Synthesis of novel curcumin analogues and their evaluation as selective cyclooxygenase-1 (COX-1) inhibitors

Curcumin and omega-3 polyunsaturated fatty acids as bioactive food components with synergistic effects on Alzheimer's disease

Curcumin and omega-3 polyunsaturated fatty acids (ω-3 PUFA) are multifunctional compounds which play an important role in Alzheimer's disease (AD) and little has been addressed about the role of these two compounds together in the progression of the disease. There is evidence of the beneficial effect of combined administration of ω-3 PUFA and other dietary supplements such as vitamins and polyphenols in the prevention of AD, although much remains to be understood about their possible complementary or synergistic activity. Therefore, the objective of this work is to review the research focused on studying the effect and mechanisms of action of curcumin, ω-3 PUFA, and the combination of these nutraceutical compounds, particularly on AD, and to integrate the possible ways in which these compounds can potentiate their effect. The most important pathophysiologies that manifest in AD will be addressed, in order to have a better understanding of the mechanisms of action through which these bioactive compounds exert a neuroprotective effect.

Rotational constriction of curcuminoids impacts 5-lipoxygenase and mPGES-1 inhibition and evokes a lipid mediator class switch in macrophages

Polypharmacological targeting of lipid mediator networks offers potential for efficient and safe anti-inflammatory therapy. Because of the diversity of its biological targets, curcumin (1a) has been viewed as a privileged structure for bioactivity or, alternatively, as a pan-assay interference (PAIN) compound. Curcumin has actually few high-affinity targets, the most remarkable ones being 5-lipoxygenase (5-LOX) and microsomal prostaglandin E2 synthase (mPGES)-1. These enzymes are critical for the production of pro-inflammatory leukotrienes and prostaglandin (PG)E2, and previous structure-activity-relationship studies in this area have focused on the enolized 1,3-diketone motif, the alkyl-linker and the aryl-moieties, neglecting the rotational state of curcumin, which can adopt twisted conformations in solution and at target sites. To explore how the conformation of curcuminoids impacts 5-LOX and mPGES-1 inhibition, we have synthesized rotationally constrained analogues of the natural product and its pyrazole analogue by alkylation of the linker and/or of the ortho aromatic position(s). These modifications strongly impacted 5-LOX and mPGES-1 inhibition and their systematic analysis led to the identification of potent and selective 5-LOX (3b, IC50 = 0.038 µM, 44.7-fold selectivity over mPGES-1) and mPGES-1 inhibitors (2f, IC50 = 0.11 µM, 4.6-fold selectivity over 5-LOX). Molecular docking experiments suggest that the C2-methylated pyrazolocurcuminoid 3b targets an allosteric binding site at the interface between catalytic and regulatory 5-LOX domain, while the o, o'-dimethylated desmethoxycurcumin 2f likely binds between two monomers of the trimeric mPGES-1 structure. Both compounds trigger a lipid mediator class switch from pro-inflammatory leukotrienes to PG and specialized pro-resolving lipid mediators in activated human macrophages.

Curcumin and its uses in active and smart food packaging applications - a comprehensive review

Active and intelligent food packaging is an innovative technology to prevent food contamination and ensure food quality and safety. Active packaging protects the food from microbial contamination, while smart or intelligent packaging enables monitoring the freshness of the food or quality change in real-time. Curcumin, one of the most well-known natural colorants, has received a lot of attention for its excellent functional properties and ability to change color with changes in pH. Curcumin, the golden component of turmeric, a spice widely used in food since ancient times, is a cost-effective and abundant biomaterial with various biological properties such as antioxidant, antibacterial, antiviral, antitumor, and anti-inflammatory. Recently, active packaging or intelligent packaging systems have been actively developed using the functional properties of curcumin. In this review, we briefly reviewed curcumin's basic biological functions and discussed comprehensive and recent progress in using curcumin in various polymer-based active and smart food packaging applications.

Co(II) complexes of curcumin and a ferrocene-based curcuminoid: a study on photo-induced antitumor activity

Co(II) complexes having a ferrocene-based curcuminoid (Fc-curH) ligand viz. [Co(L)₂(Fc-cur)]ClO₄ (1, 2), where L is phenanthroline base, namely, 1,10-phenanthroline (phen in 1) and dipyrido[3,2-a:2',3'-c]phenazine (dppz in 2) have been synthesized, characterized and evaluated as photochemotherapeutic agents in vitro. The corresponding Co(II) complexes of the naturally occurring polyphenol curcumin (curH), namely, [Co(L)₂(cur)]ClO₄ (3, 4), where L is phen (in 3) and dppz (in 4) were synthesized and their photo-induced anticancer activities compared with their ferrocene containing counterparts 1 and 2. The Co(II) acetylacetonato complex viz. [Co(phen)₂(acac)]ClO₄ (5) was structurally characterized through X-ray crystallography and used as control for cellular experiments. The Co(II) complexes having ferrocene-based curcuminoid are remarkably stable at physiological condition with higher lipophilicity compared to their curcumin analogues. The complexes display significant binding propensity to calf thymus (ct) DNA and human serum albumin (HSA). The complexes 1-4 display remarkable visible light induced cytotoxicity with the ferrocenyl analogues showing more phototoxic index (PI). The Co(II) curcumin complexes localize in the nucleus and mitochondria of A549 cells. The primary cell death mechanism is believed to be apoptotic in nature induced by light assisted generation of reactive oxygen species (ROS).Graphic abstract.

