Hydrazinocurcumin, a novel synthetic curcumin derivative, is a potent inhibitor of endothelial cell proliferation

Mechanics insights of curcumin in myocardial ischemia: Where are we standing?

Cardiovascular disorders are known as one of the main health problems which are associated with mortality worldwide. Myocardial ischemia (MI) is improper blood supply to myocardium which leads from serious complications to life-threatening problems like AMI, atherosclerosis, hypertension, cardiac-hypertrophy as well as diabetic associated complications as diabetic atherosclerosis/cardiomyopathy/hypertension. Despite several efforts, the current therapeutic platforms are not related with significant results. Hence, it seems, developing novel therapies are required. In this regard, increasing evidences indicated, curcumin (CRC) acts as cardioprotective agent. Given that CRC and its analogs exert their cardioprotective effects via affecting on a variety of cardiovascular diseases-related mechanisms (i.e., Inflammation, and oxidative stress). Herein, for first time, we have highlighted the protective impacts of CRC against MI. This review might be a steppingstone for further investigation into the clinical implications of the CRC against MI. Furthermore, it pulls in light of a legitimate concern for scientific community, seeking novel techniques and characteristic dynamic biopharmaceuticals for use against myocardial ischemia.

Curcumin as an Alternative Epigenetic Modulator: Mechanism of Action and Potential Effects

Curcumin (a polyphenolic compound in turmeric) is famous for its potent anti-inflammatory, anti-oxidant, and anti-cancer properties, and has a great potential to act as an epigenetic modulator. The epigenetic regulatory roles of curcumin include the inhibition of DNA methyltransferases (DNMTs), regulation of histone modifications via the regulation of histone acetyltransferases (HATs) and histone deacetylases (HDACs), regulation of microRNAs (miRNA), action as a DNA binding agent and interaction with transcription factors. These mechanisms are interconnected and play a vital role in tumor progression. The recent research has demonstrated the role of epigenetic inactivation of pivotal genes that regulate human pathologies such as cancers. Epigenetics helps to understand the mechanism of chemoprevention of cancer through different therapeutic agents. In this regard, dietary phytochemicals, such as curcumin, have emerged as a potential source to reverse epigenetic modifications and efficiently regulate the expression of genes and molecular targets that are involved in the promotion of tumorigenesis. The curcumin may also act as an epigenetic regulator in neurological disorders, inflammation, and diabetes. Moreover, curcumin can induce the modifications of histones (acetylation/deacetylation), which are among the most important epigenetic changes responsible for altered expression of genes leading to modulating the risks of cancers. Curcumin is an effective medicinal agent, as it regulates several important molecular signaling pathways that modulate survival, govern anti-oxidative properties like nuclear factor E2-related factor 2 (Nrf2) and inflammation pathways, e.g., nuclear factor kappa B (NF-κB). Curcumin is a potent proteasome inhibitor that increases p-53 level and induces apoptosis through caspase activation. Moreover, the disruption of 26S proteasome activity induced by curcumin through inhibiting DYRK2 in different cancerous cells resulting in the inhibition of cell proliferation opens up a new horizon for using curcumin as a potential preventive and treatment approach in proteasome-linked cancers. This review presents a brief summary of knowledge about the mechanism of epigenetic changes induced by curcumin and the potential effects of curcumin such as anti-oxidant activity, enhancement of wound healing, modulation of angiogenesis and its interaction with inflammatory cytokines. The development of curcumin as a clinical molecule for successful chemo-prevention and alternate therapeutic approach needs further mechanistic insights.

Histone acetyltransferase inhibitors: An overview in synthesis, structure-activity relationship and molecular mechanism

Acetylation, a key component in post-translational modification regulated by HATs and HDACs, is relevant to many crucial cellular contexts in organisms. Based on crucial pharmacophore patterns and the structure of targeted proteins, HAT inhibitors are designed and modified for higher affinity and better bioactivity. However, there are still some challenges, such as cell permeability, selectivity, toxicity and synthetic availability, which limit the improvement of HAT inhibitors. So far, only few HAT inhibitors have been approved for commercialization, indicating the urgent need for more successful and effective structure-based drug design and synthetic strategies. Here, we summarized three classes of HAT inhibitors based on their sources and structural scaffolds, emphasizing on their synthetic methods and structure-activity relationships and molecular mechanisms, hoping to facilitate the development and further application of HAT inhibitors.

