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The aim of this study is to develop co-encapsulation of quercetin (QCT) and superparamagnetic iron oxide nanoparticles (SPIONs) into methoxy-poly(ethylene glycol)-b-oligo(ɛ-caprolactone), mPEG750-b-OCL-Bz micelles (QCT-SPION-loaded micelles) for inhibition of hepatitis B virus-transfected hepatocellular carcinoma (HepG2.2.15) cell growth. QCT-SPION-loaded micelles were prepared using film hydration method. They were spherical in shape with an average size of 22-55 nm. The best QCT-SPION-loaded micelles showed entrapment efficiency and loading capacity of QCT at 70% and 3.5%, respectively, and of SPIONs at 15% and 0.8%, respectively. Transverse (T2) relaxivity of SPIONs was 137 mM-1s-1. SPION clusters present inside the core of QCT-SPION-loaded micelles increased T2 relaxivity value (246 mM-1s-1) indicating the good magnetic resonance imaging sensitivity of QCT-SPION-loaded micelles in comparison with SPIONs. QCT-SPION-loaded micelles could be taken up by HepG2.2.15 cells and showed higher cytotoxicity than QCT. Furthermore, these cells were arrested by QCT-SPION-loaded micelles at the G0/G1 phase of cell cycle. QCT-SPION-loaded micelles accumulated in the vicinity of Neodymium Iron Boron (NdFeB) magnetic disc, resulting in the potent inhibition of cancer cell growth at the strong magnetic field strength. In conclusion, mPEG750-b-OCL-Bz micelles are a promising multi-functional vehicle for co-delivery of QCT and SPIONs for disease monitoring and therapies of hepatocellular carcinoma.

We investigated the possibility to grow molecularly porous amino-silane layers on glass-like substrates. The goal of this work is to show that it is possible to substantially increase the sensitivity of a fluorescence sensor by adjusting the functionalization strategy. Two methods are studied, one using APTMS only and another one using both APTMS and APDMS. We show that, using the second method, sensor sensitivity is improved by a factor of about 5. In order to demonstrate this, we applied the technique to the grafting of fluorescein in order to build a fluorescence pH sensor.

This research was designed to visualize cellular response – in particular the generation of intracellular ROS – to stimulation by polycyclic aromatic hydrocarbon (PAH). We used chloroauric acid (HAuCl4) as a molecular probe for visualizing intracellular ROS generated by the stimulation of benzo[a]pyrene (BaP). The chloroauric acid undergoes a spontaneous reduction reaction, assisted by the intracellular ROS, into gold nanoclusters (AuNCs). As a result, we can visualize the ROS via optical imaging technique. According to MTT assay, the chloroauric acid exhibited good biocompatibility. The AuNCs produced in the cells were approximately 2–3 nm in diameter with a green fluorescent property. Cellular imaging showed that BaP induced the formation of AuNCs within the cells, leading to a high relative cellular fluorescent intensity with a considerable extent of scatter light. Thus, this probe is an efficient molecular imaging probe for visualizing intracellular ROS.

In this study, quercetin (QCT), a flavonoid with high anticancer potential, was loaded into polymeric micelles of PEG-OCL (poly(ethylene glycol)-b-oligo(ε-caprolactone)) with naphthyl or benzyl end groups in order to increase its aqueous solubility. The cytostatic activity of the QCT-loaded micelles toward different human cancer cell lines and normal cells was investigated. The results showed that the solubility of QCT entrapped in mPEG750-b-OCL micelles was substantially increased up to 1 mg/ml, which is approximately 110 times higher than that of its solubility in water (9 μg/ml). The average particle size of QCT-loaded micelles ranged from 14 to 19 nm. The QCT loading capacity of the polymeric micelles with naphthyl groups was higher than that with benzyl groups (10% and 6%, respectively). QCT-loaded, benzyl- and naphthyl-modified micelles effectively inhibited the growth of both sensitive and resistance cancer cells (human erythromyelogenous leukemia cells (K562) and small lung carcinoma cells (GLC4)). However, the benzyl-modified micelles have a good cytocompatibility (in the concentration range investigated (up to 100 μg/ml), they are well tolerated by living cells), whereas their naphthyl counterparts showed some cytotoxicity at higher concentrations (60-100 μg/ml). Flow cytometry demonstrated that the mechanism underlying the growth inhibitory effect of QCT in its free form was inducing cell cycle arrest at the G2/M phase. Benzyl-modified micelles loaded with QCT also exhibited this cycle arresting the effect of cancer cells. In conclusion, this paper shows the enhancement of solubility and cell cycle arrest of QCT loaded into micelles composed of mPEG750-b-OCL modified with benzyl end groups. These micelles are therefore considered to be an attractive vehicle for the (targeted) delivery of QCT to tumors.

