Galangin Attenuates Isoproterenol-Induced Inflammation and Fibrosis in the Cardiac Tissue of Albino Wistar Rats.

Galangin (GA) is an active flavonoid of the rhizome of Alpinia galanga that belongs to the ginger family. GA exhibit potent anti-inflammatory properties. Therefore, we evaluated the preventive effects of GA against isoproterenol (ISO)-induced inflammation and myocardial fibrosis in male albino Wistar rats. We found that GA (1 mg/kg b.wt.) pretreatment attenuated the ISO-mediated (5 mg/kg b.wt. for 14 consecutive days) elevation of heart rate, activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase-MB (CKMB) in the rat serum. We also noticed that GA prevented the ISO-mediated cardiac markers i.e. cardiac troponin T and I (cTnT and cTnI) expression in the serum of rats. Further, GA pretreatment prevented ISO-mediated lipid peroxidation and diminished blood pressure and loss of antioxidants status in the heart tissue of ISO treated rats. In addition, GA treatment modulates ISO-induced alterations the expressions of tissue inhibitor of metalloproteinases-1 (TIMP-1), p-AKT, glycogen synthase kinase-3ß (p-GSK-3ß) and peroxisome proliferators-activated receptor-γ (PPAR-γ) in the heart tissue. Furthermore, molecular analysis (PCR array and western blot) revealed that GA pretreatment prevented inflammation and fibrosis related gene expression pattern in ISO-induced rats. Taken together, the results indicate the cardioprotective effect of GA against ISO-induced inflammation and fibrosis. The antioxidant and anti-inflammatory potential of GA could be considered for its cardioprotective effect in the ISO-treated rats.

Opuntiol Prevents Photoaging of Mouse Skin via Blocking Inflammatory Responses and Collagen Degradation.

In the present study, we investigated the potential of opuntiol, isolated from Opuntia ficus-indica, against UVA radiation-mediated inflammation and skin photoaging in experimental animals. The skin-shaved experimental mouse was subjected to UVA exposure at the dosage of 10 J/cm2 per day for ten consecutive days (cumulative UVA dose: 100 J/cm2). Opuntiol (50 mg/kg b.wt.) was topically applied one hour before each UVA exposure. UVA (100 J/cm2) exposure induces epidermal hyperplasia and collagen disarrangement which leads to the photoaging-associated molecular changes in the mouse skin. Opuntiol pretreatment prevented UVA-linked clinical macroscopic skin lesions and histological changes in the mouse skin. Further, opuntiol prevents UVA-linked dermal collagen fiber loss in the mouse skin. Short-term UVA radiation (100 J/cm2) activates MAPKs through AP-1 and NF-κB p65 transcriptional pathways and subsequently induces the expression of inflammatory proteins and matrix-degrading proteinases in the mouse skin. Interestingly, opuntiol pretreatment inhibited UVA-induced activation of iNOS, VEGF, TNF-α, and COX-2 proteins and consequent activation of MMP-2, MMP-9, and MMP-12 in the mouse skin. Moreover, opuntiol was found to prevent collagen I and III breakdown in UVA radiation-exposed mouse skin. Thus, opuntiol protects mouse skin from UVA radiation-associated photoaging responses through inhibiting inflammatory responses, MAPK activation, and degradation of matrix collagen molecules.

Crude Cell-Free Extract From Deinococcus radiodurans Exhibit Anticancer Activity by Inducing Apoptosis in Triple-Negative Breast Cancer Cells.

Extremophilic organisms have the potential to tolerate extremely challenging environments of nature. This property can be accredited to its production of novel secondary metabolites that possess anticancer and other pharmaceutical values. The present study was aimed to investigate the anticancer activity of crude secondary metabolite extract (CSME) obtained from the radiation-tolerant bacterium Deinococcus radiodurans in triple-negative human breast carcinoma (MDA-MB-231) cells. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay showed the antiproliferative potential of CSME in MDA-MB-231 cells (IC50 = 25 µg/ml) and MCF-7 cells (IC50 = 10 µg/ml). Further, the CSME treatment led to the production of intracellular reactive oxygen species (ROS) and nuclear membrane alterations with the formation of apoptotic bodies in MDA-MB-231 cells. Considerable DNA damage and low antioxidant status were observed in CSME-treated MDA-MB-231 cells. The results also showed that the CSME treatment induced apoptotic markers expression in MDA-MB-231 cells. Western blot results illustrated significant upregulation of p53, caspase-3, and caspase-9 proteins expression. Then, we analyzed the presence of secondary metabolites which may be linked with antiproliferative potential of CSME by gas chromatography-mass spectrometry (GC-MS). The results illustrated the presence of 23 bioactive compounds some of which are already reported to possess anticancer properties. The study indicates that the CSME of D. radiodurans possess anticancer properties and exhibit the potential to be used as an anticancer agent.