Dietary polyphenols in chemoprevention and synergistic effect in cancer: Clinical evidences and molecular mechanisms of action

BACKGROUND

Epidemiological studies has revealed that a diet rich in fruits and vegetables could lower the risk of certain cancers. In this setting, natural polyphenols are potent anticancer bioactive compounds to overcome the non-target specificity, undesirable cytotoxicity and high cost of treatment cancer chemotherapy.

PURPOSE

The review focuses on diverse classifications of the chemical diversity of dietary polyphenol and their molecular targets, modes of action, as well as preclinical and clinical applications in cancer prevention.

RESULTS

The dietary polyphenols exhibit chemo-preventive activity through modulation of apoptosis, autophagy, cell cycle progression, inflammation, invasion and metastasis. Polyphenols possess strong antioxidant activity and control multiple molecular events through activation of tumor suppressor genes and inhibition of oncogenes involved in carcinogenesis. Numerous in vitro and in vivo studies have evidenced that these dietary phytochemicals regulate critical molecular targets and pathways to limit cancer initiation and progression. Moreover, natural polyphenols act synergistically with existing clinically approved drugs. The improved anticancer activity of combinations of polyphenols and anticancer drugs represents a promising perspective for clinical applications against many human cancers.

CONCLUSION

The anticancer properties exhibited by dietary polyphenols are mainly attributed to their anti-metastatic, anti-proliferative, anti-angiogenic, anti-inflammatory, cell cycle arrest, apoptotic and autophagic effects. Hence, regular consumption of dietary polyphenols as food or food additives or adjuvants can be a promising tactic to preclude adjournment or cancer therapy.

Natural Product Inhibitors of Cyclooxygenase (COX) Enzyme: A Review on Current Status and Future Perspectives

BACKGROUND

Several clinically used COX-1 and COX-2 inhibitor drugs were reported to possess severe side effects like GI ulcers and cardiovascular disturbances, respectively. Natural products being structurally diverse always attracted the attention of chemists/ medicinal chemists as a potential source of lead molecules in the drug discovery process. COX-2 inhibitory natural products also possess potential cancer chemopreventive property against various cancers including that of colon, breast and prostate.

METHODS

Various in vitro, in vivo and in silico standardized methods were used to evaluate COX inhibition property of different secondary metabolites isolated from plant, microbial and marine origin.

RESULTS

We had earlier reported a detailed account of natural product inhibitors of COX reported during 1995-2005, in 2006. In the proposed review, we report 158 natural product inhibitors of COX during 2006 to 2019 belonging to various secondary metabolite classes such as alkaloids, terpenoids, polyphenols as flavonoids, chromones, coumarins, lignans, anthraquinones, naphthalenes, curcuminoids, diarylheptanoids and miscellaneous compounds of plant and marine origin. Further Structure Activity Relationship (SAR) studies of possible leads are also included in the article.

CONCLUSION

COX inhibitors served as a potential source of lead molecules for the discovery and development of anti-inflammatory drugs. Compilation of natural product and semisynthetic inhibitors of COX may serve as valuable information to the researchers who are looking for possible lead molecules from a natural source to conduct further preclinical and clinical studies.

Pyrrolizine-5-carboxamides: Exploring the impact of various substituents on anti-inflammatory and anticancer activities

Towards optimization of the pyrrolizine-5-carboxamide scaffold, a novel series of six derivatives (4a-c and 5a-c) was prepared and evaluated for their anti-inflammatory, analgesic and anticancer activities. The (EZ)-7-cyano-6-((4-hydroxybenzylidene)amino)-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4b) and (EZ)-6-((4-chlorobenzylidene)-amino)-7-cyano-N-(p-tolyl)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5b) bearing the electron donating methyl group showed the highest anti-inflammatory activity while (EZ)-6-((4-chlorobenzylidene)amino)-7-cyano-N-phenyl-2,3-dihydro-1H-pyrrolizine-5-carboxamide (5a) was the most active analgesic agent. Cytotoxicity of the new compounds was evaluated against the MCF-7, A2780 and HT29 cancer cell lines using the MTT assay. Compounds 4b and 5b displayed high anticancer activity with IC50 in the range of 0.30-0.92 μmol L-1 against the three cell lines, while compound (EZ)-N-(4-chlorophenyl)-7-cyano-6-((4-hydroxybenzylidene)-amino)-2,3-dihydro-1H-pyrrolizine-5-carboxamide (4c) was the most active against MCF-7 cells (IC50 = 0.08 μmol L-1). Both the anti-inflammatory and anticancer activities of the new compounds were dependent on the type of substituent on the phenyl rings. Substituents with opposite electronic effects on the two phenyl rings are preferable for high cytotoxicity against the MCF-7 and A2780 cells. COX inhibition was suggested as the molecular mechanism of the anti-inflammatory activity of the new compounds while no clear relationship could be observed between COX inhibition and anticancer activity. Compound 5b, the most active against the three cell lines, induced dose-dependent early apoptosis with 0.1-0.2 % necrosis in MCF-7 cells. New compounds showed promising drug-likeness scores while the docking study revealed high binding affinity to COX-2. Taken together, this study highlighted the significant impact of the substituents on the anti-inflammatory and anticancer activity of pyrrolizine-5-carboxamides, which could help in further optimization to discover good leads for the treatment of cancer and inflammation.

