Structure-activity relationship studies of curcumin analogues

Natural products and derivatives for breast cancer treatment: From drug discovery to molecular mechanism

BACKGROUND

Breast cancer stands as the most common malignancy among women globally and a leading cause of cancer-related mortality. Conventional treatments, such as surgery, hormone therapy, radiotherapy, chemotherapy, and small-molecule targeted therapy, often fall short of addressing the complexity and heterogeneity of certain breast cancer subtypes, leading to drug resistance and metastatic progression. Thus, the search for novel therapeutic targets and agents is imperative. Given their low toxicity and abundant variety, natural products and their derivatives are increasingly considered valuable sources for small-molecule anticancer drugs.

PURPOSE

This review aims to elucidate the pharmacological impacts and underlying mechanisms of active compounds found in select natural products and their derivatives, primarily focusing on breast cancer treatment. It intends to underscore the potential of these substances in combating breast cancer and guide future research directions for the development of natural product-based therapeutics.

METHODS

We conducted comprehensive searches in electronic databases such as PubMed, Web of Science, and Scopus until October 2023, using keywords such as 'breast cancer', 'natural products', 'derivatives', 'mechanism', 'signaling pathways', and various keyword combinations.

RESULTS

The review presents a spectrum of phytochemicals, including but not limited to flavonoids, polyphenols, and alkaloids, and examines their actions in various animal and cellular models of breast cancer. The anticancer effects of these natural products and derivatives are manifested through diverse mechanisms, including induction of cell death via apoptosis and autophagy, and suppression of tumor angiogenesis.

CONCLUSION

An increasing array of natural products and their derivatives are proving effective against breast cancer. Future therapeutic strategies can benefit from strategic enhancement of the anticancer properties of natural compounds, optimization for targeted action, improved bioavailability, and minimized side effects. The forthcoming research on natural products should prioritize these facets to maximize their therapeutic potential.

The Antitumoral Effect In Ovo of a New Inclusion Complex from Dimethoxycurcumin with Magnesium and Beta-Cyclodextrin

Breast cancer is one of the leading causes of death in the female population because of the resistance of cancer cells to many anticancer drugs used. Curcumin has cytotoxic activities against breast cancer cells, although it has limited use due to its poor bioavailability and rapid metabolic elimination. The synthesis of metal complexes of curcumin and curcuminoids is a relevant topic in the search for more active and selective derivatives of these molecular scaffolds. However, solubility and bioavailability are concomitant disadvantages of these types of molecules. To overcome such drawbacks, the preparation of inclusion complexes offers a chemical and pharmacologically safe option for improving the aqueous solubility of organic molecules. Herein, we describe the preparation of the inclusion complex of dimethoxycurcumin magnesium complex (DiMeOC-Mg, (4)) with beta-cyclodextrin (DiMeOC-Mg-BCD, (5)) in the stoichiometric relationship 1:1. This new inclusion complex's solubility in aqueous media phosphate buffer saline (PBS) was improved by a factor of 6x over the free metal complex (4). Furthermore, 5 affects cell metabolic rate, cell morphology, cell migration, induced apoptosis, and downregulation of the matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), and signal transducer and activator of transcription-3 (STAT3) expression levels on MD Anderson metastasis breast-231 cancer (MDA-MB-231) cell lines. Results of an antitumor assay in an in ovo model showed up to 30% inhibition of tumor growth for breast cancer (MDA-MB-231) when using (5) (0.650 mg/kg dose) and 17.29% inhibition with the free homoleptic metal complex (1.5 mg/kg dose, (4)). While the formulation of inclusion complexes from metal complexes of curcuminoids demonstrates its usefulness in improving the solubility and bioavailability of these metallodrugs, the new compound (5) exhibits excellent potential for use as a therapeutic agent in the battle against breast cancer.

Curcumin-Piperlongumine Hybrid Molecule Increases Cell Cycle Arrest and Apoptosis in Lung Cancer through JNK/c-Jun Signaling Pathway

The instability of curcumin's structure and the toxic side effects of piperlongumine have limited their potential applications in cancer treatment. To overcome these challenges, we designed and synthesized a novel curcumin-piperlongumine hybrid molecule, 3-[(E)-4-hydroxy-3-methoxybenzylidene]-1-[(E)-3-(3,4,5-trimethoxyphenyl)acryloyl]piperidin-2-one (CP), using a molecular hybridization strategy. CP exhibited enhanced structural stability and safety compared with its parent compounds. Through in vitro and in vivo biological activity screenings, CP effectively inhibited cell proliferation, caused cell cycle arrest in the G2/M phase, and induced apoptosis. Mechanistically, CP-induced apoptosis was partially mediated by cell cycle arrest. Furthermore, we discovered that CP induces cell cycle arrest and apoptosis through the regulation of JNK signaling. These findings highlight the potential of CP as a promising therapeutic agent for lung cancer treatment.