Correction to: Understanding the survival mechanisms of Deinococcus radiodurans against oxidative stress by targeting thioredoxin reductase redox system.

The correction does not affect the discussion or conclusions of the article. The correct image is given below.

Folate-Gold-Bilirubin Nanoconjugate Induces Apoptotic Death in Multidrug-Resistant Oral Carcinoma Cells.

BACKGROUND: Gold nanoparticles (GNPs) are receiving increasing attention as drug delivery carriers due to their high surface-to-volume ratio, hydrophilicity, and functionality. Drug delivery by nanocarriers has the potential to bypass P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) by altering the drug internalization mechanism and/or intracellular release pattern, inhibiting the activity of ABC-transporter efflux pumps, or downregulating the expression of genes responsible for the activity of efflux pumps. OBJECTIVE: We developed a folate-gold-bilirubin (FGB) nanoconjugate to reverse MDR in P-expressing KB-ChR-8-5 cells. METHODS: The P-gp overexpressing KB-ChR-8-5 cells were incubated with the FGB nanoconjugate, bilirubin, or GNPs. Various cellular endpoints, such as cytotoxicity, ROS generation, DNA damage, and apoptosis, were analyzed using analytical methods. Further, a KB-ChR-8-5 cell-bearing tumor xenograft was developed and the anticancer potential of the prepared FGB nanoparticles was compared to that of bilirubin or GNPs in this preclinical model. RESULTS: The FGB nanoconjugate was found to be a stronger inhibitor of the viability of multidrug-resistant KB-ChR-8-5 cells than bilirubin and GNPs treatment alone. The nanoconjugate induced reactive oxygen species (ROS) formation, DNA strand breaks, and apoptotic morphological changes in the P-gp-overexpressing drug-resistant cells to a greater degree than bilirubin treatment alone. Also, the FGB nanoparticles led to stronger suppression of tumor development in the KB-ChR-8-5 xenograft mouse model than achieved with bilirubin treatment alone. Thus, the present results suggest that the FGB nanoconjugate suppresses tumor growth in drug-resistant tumor cells by inducing apoptotic cell death. CONCLUSION: FGB nanoparticles significantly inhibit tumor growth, probably through the folate receptor, which is highly expressed in KB cells. Hence, folate-gold-bilirubin nanoparticles could be a promising agent for inducing apoptosis in P-gp-overexpressing drug-resistant cancer cells.

Understanding the survival mechanisms of Deinococcus radiodurans against oxidative stress by targeting thioredoxin reductase redox system.

The principal objective of this study is to determine the resistance of Deinococcus radiodurans to hydrogen peroxide (H2O2) induced oxidative stress by inhibiting its thioredoxin reductase (TrxR) antioxidant system. Treatment of D. radiodurans with different TrxR inhibitors such as ebselen, epigallocatechin gallate and auranofin displayed this organism sensitivity to H2O2 treatment in a concentration-dependent manner. We observed that D. radiodurans showed greater resistance to H2O2 treatment. Further, it has also been noticed that TrxR redox system was suppressed by TrxR inhibitors and that this response might be associated with the oxidative stress-mediated cell death in D. radiodurans. Thus, TrxR inhibitors affect the resistance of the D. radiodurans through suppression of its thioredoxin redox pathway via the inhibition of TrxR. Results from this study proved that TrxR plays an important role as an antioxidant enzyme by scavenging intracellular ROS, and thus contributing to the resistance of D. radiodurans towards oxidative stress.

Computational models for predicting anticancer drug efficacy: A multi linear regression analysis based on molecular, cellular and clinical data of oral squamous cell carcinoma cohort.

