V. Badireenath Konkimalla

Poly-є-caprolactone based formulations for drug delivery and tissue engineering: A review

Biodegradable polymer based novel drug delivery systems have provided many avenues to improve therapeutic efficacy and pharmacokinetic parameters of medicinal entities. Among synthetic biodegradable polymer, poly-є-caprolactone (PCL) is a polymer with very low glass transition temperature and melting point. Owing to its amicable nature and tailorable properties it has been trialed in almost all novel drug delivery systems and tissue engineering application in use/investigated so far. This review aims to provide an up to date of drugs incorporated in different PCL based formulations, their purpose and brief outcomes. Demonstrated PCL formulations with or without drugs, intended for drug delivery and/or tissue engineering application such as microsphere, nanoparticles, scaffolds, films, fibers, micelles etc. are categorized based on method of preparation.

Evidence-based Chinese medicine for cancer therapy.

In contrast to western medicine (WM), traditional Chinese medicine (TCM) does not focus on a single target but on multiple targets involved in a particular disease condition by applying diverse modalities, such as herbal medicine, acupuncture, moxibustion, etc. There is no pre-determined treatment procedure in TCM, and every patient condition is handled individually. Such patient-tailored treatments have a millennia-old tradition in TCM. Illustrative examples of the power of TCM have been documented in cancer research, i.e., camptothecin, homoharringtonine, or arsenic trioxide. On the other hand, one major reason for reluctance of western academia towards TCM is due to the lack of clinical studies of TCM receipts. This situation is changing very recently, and a number of clinical studies were conducted on TCM providing convincing evidence for the first time to gain credibility and reputation outside China. Clinical trials with TCM remedies focus on three major fields in cancer research: (1) improvement of poor treatment response rates towards standard chemo- and radiotherapy, (2) reduction of severe adverse effects of standard cancer therapy, and (3) unwanted interactions of standard therapy with herbal medicines. Efficacy and safety of TCM treatments depend on the quality of TCM products. Appropriate quality assurance and control of TCM products as well as sustainable production methods are pre-conditions for the implementation of TCM in cancer therapy at an international level. In conclusion, the most important question for recognition and implementation of TCM into WM concerns the clinical evidence for the efficacy of TCM and international quality standards for TCM products.

Prediction of Broad Spectrum Resistance of Tumors towards Anticancer Drugs

Purpose: Drug resistance is a major obstacle in cancer chemotherapy. Although the statistical probability of therapeutic success is known for larger patient groups from clinical therapy trials, it is difficult to predict the individual response of tumors. The concept of individualized therapy aims to determine in vitro the drug response of tumors beforehand to choose effective treatment options for each individual patient. Experimental Design: We analyzed the cross-resistance profiles of different tumor types (cancers of lung, breast, and colon, and leukemia) towards drugs from different classes (anthracyclines, antibiotics, Vinca alkaloids, epipodophyllotoxins, antimetabolites, and alkylating agents) by nucleotide incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Hierarchical cluster analysis and COMPARE analyses were applied. Results: Tumors exert broad resistance profiles, e.g., tumors resistant to one drug tend to also be resistant to other drugs, whereas sensitive tumors reveal sensitivity towards many drugs. Interestingly, the broad spectrum resistance phenotype could reliably be predicted by doxorubicin alone. Expression of the ATP-binding cassette transporter P-glycoprotein (ABCB1, MDR1) and the proliferative activity of tumors were identified as underlying mechanisms of broad spectrum resistance. To find novel compounds with activity against drug-resistant tumors, a database with 2,420 natural products was screened for compounds acting independent of P-glycoprotein and the proliferative state of tumor cells. Conclusions: Tumors exert cross-resistance profiles much broader than the classical multidrug resistance phenotype. Broad spectrum resistance can be predicted by doxorubicin due to the multifactorial mode of action of this drug. Novel cytotoxic compounds from natural resources might be valuable tools for strategies to bypass broad spectrum resistance.

Polymeric modification and its implication in drug delivery: poly-ε-caprolactone (PCL) as a model polymer.