Effects of curcumin and ursolic acid in prostate cancer: A systematic review

The major barriers to phytonutrients in prostate cancer therapy are non-specific mechanisms and bioavailability issues. Studies have pointed to a synergistic combination of curcumin (CURC) and ursolic acid (UA). We investigate this combination using a systematic review process to assess the most likely mechanistic pathway and human testing in prostate cancer. We used the PRISMA statement to screen titles, abstracts, and the full texts of relevant articles and performed a descriptive analysis of the literature reviewed for study inclusion and consensus of the manuscript. The most common molecular and cellular pathway from articles reporting on the pathways and effects of CURC (n = 173) in prostate cancer was NF-κB (n = 25, 14.5%). The most common molecular and cellular pathway from articles reporting on the pathways and effects of UA (n = 24) in prostate cancer was caspase 3/caspase 9 (n = 10, 41.6%). The three most common molecular and cellular pathway from articles reporting on the pathways and effects of both CURC and UA (n = 193) in prostate cancer was NF-κB (n = 28, 14.2%), Akt (n = 22, 11.2%), and androgen (n = 19, 9.6%). Therefore, we have identified the potential synergistic target pathways of curcumin and ursolic acid to involve NF-κB, Akt, androgen receptors, and apoptosis pathways. Our review highlights the limited human studies and specific effects in prostate cancer.

Mechanism insights of curcumin and its analogues in cancer: An update

Cancer is the world's second leading cause of mortality and one of the major public health problems. Cancer incidence and mortality rates remain high despite the great advancements in existing therapeutic, diagnostic, and preventive approaches. Therefore, a quest for less toxic and more efficient anti-cancer strategies is still at the forefront of the current research. Traditionally important, curcumin commonly known as a wonder molecule has received considerable attention as an anti-cancer, anti-inflammatory, and antioxidant candidate. However, limited water solubility and low bioavailability restrict its extensive utility in different pathological states. The investigators are making consistent efforts to develop newer strategies to overcome its limitations by designing different analogues with better pharmacokinetic and pharmacodynamic properties. The present review highlights the recent updates on curcumin and its analogues with special emphasis on various mechanistic pathways involved in anti-cancer activity. In addition, the structure-activity relationship of curcumin analogues has also been precisely discussed. This article will also provide key information for the design and development of newer curcumin analogues with desired pharmacokinetic and pharmacodynamic profiles and will provide in depth understanding of molecular pathways involved in the anti-cancer activities.

Modified Curcumins as Potential Drug Candidates for Breast Cancer: An Overview

Breast cancer (BC), the most common malignancy in women, results from significant alterations in genetic and epigenetic mechanisms that alter multiple signaling pathways in growth and malignant progression, leading to limited long-term survival. Current studies with numerous drug therapies have shown that BC is a complex disease with tumor heterogeneity, rapidity, and dynamics of the tumor microenvironment that result in resistance to existing therapy. Targeting a single cell-signaling pathway is unlikely to treat or prevent BC. Curcumin (a natural yellow pigment), the principal ingredient in the spice turmeric, is well-documented for its diverse pharmacological properties including anti-cancer activity. However, its clinical application has been limited because of its low solubility, stability, and bioavailability. To overcome the limitation of curcumin, several modified curcumin conjugates and curcumin mimics were developed and studied for their anti-cancer properties. In this review, we have focused on the application of curcumin mimics and their conjugates for breast cancer.

Synthesis of Novel Bis-imino and Bis-amino Curcuminoids for Evaluation of Their Anticancer and Antibacterial Activity

A new set of curcumin analogues with a Schiff base moiety were synthesized from a bis-aldehyde derivative of hydroxybenzylidene cyclohexanone and various alicyclic and aromatic amines. The single crystals of compound 2 (bis-aldehyde), compound 3b (bis-cyclohexylimino derivative), and compound 3c (bis-1-imino piperidyl derivative) were developed. The said bis-imino and bis-amino curcuminoids were tested for anticancer activity against MCF-7 utilizing the conventional MTT assay. These Schiff bases had significantly higher anticancer efficacy than curcumin and methotrexate against MCF-7 cell lines. Compounds 3k, 3b, and 3l have the highest efficacy among all synthesized curcuminoids. The MTT results are in accordance with the binding affinities found by docking the said molecules with HER2 Tyrosine Kinase (HER2-TK). Compound 3b is identified as a promising HER2-TK inhibitor and also shows effective inhibition against Gram-positive bacteria Staphylococcus aureus.

Synthesis, DFT Analyses, Antiproliferative Activity, and Molecular Docking Studies of Curcumin Analogues

