Abstracts


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Merging Traditional Chinese Medicine with Modern Drug Discovery Technologies to Find Novel Drugs and Functional Foods
Rocky Graziose, Mary Ann Lila and Ilya Raskin

Traditional Chinese Medicines (TCM) are rapidly gaining attention in the West as sources of new drugs, dietary supplements and functional foods. However, lack of consistent manufacturing practices and quality standards, fear of adulteration, and perceived deficiencies in scientific validation of efficacy and safety impede worldwide acceptance of TCM. In addition, Western pharmaceutical industries and regulatory agencies are partial toward single ingredient drugs based on synthetic molecules, and skeptical of natural product mixtures. This review concentrates on three examples of TCM-derived pharmaceuticals and functional foods that have, despite these usual obstacles, risen to wide acceptance in the West based on their remarkable performance in recent scientific investigations. They are: Sweet wormwood (Artemisia annua), the source of artemisinin, which is the currently preferred single compound anti-malarial drug widely used in combination therapies and recently approved by US FDA; Thunder god vine (Tripterygium wilfordii) which is being developed as a botanical drug for rheumatoid arthritis; and green tea (Camellia sinensis) which is used as a functional beverage and a component of dietary supplements.


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Traditional Chinese Medicines (TCMs) for Molecular Targeted Therapies of Tumours
Mahmoud Youns, Jörg D. Hoheisel and Thomas Efferth

Scientific progress in genetics, cell and molecular biology has greatly ameliorated our comprehensive understanding of the molecular mechanisms of neoplastic transformation and progression. The rapidly advancing identification of molecular targets in human cancers during the last decade has provided an excellent starting point for the development of novel therapeutics. A huge variety of potential molecular targets have been identified, many of which are already in the market for therapeutic purposes. It is now becoming possible to target pathways and/or molecules that are crucial in maintaining the malignant phenotype. Traditional Chinese medicine (TCM) is often considered as alternative or complementary medicine. TCM represents a holistic approach and lacks high-quality scientific evidence on its effectiveness. Therefore, it is frequently regarded with some scepticism by western academic medicine. In this review, we report that application of modern technologies allowed identification of novel molecular targets modulating the anti-tumour activity of natural products derived from TCM. Moreover, we tried to cross the bridge between TCM and Western modern medicine to be able to implement them for the sake of cancer patients.


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Chemoinformatics Approaches for Traditional Chinese Medicine Research and Case Application in Anticancer Drug Discovery
Xue-Juan Li, De-Xin Kong and Hong-Yu Zhang

Traditional Chinese Medicine (TCM), which has been used for thousands of years to treat diseases, provides unique theoretical and practical methodologies for disease control. With the increasing accumulation of TCM data, it is imperative to study and analyze these resources with modern technologies and to elucidate the molecular mechanisms of TCM therapy. However, the philosophy, framework and technique of TCM are quite different from those of Western medicine, which causes complications when attempting to design modern drug treatments based on TCM. To meet this challenge, some basic chemoinformatics techniques, including molecular similarity searching, virtual screening and inverse docking, have been utilized in an attempt to gain a deeper understanding of TCM and to accelerate the TCM-based drug discovery. Recent progress on the use of chemoinformatics in TCM research will be discussed and an example of the preliminary application of chemoinformatics methods in anticancer drug design will be provided.


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Molecular Basis of Traditional Chinese Medicine in Cancer Chemoprevention
Steven Wang, Sravan Penchala, Sunil Prabhu, Jeffrey Wang and Ying Huang

Cancer is the second leading cause of death, for which current therapeutic approaches are still very limited. Chemoprevention is an important approach to decreasing cancer morbidity and mortality by the use of non-toxic natural or synthetic substances to reverse the processes of initiation and subsequent progression of cancer. A substantial amount of evidence from human, animal and cell line studies has shown that many herbal products used for traditional Chinese medicine (TCM) can exert chemopreventive effects. The underlying theory for TCM to treat or prevent cancer is to bring the patient back to a healthy state by modifying multiple cancer-causing events. Since carcinogenesis involves multiple abnormal genes/pathways, using TCM in cancer chemoprevention may be superior to the agents targeting a single molecular target alone. However, before TCM can be accepted universally as complementary and alternative medicine for cancer treatment and prevention, it is crucial to understand the molecular basis for their effects. This review highlights several known molecular mechanisms of selected TCM in chemoprevention. Many TCM products or single active components have been reported to inhibit a variety of processes in cancer cell growth, invasion and metastasis by modulating a wide range of molecular targets, including cyclooxygenase-2 (COX-2), nuclear factor-Kappa B (NF-κB) and nuclear factor erythroid 2 -related factor 2 (Nrf2)-mediated antioxidant signaling pathways. The TCM and their active components with potent chemopreventive effects can be considered as promising lead agents for the design of more effective and less toxic agents for cancer chemoprevention.


