Aqueous and cosolvent solubility data for drug-like organic compounds

Recently 2 QSPR-based in silico models were developed in our laboratories to predict the aqueous and non-aqueous solubility of drug-like organic compounds. For the intrinsic aqueous solubility model, a set of 321 structurally diverse drugs was collected from literature for the analysis. For the PEG 400 cosolvent model, experimental data for 122 drugs were obtained by a uniform experimental procedure at 4 volume fractions of PEG 400 in water, 0%, 25%, 50%, and 75%. The drugs used in both models represent a wide range of compounds, with log P values from -5 to 7.5, and molecular weights from 100 to >600 g/mol. Because of the standardized procedure used to collect the cosolvent data and the careful assessment of quality used in obtaining literature data, both data sets have potential value for the scientific community for use in building various models that require experimental solubility data.     

药物设计和研发中的定量构动关系研究进展

概述定量构动关系研究的内容和方法。综述定量构动关系研究中对药动学特性的预测,包括对药物吸收、分布、代谢和排泄特征的预测,以及定量构动关系研究对药物设计和研发的指导意义。     

Determination of a Human Hepatic Microsomal Scaling Factor for Predicting in Vivo Drug Clearance

Purpose To determine a microsomal scaling factor for human liver suitable for prediction of in vivo drug clearance from in vitro data and to explore the role of inter-liver variability in this factor on the reported underprediction from microsomal parameters. Methods Cytochrome P450 (henceforth P450) content in whole homogenates and microsomes from 38 donor livers was used to determine a microsomal scaling factor. In a subset (n = 20) of these preparations, individual P450 enzymes were examined by Western blotting and selective probe activities were determined. Results The scaling factor from 38 livers averaged 40 mg microsomal protein per gram liver with a coefficient of variation of 31%. Western blotting experiments indicated that there was no P450 enzyme-specific trend in the distribution of individual P450 enzymes in liver microsomes relative to whole homogenate. Predictions based on an average scaling factor resulted in a satisfactory prediction of intrinsic clearance of three benzodiazepines similar to that obtained using individual factors for the same livers. Conclusion A value for human liver microsomal scaling of 40 mg microsomal protein per gram liver has been established. The reason for underprediction previously reported for 52 different drug substrates was not the use of an incorrect value for the scaling factor.     

Analysis of Drug Permeation Across Caco-2 Monolayer: Implication for Predicting In Vivo Drug Absorption

Purpose. The aim of the present work is to characterize in vitro drug permeation processes across Caco-2 monolayer and to identify the advantages of this cultured cell system in predicting in vivo drug absorption after oral administration. Methods. The passive permeability of various drugs through Caco-2 monolayer was measured using Ussing-type chambers and compared with that of the isolated rat jejunum and colon. The in vivo drug permeability to the intestinal membrane was estimated by means of an intestinal perfusion study using the rat jejunum. Results. In Caco-2 monolayer, drug permeability increased with increasing drug lipophilicity and showed a good linear relationship with the in vivo permeability. In contrast, in the isolated jejunum and colon, the permeability of high lipophilic drugs was almost constant and, propranolol, a drug with the highest lipophilicity, hardly passed through the jejunal membrane in vitro. As a result, there was no significant relationship between in vitro and in vivo drug permeability in rat jejunum. However, the amount of drugs accumulated in the jejunal mucosa increased with increasing drug lipophilicity even under the in vitro condition. Conclusions. The permeation and the accumulation studies suggested that the rate-limiting process of in vitro permeation of lipophilic drugs through the intestinal membrane differs from that of in vivo drug absorption. On the other hand, drug permeation through Caco-2 monolayer, which consists of an epithelial cell layer and a supporting filter, is essentially the same process as that of in vivo drug absorption. We concluded that the simple monolayer structure of a cultured cell system provides a distinct advantage in predicting in vivo drug absorption.     