With 19.3 million new cases and almost 10 million deaths in 2020, cancer has become a leading cause of death today. Curcumin and its analogues were found to have promising anticancer activity. Inspired by curcumin’s promising anticancer activity, we prepared three semi-synthetic analogues by chemically modifying the diketone function of curcumin to its pyrazole counterpart. The curcumin analogues (3a−c) were synthesized by two different methods, followed by their DFT analyses to study the HOMO/LUMO configuration to access the stability of compounds (∆E = 3.55 to 3.35 eV). The curcumin analogues (3a−c) were tested for antiproliferative activity against a total of five dozen cancer cell lines in a single (10 µM) and five dose (0.001 to 100 µM) assays. 3,5-Bis(4-hydroxy-3-methoxystyryl)-1H-pyrazole-1-yl-(phenoxy)ethanone (3b) and 3,5-bis(4-hydroxy-3-methoxystyryl)-1H-pyrazole-1-yl-(2,4-dichlorophenoxy)ethanone (3c) demonstrated the most promising antiproliferative activity against the cancer cell lines with growth inhibitions of 92.41% and 87.28%, respectively, in a high single dose of 10 µM and exhibited good antiproliferative activity (%GIs > 68%) against 54 out of 56 cancer cell lines and 54 out of 60 cell lines, respectively. The compound 3b and 3c demonstrated the most potent antiproliferative activity in a 5-dose assay with GI50 values ranging between 0.281 and 5.59 µM and 0.39 and 0.196 and 3.07 µM, respectively. The compound 3b demonstrated moderate selectivity against a leukemia panel with a selectivity ratio of 4.59. The HOMO-LUMO energy-gap (∆E) of the compounds in the order of 3a > 3b > 3c, was found to be in harmony with the anticancer activity in the order of 3c ≥ 3b > 3a. Following that, all of the curcumin analogues were molecular docked against EGFR, one of the most appealing targets for antiproliferative activity. In a molecular docking simulation, the ligand 3b exhibited three different types of interactions: H-bond, π-π-stacking and π-cationic. The ligand 3b displayed three H-bonds with the residues Met793 (with methoxy group), Lys875 (with phenolic group) and Asp855 (with methoxy group). The π-π-stacking interaction was observed between the phenyl (of phenoxy) and the residue Phe997, while π-cationic interaction was displayed between the phenyl (of curcumin) and the residue Arg841. Similarly, the ligand 3c displayed five H-bonds with the residue Met793 (with methoxy and phenolic groups), Lys845 (methoxy group), Cys797 (phenoxy oxygen), and Asp855 (phenolic group), as well as a halogen bond with residue Cys797 (chloro group). Furthermore, all the compound 3a−c demonstrated significant binding affinity (−6.003 to −7.957 kcal/mol) against the active site of EGFR. The curcumin analogues described in the current work might offer beneficial therapeutic intervention for the treatment and prevention of cancer. Future anticancer drug discovery programs can be expedited by further modifying these analogues to create new compounds with powerful anticancer potentials.

Bioactive Diarylpentanoids: Insights into the Biological Effects beyond Antitumor Activity and Structure-Activity Relationships

Diarylpentanoids, a class of natural products and their synthetic analogs which are structurally related to chalcones, have gained increasing attention due to their wide array of biological activities, including antitumor, anti-infective, antioxidant, anti-inflammatory, antidiabetic, anti-hyperuricemic, and neuroprotective properties. Previously, we reviewed diarylpentanoids with promising antitumor activity. However, in view of the wide range of biological activities described for this class of compounds, the purpose of this review is to provide a more detailed overview of the synthetic bioactive diarylpentanoids that have been described over the last two decades, beyond simply their antitumor effects. A total of 745 compounds were found, highlighting the main synthetic methodologies used in their synthesis as well as the structure-activity relationship studies and structural features for all activities reported. Collectively, this review highlights the diarylpentanoid scaffold as a promising starting point for the development of new therapeutic agents.

Recent advances of curcumin derivatives in breast cancer

Curcumin is a potential plant-derived drug for the treatment of breast cancer. Poor solubility and bioavailability are the main factors that limit its clinical application. Various structural modification strategies have been developed to improve the anti-breast cancer activity of curcumin. This review focuses on the difference of modification sites and heterocyclic/non-heterocyclic modifications to systematically summarize curcumin derivatives with better anti-breast cancer activity.

In silico docking and ADME study of deketene curcumin derivatives (DKC) as an aromatase inhibitor or antagonist to the estrogen-alpha positive receptor (Erα+): potent application of breast cancer

Regardless of many extensive studies, hormonal-based breast cancer is the most common cause of cancer-related mortality of females worldwide. Indeed, estrogen receptor-positive (ER +) is the communal subtype in breast cancer. To treat this, three types of medications are typically used: selective estrogen receptor modulators (SERMs), selective estrogen receptor down modulators (SERDMs), and aromatase inhibitors (AIs), all of which directly interact with the activation of the estrogen signaling pathway and its formation. Despite their effectiveness, the development of new treatments is required since clinical efficacy is restricted owing to resistance. As a result, in silico studies for drug discovery are booming over the decades because of their affordability and less time-consuming features. Here, 25 deketene curcumin derivatives have been selected for docking studies through MVD software over the positive type of breast cancer through both the treatment hosts Erα + receptor and aromatase. DKC compounds are used because they have several pharmacological uses, including anti-cancer, anti-diabetic, anti-viral, anti-fungal, and anti-bacterial properties. Moreover, an ADME study was carried out for DKC derivatives that reveal the optimum drug-likeness profile. From 25 derivatives, the results showed a better MolDock score, hydrogen bonding, and steric interaction between compounds DKC-10, DKC-20, and DKC-21 with Erα + and aromatase. Although the study was done on both the treatable path hosts, better results were obtained with Erα + as an antagonist. Therefore, it is proposed that three selected DKC derivatives would be better therapeutic agents against breast cancer.

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

Perspectives for synthetic curcumins in chemoprevention and treatment of cancer: An update with promising analogues

Curcumin, a pure compound extracted from the flowering plant, turmeric (Curcuma longa. Zingiberaceae), is a common dietary ingredient found in curry powder. It has been studied extensively for its anti-inflammatory, antioxidant, antimicrobial and anti-tumour activities. Evidence is accumulating demonstrating its potential in chemoprevention and as an anti-tumour agent for the treatment of cancer. Despite demonstrated safety and tolerability, the clinical application of curcumin is frustrated by its poor solubility, metabolic instability and low oral bioavailability. Consequently researchers have tried novel techniques of formulation and delivery as well as synthesis of analogues with enhanced properties to overcome these barriers. This review presents the synthetic analogues of curcumin that have proven their anticancer potential from different studies. It also highlights studies that combined these analogues with approved chemotherapies and delivered them via novel techniques. Currently, there are no reports of clinical studies on any of the synthetic congeners of curcumin and this presents an opportunity for future research. This review presents the synthetic analogues of curcumin and makes a compelling argument for their potential application in the management of cancerous disease.