An Overview of Novel Dietary Supplements and Food Ingredients in Patients with Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Metabolic syndrome (MetS) is characterized by interconnected factors related to metabolic disturbances, and is directly related to the occurrence of some diseases such as cardiovascular diseases and type 2 diabetes. MetS is described as one or both of insulin resistance and visceral adiposity, considered the initial causes of abnormalities that include hyperglycemia, elevated blood pressure, dyslipidemia, elevated inflammatory markers, and prothrombotic state, as well as polycystic ovarian syndrome in women. Other than in MetS, visceral adiposity and the pro-inflammatory state are also key in the development of non-alcoholic fatty liver disease (NAFLD), which is the most prevalent chronic liver disease in modern society. Both MetS and NAFLD are related to diet and lifestyle, and their treatment may be influenced by dietary pattern changes and the use of certain dietary supplements. This study aimed to review the role of food ingredients and supplements in the management of MetS and NAFLD specifically in human clinical trials. Moreover, bioactive compounds and polyunsaturated fatty acids (PUFAs) may be used as strategies for preventing the onset of and treatment of metabolic disorders, such as MetS and NAFLD, improving the inflammatory state and other comorbidities, such as obesity, dyslipidemias, and cardiovascular diseases (CVD).

Curcumin: Synthesis optimization and in silico interaction with cyclin dependent kinase

Curcumin is a natural product with enormous biological potential. In this study, curcumin synthesis was revisited using different reaction solvents, a catalyst (n-butylamine) and a water scavenger [(n-BuO)3B], to develop the optimal procedure for its rapid acquisition. During synthesis, solvent choice was found to be an important parameter for better curcumin yield and high purity. In a typical reaction, acetyl acetone was treated with boron trioxide, followed by condensation with vanillin in the presence of tri-n-butyl borate as water scavenger and n-butylamine as catalyst at 80 °C in ethyl acetate to afford curcumin. Moreover, curcumin was also extracted from turmeric powder and spectroscopic properties such as IR, MS, 1H NMR and 13C NMR with synthetic curcumin were established to identify any impurity. The purity of synthetic and extracted curcumin was also checked by TLC and HPLC-DAD. To computationally assess its therapeutic potential against cyclin dependent kinases (CDKs), curcumin was docked in different isoforms of CDKs. It was observed that it did not dock at the active sites of CDK2 and CDK6. However, it could enter into weak interactions with CDK4 protein.

Pyrrolizines: Design, synthesis, anticancer evaluation and investigation of the potential mechanism of action

A novel set of pyrrolizine-5-carboxamides has been synthesized and evaluated for their anticancer potential against human breast MCF-7, lung carcinoma A549 and hepatoma Hep3B cancer cell lines. Compound 10c was the most active against MCF-7 with IC₅₀ value of 4.72µM, while compound 12b was the most active against A549 and Hep3B cell lines. Moreover, kinases/COXs inhibition and apoptosis induction were suggested as potential molecular mechanisms for the anticancer activity of the novel pyrrolizines based on their structural features. The new compounds significantly inhibited COX-1 and COX-2 with IC₅₀ values in the ranges of 5.78-11.96µM and 0.1-0.78µM, respectively with high COX-2 selectivity over COX-1. Interestingly, the most potent compound in MTT assay, compound 12b, exhibited high inhibitory activity against COX-2 with selectivity index (COX-1/COX-2)>100. Meanwhile, compound 12b displayed weak to moderate inhibition of six kinases with inhibition% (7-20%) compared to imatinib (inhibition%=1-38%). The results of cell cycle analysis, annexin V PI/FITC apoptosis assay and caspase-3/7 assay revealed that compound 12b has the ability to induce apoptosis. The docking results of compound 12b into the active sites of COXs, ALK1 and Aurora kinases indicated that it fits nicely inside their active sites. Overall, the current study highlighted the significant anticancer activity of the newly synthesized pyrrolizines with a potential multi-targeted mechanism which could serve as a base for future studies and further structural optimization into potential anticancer agents.

An overview of structure-activity relationship studies of curcumin analogs as antioxidant and anti-inflammatory agents

Curcumin, extracted mainly from Curcuma longa rhizomes, has been reported to possess potent anti-inflammatory and anti-oxidant activities. Although safe at higher doses and exhibiting multiple biological activities, curcumin still has the problem of poor bioavailability which has been an attractive area of research over the last few years. A number of efforts have been made by modifying structural features of curcumin. This review highlights the structurally modified and more stable newly synthesized curcumin analogs that have been screened against antioxidant and anti-inflammatory activities. Also the structure-activity relationship to gain insight into future guidelines for scheming new compounds has been discussed, and further these analogs being more stable may serve as promising agents for use in different pathological conditions.