BACKGROUND AND OBJECTIVES: The computational prediction of drug responses based on the analysis of multiple clinical features of the tumor will be a novel strategy for accomplishing the long-term goal of precision medicine in oncology. The cancer patients will be benefitted if we computationally account all the tumor characteristics (data) for the selection of most effective and precise therapeutic drug. In this study, we developed and validated few computational models to predict anticancer drug efficacy based on molecular, cellular and clinical features of 31 oral squamous cell carcinoma (OSCC) cohort using computational methods. METHODS: We developed drug efficacy prediction models using multiple tumor features by employing the statistical methods like multi linear regression (MLR), modified MLR-weighted least square (MLR-WLS) and enhanced MLR-WLS. All the three developed drug efficacy prediction models were then validated using the data of actual OSCC samples (train-test ratio 31: 31) and actual Vs hypothetical samples (train-test ratio 31: 30). The selected best statistical model i.e. enhanced MLR-WLS has then been cross-validated (CV) using 341 theoretical tumor data. Finally, the performances of the models were assessed by the level of learning confidence, significance, accuracy and error terms. RESULTS: The train-test process for the real tumor samples of MLR-WLS method revealed the drug efficacy prediction enhancement and we observed that there was very less priming difference between actual and predicted. Furthermore, we found there was a less difference between actual apoptotic priming and predicted apoptotic priming for the tumors 6, 8, 21 and 30 whereas, for the remaining tumors there were no differences between predicted and actual priming data. The error terms (Actual Vs Predicted) also revealed the reliability of enhanced MLR-WLS model for drug efficacy prediction. CONCLUSION: We developed effective computational prediction models using MLR analysis for anticancer drug efficacy which will be useful in the field of precision medicine to choose the choice of drug in a personalized manner. We observed that the enhanced MLR-WLS model was the best fit to predict anticancer drug efficacy which may have translational applications.

Ferulic acid reverses P-glycoprotein-mediated multidrug resistance via inhibition of PI3K/Akt/NF-κB signaling pathway.

In this study, the modulatory effect of ferulic acid on P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) was examined in KB ChR8-5 resistant cells and drug-resistant tumor xenografts. We observed that ferulic acid enhanced the cytotoxicity of doxorubicin and vincristine in the P-gp overexpressing KB ChR8-5 cells. Further, ferulic acid enhances the doxorubicin induced γH2AX foci formation and synergistically augmented doxorubicin-induced apoptotic signaling in the drug-resistant cells. It has also been noticed that NF-κB nuclear translocation was suppressed by ferulic acid and that this response might be associated with the modulation of phosphatidyinositol 3-kinase (PI3K)/Akt/signaling pathway. We also found that ferulic acid and doxorubicin combination reduced the size of KB ChR8-5 tumor xenograft by threefold as compared to doxorubicin-alone treated group. Thus, ferulic acid contributes to the reversal of the MDR through suppression of P-gp expression via the inhibition of PI3K/Akt/NF-κB signaling pathway.

Alpha-pinene attenuates UVA-induced photoaging through inhibition of matrix metalloproteinases expression in mouse skin.

AIM: The present study was designed to examine the role of alpha-pinene (AP) against skin photoaging in UVA-irradiated mice. MATERIALS AND METHODS: Swiss albino mice were subjected to UVA-irradiation at the rate of 10 J/cm2 per day for ten days, totally mouse received 100 J/cm2. One hour prior to each UVA-exposure, the mouse skin was topically treated with AP (100 mg kg/b·wt). Biochemical methods were employed to study the status of antioxidant enzymes and lipid peroxidation. Histopathological observations were performed using hematoxylin and eosin (H & E) and Verhoeff van Gieson (VVG) staining in the mouse skin. The inflammatory and apoptotic protein expression was studied by immunohistochemical and Western blot methods. The mRNA expression of matrix metalloproteinases was determined by qRT-PCR and Western blot analysis. KEY FINDINGS: We found that AP pretreatment substantially ameliorated UVA-induced depletion of antioxidant enzymes and prevented UVA-induced lipid peroxidation in the mouse skin. Further, AP effectively inhibited UVA-induced activation of pro-angiogenic (iNOS and VEGF), inflammatory proteins (TNF-α, IL-6, and COX-2) expression and prevented the activation of NF-κB p65 in the mouse skin. Additionally, AP inhibited UVA-mediated apoptotic mediators (Bax, Bcl-2, caspase-3 and caspase 9) expression in the mouse skin. Moreover, AP inhibited mRNA expression of matrix metalloproteinases (MMP-13 and MMP-9) and tissue type IV collagenase (MMP-2) expression in the mouse skin. Histological studies showed that AP remarkably prevented the dermal tissue damage in UVA-irradiated mice. CONCLUSION: Thus, AP treatment effectively prevented UVA-induced photoaging probably through its antioxidant property.