Curcumin Loaded and Co-loaded Nanosystems: A Review from a Biological Activity Enhancement Perspective

BACKGROUND

Curcumin is a natural phenolic compound exhibiting multiple bioactivities that have been evaluated in vitro, in vivo as well as through clinical studies in humans. Some of them include antimicrobial, antioxidant, anti-inflammatory, and central nervous system protective effects. Further, curcumin is generally recognized as a safe substance because of its low toxicity. However, its molecular structure is susceptible to changes in pH, oxidation, photodegradation, low aqueous solubility, and biotransformation compromising its bioavailability; these drawbacks are successfully addressed through nanotechnology.

OBJECTIVE

The present review systematizes findings on the enhancement of curcumin's beneficial effects when it is loaded and co-loaded into different types of nanosystems covering liposomes, polymeric and solid-lipid nanoparticles, nanostructured lipid carrier, lipid-polymeric hybrids, self- -assembled and protein-based core-shell systems in relation to its antimicrobial, antioxidant, anti-inflammatory and central nervous system protective bioactivities.

CONCLUSION

Curcumin is a versatile molecule capable of exerting antimicrobial, antioxidant, anti- inflammatory, and central nervous system protective effects in an enhanced manner using the possibilities offered by the nanotechnology-based approach. Its enhanced bioactivities are associated with increments in solubility, stability, bioavailability, as well as in improved intracellular uptake and cell internalization. These advantages, in addition to curcumin's low toxicity, indicate the potential of curcumin to be loaded and co-loaded into nanosystems capable of providing a controlled release and targeted administration.

Styrylpyrazoles: Properties, Synthesis and Transformations

The pyrazole nucleus and its reduced forms, pyrazolines and pyrazolidine, are privileged scaffolds in medicinal chemistry due to their remarkable biological activities. A huge number of pyrazole derivatives have been studied and reported over time. This review article gives an overview of pyrazole derivatives that contain a styryl (2-arylvinyl) group linked in different positions of the pyrazole backbone. Although there are studies on the synthesis of styrylpyrazoles dating back to the 1970s and even earlier, this type of compound has rarely been studied. This timely review intends to summarize the properties, biological activity, methods of synthesis and transformation of styrylpyrazoles; thus, highlighting the interest and huge potential for application of this kind of compound.

The Curcumin Analogue, MS13 (1,5-Bis(4-hydroxy-3- methoxyphenyl)-1,4-pentadiene-3-one), Inhibits Cell Proliferation and Induces Apoptosis in Primary and Metastatic Human Colon Cancer Cells

The cytotoxic and apoptotic effects of turmeric (Curcuma longa) on colon cancer have been well documented but specific structural modifications of curcumin have been shown to possess greater growth-suppressive potential on colon cancer than curcumin. Therefore, the aim of this study is to identify the anti-cancer properties of curcumin analogue-MS13, a diarylpentanoid on the cytotoxicity, anti-proliferative and apoptotic activity of primary (SW480) and metastatic (SW620) human colon cancer cells. A cell viability assay showed that MS13 has greater cytotoxicity effect on SW480 (EC₅₀: 7.5 ± 2.8 µM) and SW620 (EC₅₀: 5.7 ± 2.4 µM) compared to curcumin (SW480, EC₅₀: 30.6 ± 1.4 µM) and SW620, EC₅₀: 26.8 ± 2.1 µM). Treatment with MS13 at two different doses 1X EC₅₀ and 2X EC₅₀ suppressed the colon cancer cells growth with lower cytotoxicity against normal cells. A greater anti-proliferative effect was also observed in MS13 treated colon cancer cells compared to curcumin at 48 and 72 h. Subsequent analysis on the induction of apoptosis showed that MS13 treated cells exhibited morphological features associated with apoptosis. The findings are also consistent with cellular apoptotic activities shown by increased caspase-3 activity and decreased Bcl-2 protein level in both colon cancer cell lines. In conclusion, MS13 able to suppress colon cancer cell growth by inhibiting cell proliferation and induce apoptosis in primary and metastatic human colon cancer cells.

Tubulin-Binding 3,5-Bis(styryl)pyrazoles as Lead Compounds for the Treatment of Castration-Resistant Prostate Cancer