Problem statement: We have previously analyzed the interaction of BSA with flavonoids by using FRET. In this study, the role of BSA on increasing in solubility and on carrying the quercetin derivatives thus enhanced their anticancer efficacy against drug-sensitive and drug-resistant cells were conducted. Approach: The macroscopic (KD) and microscopic (kd) binding constant of the complexation and the cellular partition of molecules were analyzed using FRET and HPLC method, respectively. Results: The KD values reflex the stability of complexes was in the order of rutin > quercetrin > quercetin. BSA was a suitable carrier of quercetin (KD = 1.68×105 M−1) which spontaneously release the molecule into solutions and cells. The substitution of rhamnoside (KD = 1.37×105 M−1) and rutinoside (KD = 5.0×104 M−1) at C3 yielded an increase in stability of the complexes. Rutin was tightly bound to BSA resulting in the changes in mode of action. Conclusion: The macroscopic binding constant was directly influenced on the cellular uptake of molecules and the suitable range of binding constant was KD≥105 M−1 by which the carrier can be useful for increasing the solubility of drug and also spontaneously release the drug into the solution and cells.

Problem statement: Cellular drug resistance to anticancer agents is major obstacle in cancer chemotherapy and the mechanisms by which these MDR cells possess for protecting themselves to survive prolonged exposure to cytotoxic agents still debating. The study aimed to clarify the role of P-glycoprotein (Pgp) and enhanced drug sequestration in lysosomes to confer the multidrug resistance K562 cells with varied degree of Pgp expression. Approach: Erythromyelogenous leukemic K562 and its corresponding Pgp-over expression K562/adr (RF= 26.5) and K562/10000 (RF = 39.6) cells were used. The transport of intrinsic fluorescence molecules including acridine orange and pirarubicin across plasma membrane of living cells was performed by using spectrofluorometric and flow cytometric analysis. Results: Pirarubicin passively diffused through the plasma membrane of K562, K562/adr and K562/10000 cells with the same values of k+ = 3.4±0.3 pL. s-1.cell-1. Similar results were found for acridine orange, which passively diffused through plasma membrane of these cell lines about 30-fold faster than pirarubicin. The mean rate of Pgp-mediated efflux coefficient (ka) of pirarubicin was equal to 2.6 ± 0.9 pL.s-1.cell-1 for K562/adr and 4.7 ± 1.0 pL.s-1.cell-1 for K562/10000 cells. The Pgp-mediated efflux of acridine orange could not be determined for K562/adr cells while an enhancement of exocytosis in K562/10000 cells was characterized. The acridine orange exhibited antiproliferative activity and IC50 for K562, K562/adr and K562/10000 cells was 447±40, 715±19 and 1,719±258 nM, respectively. Cytotoxicity of acridine orange was increased by 2-fold in the presence of and 25 nM monensin. Conclusion: The results clearly demonstrated for the first time that by using the same methods and cell lines. The predominant cellular defense mechanism determined in multidrug resistant cells depends upon the nature of molecular probes used. As molecular probe, pirarubicin clearly showed that the Pgp-mediated efflux of drug play as predominant mechanism while AO clearly demonstrated the role of drug sequestration in lysosomes following an enhance exocytosis in both MDR sublines.