Predicting Oral Absorption of Drugs: A Case Study with a Novel Class of Antimicrobial Agents

Purpose. The purpose of this work was to evaluate an oral absorption prediction model, maximum absorbable dose (MAD), which predicts a theoretical dose of drug that could be absorbed across rat intestine based on consideration of intestinal permeability, solute solubility, intestinal volume, and residence time. Methods. In the present study, Caco-2 cell permeability, as a surrogate for rat intestinal permeability, and aqueous solubility were measured for 27 oxazolidinones. The oxazolidinones are a novel class of potential antibacterial agents currently under investigation. These values were used to estimate MAD for each of the compounds. Finally, these predicted values were compared to previously measured bioavailability data in the rat in order to estimate oral absorption properties. Results. A reasonably good correlation between predicted dose absorbed and bioavailability was observed for most of the compounds. In a few cases involving relatively insoluble compounds, absorption was underestimated. For these compounds while aqueous solubility was low, solubility in 5% polysorbate 80 was significantly higher, a solvent possibly more representative of the small intestinal lumen. Conclusions. These results suggest that MAD may be useful for prioritizing early discovery candidates with respect to oral absorption potential. In the case of compounds with poor aqueous solubility, additional factors may have to be considered such as solubility in the intestinal lumen.     

Use of an in Vitro Model for the Assessment of Muscle Damage from Intramuscular Injections: in Vitro-in Vivo Correlation and Predictability with Mixed Solvent Systems

The potential of binary mixtures of propylene glycol–water, ethanol–water, and polyethylene glycol 400–water to cause skeletal muscle damage (myotoxicity) following intramuscular injection was examined with an in vitro model using the isolated rat muscle. At moderate concentrations (20–40%, v/v) of the organic cosolvent, the order of myotoxicity was propylene glycol > ethanol polyethylene glycol 400. The in vitro results were then compared with in vivo toxicity in rabbits after injection of normal saline, 40% (v/v) polyethylene glycol 400, 40% (v/v) propylene glycol, indocyanine green in normal saline, and indocyanine green in 40% (v/v) propylene glycol. Employing the area under the creatine kinase activity curve from 0 to 72 hr as the index of skeletal muscle damage, an excellent in vitro–in vivo correlation was observed. The basic myotoxicity relationships obtained from the binary cosolvent systems were then used to examine the myotoxicity of ternary organic cosolvent mixtures. Several mixed solvent systems with the same theoretical molar solubilization power for a model compound, diazepam, were selected to determine (1) if myotoxicity can be reduced by changing the composition of the ternary mixtures and (2) if myotoxicity of the individual components is additive. For the solvent systems containing propylene glycol, ethanol, and water, the total myotoxicity equaled the sum of the individual myotoxicity of each component. In contrast, for the solvent systems containing polyethylene glycol 400, the total myotoxicity was only half of the sum of individual toxicities. These results suggest that polyethylene glycol 400 in mixed cosolvent systems might have a protective effect on the myotoxicity generated by intramuscular injections.     

Evaluation of Human Liver Slices and Reporter Gene Assays as Systems for Predicting the Cytochrome P450 Induction Potential of Drugs in Vivo in Humans

Purpose The aim of the study was to investigate the feasibility of predicting human in vivo cytochrome P450 (CYP) induction properties of drugs using in vitro methods. Methods The CYP induction potential of compounds was tested in human liver slices and in reporter gene assays for the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR). Results In human liver slices, CYP activities decreased dramatically over the experimental period, whereas mRNA levels could reliably be used to investigate CYP1A, 2C9, and 3A4 induction. However, the interindividual variations and demanding experimentation limit the use of liver slices in screening programs. Reporter gene assays are robust and reliable assays, amenable to high throughput screening. Several compounds activated AhR. The relevance of this activation, however, needs to be further investigated since there are no clear reports on drugs inducing CYP1A in vivo. The results from the PXR assay could be used to correctly classify compounds with known CYP3A induction properties when relating in vivo AUC_tot to PXR EC₅₀ values. Conclusions Liver slices are a valuable model to study the regulation of a larger number of enzymes by single compounds. The PXR reporter gene assay could be used as a reliable screening method to predict CYP3A induction in vivo.     

An in Vitro/in Vivo Correlation for the Disintegration and Onset of Drug Release from Enteric-Coated Pellets

An empirical mass-transfer model for enteric-coating dissolution that uses in vitro dissolution data to characterize the pH-dependent solubility properties of the polymer film and a mass-transfer coefficient determined from in vivo dissolution or disintegration studies is developed. Once the in vivo mass- transfer coefficient has been evaluated, it can be used in conjunction with in vitro dissolution data from other formulations to predict the in vivo time to disintegration and onset of drug release. Results of in vitro dissolution experiments using the USP basket dissolution apparatus and in vivo disintegration experiments using gamma scintigraphy with four enteric-coated pellet formulations are presented. The good agreement among the in vivo mass-transfer coefficients that were determined supports the validity of the model.     