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Transporter-Mediated Multidrug Resistance and its Modulation by Chinese Medicines and Other Herbal Products
Zhijun Wang, Ranadheer Ravula, Mingju Cao, Moses Chow and Ying Huang

The main cause of failure in cancer drug therapy is the emergence of cellular resistance to drugs. Cancer cells, after exposure to one drug, can become simultaneously insensitive to mechanistically and chemically unrelated drugs, a phenotype known as multidrug resistance (MDR). Although a number of mechanisms have been proposed to mediate MDR, the classical cellular mechanism involves the overexpression of several members of the ATP-binding cassette (ABC) superfamily of transporters, leading to increased efflux and decreased intracellular drug accumulation. Among these, P-glycoprotein (P-gp, ABCB1), MRP1 (ABCC1) and BCRP (ABCG2) are the main transporters conferring MDR. These transporters are frequently detected in recurrent cancer cells or cancer stem cells. To overcome MDR, various studies have been conducted to investigate the potential to discover effective MDR modulators from Chinese medicines (CMs) and other herbal products because many of these have been used for centuries without harmful side effects. This review summarizes: i) The contribution of P-gp, MRP1 and BCRP in cancer drug resistance; ii) known mechanisms of action for MDR modulators; iii) commonly used methods for identification and evaluation of novel modulators of transporter- mediated MDR; and iv) the modulating effects of CMs and other natural products on ABC transporters and MDR. The CM and their active components with potent modulating effects on MDR can be considered as promising lead agents for the design of more effective and less toxic drugs to overcome MDR.


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Emerging In Vitro Tools to Evaluate Cytochrome P450 and Transporter- Mediated Drug-Drug Interactions
Chuang Lu, Mingxiang Liao, Lawrence Cohen and Cindy Q. Xia

Drug-drug interactions DDI comprise a significant cause of morbidity and mortality worldwide as they may lead to adverse clinical events, result in decrease/inactivation of the therapeutic effect of a drug, may enhance drug toxicity and indirectly compromise treatment outcomes and adherence. Drug transporters and drug metabolism enzymes govern drug absorption, distribution, metabolism, and elimination (ADME). Inhibition or induction of transporter and drug metabolism enzymes can alter the ADME of a co-administered drug, which may lead to drug-induced toxicity or lack of efficacy. This review assesses our current understanding of the in vitro methods of evaluating CYPs and transporter- mediated DDI. The DDI prediction models based on in vitro assays are also discussed in this review. The applications, advantages and limitations of each method are also addressed in this review.


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Glutathione Modulation and Oxidative Stress in Human Liver Slices
Alison E.M. Vickers, Robyn L. Fisher and John R. Sinclair

Glutathione (GSH) levels are modulated in human liver slices to evaluate if drug induced liver injury is enhanced by a poor liver GSH status. Liver slice GSH levels were decreased by: 1) BSO (L-buthionine-S-sulfoximine) to inhibit GSH synthesis, and by 2) APAP (acetaminophen) which consumes GSH via conjugation to a metabolite. In this study, methimazole (MMI) liver injury was evaluated in the presence of a poor GSH status. MMI was selected because its structural thione moiety is linked with hepatotoxicity and during metabolism GSH is co-oxidized. MMI (500-1000 µM) affected oxidative stress pathways and mitochondrial function, resulting in lower liver slice GSH and ATP levels. Co-incubation of MMI with BSO or APAP led to further decreases of GSH and ATP levels in some human livers, at time points and concentrations not detected with MMI alone. Variation in human response was evident and demonstrated that some subjects with a poor liver GSH status could be further compromised with high MMI concentrations. MMI induced an up-regulation of gene expression linked with the GSH pathway, mitochondrial GSH and inflammation. Co-treatment of MMI with BSO induced a mixed response of oxidative stress related genes and an up-regulation of heat shock genes. The combination of MMI with APAP increased the expression of genes involved with oxidative stress and anti-oxidant defense, likely to protect the cells from mitochondrial injury. In summary, MMI induces oxidative stress at high concentrations, which can be augmented when liver GSH levels are decreased by the co-administration of some drugs or health status.