Multidrug resistance was an obstacle in cancer chemotherapy because the cells decreased their intracellular drug accumulation by energy-dependent compounds efflux pumps such as P-glycoprotein (P-gp). This study observed some iodinated radiographic contrast media, diatrizoate, iopromide and iotrolan affected the cellular energetic state and the kinetics of P-gp in drug-sensitive K562 and drug resistant K562/adr cell lines using spectrophotometer and spectrofluorometer. By colorimetric MTT assay, it was found that contrast media (0-3500 μM) had no effect on both K562 and K562/adr cell viabilities, but in co-treatment with daunorubicin (DNR), diatrizoate decreased cell viability in K562/adr cells by decreasing ICso of DNR from 610.7 ±74.5 nM to 360±108.9 nM. The change in cellular energetic state was studied using rhodamine B as a probe to estimate mitochondrial membrane potential (ΔΨm). The results showed that 3500 μM diatrizoate decreased ΔΨm from 162.2±0.3 mV to 86.9±9.9 mV in K562/adr cells. The kinetics of P-gp-mediated efflux of DNR could be reduced by diatrizoate from 0 (no inhibition) to 0.65±0.11. This inhibition could be partially prevented in co-incubation with 20 nM concanamycin A or 10 μM cytochalasin B. Among the three molecules, diatrizoate showed the best efficiency. It could be proposed for further studies that diatrizoate could be used as MDR identification or MDR imaging and also acted as MDR sensitizing agent in cancer treatments.

Problem statement: Plant derived fungicides are now being subjects of many research groups. These secondary metabolites have enormous potential to inspire and influence modern agrochemical research. The study aimed to investigate the antifungal activity and their potential use as fungicides in the agriculture of crude extracts and purified compounds derived from plants used in traditional medicines. Approach: Four medicinal plants including A. galanga, C. longa, B. pandurata and C. odorata were selected and percolated with hexane, ethyl acetate, acetone or methanol. The extracts were purified and elucidated their chemical structures. Disc mycelial growth inhibition was applied in order to determine their anti P. capsici activity and the field study was performed to determine their potential use in controlling fungal infection in chili plants compared with commercial fungicides such as captan and bio-control Trichoderma virens. Results: All crude extract inhibited mycelial growth of the fungus performed with similar efficacy. ED90 was equal to 300 ppm. Among plants studied B. pandurata was the most potent against P. capsici. The proposed active ingredients were pinostrobin and pinocembrin. In the field study, pinocembrin mediated the same anti P. capsici activity as captan. B. pandurata can protect chili from infection, thus increasing crop yield of chili comparable to Trichoderma virens. Conclusion: The results clearly showed that the extracts of the four plants studied could be considered as potential sources of novel fungicides. Particularly, B. pandurata has a very high potential as raw material for developing the antifungal molecule of non-petrochemical, naturally eco-friendly, easily obtainable and not toxic to human beings and environment, at least for use in chili growing.

The objectives of this study were to investigate the behavior of flavonoids in an aqueous physiological buffer and to determine the structural and functional group substitution which is responsible for their anticancer action. The de- protonated anionic form of 7 flavonoids can easily be determined using spectrophotometry, and owing to its charged state, is highly soluble in aqueous physiological buffer and is not prone to aggregation. The protonated form of these 7 flavon- oids is much less soluble and tends to aggregate following precipitation. For all flavonoids studied except catechin and 5,5� -dihydroxy-6,7,3� ,4� -tetramethoxyflavone, it was possible to determine the rates of deprotonation; pKa value of eri- odictyol, apigenin, kaempferol, quercetin, WP 279, and WP 283 was equal to 7.00, 8.72, 7.86, 8.30, 7.70 and 9.90, respec- tively. The methoxyl group substitutions in place of hydrogen atoms and/or hydroxyl groups at various positions of car- bon atoms in ring A, B and C particularly WP 283 resulted in an increase in the solubility, lipophilicity, and specifically its anticancer efficacy (by 60-fold). The neutral forms of flavonoids are predominantly active molecules and the active sites responsible for anticancer activity are found in ring A and C, especially C4=O, C5-OH and C2=C3.