Alves L, Brocksom TJ, de Oliveira KT. Combining batch and continuous flow setups in the end-to-end synthesis of naturally occurring curcuminoids

A successful end-to-end continuous flow synthesis of pure curcumin (1) and two other natural derivatives present in turmeric is described.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

The antioxidant activity of some curcuminoids and chalcones

The antioxidant properties of the synthetic compound (C1)–(C8), which comprised 7 curcuminoids and a chalcone, were evaluated by two complementary assays, DPPH and β-carotene/linoleic acid. It was found that, in general, the free radical scavenging ability of (C1)–(C8) was concentration-dependent. Compounds (C1) and (C4), which contained (4-OH) phenolic groups, were found to be highly potent antioxidants with higher antioxidant values than BHT suggesting that synthetic curcuminoids are more potent antioxidants than standard antioxidants like BHT. Using β-carotene-linoleic acid assay, only the water-soluble 2, 4,6-trihydroxyphenolic chalcone (C5) showed 85.2 % inhibition of the formation of conjugated dienes reflecting on its potent antioxidant activity.

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.

Synthesis of dihydropyrazole sulphonamide derivatives that act as anti-cancer agents through COX-2 inhibition

COX-2 has long been exploited in the treatment of inflammation and relief of pain; however, research increasingly suggests COX-2 inhibitors might possess potential benefits to thwart tumour processes. In the present study, we designed a series of novel COX-2 inhibitors based on analysis of known inhibitors combined with an in silico scaffold modification strategy. A docking simulation combined with a primary screen in vitro were performed to filter for the lead compound, which was then substituted, synthesized and evaluated by a variety of bioassays. Derivative 4d was identified as a potent COX-2 enzyme inhibitor and exerted an anticancer effect through COX-2 inhibition. Further investigation confirmed that 4d could induce A549 cell apoptosis and arrest the cell cycle at the G2/M phase. Moreover, treatment with 4d reduced A549 cell adhesive ability and COX-2 expression. The morphological variation of treated cells was also visualized by confocal microscopy. Overall, the biological profile of 4d suggests that this compound may be developed as a potential anticancer agent.

Chemical conjugation of 2-hexadecynoic acid to C5-curcumin enhances its antibacterial activity against multi-drug resistant bacteria

The first total synthesis of a C5-curcumin-2-hexadecynoic acid (C5-Curc-2-HDA, 6) conjugate was successfully performed. Through a three-step synthetic route, conjugate 6 was obtained in 13% overall yield and tested for antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains. Our results revealed that 6 was active against eight MRSA strains at MICs that range between 31.3 and 62.5 μg/mL. It was found that the presence of 2-hexadecynoic acid (2-HDA, 4) in conjugate 6 increased 4-8-fold its antibacterial activity against MRSA strains supporting our hypothesis that the chemical connection of 4 to C5-curcumin (2) increases the antibacterial activity of 2 against Gram-positive bacteria. Combinational index (CIn) values that range between 1.6 and 2.3 were obtained when eight MRSA strains were treated with an equimolar mixture of 2 and 4. These results demonstrated that an antagonistic effect is taking place. Finally, it was investigated whether conjugate 6 can affect the replication process of S. aureus, since this compound inhibited the supercoiling activity of the S. aureus DNA gyrase at minimum inhibitory concentrations (MIC) of 250 μg/mL (IC50=100.2±13.9 μg/mL). Moreover, it was observed that the presence of 4 in conjugate 6 improves the anti-topoisomerase activity of 2 towards S. aureus DNA gyrase, which is in agreement with results obtained from antibacterial susceptibility tests involving MRSA strains.

Reduction of delayed onset muscle soreness by a novel curcumin delivery system (Meriva®): a randomised, placebo-controlled trial

BACKGROUND

Delayed onset muscle soreness (DOMS) due to eccentric muscle activity is associated with inflammatory responses and production of reactive oxygen species (ROS) that sustain both inflammation and oxidative stress. Curcumin, a powerful promoter of anti-oxidant response, is one of the best-investigated natural products, and is now commercially available as a lecithin delivery system (Meriva®, Indena SpA, Milan) with improved bio-availability. The aim of this study was to test whether curcumin could attenuate damage from oxidative stress and inflammation related to acute muscle injury induced by eccentric continuous exercise.

METHODS

This was a randomised, placebo-controlled, single-blind pilot trial. Twenty male healthy, moderately active volunteers were randomised to curcumin given as the Phytosome® delivery system 1 g twice daily (200 mg curcumin b.i.d.) or matching placebo. Supplementation was initiated 48 hours prior to a downhill running test and was continued for 24 hours after the test (4 days in total). Muscle damage was quantified by magnetic resonance imaging, laboratory tests and histological analyses on muscle samples obtained 48 hours after the test. Patient-reported pain intensity was also recorded.

RESULTS

Subjects in the curcumin group reported less pain in the lower limb as compared with subjects in the placebo group, although significant differences were observed only for the right and left anterior thighs. Significantly fewer subjects in the curcumin group had MRI evidence of muscle injury in the posterior or medial compartment of both thighs. Increases in markers of muscle damage and inflammation tended to be lower in the curcumin group, but significant differences were only observed for interleukin-8 at 2 h after exercise. No differences in markers of oxidative stress and muscle histology were observed.