Biodegradable polymers provided the opportunity to explore beyond conventional drug delivery and turned out to be the focus of current drug delivery. In spite of availability of diverse class of polymers, several of these polymers lack important physicochemical and biological properties, limiting their widespread application in pharmaceutical drug delivery. However, most polymers in the form of blends, copolymers and functionally modified polymers have exhibited their applicability to overcome specific limitations and to produce novel and/or functionalized formulations for drug delivery as well as tissue engineering. This review aims to provide the need of polymeric modification, approaches adopted to modify and their scope. Special emphasis has been given to synthetic polyester PCL, as it is widely demonstrated in its modified form to overcome its problem of hydrophobicity and much slower degradation over the past decade. Past studies show a significantly higher utility of modified form of PCL in comparison to its native form. From the statistical analysis of these modifications and the formulations prepared, we present a basic understanding of the impact of selective modifications on the formulation design. In conclusion, we remark that a thorough understanding of the polymer and its modification has a huge potential to be the future trend for drug delivery and tissue engineering applications.

Design, Synthesis, and Evaluation of Thiol-Activated Sources of Sulfur Dioxide (SO2) as Antimycobacterial Agents

Here, 2,4-dinitrophenylsulfonamides with tunable cysteine-activated SO(2) release profiles with half-lives of SO(2) release varying from 2 to 63 min are reported. N-Benzyl-2,4-dinitrobenzenesulfonamide (6), which is prepared in one step from commercial sources, had a potency (MIC = 0.15 μM) of inhibiting Mycobacterium tuberculosis (Mtb) higher than the clinical agent isoniazid (MIC = 0.37 μM).

The Role of Downstream Signaling Pathways of the Epidermal Growth Factor Receptor for Artesunates Activity in Cancer Cells

Epidermal growth factor (EGF) and its receptor (EGFR) as well as the EGFR-coupled Ras>Raf>MEK>ERK pathway are known to affect the survival of cancer cells upon chemotherapeutic treatment. In the present investigation, we analyzed the role of EGFR signaling pathways for the activity of artesunate towards cancer cells. The microarray-based mRNA expression of genes involved in EGFR signaling pathway was correlated with the 50% inhibition concentrations (IC50) of 55 tumor cell lines for artesunate. The log10IC50 values were in a range of -6.609 to -4.0M. Candidate genes identified by this approach were then experimentally validated by transfecting cell lines with corresponding cDNA vectors and treating them with artesunate. Indeed, we observed that the Ras>Raf>MEK>ERK pathway is an important signaling route for the response of tumor cells to artesunate. As exemplarily shown for artesunate, the application of such a combined approach to identify signal transduction pathways involved in the response of tumor cells to cytotoxic compounds might foster the development of novel molecular targeted therapies for cancer treatment.

Diagnosis and therapy of oral squamous cell carcinoma

Oral squamous cell carcinoma ranks among the top ten most common cancers worldwide. Despite the success in diagnosis and therapy during the past 30 years, oral squamous cell carcinoma still belongs to the tumor types with a very unfavorable prognosis. In an effort to identify genomic alterations with prognostic relevance, we applied the comparative genomic hybridization technique on oral squamous cell carcinoma. The tumors exhibited from five up to 47 DNA copy number alterations, indicating a considerable degree of genomic imbalance. Out of 35 tumors, 19 showed a gain of chromosome band 7p12. Genomic imbalances were investigated by hierarchical cluster analysis and clustered image mapping to investigate whether genomic profiles correlate with clinical data. Results of the present investigation show that profiling of genomic imbalances in general, and especially of the epidermal growth factor receptor (EGFR) on 7p12, may be suitable as prognostic factors. In order to identify small-molecule inhibitors for EGFR, we established a database of 531 natural compounds derived from medicinal plants used in traditional Chinese medicine. Candidate compounds were identified by correlation analysis using the Kendall τ-test of IC50 values of tumor cell lines and microarray-based EGFR mRNA expression. Further validation was performed by molecular docking studies using the AutoDock program with the crystal structure of EGFR tyrosine kinase domain as docking template. We estimate these results will be a further step toward the ultimate goal of individualized, patient-adapted tumor treatment based on tumor molecular profiling.

Synthesis, thiol-mediated reactive oxygen species generation profiles and anti-proliferative activities of 2,3-epoxy-1,4-naphthoquinones

Here, we report that thiol-mediated decomposition of 2,3-epoxy-1,4-naphthoquinones to generate peroxide, a reactive oxygen species (ROS), could be modulated by changing the substitution pattern on the aryl ring and the epoxide. Epoxides which generated higher amounts of peroxide upon reaction with thiols were better inhibitors of human leukaemia (THP1) cell proliferation.