Correlation Between Oral Drug Absorption in Humans,and Apparent Drug Permeability in TC-7 Cells,A Human Epithelial Intestinal Cell Line: Comparison with the Parental Caco-2 Cell Line

Purpose. To determine and compare the relationship between in vivo oral absorption in humans and the apparent permeability coefficients (P _app ) obtained in vitro on two human intestinal epithelial cell lines, the parental Caco-2 and the TC-7 clone. Methods. Both cell lines were grown for 5–35 days on tissue culture-treated inserts. Cell monolayers were analysed for their morphology by transmission electron micrography, and for their integrity with respect to transepithelial electrical resistance, mannitol and PEG-4000 transport, and cyclosporin efflux. P _app were determined for 20 compounds exhibiting large differences in chemical structure, molecular weight, transport mechanisms, and percentage of absorption in humans. Results. The TC-7 clone exhibits morphological characteristics similar to those of the parental Caco-2 cell line, concerning apical brush border, microvilli, tight junctions and polarisation of the cell line. The TC-7 clone however appeared more homogenous in terms of cell size. Both cell lines achieved a similar monolayer integrity towards mannitol and PEG-4000. Monolayer integrity was achieved earlier for the TC-7 clone, mainly due to its shorter doubling time, i.e. 26 versus 30 hours for parental Caco-2 cells. When using cyclosporin A as a P-glycoprotein substrate, active efflux was lower in the TC-7 clone than in the parental Caco-2 cells. The P_app and mechanisms of transport (paracellular or transcellular routes, passive diffusion and active transport) were determined for 20 drugs. A relationship was established between the in vivo oral absorption in humans and P_app values, allowing to determine a threshold value for P_appof 2 10^–6 cm/sec, above for which a 100% oral absorption could be expected in humans. Both correlation curves obtained with the two cell types, were almost completely superimposable. These studies also confirmed that the dipeptide transporter is underexpressed in both cell lines. Conclusions. On the basis of morphological parameters, biochemical activity and drug transport characteristics, the TC-7 clone appeared to be a valuable alternative to the use of parental Caco-2 cells for drug absorption studies.     

A Theoretical Basis for a Biopharmaceutic Drug Classification: The Correlation of in Vitro Drug Product Dissolution and in Vivo Bioavailability

A biopharmaceutics drug classification scheme for correlating in vitro drug product dissolution and in vivo bioavailability is proposed based on recognizing that drug dissolution and gastrointestinal permeability are the fundamental parameters controlling rate and extent of drug absorption. This analysis uses a transport model and human permeability results for estimating in vivo drug absorption to illustrate the primary importance of solubility and permeability on drug absorption. The fundamental parameters which define oral drug absorption in humans resulting from this analysis are discussed and used as a basis for this classification scheme. These Biopharmaceutic Drug Classes are defined as: Case 1. High solubility-high permeability drugs, Case 2. Low solubility-high permeability drugs, Case 3. High solubility-low permeability drugs, and Case 4. Low solubility-low permeability drugs. Based on this classification scheme, suggestions are made for setting standards for in vitro drug dissolution testing methodology which will correlate with the in vivo process. This methodology must be based on the physiological and physical chemical properties controlling drug absorption. This analysis points out conditions under which no in vitro-in vivo correlation may be expected e.g. rapidly dissolving low permeability drugs. Furthermore, it is suggested for example that for very rapidly dissolving high solubility drugs, e.g. 85% dissolution in less than 15 minutes, a simple one point dissolution test, is all that may be needed to insure bioavailability. For slowly dissolving drugs a dissolution profile is required with multiple time points in systems which would include low pH, physiological pH, and surfactants and the in vitro conditions should mimic the in vivo processes. This classification scheme provides a basis for establishing in vitro-in vivo correlations and for estimating the absorption of drugs based on the fundamental dissolution and permeability properties of physiologic importance.     