This article examines a non-invasive spectrofluorometric method using the 2′,7′-dichlorofluorescein diacetate (DCHF-DA) assay for quantifying the intracellular reactive oxygen species (ROSi) produced in four cultured cancer cell lines: drug-sensitive (K562) and drug-resistant (K562/adr) human erythromyelogenous leukemia cell lines, and drug-sensitive (GLC4) and drug-resistant (GLC4/adr) human small cell lung carcinoma cell lines. The oxidation of the probe to the fluorescent dichlorofluorescein (DCF) was continuously monitored by following the DCF fluorescence intensity as a function of time using a standard spectrofluorometer in the presence of an extracellular DCF fluorescence quencher (Co2+). By fitting the spectrofluorometric data to a kinetic model based on the following two reactions: (i) deacetylation of DCHF-DA to the oxidant-sensitive compound 2′,7′-dichlorofluorescein (DCHF) by cellular esterase enzymes (pseudo-first-order rate constant: ke) and (ii) oxidation of DCHF by ROSi (second-order rate constant: k2), the parameters intervening in DCF formation, ke and the product of k2 by the ROSi concentration, were quantitatively determined for the different cell lines studied. The results revealed that the intracellular esterase content or activity is similar in K562, K562/adr, and GLC4 cells, but 5-fold higher in GLC4/adr cells. The product k2[ROSi] was found to be similar in the four cell lines considered, with a mean value of (5.3±0.9)×10−7 cell−1 s−1. Assuming that H2O2 (in combination with peroxidases) is the primary responsible species for DCHF oxidation in intact cells, and using the rate constant value k 2 = 790 ± 62 M - 1 s - 1 established in our laboratory for the reaction of DCHF with H2O2 in the presence of horseradish peroxidase, the mean value of the intracellular levels of ROSi in those cells was estimated to be 0.67±0.16 nM per cell. Such a value compares favorably to H2O2 intracellular steady-state concentrations that have been estimated in the literature for a few other cell types.

Natural products from plants such as flavonoids are potential drugs to overcome multidrug resistance (MDR) in cancer treatments. However, their modes of action are still unclear. In this study, the effects of quercetin on mitochondrial membrane potential (ΔΨm) change as well as quercetin's ability to induce apoptosis and inhibit Pgp-mediated efflux of 99mTc-MIBI in K562/adr cells were investigated. Quercetin exhibits cytotoxicity against erythroleukemic cells: IC50 are 11.0 ± 2.0 µmol/L and 5.0 ± 0.4 µmol/L for K562 and K562/adr, respectively. Quercetin induces cell death via apoptosis in both K562 and K562/adr cells and does not inhibit Pgp-mediated efflux of 99mTc-MIBI. Quercetin (10 µmol/L, 3 h) and etoposide (100 µmol/L, 24 h) induce similar levels of apoptosis in K562 and K562/adr cells. Quercetin induces an increase followed by a decrease in |ΔΨm| value depending on its concentration. A decrease in the |ΔΨm| value is associated with an increase in the percentage of early apoptotic cells. It is clearly shown that quercetin results in a spontaneous ΔΨm change during apoptotic induction. Therefore, quercetin is potentially an apoptotic-inducing agent, which reacts at the mitochondrial level.Key words: multidrug resistance (MDR), quercetin, apoptosis, 99mTc-Annexin V, mitochondrial membrane potential (ΔΨm), 99mTc-MIBI.