Alpha pinene modulates UVA-induced oxidative stress, DNA damage and apoptosis in human skin epidermal keratinocytes.

AIMS: This study aims to evaluate the protective effect of alpha pinene (AP), an essential oil monoterpene, against ultraviolet-A (UVA; 320-400 nm) induced cellular damages in human skin epidermal keratinocytes (HaCaT cells). MATERIALS AND METHODS: In this study, HaCaT cells were subjected to single UVA-irradiation (10 J/cm2) in the presence and absence of AP (30 µM) then different cellular end points were analyzed. The protective effect of AP against UVA-induced cytotoxicity was evaluated by MTT-based metabolic assay. Generation of reactive oxygen species (ROS), alteration of mitochondrial membrane potential (MMP), DNA single- and double strand breaks (SSBs and DSBs) and apoptotic morphological changes during different treatment conditions were measured by fluorescence microscopy and spectrofluorometry. Modulatory role of AP against UVA-mediated inflammatory markers expression, nucleotide excision repair (NER) proteins and apoptotic markers expression during AP and/or UVA treatment were studied by western blot. KEY FINDINGS: Pretreatment with AP prevented UVA-induced cytotoxicity, generation of ROS, lipid peroxidation and DNA stand breaks probably through its antioxidant property. AP also inhibited UVA-induced inflammatory mediators such as NF-κB, TNF-α and IL-6 expression in HaCaT cells. Further, AP modulates NER proteins via activation of p53 and p21 thereby subsequently prevent the formation of UVA-induced cyclobutane pyrimidine dimers (CPDs). We also noticed that AP inhibits apoptotic cell death by preventing UVA-induced loss of mitochondrial membrane potential through modulating Bax/Bcl-2 expression in HaCaT cells. SIGNIFICANCE: The present findings suggest that AP prevent UVA-induced oxidative stress, inflammation, DNA damages and apoptosis in human skin cells.

Predicting Tumor Sensitivity to Chemotherapeutic Drugs in Oral Squamous Cell Carcinoma Patients.

Oral Squamous Cell Carcinoma (OSCC) patients respond poorly to chemotherapy. We analyzed the expression of 11 drug response-related genes in 31 OSCC biopsies, collected prior to any treatment, using custom-designed PCR array. Further, we investigated the drug response pattern of selected anticancer drugs by BH3 (Bcl2 Homology-3) profiling in the primary cells isolated from OSCC tissues. Then, we correlated the results of drug-response gene expression pattern with apoptotic priming to predict tumor response to chemotherapy. The best performing drug (BPD) and response differences (RD) between the drugs were identified using statistical methods to select the best choice of drug in a personalized manner. Based on the correlation, we classified OSCC tumors as sensitive (13 tumors), moderately responsive (16 tumors) or resistant (2 tumors) to chemotherapy. We found that up-regulation of genes linked with drug resistance facilitates survival of tumor samples, which was revealed by the percentage of apoptotic priming. Moreover, we found that paclitaxel-induced 40-45% apoptotic priming compared to other drugs. Average response difference (RD) analysis showed that 80% of tumors responded well to paclitaxel as compared to other drugs studied. Therefore, gene expression analysis with BH3 profiling reveals drug sensitivity that could be translated for drug selection before treatment.

Protective effect of Juglans regia L. against ultraviolet B radiation induced inflammatory responses in human epidermal keratinocytes.