Carotenoids: biochemistry, pharmacology and treatment

Carotenoids and retinoids have several similar biological activities such as antioxidant properties, the inhibition of malignant tumour growth and the induction of apoptosis. Supplementation with carotenoids can affect cell growth and modulate gene expression and immune responses. Epidemiological studies have shown a correlation between a high carotenoid intake in the diet with a reduced risk of breast, cervical, ovarian, colorectal cancers, and cardiovascular and eye diseases. Cancer chemoprevention by dietary carotenoids involves several mechanisms, including effects on gap junctional intercellular communication, growth factor signalling, cell cycle progression, differentiation-related proteins, retinoid-like receptors, antioxidant response element, nuclear receptors, AP-1 transcriptional complex, the Wnt/β-catenin pathway and inflammatory cytokines. Moreover, carotenoids can stimulate the proliferation of B- and T-lymphocytes, the activity of macrophages and cytotoxic T-cells, effector T-cell function and the production of cytokines. Recently, the beneficial effects of carotenoid-rich vegetables and fruits in health and in decreasing the risk of certain diseases has been attributed to the major carotenoids, β-carotene, lycopene, lutein, zeaxanthin, crocin (/crocetin) and curcumin, due to their antioxidant effects. It is thought that carotenoids act in a time- and dose-dependent manner. In this review, we briefly describe the biological and immunological activities of the main carotenoids used for the treatment of various diseases and their possible mechanisms of action.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Biological evaluation and molecular docking studies of new curcuminoid derivatives: Synthesis and characterization

In the present study, three series of dimethylamino curcuminoids viz. 4-phenylaminomethyl curcumin (3a-d), arylidene curcumin (3e) and pyrazole curcumin (3f-i) derivatives have been synthesized and studied for their in vitro anti-inflammatory, antioxidant and antibacterial activities. Synthesized dimethylamino curcuminoid derivatives namely 3d, 3e, 3h and 3i have shown potent anti-inflammatory properties than parent curcumin. Molecular docking interactions of dimethylamino curcuminoids derivatives against cyclooxygenase enzymes (COX-1 and COX-2) were studied.

Molecular mechanisms underlying chemopreventive potential of curcumin: Current challenges and future perspectives

In recent years, natural compounds have received considerable attention in preventing and curing most dreadful diseases including cancer. The reason behind the use of natural compounds in chemoprevention is associated with fewer numbers of side effects than conventional chemotherapeutics. Curcumin (diferuloylmethane, PubMed CID: 969516), a naturally occurring polyphenol, is derived from turmeric, which is used as a common Indian spice. It governs numerous intracellular targets, including proteins involved in antioxidant response, immune response, apoptosis, cell cycle regulation and tumor progression. A huge mass of available studies strongly supports the use of Curcumin as a chemopreventive drug. However, the main challenge encountered is the low bioavailability of Curcumin. This extensive review covers various therapeutic interactions of Curcumin with its recognized cellular targets involved in cancer treatment, strategies to overcome the bioavailability issue and adverse effects associated with Curcumin consumption.

Triazole-curcuminoids: A new class of derivatives for 'tuning' curcumin bioactivities?

Curcumin is a unique blend of pharmacophores responsible for the pleiotropy of this natural pigment. In the present study we have replaced the 1,3-dicarbonyl moiety with a 1,2,3-triazole ring to furnish a new class of triazole-curcuminoids as a possible strategy to generate new compounds with different potency and selectivity compared to curcumin. We obtained a proof-of-principle library of 28 compounds tested for their cytotoxicity (SY-SY5Y and HeLa cells) and for their ability to inhibit NF-κB. Furthermore, we also generated 1,3-dicarbonyl curcuminoids of selected click compounds. Triazole-curcuminoids lost their ability to be Michael's acceptors, yet maintained some of the features of the parent compounds and disclosed new ones. In particular, we found that some compounds were able to inhibit NF-κB without showing cytotoxicity, while others, unlike curcumin, activated NF-κB signalling. This validates the hypothesis that click libraries can be used to investigate the biological activities of curcumin as well as generate analogs with selected features.