CONCLUSIONS

Curcumin has the potential for preventing DOMS, as suggested by its effects on pain intensity and muscle injury. Larger studies are needed to confirm these results and further clarify the mechanism of action of curcumin.

A double-blind, placebo-controlled randomised trial evaluating the effect of a polyphenol-rich whole food supplement on PSA progression in men with prostate cancer--the U.K. NCRN Pomi-T study

Background:

Polyphenol-rich foods such as pomegranate, green tea, broccoli and turmeric have demonstrated anti-neoplastic effects in laboratory models involving angiogenesis, apoptosis and proliferation. Although some have been investigated in small, phase II studies, this combination has never been evaluated within an adequately powered randomised controlled trial.

Methods:

In total, 199 men, average age 74 years, with localised prostate cancer, 60% managed with primary active surveillance (AS) or 40% with watchful waiting (WW) following previous interventions, were randomised (2:1) to receive an oral capsule containing a blend of pomegranate, green tea, broccoli and turmeric, or an identical placebo for 6 months.

Results:

The median rise in PSA in the food supplement group (FSG) was 14.7% (95% confidence intervals (CIs) 3.4–36.7%), as opposed to 78.5% in the placebo group (PG) (95% CI 48.1–115.5%), difference 63.8% (P=0.0008). In all, 8.2% of men in the FSG and 27.7% in the PG opted to leave surveillance at the end of the intervention (χ²P=0.014). There were no significant differences within the predetermined subgroups of age, Gleason grade, treatment category or body mass index. There were no differences in cholesterol, blood pressure, blood sugar, C-reactive protein or adverse events.

Conclusions:

This study found a significant short-term, favourable effect on the percentage rise in PSA in men managed with AS and WW following ingestion of this well-tolerated, specific blend of concentrated foods. Its influence on decision-making suggests that this intervention is clinically meaningful, but further trials will evaluate longer term clinical effects, and other makers of disease progression.

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.

Analysis of the anticancer activity of curcuminoids, thiotryptophan and 4-phenoxyphenol derivatives

Curcumin, a non-nutritive yellow pigment derived from the rhizome of Curcuma longa (turmeric), is considered to be an established nutraceutical with anticancer activity. Turmeric contains three principal components, curcumin, demethoxycurcumin and bisdemethoxycurcumin, of which curcumin is most abundant and potent. The concurrence of a high consumption of turmeric and a low incidence of prostate cancer in Asian countries may suggest a role for curcumin in chemoprevention. Curcumin has been identified to exhibit anti-inflammatory, anti-oxidative and anticarcinogenic properties. Since the compound does not exhibit side effects, curcumin has been designated for several clinical trials as a treatment for human cancers. The pro-apototic, antioxidant and anti-inflammatory characteristics of curcumin are implicated in its anticancer activity, yet the mechanism of action of curcumin remains unknown. To achieve an effective pharmacological outcome, curcumin must reach and sustain appropriate levels at the site of action. However, the main disadvantage of curcumin is its high metabolic instability and poor aqueous solubility that limits its systemic bioavailability. To overcome this difficulty, the present study tested the anticancer activity of new curcumin-like compounds (E21cH and Q012095H). Also, the use of new medicaments requires an understanding of their pharmacokinetic profiles and targets. Thus, molecular modeling methods were used to identify the targets of curcumin and curcumin-like compounds compared with other anticancer drugs (Q012138 and Q012169AT), which were used as the controls. The present study identified several enzymes that are targeted by curcumin, aldo-keto reductase family 1 member B10 (AKR1B10), serine/threonine-protein kinase, protein kinase C, matrix metalloproteinase (MMP), cyclooxygenase and epidermal growth factor receptor, which were tested as targets for these anticancer chemicals. All the examined small compounds demonstrated anticancer activity in the in vitro experiments and may impact cancer cells by acting on AKR1B10, MMP-9 and their targets.

Perspectives on new synthetic curcumin analogs and their potential anticancer properties

Curcumin is the active component of dried rhizome of Curcuma longa, a perennial herb belonging to ginger family, cultivated extensively in south and southeastern tropical Asia. It is widely consumed in the Indian subcontinent, south Asia and Japan in traditional food recipes. Extensive research over last few decades has shown that curcumin is a potent anti-inflammatory agent with powerful therapeutic potential against a variety of cancers. It suppresses proliferation and metastasis of human tumors through regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases and other enzymes. It induces apoptotic cell death and also inhibits proliferation of cancer cells by cell cycle arrest. Pharmacokinetic data has shown that curcumin undergoes rapid metabolism leading to glucuronidation and sulfation in the liver and excretion in the feces, which accounts for its poor systemic bioavailability. The compound has, therefore, been formulated and administered using different drug delivery systems such as liposomes, micelles, polysaccharides, phospholipid complexes and nanoparticles that can overcome the limitation of bioavailability to some extent. Attempts to avoid rapid metabolism of curcumin until now have been met with limited success. This has prompted researchers to look for new synthetic curcumin analogs in order to overcome the drawbacks of limited bioavailability and rapid metabolism, and gain efficacy with reduced toxicity. In this review we provide a summarized account of novel synthetic curcumin formulations and analogs, and the recent progress in the field of cancer prevention and treatment.