BACKGROUND: Juglans regia L. has a history of traditional medicinal use for the treatment of various maladies and have been documented with significant antioxidant and antiinflammatory properties. Although all parts of the plant are medicinally important, but male the flower of the plant has not been yet investigated against the photo-damage. PURPOSE: The present study, we sought to determine the photoprotective effect of the male flower of J. regia L. against ultraviolet-B radiation-induced inflammatory responses in human skin cells. METHODS: The profile of pharmacological active compounds present in the male flower of J. regia was analyzed by GC-MS. Then, the antioxidant property of methanolic extract of J. regia (MEJR) was analyzed by in vitro free radical scavenging assays. Further, we analyzed the sun protection factor of this extract by spectrophotometry. Moreover, we investigated the photoprotective effect of MEJR against UVB induced inflammatory signaling in human epidermal cells. Human skin epidermal keratinocytes (HaCaT) were pretreated with the MEJR (80 µg/ml), 30 min prior to UVB-irradiation at a dose of 20 mJ/cm2 and were investigated for lipid peroxidation, enzymatic antioxidants activity, apoptosis and inflammatory markers expression level. RESULTS: The GC-MS results showed the presence of good amount of pharmacologically active compounds in the MEJR. We observed that the MEJR possess significant free radical scavenging activity and it was comparable with standard antioxidants. Further, the MEJR exhibits 8.8 sun-protection-factor (SPF) value. Pretreatment with MEJR, 30 min prior to UVB-irradiation, prevented ROS generation, lipid peroxidation and restored the activity of antioxidant status in HaCaT cells. Moreover, MEJR pretreatment significantly prevented UVB activated inflammatory markers like TNF-α, IL-1, IL-6, NF-κB, COX-2 in HaCaT. CONCLUSION: The present findings suggest that MEJR exhibit photoprotective effects and hence it may be useful for the treatment of inflammation related responses. The pharmacological mechanism of MEJR partly associated with its UV absorbance, modulation of inflammatory signaling as well as due to its free radical scavenging capability.

Juglans regia L. protects against UVB induced apoptosis in human epidermal keratinocytes.

The present study was aimed to investigate the photoprotective effect of the male flower of J. regia L. (MEJR) against ultraviolet-B induced apoptosis in human skin cells. Human skin epidermal keratinocytes were pretreated with the MEJR (80 µg/ml, has been selected after MTT assay), prior to 30 min UVB-irradiation at a dose of 20 mJ/cm2. Mitochondrial membrane potential was evaluated using Rhodamine-123 staining; the % apoptosis by Hoechst staining and acridine orange staining; DNA damage was measured by comet assay. The levels of p53, Bax, Bcl-xL, Bcl-2, Cytochrome c, Caspase-9 and Caspase-3 expression in HaCaT cells were analyzed by western blotting and RT-PCR. Pretreatment with MEJR 80 µg/ml prior to UVB-irradiation significantly prevents apoptotic characteristics, DNA damage and loss of mitochondrial membrane potential. Thus, MEJR protects UVB-mediated human skin cells, by modulating the expression of apoptotic markers and UVB-induced DNA damage in HaCaT cells.

Linalool prevents oxidative stress activated protein kinases in single UVB-exposed human skin cells.

Ultraviolet-B radiation (285-320 nm) elicits a number of cellular signaling elements. We investigated the preventive effect of linalool, a natural monoterpene, against UVB-induced oxidative imbalance, activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling in HDFa cells. We observed that linalool treatment (30 µM) prevented acute UVB-irradiation (20 mJ/cm2) mediated loss of activities of antioxidant enzymes in HDFa cells. The comet assay results illustrate that linalool significantly prevents UVB-mediated 8-deoxy guanosine formation (oxidative DNA damage) rather than UVB-induced cyclobutane pyrimidine (CPD) formation. This might be due to its ability to prevent UVB-induced ROS formation and to restore the oxidative imbalance of cells. This has been reflected in UVB-induced overexpression of MAPK and NF-κB signaling. We observed that linalool inhibited UVB-induced phosphorylation of ERK1, JNK and p38 proteins of MAPK family. Linalool inhibited UVB-induced activation of NF-κB/p65 by activating IκBa. We further observed that UVB-induced expression of TNF-α, IL6, IL-10, MMP-2 and MMP-9 was modulated by linalool treatment in HDFa cells. Thus, linalool protects the human skin cells from the oxidative damages of UVB radiation and modulates MAPK and NF-κB signaling in HDFa cells. The present findings substantiate that linalool may act as a photoprotective agent against UVB-induced skin damages.