Synthesis of Bis-pyrrolizidine-Fused Dispiro-oxindole Analogues of Curcumin via One-Pot Azomethine Ylide Cycloaddition: Experimental and Computational Approach toward Regio- and Diastereoselection

Curcumin has been transformed to racemic curcuminoids via an azomethine ylide cycloaddition reaction using isatin/acenaphthoquinone and proline as the reagents. The products were characterized by extensive 1D/2D NMR analysis and single-crystal X-ray crystallographic studies. The enantiomers of one racemic product were separated by HPLC on a Chiralcel OD-H column and were indeed confirmed by the CD spectra of the separated enantiomers.

Fluorination Effects on NOS Inhibitory Activity of Pyrazoles Related to Curcumin

A series of new (E)-3(5)-[β-(aryl)-ethenyl]-5(3)-phenyl-1H-pyrazoles bearing fluorine atoms at different positions of the aryl group have been synthesized starting from the corresponding β-diketones. All compounds have been characterized by elemental analysis, DSC as well as NMR (¹H, ¹³C, ¹⁹F and ¹⁵N) spectroscopy in solution and in solid state. Three structures have been solved by X-ray diffraction analysis, confirming the tautomeric forms detected by solid state NMR. The in vitro study of their inhibitory potency and selectivity on the activity of nNOS and eNOS (calcium-calmodulin dependent) as well as iNOS (calcium-calmodulin independent) isoenzymes is presented. A qualitative structure–activity analysis allowed the establishment of a correlation between the presence/absence of different substituents with the inhibition data proving that fluorine groups enhance the biological activity. (E)-3(5)-[β-(3-Fluoro-4-hydroxyphenyl)-ethenyl]-5(3)-phenyl-1H-pyrazole (13), is the best inhibitor of iNOS, being also more selective towards the other two isoforms.

Synthesis and characterization of 18F-labeled hydrazinocurcumin derivatives for tumor imaging

Radiolabeled hydrazinocurcumin derivatives, [¹⁸F]1 and [¹⁸F]2 were synthesized and both radioligands were resistant to reductive metabolism. MicroPET images of C6 glioma xenografted mice showed high tumor uptake and retention of [¹⁸F]2.

Ensemble docking and molecular dynamics identify knoevenagel curcumin derivatives with potent anti-EGFR activity

Epidermal growth factor receptor tyrosine kinase (EGFR-TK) is an attractive target for cancer therapy. Despite a number of effective EGFR inhibitors that are constantly expanding and different methods being employed to obtain novel compounds, the search for newer EGFR inhibitors is still a major scientific challenge. In the present study, a molecular docking and molecular dynamics investigation has been carried out with an ensemble of EGFR-TK structures against a synthetically feasible library of curcumin analogs to discover potent EGFR inhibitors. To resolve protein flexibility issue we have utilized 5 EGFR wild type crystal structures during docking as this gives improved possibility of identifying an active compound as compared to using a single crystal structure. We then identified five curcumin analogs representing different scaffolds that can serve as lead molecules. Finally, the 5 ns molecular dynamics simulation shows that knoevenagel condensate of curcumin specifically C29 and C30 can be used as starting blocks for developing effective leads capable of inhibiting EGFR.

Synthesis of novel quinoline-2-one based chalcones of potential anti-tumor activity

Novel quinoline-2-one based chalcones were synthesized from a Claisen-Schmidt condensation by using the couple KOH/1,4-dioxane as reaction medium. A relatively stable aldol was isolated and identified as the intermediate species in the formation of the target chalcones. Nine of the obtained compounds were in vitro screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines. Products 16c, 16d, 16h and 27 exhibited the highest activity, being compound 27 the most active, displaying remarkable activity against 50 human tumor cell lines, thirteen of them with GI(50) values ≤1.0 μM, being the HCT-116 (Colon, GI(50) = 0.131 μM) and LOX IMVI (Melanoma, GI(50) = 0.134 μM) the most sensitive strains. Compound 27 was referred to in vivo acute toxicity and hollow fiber assay by the Biological Evaluation Committee of the NCI. The acute toxicity study indicated that compound 27 was well tolerated intraperitoneally (150 mg/kg/dose) by athymic nude mice. This compound may possibly be used as lead compound for developing new anticancer agents.