The microtubule-binding taxanes, docetaxel and cabazitaxel, are administered intravenously for the treatment of castration-resistant prostate cancer (CRPC) as the oral administration of these drugs is largely hampered by their low and highly variable bioavailabilities. Using a simple, rapid, and environmentally friendly microwave-assisted protocol, we have synthesized a number of 3,5-bis(styryl)pyrazoles 2a-l, thus allowing for their screening for antiproliferative activity in the androgen-independent PC3 prostate cancer cell line. Surprisingly, two of these structurally simple 3,5-bis(styryl)pyrazoles (2a and 2l) had concentrations which gave 50% of the maximal inhibition of cell proliferation (GI₅₀) in the low micromolar range in the PC3 cell line and were thus selected for extensive further biologic evaluation (apoptosis and cell cycle analysis, and effects on tubulin and microtubules). Our findings from these studies show that 3,5-bis[(1E)-2(2,6-dichlorophenyl)ethenyl]-1H-pyrazole 2l 1) caused significant effects on the cell cycle in PC3 cells, with the vast majority of treated cells in the G₂/M phase (89%); 2) induces cell death in PC3 cells even after the removal of the compound; 3) binds to tubulin [dissociation constant (K_d) 0.4 ± 0.1 μM] and inhibits tubulin polymerization in vitro; 4) had no effect upon the polymerization of the bacterial cell division protein FtsZ (a homolog of tubulin); 5) is competitive with paclitaxel for binding to tubulin but not with vinblastine, crocin, or colchicine; and 6) leads to microtubule depolymerization in PC3 cells. Taken together, these results suggest that 3,5-bis(styryl)pyrazoles warrant further investigation as lead compounds for the treatment of CRPC. SIGNIFICANCE STATEMENT: The taxanes are important components of prostate cancer chemotherapy regimens, but their oral administration is hampered by very low and highly variable oral bioavailabilities resulting from their poor absorption, poor solubility, high first-pass metabolism, and efficient efflux by P-glycoprotein. New chemical entities for the treatment of prostate cancer are thus required, and we report here the synthesis and investigation of the mechanism of action of some bis(styryl)pyrazoles, demonstrating their potential as lead compounds for the treatment of prostate cancer.

Curcumin: a phytochemical modulator of estrogens and androgens in tumors of the reproductive system

Curcumin (Cur) is an active derivative extracted from turmeric which exerts a wide range of interactions with biomolecules through complex signaling pathways. Cur has been extensively shown to possess potential antitumor properties. In addition, there is growing body of evidence suggesting that Cur may exert potential anti-estrogen and anti-androgen activity. In vitro and in vivo studies suggest that anticancer properties of Cur against tumors affecting the reproductive system in females and males may be underlied by the Cur-mediated inhibition of androgen and estrogen signaling pathways. In this review we examine various studies assessing the crosstalk between Cur and both androgen and estrogen hormonal activity. Also, we discuss the potential chemopreventive and antitumor role of Cur in the most prevalent cancers affecting the reproductive system in females and males.

Effects of green synthesised silver nanoparticles (ST06-AgNPs) using curcumin derivative (ST06) on human cervical cancer cells (HeLa) in vitro and EAC tumor bearing mice models

Background

In recent years, green synthesized silver nanoparticles have been increasingly investigated for their anti-cancer potential. In the present study, we aimed at the biosynthesis of silver nanoparticles (AgNPs) using a curcumin derivative, ST06. Although, the individual efficacies of silver nanoparticles or curcumin derivatives have been studied previously, the synergistic cytotoxic effects of curcumin derivative and silver nanoparticles in a single nanoparticulate formulation have not been studied earlier specifically on animal models. This makes this study novel compared to the earlier synthesized curcumin derivative or silver nanoparticles studies. The aim of the study was to synthesize ST06 coated silver nanoparticles (ST06-AgNPs) using ST06 as both reducing and coating agent.

Methods

The synthesized nanoparticles AgNPs and ST06-AgNPs were characterised for the particle size distribution, morphology, optical properties and surface charge by using UV-visible spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). Elemental composition and structural properties were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). The presence of ST06 as capping agent was demonstrated by Fourier transform infrared spectroscopy (FTIR).

Results

The synthesized nanoparticles (ST06-AgNPs) were spherical and had a size distribution in the range of 50–100 nm. UV-Vis spectroscopy displayed a specific silver plasmon peak at 410 nm. The in vitro cytotoxicity effects of ST06 and ST06-AgNPs, as assessed by MTT assay, showed significant growth inhibition of human cervical cancer cell line (HeLa). In addition, studies carried out in EAC tumor-induced mouse model (Ehrlich Ascites carcinoma) using ST06-AgNPs, revealed that treatment of the animals with these nanoparticles resulted in a significant reduction in the tumor growth, compared to the control group animals.

Conclusion

In conclusion, green synthesized ST06-AgNPs exhibited superior anti-tumor efficacy than the free ST06 or AgNPs with no acute toxicity under both in vitro and in vivo conditions. The tumor suppression is associated with the intrinsic apoptotic pathway. Together, the results of this study suggest that ST06-AgNPs could be considered as a potential option for the treatment of solid tumors.

Recent advances of analogues of curcumin for treatment of cancer

Curcumin (CU), an edible natural pigment from Curcuma Longa, has demonstrated extensive anti-tumor effect in vivo and in vitro. With the property of reversing drug resistance and low toxicity, CU has been considered to develop a new adjuvant chemotherapy protocol of cancer. However, the poor stability, solubility, in vivo bioavailability and weak activity of CU greatly limit its clinical application. Therefore, CU analogues have been extensively studied. Starting from the study of natural CU analogues, multiple approaches are being sought to obtain more stable, soluble and effective analogues of CU. This review focuses on the progress of these approaches to more potent CU analogues.