Perspectives on new synthetic curcumin analogs and their potential anticancer properties

Curcumin is the active component of dried rhizome of Curcuma longa, a perennial herb belonging to ginger family, cultivated extensively in south and southeastern tropical Asia. It is widely consumed in the Indian subcontinent, south Asia and Japan in traditional food recipes. Extensive research over last few decades has shown that curcumin is a potent anti-inflammatory agent with powerful therapeutic potential against a variety of cancers. It suppresses proliferation and metastasis of human tumors through regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases and other enzymes. It induces apoptotic cell death and also inhibits proliferation of cancer cells by cell cycle arrest. Pharmacokinetic data has shown that curcumin undergoes rapid metabolism leading to glucuronidation and sulfation in the liver and excretion in the feces, which accounts for its poor systemic bioavailability. The compound has, therefore, been formulated and administered using different drug delivery systems such as liposomes, micelles, polysaccharides, phospholipid complexes and nanoparticles that can overcome the limitation of bioavailability to some extent. Attempts to avoid rapid metabolism of curcumin until now have been met with limited success. This has prompted researchers to look for new synthetic curcumin analogs in order to overcome the drawbacks of limited bioavailability and rapid metabolism, and gain efficacy with reduced toxicity. In this review we provide a summarized account of novel synthetic curcumin formulations and analogs, and the recent progress in the field of cancer prevention and treatment.

Curcumin reduces prostaglandin E2, matrix metalloproteinase-3 and proteoglycan release in the secretome of interleukin 1β-treated articular cartilage

Objective:Curcumin (diferuloylmethane) is a phytochemical with potent anti-inflammatory and anti-oxidant properties, and has therapeutic potential for the treatment of a range of inflammatory diseases, including osteoarthritis (OA). The aim of this study was to determine whether non-toxic concentrations of curcumin can reduce interleukin-1beta (IL-1β)-stimulated inflammation and catabolism in an explant model of cartilage inflammation.

Methods:Articular cartilage explants and primary chondrocytes were obtained from equine metacarpophalangeal joints. Curcumin was added to monolayer cultured primary chondrocytes and cartilage explants in concentrations ranging from 3μM-100μM. Prostaglandin E ₂ (PGE ₂) and matrix metalloproteinase (MMP)-3 release into the secretome of IL-1β-stimulated explants was measured using a competitive ELISA and western blotting respectively. Proteoglycan (PG) release in the secretome was measured using the 1,9-dimethylmethylene blue (DMMB) assay. Cytotoxicity was assessed with a live/dead assay in monolayer cultures after 24 hours, 48 hours and five days, and in explants after five days.

Results:Curcumin induced chondrocyte death in primary cultures (50μM p<0.001 and 100μM p<0.001) after 24 hours. After 48 hours and five days, curcumin (≥25μM) significantly increased cell death ( p<0.001 both time points). In explants, curcumin toxicity was not observed at concentrations up to and including 25μM after five days. Curcumin (≥3μM) significantly reduced IL-1β-stimulated PG ( p<0.05) and PGE ₂ release ( p<0.001) from explants, whilst curcumin (≥12μM) significantly reduced MMP-3 release ( p<0.01).

Conclusion: Non-cytotoxic concentrations of curcumin exert anti-catabolic and anti-inflammatory effects in cartilage explants.

Curcumin: an anti-inflammatory molecule from a curry spice on the path to cancer treatment

Oxidative damage and inflammation have been pointed out in preclinical studies as the root cause of cancer and other chronic diseases such as diabetes, hypertension, Alzheimer's disease, etc. Epidemiological and clinical studies have suggested that cancer could be prevented or significantly reduced by treatment with anti-oxidant and anti-inflammatory drugs, therefore, curcumin, a principal component of turmeric (a curry spice) showing strong anti-oxidant and anti-inflammatory activities, might be a potential candidate for the prevention and/or treatment of cancer and other chronic diseases. However, curcumin, a highly pleiotropic molecule with an excellent safety profile targeting multiple diseases with strong evidence on the molecular level, could not achieve its optimum therapeutic outcome in past clinical trials, largely due to its low solubility and poor bioavailability. Curcumin can be developed as a therapeutic drug through improvement in formulation properties or delivery systems, enabling its enhanced absorption and cellular uptake. This review mainly focuses on the anti-inflammatory potential of curcumin and recent developments in dosage form and nanoparticulate delivery systems with the possibilities of therapeutic application of curcumin for the prevention and/or treatment of cancer.

Catalytic asymmetric Michael addition with curcumin derivative

Catalytic asymmetric Michael additions with curcumin derivatives were achieved by a new series of tertiary amine-thiourea organocatalysts to afford the Michael adducts in high yields and excellent enantioselectivities.