Overcoming MDR (multidrug resistance) phenomena is a crucial aspect of cancer chemotherapy research. Artemisinin and its derivatives have been found to inhibit the proliferation of cancer cells in the microM range. They poorly inhibited the function of P-glycoprotein and did not inhibit the function of MRP1-protein. The concentrations required to inhibit by 50% the function of P-glycoprotein are 110+/-5 microM. Artemisinin, artesunate and dihydroartemisinin efficiently decreased the mitochondrial membrane potential, leading to a decrease in intracellular ATP in all cell lines tested: by 30 to 50% at 5 microM. Artemisinin, artesunate and dihydroartemisinin increased cytotoxicity of pirarubicin and doxorubicin in P-glycoprotein-overexpressing K562/adr, and in MRP1-overexpressing GLC4/adr, with the delta(0.5) ranging from 200 to 860 nM, but not in their corresponding drug-sensitive cell lines. In this range of concentrations these compounds did not decrease the function of P-glycoprotein, suggesting a mechanism by which the drugs did not reverse MDR phenomenon at the P-glycoprotein level but at the mitochondrial level.

The new potential tracer of bone imaging, AHBDP-Sn(II)-TcO.3H2O was synthesized by reducing the TcO4− to TcO2+ in the presence of AHBDP and Sn(ll)’s reducing agent. We found that tin rapidly forms a stable complex with AHBDP, giving AHBDP-Sn(II).3H2O. In the excess of AHBDP-Sn(ll).3H2O, the AHBDP-Sn(II).3H2O coordinates with TcO2+ to give AHBDP-Sn(II)-TcO.3H2O which could polymerise or oligomerise to give hydrophobic species. The overall process appears as a first-order reaction (K= 0.67 ± 0.005s−1). In rats, the fixation of AHBDP-Sn(II)-99m TcO. 3H2O on bone is homogeneous and the scintigraphic images have the same quality as those of 1-hydroxymethane-1,1-diphosphonate-Technetium (HMDP-99mTc). The activity in non-target organs was neglible.

The number of patients with cancer is increasing. New therapeutic agents to overcome drug-resistant tumors are urgently needed. Cyrtosperma johnstonii N.E. Br. (Araceae) is used for treatment of cancer in Thai traditional medicine. This study aimed to evaluate antioxidant activity and cytotoxicity of C. johnstonii extracts on human cancer cells.Dried powder of C. johnstonii rhizomes was extracted with several solvents. The 0.1 mg/ml extract solution was tested for antioxidant activity by 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) assays. Color formation from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to determine cell viability. Standardization of the extract was performed by high-performance liquid chromatography (HPLC) with photodiode array detector at 254 and 360 nm. Cell cycle arrest was evaluated by flow cytometry after 5 min, 12 h and 24 h treated with 20 µg/ml of the acetone extract.The acetone extract exhibited the highest phenolic content and antioxidant activity (TEAC and EC values = 19.2 ± 0.14 and 19.2 ± 0.31 mM/mg, respectively). The IC₅₀ values for leukemia ranged from 11 ± 1 to 29 ± 3 µg/ml and from 5 ± 2 to 6 ± 0 µg/ml for small cell lung carcinoma cells. Cell cycle arrest occurred at the G2/M phase followed by apoptosis. HPLC analysis revealed that rutin is the major constituents of the extract.The acetone extract of C. johnstoni is a promising source of natural antioxidants and anticancer. The extract inhibits cancer cells effectively with less effect on normal cells.

The oxidation of sodium diethyldithiocarbamate (DDC) by hydrogen peroxide or superoxide radicals has been investigated. Hydrogen peroxide oxidizes DDC, leading to the formation of a hydrated form of disulfiram, a dimer of DDC having a disulfide group. In equimolar conditions, the overall process appears as a first-order reaction (k = 0.025±0.005 s −1 ), the first step being a second-order reaction (k = 5.0±0.1mol −1 .1. s −1 ). No radical intermediate was observed in this process. In the presence of an excess of any of the reagents, the hydrated form of disulfiram transforms into different products corresponding to the fixation of oxygen by sulfur atoms or replacement of C = S group by ketone function, in the presence of an excess of hydrogen peroxide. Superoxide anions (produced by steady-state 60 Co γ-radiolysis) oxidize DDC, yielding similar products to those obtained with hydrogen peroxide with a maximum oxidation G-value of 0.3 μmol.J −1 . The rate constant k(O 2 ·− + DDC) is equal to 900 mol −1 . 1. s −1 .