Drug Distribution in Human Skin Using Two Different In Vitro Test Systems: Comparison with In Vivo Data

Purpose. Two in vitro test systems used to study drug penetration into human skin—the Franz diffusion cell (FD-C) and the Saarbruecken penetration model (SB-M)—were evaluated, and the results were compared with data gained under analogous in vivo conditions. Methods. Excised human skin was used in all in vitro experiments. Flufenamic acid dissolved in wool alcohols ointment, was chosen as a model drug, and the preparation was applied using infinite dose conditions. To acquire quantitative information about the drug penetration, the skin was segmented into surface parallel sections at the end of each experiment, first by tape stripping the stratum corneum (SC), and second by cutting the deeper skin layers with a cryomicrotome. The flufenamic acid was extracted from each sample and assayed by high performance liquid chromatography (HPLC). For in vivo experiments, only the tape stripping technique was used. Results. a) Drug penetration into the SC: In both in vitro test systems the total drug amounts detected in the SC were found to increase over the different incubation times. Similar conditions were obtained in vivo, but on a lower level. Using Michaelis-Menten kinetics, the m_max value was calculated for the skin of two donors. The relations of the m_max values for the FD-C and the SB-M closely correspond (1.26 [donor 1] and 1.29 [donor 2]). A direct linear correlation of the drug amount in the SC and the time data were found for in vivo with both in vitro test systems.%b) Drug penetration into the deeper skin layers: The detected drug amounts in the deeper skin layers continuously increased with the incubation time in the SB-M, while in the FD-C, only very small drug amounts were observed after incubation times of 30 and 60 minutes. It was also noticed, that the drug amounts rose steeply at time points 3 and 6 hours. Additional studies showed a remarkable penetration of water into the skin from the basolateral acceptor compartment in the FD-C. This could explain the different drug transport into the deeper skin layers between the two in vitro test systems. Conclusions. Both in vitro models showed comparable results for the drug penetration into the SC and a robust correlation with in vitro data. Different results were obtained for the deeper skin layers. Whether a correlation between in vitro and in vivo data is also possible here has to be investigated by further experiments.     

Methods to Assess in Vitro Drug Release from Injectable Polymeric Particulate Systems

This review provides a compilation of the methods used to study real-time (37°C) drug release from parenteral microparticulate drug delivery systems administered via the subcutaneous or intramuscular route. Current methods fall into three broad categories, viz., sample and separate, flow-through cell, and dialysis techniques. The principle of the specific method employed along with the advantages and disadvantages are described. With the “sample and separate” technique, drug-loaded microparticles are introduced into a vessel, and release is monitored over time by analysis of supernatant or drug remaining in the microspheres. In the “flow-through cell” technique, media is continuously circulated through a column containing drug-loaded microparticles followed by analysis of the eluent. The “dialysis” method achieves a physical separation of the drug-loaded microparticles from the release media by use of a membrane, which allows for sampling without interference of the microspheres. With all these methods, the setup and sampling techniques seem to influence in vitro release; the results are discussed in detail, and criteria to aid in selection of a method are stated. Attempts to establish in vitro–in vivo correlation for these injectable dosage forms are also discussed. It would be prudent to have an in vitro test method for microparticles that satisfies compendial and regulatory requirements, is user friendly, robust, and reproducible, and can be used for quality-control purposes at real-time and elevated temperatures.     

Dissolution Testing as a Prognostic Tool for Oral Drug Absorption: Immediate Release Dosage Forms

Dissolution tests are used for many purposes in the pharmaceutical industry: in the development of new products, for quality control and, to assist with the determination of bioequivalence. Recent regulatory developments such as the Biopharmaceutics Classification Scheme have highlighted the importance of dissolution in the regulation of post-approval changes and introduced the possibility of substituting dissolution tests for clinical studies in some cases. Therefore, there is a need to develop dissolution tests that better predict the in vivo performance of drug products. This could be achieved if the conditions in the gastrointestinal tract were successfully reconstructed in vitro. The aims of this article are, first, to clarify under which circumstances dissolution testing can be prognostic for in vivo performance, and second, to present physiological data relevant to the design of dissolution tests, particularly with respect to the composition, volume, flow rates and mixing patterns of the fluids in the gastrointestinal tract. Finally, brief comments are made in regard to the composition of in vitro dissolution media as well as the hydrodynamics and duration of the test.     