Curcumin and its analogues: potential anticancer agents

This review chronicles the exploration of the curcumin in terms of development of analogues for the anticancer activity over the last century. Curcumin is a natural phytochemical obtained from dried root and rhizome of Turmeric (Curcuma Longa). It has been shown to interfere with multiple cell signaling pathways, including apoptosis (activation of caspases and downregulation of antiapoptotic gene products), proliferation (HER-2, EGFR, and AP-1), angiogenesis (VEGF), and inflammation (NF-kappaB, TNF, IL-6, IL-1, COX-2, and 5-LOX). In the last decade it has been much explored and various synthetic analogues have been prepared and evaluated for various pharmacological activities. Most of the analogues have shown very good anticancer activity in various models and various cell lines. However, some analogues have also shown antioxidant, anti-HIV, antimutagenic, antiangiogenic, antimalarial, antitubercular, antiandrogenic, COX inhibitory activities. Few analogues have shown very potent results and may be considered as clinical candidates for the development of future anticancer agent. This review contains 728 curcumin analogues and covers the literature from 1815 to mid 2009 and 93 references are cited.

Predicting cyclooxygenase inhibition by three-dimensional pharmacophoric profiling. Part II: Identification of enzyme inhibitors from Prasaplai, a Thai traditional medicine

Prasaplai is a medicinal plant mixture that is used in Thailand to treat primary dysmenorrhea, which is characterized by painful uterine contractility caused by a significant increase of prostaglandin release. Cyclooxygenase (COX) represents a key enzyme in the formation of prostaglandins. Former studies revealed that extracts of Prasaplai inhibit COX-1 and COX-2. In this study, a comprehensive literature survey for known constituents of Prasaplai was performed. A multiconformational 3D database was created comprising 683 molecules. Virtual parallel screening using six validated pharmacophore models for COX inhibitors was performed resulting in a hit list of 166 compounds. 46 Prasaplai components with already determined COX activity were used for the external validation of this set of COX pharmacophore models. 57% of these components were classified correctly by the pharmacophore models. These findings confirm that the virtual approach provides a helpful tool (i) to unravel which molecular compounds might be responsible for the COX-inhibitory activity of Prasaplai and (ii) for the fast identification of novel COX inhibitors.

Anti-inflammatory effect of bee pollen ethanol extract from Cistus sp. of Spanish on carrageenan-induced rat hind paw edema

Background

Bee pollen, a honeybee product, is the feed for honeybees prepared themselves by pollens collecting from plants and has been consumed as a perfect food in Europe, because it is nutritionally well balanced. In this study, we aimed to investigate the anti-inflammatory effect of bee pollen from Cistus sp. of Spanish origin by a method of carrageenan-induced paw edema in rats, and to investigate the mechanism of anti-inflammatory action and also to elucidate components involved in bee pollen extracted with ethanol.

Methods

The bee pollen bulk, its water extract and its ethanol extract were administered orally to rats. One hour later, paw edema was produced by injecting of 1% solution of carrageenan, and paw volume was measured before and after carrageenan injection up to 5 h. The ethanol extract and water extract were measured COX-1 and COX-2 inhibitory activities using COX inhibitor screening assay kit, and were compared for the inhibition of NO production in LPS-stimulated RAW 264.7 cells. The constituents of bee pollen were purified from the ethanol extract subjected to silica gel or LH-20 column chromatography. Each column chromatography fractions were further purified by repeated ODS or silica gel column chromatography.

Results

The bee pollen bulk mildly suppressed the carrageenan-induced paw edema and the water extract showed almost no inhibitory activity, but the ethanol extract showed relatively strong inhibition of paw edema. The ethanol extract inhibited the NO production and COX-2 but not COX-1 activity, but the water extract did not affect the NO production or COX activities. Flavonoids were isolated and purified from the ethanol extract of bee pollen, and identified at least five flavonoids and their glycosides.

Conclusions

It is suggested that the ethanol extract of bee pollen show a potent anti-inflammatory activity and its effect acts via the inhibition of NO production, besides the inhibitory activity of COX-2. Some flavonoids included in bee pollen may partly participate in some of the anti-inflammatory action. The bee pollen would be beneficial not only as a dietary supplement but also as a functional food.

Design and synthesis of androgen receptor antagonists with bulky side chains for overcoming antiandrogen resistance

Incorporation of curcumin and beta-ionone into one chemical entity led to identification of a novel antiandrogen with two bulky side chains, 6, which is a pure antagonist of the wild-type and the T877A, W741C, and H874Y mutated androgen receptors (AR), showing no cross-reactivity with progesterone receptor and low micromolar cytotoxicity in LNCaP, PCa-2b, 22Rv1, and C4-2B prostate cancer cells. Molecular modeling indicates 6 adopts a "Y"-shape conformation and forms multiple hydrogen bonds with AR backbone.