Inhibition of inducible nitric oxide synthase by bis(helenalinyl)glutarate in RAW264.7 macrophages

Nitric oxide (NO) plays a role in various physiological and pathophysiological conditions such as immunoregulatory and inflammatory processes. Hence, NO and its generating enzyme, inducible nitric oxide synthase (iNOS) may not only be of diagnostic and prognostic value, but may also serve as targets for novel therapeutic options. In the present investigation, we have screened a phytochemical library by correlating the IC(50) values for 531 natural products of 60 cell lines with the microarray-based mRNA expression of 95 genes known to be involved in NO metabolism and signaling with the aim to identify candidate compounds as inhibitors for NO metabolism and signaling. We identified bis(helenalinyl)glutarate (BHG) as putative candidate compound. Indeed, BHG inhibited NO production (IC(50) value: 0.90+/-0.04microM) and down-regulated iNOS protein expression (IC(50) value: 1.12+/-0.16microM) of RAW264.7 mouse macrophages in the presence of lipopolysaccharide and interferon-gamma. Performing XTT cytotoxicity assays, we found that BHG inhibited cell growth in a dose-dependent manner with an IC(50) value of 5.6microM. To gain insight into molecular pathways involved in NO inhibition and cytotoxicity, we performed microarray experiments which were exemplarily validated by real-time RT-PCR. A total of 227 genes (67 up- and 160 down-regulated) were obtained, which exhibited significant differences in mRNA regulation between BHG-treated and untreated RAW264.7 macrophages. Sixteen of 227 genes are known to be involved in NO-signaling. Pathway analyses revealed that further five and four down-regulated genes belong to the glucocorticoid receptor and interleukin-1 and interleukin-10 pathways, respectively. An interference of these two pathways and NO is known for inflammation and auto-immune diseases. The therapeutic potential of this compound has to be explored in the future.

Separation and isolation of tautomers of 2-hydroxy-4-naphthoquinone-1-oxime derivatives by liquid chromatography: Antiproliferative activity and DFT studies

AbstractReversed phase HPLC separation and isolation of isomers of 2-hydroxy-4-naphthoquinone-1-oxime (Lwox) and 3-methyl-2-hydroxy-4-naphthoquinone-1-oxime (Phox) have been investigated. Two distinct peaks are observed in the chromatogram of Lwox and are assigned to ‘para’ tautomer; 2-hydroxy-4-naphthoquinone-1-oxime (3) and ‘ortho’ tautomer; 4-hydroxy-2-naphthoquinone-1-oxime (4). The tautomeric equilibrium of 3 and 4 has been manipulated by incrementally increasing the pH of the mobile phase from 2.5 to 10.5, and altering the solvent polarity. At pH > 6.8 the tautomers are well-separated from each other. There is no separation of Phox isomers between pH 2.5 and 10.5. Isolation of the tautomers has been carried out by preparative HPLC, with 3 and 4 obtained as ammonium bicarbonate adducts and characterized by LC-MS, FT-IR, and UV-visible spectroscopy. Red-orange 3 is characterized by a paranaphthoquinone stretch at 1287 cm−1 and a charge transfer band at 420 nm; yellow 4 exhibits, a similar stretch at 1246 cm−1 and absorption band at 406 nm. Compounds 3 and 4 were screened for selective antiproliferative activity in three cancer cell lines of different tissue types (COLO 205 (human colorectal adenocarcinoma), U87 MG (glioblastoma astrocytoma) and MIAPaCa-2 (human pancreatic carcinoma). Geometry-optimized structures for tautomers 3 and 4 (3′ and 4′ in Phox) were computed using the B3LYP method. Structures, 3 and 3′ are 4.7 and 5.8 kcal mol−1 more stabilized than 4 and 4′, respectively, as a result of a hydrogen bond interaction between the 2-hydroxyl group and the nitrogen of the oxime. FigureReversed phase chromatographic separation and isolation of tautomers of naphthoquinoneoximes is studied. Geometryoptimized structures for tautomers were computed using the B3LYP method. The separated tautomers are screened for cytotoxicity in three cancer cell lines COLO 205 (human colorectal adenocarcinoma), U87 MG (glioblastoma astrocytoma) and MIAPaCa-2 (human pancreatic carcinoma).