7-Hydroxycoumarin prevents UVB-induced activation of NF-κB and subsequent overexpression of matrix metalloproteinases and inflammatory markers in human dermal fibroblast cells.

Ultraviolet B (UVB) irradiation alters multiple molecular pathways in the skin, thereby inducing skin damage. Human dermal fibroblasts (HDFa) were subjected to single UVB-irradiation (18mJ/cm(2)) resulting in reactive oxygen species (ROS) generation, oxidative DNA damage and upregulation of nuclear factor kappa B (NF-κB) expression. Further, it has been observed that there was a significant cytokine production (TNF-α and IL-6) in UVB irradiated HDFa cells. Our results show that 7-hydroxycoumarin (7-OHC) prevents UVB-induced activation of NF-κB thereby subsequently preventing the overexpression of TNF-α and IL-6 in HDFa cells. Further, 7-OHC prevents UVB-induced activation of cyclooxygenase-2 (COX-2) expression, an inflammatory mediator in skin cells. Moreover, 7-OHC inhibited mRNA expression pattern of matrix metalloproteinases (MMP-1 and MMP-9) in UVB irradiated skin cells. Furthermore, 7-OHC restored antioxidant status, thereby scavenging the excessively generated ROS; consequently preventing the oxidative DNA damage. It has also been noticed that 7-OHC prevents UVB mediated DNA damage through activation of DNA repair enzymes such as XRCC1 and HOGG1. In this study, we treated HDFa cells with 7-OHC before and after UVB irradiation and we found that pretreatment showed better results when compared to posttreatment. Further, 7-OHC showed 9.8416 sun protection factor (SPF) value and it absorbs photons in the UVB wavelength rage. Thus, it has been concluded that sunscreen property, free radical scavenging potential and prevention of NF-κB activation play a role for photoprotective property of 7-OHC.

Resveratrol loaded gelatin nanoparticles synergistically inhibits cell cycle progression and constitutive NF-kappaB activation, and induces apoptosis in non-small cell lung cancer cells.

PURPOSE: Previously, we reported that the prepared resveratrol (RSV) loaded gelatin nanoparticles (GNPs) possessed enhanced anticancer effect than free RSV in non-small cell lung carcinoma cells and Swiss albino mice. The present study aims to explore the relevant mechanism of cell death induced by the combination of RSV-GNPs in NCI-H460 cells. METHODS AND RESULTS: To increase its bioavailability and anticancer efficacy, we have encapsulated RSV-GNPs by Coacervation method. The detailed methods of preparation and characterization of RSV-GNPs were reported in our earlier publication. RSV-GNPs treated cells showed a further increased level of lipid peroxidative markers, i.e. TBARS and LHP in NCI-H460 cells. Activities of antioxidant enzymes SOD, CAT, GPx and GSH levels were decreased upon the treatment with RSV-GNPs in NCI-H460 cells. The nuclear fragmentation was evaluated by DAPI staining and data showed condensed apoptotic bodies upon treatment with the combination of RSV-GNPs compared to RSV alone treatment group. In addition, cell death induced by RSV-GNPs was mainly due to apoptosis which was characterized by a nuclear DNA fragmentation in a ladder-pattern was obtained from the genomic DNA analysis. Moreover, Western blotting analysis showed that apoptosis induced by RSV-GNPs is associated with the increased Bax, p53, p21, caspase-3 protein levels, and decreased Bcl-2 and NF-κB proteins expression, which indicates the involvement of mitochondria-dependent apoptosis in the anticancer efficacy of RSV-GNPs in NCI-H460 cells. It was also found that this enhanced anticancer efficacy of RSV-GNPs induced cell arrest in the G0/G1 phase of cell cycle. CONCLUSIONS: Taken together, the results of our study clearly suggested that the cell death induced by the combination of RSV-GNPs would involve alteration in expression of p53, p21, caspase-3, Bax, Bcl-2 and NF-κB, indicating oxidative mechanism in NCI-H460 cells. Based on these results, it is concluded that GNPs is an ideal way to deliver RSV because of its high loading efficiency and superior efficacy in NCI-H460 cells.

Design and synthesis of human ABCB1 (P-glycoprotein) inhibitors by peptide coupling of diverse chemical scaffolds on carboxyl and amino termini of (S)-valine-derived thiazole amino acid.