Discovering proteasomal deubiquitinating enzyme inhibitors for cancer therapy: lessons from rational design, nature and old drug reposition

The ubiquitin proteasome system has been validated as a target of cancer therapies evident by the US FDA approval of anticancer 20S proteasome inhibitors. Deubiquitinating enzymes (DUBs), an essential component of the ubiquitin proteasome system, regulate cellular processes through the removal of ubiquitin from ubiquitinated-tagged proteins. The deubiquitination process has been linked with cancer and other pathologies. As such, the study of proteasomal DUBs and their inhibitors has garnered interest as a novel strategy to improve current cancer therapies, especially for cancers resistant to 20S proteasome inhibitors. This article reviews proteasomal DUB inhibitors in the context of: discovery through rational design approach, discovery from searching natural products and discovery from repurposing old drugs, and offers a future perspective.

The Curcumin Analogs 2-Pyridyl Cyclohexanone Induce Apoptosis via Inhibition of the JAK2-STAT3 Pathway in Human Esophageal Squamous Cell Carcinoma Cells

Multiple modifications to the structure of curcumin have been investigated with an aim to improve its potency and biochemical properties. Previously, we have synthesized a series of curcumin analogs. In the present study, the anticancer effect of 2-pyridyl cyclohexanone, one of the curcumin analogs, on esophageal carcinoma Eca109 and EC9706 cell lines and its molecular mechanisms were investigated. 2-Pyridyl cyclohexanone inhibited the proliferation of Eca109 and EC9706 cells by inducing apoptosis as indicated by morphological changes, membrane phospholipid phosphatidylserine ectropion, caspase 3 activation, and cleavage of poly(ADP-ribose) polymerase. Mechanistic studies indicated that 2-pyridyl cyclohexanone disrupted mitochondrial membrane potential, disturbed the balance of the Bcl-2 family proteins, and triggered apoptosis via the mitochondria-mediated intrinsic pathway. In 2-pyridine cyclohexanone-treated cells, the phosphorylation levels of JAK2 and STAT3 were dose-dependently decreased and p38 and p-ERK signals were notably activated in a dose-dependent manner. Moreover, we found that the addition of S3I-201, a STAT3 inhibitor, led to a decreased expression level of Bcl-2 in Eca109 cells. The chromatin immunoprecipitation assay demonstrated that STAT3 bound to the promoter of Bcl-2 in the Eca109 cells. Furthermore, the mutation of four STAT3 binding sites (−1733/−1723, −1627/−1617, −807/−797, and −134/−124) on the promote of Bcl-2 gene alone attenuated the transcriptional activation of STAT3. In addition, down-regulation of STAT3 resulted in less of transcriptional activity of STAT3 on Bcl-2 expression. These data provide a potential molecular mechanism of the apoptotic induction function of 2-pyridyl cyclohexanone, and emphasize its important roles as a therapeutic agent for esophageal squamous carcinoma.

Design, synthesis and cytotoxic effects of curcuminoids on HeLa, K562, MCF-7 and MDA-MB-231 cancer cell lines

Background

Curcumin is one of the leading compound extracted from the dry powder of Curcuma longa (Zingiberaceae family), which possess several pharmacological properties. However, in vivo administration exhibited limited applications in cancer therapies.

Results

Twenty-four curcumin derivatives have synthesized, which comprises cyclohexanone 1–10, acetone 11–17 and cyclopentanone 18–24 series. All the curcuminoids were synthesized by the acid or base catalyzed Claisen Schmidt condenstion reactions, in which β-diketone moiety of curcumin was modified with mono-ketone. These curcuminoids 1–24 were screened against HeLa, K562, MCF-7 (an estrogen-dependent) and MDA-MB-231 (an estrogen-independent) cancer cell lines. Among them, acetone series 11–17 were found to be more selective and potential cytotoxic agents. The compound 14 was exhibited (IC₅₀ = 3.02 ± 1.20 and 1.52 ± 0.60 µg/mL) against MCF-7 and MDA-MB-231 breast cancer cell lines. Among the cyclohexanone series, the compound 4 exhibited (IC₅₀ = 11.04 ± 2.80, 6.50 ± 01.80, 8.70 ± 3.10 and 2.30 ± 1.60 µg/mL) potential cytotoxicity against four proposed cancer cell lines, respectively. All the curcucminoids were characterized with the detailed ¹H NMR, IR, UV–Vis, and mass spectroscopic techniques. The structure of compound 4 was confirmed by using the single X-ray crystallography. Additionally, we are going to report the first time spectral data of (2E,6E)-2,6-bis(2-methoxybenzylidene)cyclohexanone (1). Structure–activity relationships revealed that the mono-carbonyl with 2,5-dimethoxy substituted curcuminoids could be an essential for the future drugs against cancer diseases.

Conclusions

Curcuminoids with diferuloyl(4-hydroxy-3-methoxycinnamoyl) moiety with mono carbonyl exhibiting potential cytotoxic properties. The compound 14 was exhibited (IC₅₀ = 3.02 ± 1.20 and 1.52 ± 0.60 µg/mL) against MCF-7 and MDA-MB-231 breast cancer cell lines.