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20 Years of Lipid Nanoparticles (SLN & NLC): Present State of Development & Industrial Applications
Rainer H. Müller, Ranjita Shegokar and Cornelia M. Keck

In 1990, the lipid nanoparticles were invented in the laboratories, the first patent filings took place in 1991. The lipid nanoparticles were developed as alternative to traditional carriers such as polymeric nanoparticles and liposomes. After 20 years of lipid nanoparticles, the present state of development is reviewed - academic progress but also the development state of pharmaceutical products for the benefit of patients. Meanwhile many research groups are active worldwide, their results are reviewed which cover many different administration routes: dermal and mucosal, oral, intravenous/ parenteral, pulmonary but also ocular. The lipid nanoparticles are also used for peptide/protein delivery, in gene therapy and various miscellaneous applications (e.g. vaccines). The questions of large scale production ability, accepted regulatory status of excipients, and - important for the public perception - lack of nanotoxicity are discussed, important pre-requisites for the use of each nanocarrier in products. Identical to the liposomes, the lipid nanoparticles entered first the cosmetic market, product examples are presented. Presently the pharmaceutical product development focuses on products for unmet needs and on niche products with lower development costs (e.g. ocular delivery), which can be realized also by smaller companies. A pharmaceutical perspective for the future is given, but also outlined the opportunities for non-pharmaceutical use, e.g. in nutraceuticals.


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Multifunctional Porous Silicon for Therapeutic Drug Delivery and Imaging
Hélder A. Santos, Luis M. Bimbo, Vesa-Pekka Lehto, Anu J. Airaksinen, Jarno Salonen and Jouni Hirvonen

Major challenges in drug formulation are the poor solid state stability of drug molecules, poor dissolution/solubility and/or poor pharmacokinetic properties (bioavailability), which may lead to unreliable in vitro-in vivo (IVIV) correlation. To improve current therapeutical strategies, novel means to deliver poorly water soluble active pharmaceutical ingredients, as well as to target them to specific sites or cells in the body are needed. Biomedical applications of porous silicon (PSi) have been actively investigated during the last 10 years, especially in the areas of drug delivery and imaging, due to the biocompatibility and biodegradability of PSi materials, which makes them a potential candidate for controlled drug release. In addition, the unique pore sizes and easily functionalized surface properties of PSi materials allow high drug payloads and controlled kinetics from the drug release formulations. Modification of the PSi surface properties also facilitates biofunctionalization of the surface and the possibility to attach targeting moieties (e.g., antibodies and peptides), thus enabling effective targeting of the payload. In this review, we briefly address the production methodologies of PSi, and we will mainly present and discuss several examples about the biocompatibility of PSi, the most recent in vitro and in vivo applications of PSi as a carrier in drug/protein/peptide delivery and tissue engineering, as well as PSi as a platform for drug targeting and imaging.


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Asparaginyl-tRNA Synthetase Pre-Transfer Editing Assay
Franck Danel, Patrick Caspers, Claude Nuoffer, Michael Härtlein, Michael A. Kron and Malcolm G.P.Page

Aminoacyl-tRNA synthetases (AARSs) are a structurally heterogeneous family of enzymes present in prokaryotes, archaea and eukaryotes. They catalyze the attachment of tRNA to its corresponding amino acid via an aminoacyl adenylate intermediate. Errors in protein synthesis will occur if an incorrect amino acid is attached to the tRNA. To prevent such errors, AARSs have evolved editing mechanisms that eliminate incorrect aminoacyl adenylates (pre-transfer editing) or misacylated tRNAs (post-transfer editing). Various AARSs are the targets of natural antibiotics and are considered validated targets for chemotherapy. We have developed a high-throughput screening (HTS) assay measuring the pre-transfer editing activity of pathogen-derived asparaginyl-tRNA synthetase (AsnRS). This was achieved by monitoring the formation of pyrophosphate via cleavage to phosphate, which was quantified by reaction with Malachite Green. L-Aspartate-β-hydroxamate, an asparagine analogue, was most effective in promoting the editing activity of AsnRS from Brugia malayi (BmAsnRS) and Staphylococcus epidermidis (SeAsnRS) with KM values close to 100 µM. The assay sensitivity was enhanced by the thiol agents, DTT and L-cysteine, which significantly increased the turn-over of aminoacyl adenylate by BmAsnRS, but not SeAsnRS. The HTS assay was used to screen a library of 37,120 natural-product extracts for inhibitors of BmAsnRS. A small number of extracts that inhibited the pre-transfer editing by BmAsnRS was identified for future isolation of the active component(s). The principle of this assay can be applied to all enzymes having a pre- or post-editing activity.