Nitric oxide-mediated histone hyperacetylation in oral cancer: target for a water-soluble HAT inhibitor, CTK7A

Altered histone acetylation is associated with several diseases, including cancer. We report here that, unlike in most cancers, histones are found to be highly hyperacetylated in oral squamous cell carcinoma (OSCC; oral cancer) patient samples. Mechanistically, overexpression, as well as enhanced autoacetylation, of p300 induced by nucleophosmin (NPM1) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) causes the hyperacetylation, which is nitric oxide (NO) signal dependent. Inhibition of the histone acetyltransferase (HAT) activity of p300 by a water-soluble, small molecule inhibitor, Hydrazinocurcumin (CTK7A), substantially reduced the xenografted oral tumor growth in mice. These results, therefore, not only establish an epigenetic target for oral cancer, but also implicate a HAT inhibitor (HATi) as a potential therapeutic molecule.

Structure-activity relationship studies of curcumin analogues

Two series of curcumin analogues, a total of twenty-four compounds, were synthesized and evaluated. The most potent compound, compound 23, showed potent growth inhibitory activities on both prostate and breast cancer lines with IC(50) values in sub-micromolar range, fifty times more potent than curcumin. Curcumin analogues might be potential anti-tumor agents for breast and prostate cancers.

Synthesis and biological evaluation of curcuminoid pyrazoles as new therapeutic agents in inflammatory bowel disease: effect on matrix metalloproteinases

Seven N-unsubstituted curcuminoid pyrazoles have been synthesized from the corresponding beta-diketones (including curcumin). We evaluated the possibility of curcuminoid pyrazoles regulating the activity of matrix metalloproteinases (MMPs) by human intestinal epithelial cells in vitro. Zymographic analysis revealed that three compounds significantly down-regulated MMP-9 activity on inflammation-induced intestinal epithelial cells, making them original candidates for the treatment of inflammatory bowel disease (IBD).

Curcumin-derived pyrazoles and isoxazoles: Swiss army knives or blunt tools for Alzheimer's disease?

Curcumin binds to the amyloid beta peptide (Abeta) and inhibits or modulates amyloid precursor protein (APP) metabolism. Therefore, curcumin-derived isoxazoles and pyrazoles were synthesized to minimize the metal chelation properties of curcumin. The decreased rotational freedom and absence of stereoisomers was predicted to enhance affinity toward Abeta(42) aggregates. Accordingly, replacement of the 1,3-dicarbonyl moiety with isosteric heterocycles turned curcumin analogue isoxazoles and pyrazoles into potent ligands of fibrillar Abeta(42) aggregates. Additionally, several compounds are potent inhibitors of tau protein aggregation and depolymerized tau protein aggregates at low micromolar concentrations.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Curcumin, an atoxic antioxidant and natural NFkappaB, cyclooxygenase-2, lipooxygenase, and inducible nitric oxide synthase inhibitor: a shield against acute and chronic diseases

BACKGROUND

The world suffers a tsunami of chronic diseases, and a typhoon of acute illnesses, many of which are associated with the inappropriate or exaggerated activation of genes involved in inflammation. Finding therapeutic agents which can modulate the inflammatory reaction is the highest priority in medical research today. Drugs developed by the pharmaceutical industry have thus far been associated with toxicity and side effects, which is why natural substances are of increasing interest.

METHODS

A literature search (PubMed) showed almost 1500 papers dealing with curcumin, most from recent years. All available abstracts were read. Approximately 300 full papers were reviewed.

RESULTS

Curcumin, a component of turmeric, has been shown to be non-toxic, to have antioxidant activity, and to inhibit such mediators of inflammation as NFkappaB, cyclooxygenase-2 (COX-2), lipooxygenase (LOX), and inducible nitric oxide synthase (iNOS). Significant preventive and/or curative effects have been observed in experimental animal models of a number of diseases, including arteriosclerosis, cancer, diabetes, respiratory, hepatic, pancreatic, intestinal and gastric diseases, neurodegenerative and eye diseases.

CONCLUSIONS

Turmeric, an approved food additive, or its component curcumin, has shown surprisingly beneficial effects in experimental studies of acute and chronic diseases characterized by an exaggerated inflammatory reaction. There is ample evidence to support its clinical use, both as a prevention and a treatment. Several natural substances have greater antioxidant effects than conventional vitamins, including various polyphenols, flavonoids and curcumenoids. Natural substances are worth further exploration both experimentally and clinically.