Xanthone exhibits several medicinal activities and especially it inhibits the growth of cancer cells. However, the use of xanthone is limited because of its low aqueous solubility and systemic toxicity. In the present study xanthone was loaded into poly(ethylene glycol)-b-poly[N-(2-hydroxypropyl) methacrylamide-dilactate] mPEG-b-p(HPMAm-Lac(2)) micelles in order to overcome these drawbacks. It was shown that xanthone could be loaded in these micelles up to 2 mg/mL with ~100% entrapment efficiency and ~20% loading capacity. The average particle diameter of the xanthone loaded mPEG-b-p(HPMAm-Lac(2)) micelles as determined by dynamic light scattering ranged from 84 to 112 nm. In vitro assays showed that xanthone in its free form as well as loaded in polymeric micelles had a high cytotoxicity towards both doxorubicin sensitive and, importantly, resistant cancer cells. On the other hand empty mPEG-b-p(HPMAm-Lac(2)) micelles did not show any cytotoxicity towards normal cells (PBMCs). Interestingly, the cytostatic effect of xanthone towards normal cells was masked when loaded in the micelles. The mechanism of cell growth inhibition by xanthone-loaded polymeric micelles was mediated through induction of apoptosis, as evidenced from a subdiploid peak of propidium iodide stained cells using flow cytometric analysis. From the results of this study it can be concluded that xanthone has potent anticancer activity not only on sensitive but also on doxorubicin resistant cancer cell lines. mPEG-b-p(HPMAm-Lac(2)) micelles are therefore attractive delivery systems of xanthone for the treatment of cancer.

Background Multidrug resistance (MDR) is a major obstacle in cancer treatment and is often the result of overexpression of the drug efflux protein, P-glycoprotein (P-gp), as a consequence of hyperactivation of NFκB, AP1 and Nrf2 transcription factors. In addition to effluxing chemotherapeutic drugs, P-gp also plays a specific role in blocking caspase-dependent apoptotic pathways. One feature that cytotoxic treatments of cancer have in common is activation of the transcription factor NFκB, which regulates inflammation, cell survival and P-gp expression and suppresses the apoptotic potential of chemotherapeutic agents. As such, NFκB inhibitors may promote apoptosis in cancer cells and could be used to overcome resistance to chemotherapeutic agents. Results Although the natural withanolide withaferin A and polyphenol quercetin, show comparable inhibition of NFκB target genes (involved in inflammation, angiogenesis, cell cycle, metastasis, anti-apoptosis and multidrug resistance) in doxorubicin-sensitive K562 and -resistant K562/Adr cells, only withaferin A can overcome attenuated caspase activation and apoptosis in K562/Adr cells, whereas quercetin-dependent caspase activation and apoptosis is delayed only. Interestingly, although withaferin A and quercetin treatments both decrease intracellular protein levels of Bcl2, Bim and P-Bad, only withaferin A decreases protein levels of cytoskeletal tubulin, concomitantly with potent PARP cleavage, caspase 3 activation and apoptosis, at least in part via a direct thiol oxidation mechanism. Conclusions This demonstrates that different classes of natural NFκB inhibitors can show different chemosensitizing effects in P-gp overexpressing cancer cells with impaired caspase activation and attenuated apoptosis.