In Vitro/in Vivo Correlation for 14C-Methylated Lysozyme Release from Poly(Ether-Ester) Microspheres

PURPOSE: The purpose of this study was to obtain an in vitro/in vivo correlation for the sustained release of a protein from poly(ethylene glycol) terephthalate (PEGT)/poly(butylene terephthalate) (PBT) microspheres. METHODS: Radiolabeled lysozyme was encapsulated in PEGT/PBT microspheres via a water-in-oil-in-water emulsion. Three microsphere formulations varying in copolymer composition were administered subcutaneously to rats. The blood plasma was analyzed for radioactivity content representing released lysozyme at various time points post-dose. The in vitro release was studied in phosphate-buffered saline. RESULTS: The encapsulation efficiency, calculated from the radioactivity in the outer water phase of the emulsion, varied from 60-87%. Depending on the PEG segment length and wt% PEGT, the lysozyme was released completely in vitro within 14 to 28 days without initial burst. 14C-methylated lysozyme could be detected in the plasma over the same time courses. The in vitro/in vivo correlation coefficients obtained from point-to-point analysis were greater than 0.96 for all microsphere formulations. In addition, less then 10% of administered radioactivity remained at dose site at 28 days for the microsphere formulations, indicating no notable retention of the protein at the injection site. CONCLUSION: The in vitro release in phosphate-buffered saline and the in vivo release in rats showed an excellent congruence independent of the release rate of 14C-methylated lysozyme from PEGT/PBT microspheres.     

AOTF近红外光谱技术快速测定茯苓中的水分

目的：采用AOTF近红外漫反射光谱仪,建立茯苓中水分的快速定量分析方法。方法：以空气为背景,采用漫反射方式、SNAP光谱采集软件,采集近红外光谱,光谱数据为比率模式下采集,利用偏最小二乘法（PLS）、交叉-验证法（cross-validation）及Unscrambler定量分析软件创建定量校正模型。结果：定量模型的外部验证相关系数和内部验证相关系数均能达到0.9950,通过模型外部验证,验证集相对偏差RSEP值为2.7%,验证集预测误差均方根RMSEP值为0.49,预测值和化验值的平均相对偏差为1.3%。结论：AOTF近红外漫反射光谱仪可达到对茯苓药材中水分含量快速准确测定的目的。     

Prediction of Human Drug Clearance from <Emphasis Type="Italic">in Vitro</Emphasis> and Preclinical Data Using Physiologically Based and Empirical Approaches

No HeadingPurpose. The aim of this study is to compare the accuracy of five methods for predicting in vivo intrinsic clearance (CL_int) and seven for predicting hepatic clearance (CL_h) in humans using in vitro microsomal data and/or preclinical animal data.Methods. The human CL_int was predicted for 33 drugs by five methods that used either in vitro data with a physiologic scaling factor (SF), with an empirical SF, with the physiologic and drug-specific (the ratio of in vivo and in vitro CL_int in rats) SFs, or rat CL_int directly and with allometric scaling. Using the estimated CL_int, the CL_h in humans was calculated according to the well-stirred liver model. The CL_h was also predicted using additional two methods: using direct allometric scaling or drug-specific SF and allometry.Results. Using in vitro human microsomal data with a physiologic SF resulted in consistent underestimation of both CL_int and CL_h . This bias was reduced by using either an empirical SF, a drug-specific SF, or allometry. However, for allometry, there was a substantial decrease in precision. For drug-specific SF, bias was less reduced, precision was similar to an empirical SF. Both CL_int and CL_h were best predicted using in vitro human microsomal data with empirical SF. Use of larger data set of 52 drugs with the well-stirred liver model resulted in a best-fit empirical SF that is 9-fold increase on the physiologic SF.Conclusions. Overall, the empirical SF method and the drug-specific SF method appear to be the best methods; they show lower bias than the physiologic SF and better precision than allometric approaches. The use of in vitro human microsomal data with an empirical SF may be preferable, as it does not require extra information from a preclinical study.     