P-glycoprotein (P-gp) serves as a therapeutic target for the development of multidrug resistance reversal agents. In this study, we synthesized 21 novel compounds by peptide coupling at corresponding carboxyl and amino termini of (S)-valine-based bis-thiazole and monothiazole derivatives with diverse chemical scaffolds. Using calcein-AM efflux assay, we identified compound 28 (IC50 = 1.0 µM) carrying 3,4,5-trimethoxybenzoyl and 2-aminobenzophenone groups, respectively, at the amino and carboxyl termini of the monothiazole zwitter-ion. Compound 28 inhibited the photolabeling of P-gp with [(125)I]-iodoarylazidoprazosin with IC50 = 0.75 µM and stimulated the basal ATP hydrolysis of P-gp in a concentration-dependent manner (EC50 ATPase = 0.027 µM). Compound 28 at 3 µM reduced resistance in cytotoxicity assay to paclitaxel in P-gp-expressing SW620/Ad300 and HEK/ABCB1 cell lines. Biochemical and docking studies showed site-1 to be the preferable binding site for 28 within the drug-binding pocket of human P-gp.

Design, synthesis, and biological evaluation of (S)-valine thiazole-derived cyclic and noncyclic peptidomimetic oligomers as modulators of human P-glycoprotein (ABCB1).

Multidrug resistance caused by ATP binding cassette transporter P-glycoprotein (P-gp) through extrusion of anticancer drugs from the cells is a major cause of failure in cancer chemotherapy. Previously, selenazole-containing cyclic peptides were reported as P-gp inhibitors and were also used for co-crystallization with mouse P-gp, which has 87 % homology to human P-gp. It has been reported that human P-gp can simultaneously accommodate two to three moderately sized molecules at the drug binding pocket. Our in silico analysis, based on the homology model of human P-gp, spurred our efforts to investigate the optimal size of (S)-valine-derived thiazole units that can be accommodated at the drug binding pocket. Towards this goal, we synthesized varying lengths of linear and cyclic derivatives of (S)-valine-derived thiazole units to investigate the optimal size, lipophilicity, and structural form (linear or cyclic) of valine-derived thiazole peptides that can be accommodated in the P-gp binding pocket and affects its activity, previously an unexplored concept. Among these oligomers, lipophilic linear (13) and cyclic trimer (17) derivatives of QZ59S-SSS were found to be the most and equally potent inhibitors of human P-gp (IC50 =1.5 µM). As the cyclic trimer and linear trimer compounds are equipotent, future studies should focus on noncyclic counterparts of cyclic peptides maintaining linear trimer length. A binding model of the linear trimer 13 within the drug binding site on the homology model of human P-gp represents an opportunity for future optimization, specifically replacing valine and thiazole groups in the noncyclic form.

Neuroprotective effects of hesperidin, a plant flavanone, on rotenone-induced oxidative stress and apoptosis in a cellular model for Parkinson's disease.

Rotenone a widely used pesticide that inhibits mitochondrial complex I has been used to investigate the pathobiology of PD both in vitro and in vivo. Studies have shown that the neurotoxicity of rotenone may be related to its ability to generate reactive oxygen species (ROS), leading to neuronal apoptosis. The current study was carried out to investigate the neuroprotective effects of hesperidin, a citrus fruit flavanol, against rotenone-induced apoptosis in human neuroblastoma SK-N-SH cells. We assessed cell death, mitochondrial membrane potential, ROS generation, ATP levels, thiobarbituric acid reactive substances, reduced glutathione (GSH) levels, and the activity of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) using well established assays. Apoptosis was determined in normal, rotenone, and hesperidin treated cells, by measuring the protein expression of cytochrome c (cyt c), caspases 3 and 9, Bax, and Bcl-2 using the standard western blotting technique. The apoptosis in rotenone-induced SK-N-SH cells was accompanied by the loss of mitochondrial membrane potential, increased ROS generation, the depletion of GSH, enhanced activities of enzymatic antioxidants, upregulation of Bax, cyt c, and caspases 3 and 9, and downregulation of Bcl-2, which were attenuated in the presence of hesperidin. Our data suggests that hesperidin exerts its neuroprotective effect against rotenone due to its antioxidant, maintenance of mitochondrial function, and antiapoptotic properties in a neuroblastoma cell line.