Apoptosis-inducing effects of curcumin derivatives in human bladder cancer cells

Our aim was to prepare curcumin derivatives and study their apoptosis-inducing effects on bladder cancer cells in order to establish a basis for targeted chemotherapy of cancer. n-Maleoyl-L-valine-curcumin (NVC) and n-maleoyl-glycine-curcumin (NGC) were chemically synthesized. Intracellular esterase activity of the human bladder cancer EJ cell line and renal tubular epithelial (HKC) cells was examined by 6-carboxyfluorescein diacetate fluorometry. After incubation with NVC or NGC for 6-24 h, cell viability was detected by MTT colorimetry. Cell apoptosis and apoptotic rates were measured by acridine orange/ethidium bromide staining, TUNEL labeling and flow cytometry. Intracellular caspase-3 activities were determined by spectrophotometry. The esterase activity within EJ cells was 10.2-fold higher than that of HKC cells, which was abolished by bis-p-nitrophenylphosphate, an esterase inhibitor, resulting in decreases in NVC- and NGC-mediated cell viability arrest. For EJ cells, the IC50 values of NVC (20.1 micromol/l) and NGC (18.7 micromol/l) were close to curcumin (16.5 micromol/l). Meanwhile, their IC50 values on HKC cells were, respectively, 4.06- and 3.23-fold higher than curcumin. Moreover, NVC and NGC induced apoptosis of EJ cells by 10.13-23.36 and 12.42-28.56%, respectively. Administration of these two derivatives resulted in decreased apoptosis of HKC cells compared with curcumin. The caspase-3 activities of EJ cells, but not of HKC cells, were 5.21- and 5.63-fold enhanced by NVC and NGC, respectively. Thus, novel esterase-sensitive curcumin derivatives were synthesized, which induced extensive apoptosis of bladder cancer EJ cells, but not normal cells.

Aminopeptidase-N/CD13 (EC 3.4.11.2) inhibitors: chemistry, biological evaluations, and therapeutic prospects

Aminopeptidase N (APN)/CD13 (EC 3.4.11.2) is a transmembrane protease present in a wide variety of human tissues and cell types (endothelial, epithelial, fibroblast, leukocyte). APN/CD13 expression is dysregulated in inflammatory diseases and in cancers (solid and hematologic tumors). APN/CD13 serves as a receptor for coronaviruses. Natural and synthetic inhibitors of APN activity have been characterized. These inhibitors have revealed that APN is able to modulate bioactive peptide responses (pain management, vasopressin release) and to influence immune functions and major biological events (cell proliferation, secretion, invasion, angiogenesis). Therefore, inhibition of APN/CD13 may lead to the development of anti-cancer and anti-inflammatory drugs. This review provides an update on the biological and pharmacological profiles of known natural and synthetic APN inhibitors. Current status on their potential use as therapeutic agents is discussed with regard to toxicity and specificity.

Antioxidant and antiproliferative activity of curcumin semicarbazone

A new semicarbazone derivative of curcumin (CRSC) was synthesized and examined for its antioxidant, antiproliferative, and antiradical activity and compared with those of curcumin (CR). The antioxidant activity was tested by their ability to inhibit radiation induced lipid peroxidation in rat liver microsomes. The antiproliferative activity was tested by studying the in vitro activity of CRSC against estrogen dependant breast cancer cell line MCF-7. Kinetics of reaction of (2,2'-diphenyl-1-picrylhydrazide) DPPH, a stable hydrogen abstracting free radical was studied to measure the antiradical activity using stopped-flow spectrophotometer. Finally one-electron oxidized radicals of CRSC were generated and characterized by pulse radiolysis. The results suggest that the probable site of attack for CRSC is both the phenolic OH and the imine carbonyl position. CRSC shows efficient antioxidant and antiproliferative activity although its antiradical activity is less than that of CR.