Lactococcus lactis subsp. cremoris FC alleviates symptoms of colitis induced by dextran sulfate sodium in mice

Probiotics have been used to treat human gastrointestinal inflammations including inflammatory bowel disease (IBD). However, the exact mechanisms by which probiotics act to protect against intestinal inflammation have yet to be fully elucidated. The aim of this study was to evaluate anti-inflammatory effects of Lactococcus lactis subsp. cremoris FC using in vivo and in vitro inflammation models. Colitis was induced in C57BL/6 mice by administration of 3% dextran sulfate sodium to drinking water. In the cellular level assessment, a gut inflammation model with the co-culture system consisting Caco-2 cells and RAW264.7 cells stimulated by LPS was used. Administration of L. lactis subsp. cremoris FC significantly ameliorated shortening of colon length and histological score of the colon in DSS-induce colitis mice. In addition, the treatment of L. lactis subsp. cremoris FC improved the aberrant mRNA expression in inflamed tissue near to control level through notable suppression of TNF-α (P < 0.05), IFN-γ (P < 0.05), IL-6, iNOS, and MIP-2 mRNA expression. In addition, in a gut inflammation model, treatment with L. lactis subsp. cremoris FC resulted in significant down-regulation of IL-8 mRNA expression in Caco-2 cells and inhibition of NF-κB nuclear translocation in RAW264.7 cells. Our findings indicate that administration of L. lactis subsp. cremoris FC improves negative effects of DSS-induced colitis in mice through the inhibition of inflammatory cell infiltration.     

Development of a Generalized,Quantitative Physicochemical Model of CYP3A4 Inhibition for Use in Early Drug Discovery

Purpose. To examine the structure–activity relationships for the inhibition of the activity of recombinant human CYP3A4 and to establish a generalized, quantitative physicochemical model for use in early drug discovery. Methods. Inhibition of the activity of recombinant human CYP3A4 (erythromycin N–demethylase) by 30 diverse chemicals was studied using enhanced throughput methodology. Results. There was a general, strong correlation between the IC₅₀ value determined against erythromycin N–demethylase activity and lipophilicity (LogD_7.4) (r ² = 0.68, p <0.0001). This relationship was strengthened further by subdividing the structures studied into two distinct subpopulations of chemistry within the dataset. These could be identified by the absence (r ² = 0.80, p <0.0001) or presence (r ² = 0.69, p <0.0001) of a sterically uninhindered N–containing heterocycle, more specifically a pyridine, imidazole, or triazole function. The presence of these structural motifs increased the potency of CYP3A4 inhibition by approximately 10–fold for a given lipophilicity (LogD_7.4.value). More detailed analyses of AstraZeneca compounds demonstrated that the inhibitory potency of the pyridine structure can be attenuated through direct steric effects or electronic substitution resulting in a modulation of the pKa of the pyridine nitrogen, thereby influencing its ability to interact with the CYP heme. Conclusions. A generalized, quantitative model is proposed for the inhibition of the major drug metabolizing enzyme, CYP3A4. This model indicates the importance of lipophilicity and rationalizes increased potency arising through additional interactions with the heme iron. These general relationships were shown to be applicable to a selection of compounds of interest to several early research projects.     

Lyophilized Paclitaxel Magnetoliposomes as a Potential Drug Delivery System for Breast Carcinoma via Parenteral Administration: <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">in Vivo</Emphasis> Studies

No HeadingPurpose. The study reports in vitro and biological evaluation of lyophilized negatively charged paclitaxel magnetic liposomes as a potential carrier for breast carcinoma via parenteral administration.Methods. Paclitaxel in magnetoliposomes were extracted by centrifugation and quantified by high-performance liquid chromatography (HPLC). Biological properties were studied using pharmacokinetics, in vivo distribution and cytotoxicity assays, as well as a mouse model of EMT-6 breast cancer.Methods. Pharmacokinetic studies showed that encapsulation of paclitaxel in magnetoliposomes produced marked difference over the drug in Cremophor EL/ethanol pharmacokinetics, with an increased t_1/2 19.37 h against 4.11 h. For in vivo distribution, paclitaxel concentration of lyophilized magnetoliposomes in the tumor was much higher than that of lyophilized conventional liposomes or Cremophor EL/ethanol, whereas in heart it was much lower than the latter two formulations via s.c. and i.v. administration. Lyophilized paclitaxel magnetic liposomes showed more potency on the therapy of breast cancer than other formulations via s.c. and i.p. administration.Conclusions. The current study demonstrates that paclitaxel magnetoliposomes can effectively be delivered to tumor and exert a significant anticancer activity with fewer side effects in the xenograft model.