Synergistic anti-inflammatory effects of low doses of curcumin in combination with polyunsaturated fatty acids: docosahexaenoic acid or eicosapentaenoic acid

Inflammatory response plays an important role not only in the normal physiology but also in the pathology such as cancers. As chronic inflammations are associated with malignancies, it is important to prevent inflammation-mediated neoplastic formation, promotion and/or progression. One possible intervention will be using cancer chemopreventive agents such as curcumin (CUR), a potent anti-inflammatory and anti-oxidative stress compound. Polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) are potent anti-inflammatory agents by decreasing the production of inflammatory eicosanoids, cytokines, and reactive oxygen species (ROS). The present study aims at examining whether CUR with DHA or EPA would have synergistic anti-inflammatory effects in RAW 264.7 cells. Non-toxic concentrations of single and combination of the compounds were investigated at 6, 12 and 24h. The nitric oxide (NO) suppression effects were most prominent at 24h. All the combinations of CUR and DHA or EPA with lower concentrations of CUR 5 microM and 25 microM of DHA or EPA were found to have synergistic effects in suppressing LPS-stimulated NO and endogenous NO levels. Importantly, very low doses of CUR 2.5 microM and DHA or EPA of 0.78 microM could synergistically suppress the LPS-induced prostaglandin E(2) (PGE(2)). The combinations were also found to suppress iNOS, COX-2, 5-lipoxygenase (5-LOX) and cPLA(2) but induce HO-1. Taken together, the present study clearly shows the synergistic anti-inflammatory as well as anti-oxidative stress effects of CUR and PUFA.

Curcumin in cancer management: recent results of analogue design and clinical studies and desirable future research

The ability of the curry constituent curcumin to delay the onset of cancer has been the topic of extensive research for many years. Abundant literature is devoted to mechanisms by which curcumin may mediate this activity. These insights have prompted investigations in which curcumin as lead molecule serves as a scaffold for synthetic chemical attempts to optimize pharmacological potency. Among the published analogues with notable efficacy are dimethylcurcumin, 1,5-bis(3-pyridyl)-1,4-pentadien-3-one and 3,5-bis-(2-fluorobenzylidene)-piperidinium-4-one acetate. Results of a small number of clinical pilot studies conducted with curcumin at doses of up to 12 g suggest tentatively that it is safe in humans. Prevention of adenoma recurrence constitutes a clinical paradigm worthy of further investigation for curcumin. Future clinical study should include measurement of mechanism-based pharmacodynamic parameters.

Biological activities of curcumin and its analogues (Congeners) made by man and Mother Nature

Curcumin, a yellow pigment present in the Indian spice turmeric (associated with curry powder), has been linked with suppression of inflammation; angiogenesis; tumorigenesis; diabetes; diseases of the cardiovascular, pulmonary, and neurological systems, of skin, and of liver; loss of bone and muscle; depression; chronic fatigue; and neuropathic pain. The utility of curcumin is limited by its color, lack of water solubility, and relatively low in vivo bioavailability. Because of the multiple therapeutic activities attributed to curcumin, however, there is an intense search for a "super curcumin" without these problems. Multiple approaches are being sought to overcome these limitations. These include discovery of natural curcumin analogues from turmeric; discovery of natural curcumin analogues made by Mother Nature; synthesis of "man-made" curcumin analogues; reformulation of curcumin with various oils and with inhibitors of metabolism (e.g., piperine); development of liposomal and nanoparticle formulations of curcumin; conjugation of curcumin prodrugs; and linking curcumin with polyethylene glycol. Curcumin is a homodimer of feruloylmethane containing a methoxy group and a hydroxyl group, a heptadiene with two Michael acceptors, and an alpha,beta-diketone. Structural homologues involving modification of all these groups are being considered. This review focuses on the status of all these approaches in generating a "super curcumin.".

Synthesis and anti-bacterial properties of mono-carbonyl analogues of curcumin

The synthesis of three series of curcumin analogues with mono-carbonyl is described. Their in vitro anti-bacterial activities against seven Gram-positive and Gram-negative bacteria were tested and the effect of substituents on the aryl ring and the space structure of the linking strain were discussed. It was observed that part of the derivatives displayed significant activity when compared with curcumin and most of them exhibited activity against the ampicillin-resisted Enterobacter cloacae. Compounds A12, B09, B13, B14 and C09 show remarkable antibacterial activity in vitro. The result showed that heterocycle or long-chain substituents may enhance the activity of curcumin analogues.

Curcumin: preventive and therapeutic properties in laboratory studies and clinical trials

Curcumin is a natural polyphenol used in ancient Asian medicine. Since the first article referring to the use of curcumin to treat human disease was published in The Lancet in 1937, >2,600 research studies using curcumin or turmeric have been published in English language journals. The mechanisms implicated in the inhibition of tumorigenesis by curcumin are diverse and appear to involve a combination of antiinflammatory, antioxidant, immunomodulatory, proapoptotic, and antiangiogenic properties via pleiotropic effects on genes and cell-signaling pathways at multiple levels. The potentially adverse sequelae of curcumin's effects on proapoptotic genes, particularly p53, represent a cause for current debate. When curcumin is combined with some cytotoxic drugs or certain other diet-derived polyphenols, synergistic effects have been demonstrated. Although curcumin's low systemic bioavailability after oral dosing may limit access of sufficient concentrations for pharmacologic effects in tissues outside the gastrointestinal tract, chemical analogues and novel delivery methods are in preclinical development to overcome this barrier. This article provides an overview of the extensive published literature on the use of curcumin as a therapy for malignant and inflammatory diseases and its potential use in the treatment of degenerative neurologic diseases, cystic fibrosis, and cardiovascular diseases. Despite the breadth of the coverage, particular emphasis is placed on the prevention and treatment of human cancers.