Curcumin and derivatives function through protein phosphatase 2A and presenilin orthologues in Dictyostelium discoideum

Natural compounds often have complex molecular structures and unknown molecular targets. These characteristics make them difficult to analyse using a classical pharmacological approach. Curcumin, the main curcuminoid of turmeric, is a complex molecule possessing wide-ranging biological activities, cellular mechanisms and roles in potential therapeutic treatment, including Alzheimer's disease and cancer. Here, we investigate the physiological effects and molecular targets of curcumin in Dictyostelium discoideum. We show that curcumin exerts acute effects on cell behaviour, reduces cell growth and slows multicellular development. We employed a range of structurally related compounds to show the distinct role of different structural groups in curcumin's effects on cell behaviour, growth and development, highlighting active moieties in cell function, and showing that these cellular effects are unrelated to the well-known antioxidant activity of curcumin. Molecular mechanisms underlying the effect of curcumin and one synthetic analogue (EF24) were then investigated to identify a curcumin-resistant mutant lacking the protein phosphatase 2A regulatory subunit (PsrA) and an EF24-resistant mutant lacking the presenilin 1 orthologue (PsenB). Using in silico docking analysis, we then showed that curcumin might function through direct binding to a key regulatory region of PsrA. These findings reveal novel cellular and molecular mechanisms for the function of curcumin and related compounds.

Summary: To unlock the therapeutic potential of curcumin and related compounds, we employ a tractable model system to characterise their cellular and molecular effects and propose novel targets implicated in disease.

Potential roles of chemical degradation in the biological activities of curcumin

Substantial pre-clinical and human studies have shown that curcumin, a dietary compound from turmeric, has a variety of health-promoting biological activities. A better understanding of the biochemical mechanisms for the health-promoting effects of curcumin could facilitate the development of effective strategies for disease prevention. Recent studies have shown that in aqueous buffer, curcumin rapidly degrades and leads to formation of various degradation products. In this review, we summarized and discussed the biological activities of chemical degradation products of curcumin, including alkaline hydrolysis products (such as ferulic acid, vanillin, ferulaldehyde, and feruloyl methane), and autoxidation products (such as bicyclopentadione). Though many of these degradation products are biologically active, they are substantially less-active compared to curcumin, supporting that chemical degradation has a limited contribution to the biological activities of curcumin.

Structure-Activity Relationship of Curcumin: Role of the Methoxy Group in Anti-inflammatory and Anticolitis Effects of Curcumin

Curcumin, a dietary compound from turmeric, has beneficial effects on inflammatory diseases such as inflammatory bowel disease. Most previous studies have focused on the structure-activity relationship of the thiol-reactive α,β-unsaturated carbonyl groups of curcumin, so little is known about the roles of methoxy groups in biological activities of curcumin. Here we synthesized a series of curcumin analogues with different substitution groups (R = H-, Br-, Cl-, F-, NO₂-, CH₃-, and OH-) to replace the methoxy group and evaluated their biological effects in vitro and in vivo. Curcumin, Cur-OH, and Cur-Br (25 μM) suppressed 74.91 ± 0.88, 77.75 ± 0.89, and 71.75 ± 0.90% of LPS-induced NO production, respectively (P < 0.05). Similarly, these compounds also decreased iNOS expression, COX-2 expression, and NF-κB signaling in RAW 264.7 macrophage cells (P < 0.05). However, other analogues, especially Cur-NO₂, were inactive (P > 0.05). In the dextran sulfate sodium (DSS)-induced colitis mouse model, the Cur-Br analogue also showed a beneficial effect the same as curcumin (P < 0.05), whereas the Cur-NO₂ analogue had no effect in the animal model (P > 0.05). Together, the analogues have dramatically different effects on inflammation, supporting that the substitution group on the methoxy position plays an important role in the anti-inflammatory effects of curcumin. The methoxy group is a potential structural candidate for modification to design curcumin-based drugs for inflammatory diseases.

Mannich Curcuminoids as Potent Anticancer Agents

A series of novel curcuminoids were synthesised for the first time via a Mannich-3CR/organocatalysed Claisen-Schmidt condensation sequence. Structure-activity relationship (SAR) studies were performed by applying viability assays and holographic microscopic imaging to these curcumin analogues for anti-proliferative activity against A549 and H1975 lung adenocarcinoma cells. The TNFα-induced NF-κB inhibition and autophagy induction effects correlated strongly with the cytotoxic potential of the analogues. Significant inhibition of tumour growth was observed when the most potent analogue 44 was added in liposomes at one-sixth of the maximally tolerated dose in the A549 xenograft model. The novel spectrum of activity of these Mannich curcuminoids warrants further preclinical investigations.

Synthesis of Curcuminoids and Evaluation of Their Cytotoxic and Antioxidant Properties

Curcumin (1) and ten derivatives (2–11) were synthesized and evaluated as cytotoxic and antioxidant agents. The results of primary screening by Sulforhodamine B assay against five human cancer cell lines (U-251 MG, glioblastoma; PC-3, human prostatic; HCT-15, human colorectal; K562, human chronic myelogenous leukemia; and SKLU-1, non-small cell lung cancer) allowed us to calculate the half maximal inhibitory concentration (IC₅₀) values for the more active compounds against HCT-15 and K562 cell lines. Compounds 2 and 10 were the most active against both cell lines and were more active than curcumin itself. Thiobarbituric acid reactive substances (TBARS) assay showed that 7 has potent activity; even stronger than curcumin, α-tocopherol, and quercetin.