We sought to investigate the early biological effects of chlorpyrifos among 53 Thai fruit farm workers by measuring the plasma cholinesterase (PChE) and red blood cell cholinesterase (AChE) activities, a biomarker of organophosphate (OPs) pesticide during one fruit crop. The ChE activity (V(m)/K(m)) was spectrophotometrically analyzed before and after exposing to chlorpyrifos. The V(m)/K(m) values of both non-spraying and spraying seasons are found as normal distribution pattern. The median PChE and AChE activities among farm workers in the non-spraying season were 2.3 x 10(-3) s(-1) and 7.26 x 10(-5) s(-1), respectively. The median PChE and AChE activities of the farm workers in the spraying season were 2.02 x 10(-3) s(-1) and 5.95 x 10(-5) s(-1), respectively. The mean V(m)/K(m) values of PChE shifted left (t-test, p=0.013), indicating a decrease in PChE activity in the farm workers exposed to chlorpyrifos. However, the V(m)/K(m) values of AChE in nonspraying season and in the spraying season were not different (t-test, p=0.246). We propose that PChE activity can be used as a biomarker for monitoring early toxicity induced by chlorpyrifos insecticide.

5-Aryl-3-(4-hydroxyphenyl)-1,3,4-oxadiazole-2(3H)-thiones 3 were prepared by cyclocondensation of 1-(4-hydroxyphenyl)-2-aroylhydrazines with thiophosgene. All compounds exhibited antiproliferation activity in K562, IC(50) ranging from 24 to 94 micro M comparable efficacy with apigenin and genistein and showed more potent antiproliferation of K562/adr cells, highly expressing P-glycoprotein. Compounds 3g, 3e and 3a inhibited the function of P-glycoprotein with the alpha(0.5) equal to 10+/-3 micro M, 21+/-5 micro M and 34+/-7 micro M, respectively.

We sought to investigate the apoptosis-inducing activities of quercetin, Siamois 1, and Siamois 2 against invasive estrogen-receptor negative MDA-MB 435 cells xenografted in athymic nude mice. This study clearly demonstrated that these compounds exhibited apoptosis-inducing activities in cell culture system. Quercetin (20 microg/mL), Siamois 1 (100 microg/mL), and Siamois 2 (200 microg/mL) can induce apoptotic cell death by 40 +/-5%, 44 +/- 14 %, and 31 +/- 13 %, respectively. Two-fold of IC50 of these compounds were clearly found to induce apoptosis in breast tumor tissue which can be determined by 99mTc-Annexin V scintigraphy and histological staining. This is the first report that the apoptosis-inducing effects of quercetin, Siamois 1 and Siamois 2 on the MDA-MB 435 cell in vitro were effectively extrapolated to the in vivo situation. These compounds might be considered as a simple dietary supplement and with further clinical investigation for their use as a nutrition-based intervention in breast cancer treatment.

Problem statement: Quercetin and its glycoside derivatives are increasingly receiving interests as new generation of anticancer molecules and were recognized by multidrug resistant transporters such as P-glycoprotein and MRP1 protein. Of relevance to their use as anticancer agents alone or in combination with other agents, this study aims to analyze the interaction of the compounds with the MDR transporters including P-glycoprotein and MRP1 protein in living multidrug resistant cells. Approach: The potential MDR reversing action of flavonoids was assessed by using the co-treatment of anticancer drug, pirarubicin or daunorubicin and quercetin, quercetrin or rutin compared with the series of co-treatment of pirarubicin or daunorubicin and the known inhibitor such as cyclosporine A and verapamil. The evidence of direct interaction of molecules with MDR protein was investigated by measuring the ability of inhibition of the rate of P-glycoprotein- and MRP1-mediated efflux of pirarubicin out of cells. Results: Quercetin and its glycoside derivatives efficiently inhibited cancer cell proliferation and re-sensitize the MDR cells to pirarubicin but not for daunorubicin. Our results clearly show that quercetin, quercetrin except rutin non-competitively inhibited the function of P-glycoprotein in K562/adr and MRP1 in GLC4/adr cells. The determined KI value of P-glycoprotein was equal to 0.33 µM for quercetin and 1 µM for quercetrin and KI value of MRP1 was equal to 0.45 mM for quercetin and 0.5 mM for quercetrin. Conclusion: The overall results demonstrated that quercetin, quercetrin and rutin should be considered as potential pharmaceutical molecules that might be used as MDR inhibitors.