Antiangiogenic activity of 4-O-methylgallic acid from Canavalia gladiata, a dietary legume

Development of nontoxic and biologically safe antiangiogenic agent has been highlighted as a promising way to treat angiogenesis related diseases including cancer. Herein, we isolated 4-O-methylgallic acid (4-OMGA) from the seed of Canavalia gladiata, a dietary legume, on the basis of the growth inhibitory activity for bovine aortic endothelial cells (BAECs). The compound potently inhibits endothelial cell invasion and tube formation stimulated with basic fibroblast growth factor (bFGF) at low micromolar concentrations where it shows no cytotoxicity to the cells. In addition, 4-OMGA inhibits vascular endothelial cell growth factor (VEGF) production under hypoxic condition and the production of reactive oxygen species (ROS) in the endothelial cells stimulated with VEGF. These results demonstrate that 4-OMGA is a compound having potential for an antiangiogenic agent.

Synthesis and Antitumor Activity of Some Curcumin Analogs

In this study, four new curcurmin analogs (compounds 1, 2, 17 and 18) were synthesized. 17 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)N-methylpiperidone] showed high activity with GI50, TGI, and LC50 MG-MID values of 21.3, 70.7, and 97.7 microM, respectively. 18 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)-N-ethylpiperidone] showed the highest activity in this study with GI50, TGI, LC50 MG-MID values of 4.4, 33.8, 89.1 microM, respectively. 18 is even more active than curcumin with GI50, TGI, LC50 MG-MID values of 38.4, 35.6, 66.0 microM; respectively. 8 showed moderate selectivity towards Leukemia cell line-subpanel with a ratio of 5.6 (curcumin ratio: 1.2 for the same subpanel). The in vitro anti-tumor screening reveals that the results go hand in hand with the in vitro free radical scavenging effects. The antioxidant effect of these compounds depends mainly on the stabilization of the formed phenoxy free radical for which the p-hydroxy phenyl moiety is essential. o-substitution by electron-donating groups like the o-methoxy group (and to a even higher degree by the ethoxy group) increases the stability of phenoxy free radical, hence increasing both free scavenging and anti-tumor effects. Increasing the alkyl group chain on the N in the series of substituted N-alkyl piperidones as well as the extension of conjugation, increases the stabilization of phenoxy free radical and thereby the activity towards both free radical scavenging and anti-tumor effects. This may be attributed to an increased positive inductive effect and/or increased lipophilicity of the new compounds, a fact which is proven by the superior activities of compounds 17 and 18.

Chemical genetics for therapeutic target mining

Chemical genetics is an emerging research field that utilises biologically active small molecules to study biological functions of genes and their products. The direct regulation of the protein function by the biologically active small molecules can alternate the gene mutagenesis studies utilised in conventional genetics. Like conventional genetics, chemical genetics can be divided into two concepts - 'forward' and 'reverse' chemical genetics. These approaches of chemical genetics have a tremendous impact on both functional genomics and drug development. This review focuses on the two ways in which chemical genetics can be used for therapeutic target mining and their practical application in drug development, particularly, in angiogenesis-related diseases.

Cochlioquinone A1, a new anti-angiogenic agent from Bipolaris zeicola

Cochlioquinone A1 (CoA1) was newly isolated from the culture extract of Bipolaris zeicola as a potent anti-angiogenic agent. CoA1 inhibited in vitro angiogenesis of bovine aortic endothelial cells (BAECs) such as bFGF-induced tube formation and invasion at the concentration (1 microg/mL) without cytotoxicity. Notably, CoA1 exhibited more potent inhibition activity for the growth of BAECs than that of normal and cancer cell lines investigated in this study. These results demonstrate that CoA1 is a new anti-angiogenic agent and can be developed as a new therapeutic agent for angiogenesis-related diseases.

Irreversible inhibition of CD13/aminopeptidase N by the antiangiogenic agent curcumin

CD13/aminopeptidase N (APN) is a membrane-bound, zinc-dependent metalloproteinase that plays a key role in tumor invasion and angiogenesis. Here, we show that curcumin, a phenolic natural product, binds to APN and irreversibly inhibits its activity. The direct interaction between curcumin with APN was confirmed both in vitro and in vivo by surface plasmon resonance analysis and an APN-specific antibody competition assay, respectively. Moreover, curcumin and other known APN inhibitors strongly inhibited APN-positive tumor cell invasion and basic fibroblast growth factor-induced angiogenesis. However, curcumin did not inhibit the invasion of APN-negative tumor cells, suggesting that the antiinvasive activity of curcumin against tumor cells is attributable to the inhibition of APN. Taken together, our study revealed that curcumin is a novel irreversible inhibitor of APN that binds to curcumin resulting in inhibition of angiogenesis.