aß) in the central nervous system.

In an attempt to increase selectivity vs Cathepsin D (CatD) in our BACE1 program, a series of 1,3,4,4a,10,10a-hexahydropyrano[4,3-b]chromene analogues was developed. Three different Asp-binding moieties were examined: spirocyclic acyl guanidines, aminooxazolines, and aminothiazolines in order to modulate potency, selectivity, efflux, and permeability. Using structure-based design, substitutions to improve binding to both the S3 and S2' sites of BACE1 were explored. An acyl guanidine moiety provided the most potent analogues. These compounds demonstrated 10-420 fold selectivity for BACE1 vs CatD, and were highly potent in a cell assay measuring Aß1-40 production (5-99 nM). They also suffered from high efflux. Despite this undesirable property, two of the acyl guanidines achieved free brain concentrations (Cfree,brain) in a guinea pig PD model sufficient to cover their cell IC50s. Moreover, a significant reduction of Aß1-40 in guinea pig, rat, and cyno CSF (58%, 53%, and 63%, respectively) was observed for compound 62.

Human absorption and metabolism of oleuropein and hydroxytyrosol ingested as olive (Olea europaea L.) leaf extract.

Phenolic compounds derived from the olive plant (Olea europaea L.), particularly hydroxytyrosol and oleuropein, have many beneficial effects in vitro. Olive leaves are the richest source of olive phenolic compounds, and olive leaf extract (OLE) is now a popular nutraceutical taken either as liquid or capsules. To quantify the bioavailability and metabolism of oleuropein and hydroxytyrosol when taken as OLE, nine volunteers (five males) aged 42.8 ± 7.4 years were randomized to receive either capsulated or liquid OLE as a single lower (51.1 mg oleuropein, 9.7 mg hydroxytyrosol) or higher (76.6 mg oleuropein, 14.5 mg hydroxytyrosol) dose, and then the opposite strength (but same formulation) a week later. Plasma and urine samples were collected at fixed intervals for 24 h post-ingestion. Phenolic content was analyzed by LC-ESI-MS/MS. Conjugated metabolites of hydroxytyrosol were the primary metabolites recovered in plasma and urine after OLE ingestion. Peak oleuropein concentrations in plasma were greater following ingestion of liquid than capsule preparations (0.47 versus 2.74 ng/mL; p = 0.004), but no such effect was observed for peak concentrations of conjugated (sulfated and glucuronidated) hydroxytyrosol (p = 0.94). However, the latter peak was reached earlier with liquid preparation (93 versus 64 min; p = 0.031). There was a gender effect on the bioavailability of phenolic compounds, with males displaying greater plasma area under the curve for conjugated hydroxytyrosol (11,600 versus 2550 ng/mL; p = 0.048). All conjugated hydroxytyrosol metabolites were recovered in the urine within 8 h. There was wide inter-individual variation. OLE effectively delivers oleuropein and hydroxytrosol metabolites to plasma in humans.

Herceptin-decorated salinomycin-loaded nanoparticles for breast tumor targeting.

The use of conventional chemotherapeutic drugs was emerged as challenging for breast cancer therapy, because breast cancer stem cells cannot be destroyed due to their great nature of drug resistance. In this study, a novel nanoparticulate system of Herceptin (HER)-immobilized salinomycin (SAL)-encapsulated poly(lactic-co-glycolic acid) (PLGA) (HER-SAL-PLGA) nanoparticles were constructed and investigated for breast cancer targeting. SAL-encapsulated PLGA nanoparticles were characterized for their particle size, morphology, structural and thermal properties, and drug-encapsulation efficiency. HER-SAL-PLGA nanoparticles were characterized via particle size, surface chemistry, and herceptin-immobilization efficiency. In vitro release studies were performed for both nontargeting and targeting SAL-PLGA nanoparticles, which demonstrated a controlled release of SAL from nanoparticles. Cellular uptake of the HER-SAL-PLGA nanoparticles was assessed by fluorescence and optical microscopy and flow cytometry, which showed that the HER-SAL-PLGA nanoparticles were successfully uptaken by MCF7 cells. In conclusion, this novel drug-delivery system, HER-SAL-PLGA, was suggested as a promising targeting system for breast cancer therapy.