The Role of Natural Polyphenols in the Prevention and Treatment of Cervical Cancer-An Overview

Cervical cancer represents the second leading cause of death for women worldwide. The importance of the diet and its impact on specific types of neoplasia has been highlighted, focusing again interest in the analysis of dietary phytochemicals. Polyphenols have shown a wide range of cellular effects: they may prevent carcinogens from reaching the targeted sites, support detoxification of reactive molecules, improve the elimination of transformed cells, increase the immune surveillance and the most important factor is that they can influence tumor suppressors and inhibit cellular proliferation, interfering in this way with the steps of carcinogenesis. From the studies reviewed in this paper, it is clear that certain dietary polyphenols hold great potential in the prevention and therapy of cervical cancer, because they interfere in carcinogenesis (in the initiation, development and progression) by modulating the critical processes of cellular proliferation, differentiation, apoptosis, angiogenesis and metastasis. Specifically, polyphenols inhibit the proliferation of HPV cells, through induction of apoptosis, growth arrest, inhibition of DNA synthesis and modulation of signal transduction pathways. The effects of combinations of polyphenols with chemotherapy and radiotherapy used in the treatment of cervical cancer showed results in the resistance of cervical tumor cells to chemo- and radiotherapy, one of the main problems in the treatment of cervical neoplasia that can lead to failure of the treatment because of the decreased efficiency of the therapy.

Molecular mechanisms of curcumin and its semisynthetic analogues in prostate cancer prevention and treatment

Primary prostate cancer, also known as prostate adenocarcinoma (PCa), is a devastating cancer in men worldwide. Europe and developing countries of Asia have fewer reported cases of prostate cancer compared to increasing cases in the United States with higher incidence in Black men. Risk factors associated with prostate cancer are aging, genetics, lifestyle, high body mass index as well as carcinogenic exposure to carbon-containing fuels, tobacco, and charbroiled meats. Hormone therapy and radical prostatectomy are commonly implemented treatments. The >20.000 prostate cancer deaths of 2013 suggest that there exists a need for enhanced chemopreventive and therapeutic agents for prostate cancer treatment. Fruits, vegetables, and red wines contain high levels of polyphenolic levels. Consumption of these products may provide chemoprevetion of PCa. Curcumin, the major compound from the turmeric rhizome Curcuma longa has long been used for medicinal purposes as an antiseptic and wound healing. This review focuses on curcumin's therapeutic effectiveness in vitro and in vivo in prostate cancer models. The review will highlight the mechanisms of actions of curcumin in the signaling pathways of prostate cancer.

Curcumin modified silver nanoparticles for highly efficient inhibition of respiratory syncytial virus infection

Interactions between nanoparticles and viruses have attracted increasing attention due to the antiviral activity of nanoparticles and the resulting possibility to be employed as biomedical interventions. In this contribution, we developed a very simple route to prepare uniform and stable silver nanoparticles (AgNPs) with antiviral properties by using curcumin, which is a member of the ginger family isolated from rhizomes of the perennial herb Curcuma longa and has a wide range of biological activities like antioxidant, antifungal, antibacterial and anti-inflammatory effects, and acts as reducing and capping agents in this synthetic route. The tissue culture infectious dose (TCID50) assay showed that the curcumin modified silver nanoparticles (cAgNPs) have a highly efficient inhibition effect against respiratory syncytial virus (RSV) infection, giving a decrease of viral titers about two orders of magnitude at the concentration of cAgNPs under which no toxicity was found to the host cells. Mechanism investigations showed that cAgNPs could prevent RSV from infecting the host cells by inactivating the virus directly, indicating that cAgNPs are a novel promising efficient virucide for RSV.

Preclinical In Vitro, In Vivo, and Pharmacokinetic Evaluations of FLLL12 for the Prevention and Treatment of Head and Neck Cancers

Despite its high promise for cancer prevention and therapy, the potential utility of curcumin in cancer is compromised by its low bioavailability and weak potency. The purpose of the current study was to assess the in vitro and in vivo efficacy and pharmacokinetic parameters of the potent curcumin analogue FLLL12 in SCCHN and identify the mechanisms of its antitumor effect. IC50 values against a panel of one premalignant and eight malignant head and neck cancer cell lines as well as apoptosis assay results suggested that FLLL12 is 10- to 24-fold more potent than natural curcumin depending on the cell line and induces mitochondria-mediated apoptosis. In vivo efficacy (xenograft) and pharmacokinetic studies also suggested that FLLL12 is significantly more potent and has more favorable pharmacokinetic properties than curcumin. FLLL12 strongly inhibited the expression of p-EGFR, EGFR, p-AKT, AKT, Bcl-2, and Bid and increased the expression of Bim. Overexpression of constitutively active AKT or Bcl-2 or ablation of Bim or Bid significantly inhibited FLLL12-induced apoptosis. Further mechanistic studies revealed that FLLL12 regulated EGFR and AKT at transcriptional levels, whereas Bcl-2 was regulated at the translational level. Finally, FLLL12 strongly inhibited the AKT downstream targets mTOR and FOXO1a and 3a. Taken together, our results strongly suggest that FLLL12 is a potent curcumin analogue with more favorable pharmacokinetic properties that induces apoptosis of head and neck cancer cell lines by inhibition of survival proteins including EGFR, AKT, and Bcl-2 and increasing of the proapoptotic protein Bim.

Cancer Chemoprevention Effects of Ginger and its Active Constituents: Potential for New Drug Discovery

Ginger is a commonly used spice and herbal medicine worldwide. Besides its extensive use as a condiment, ginger has been used in traditional Chinese medicine for the management of various medical conditions. In recent years, ginger has received wide attention due to its observed antiemetic and anticancer activities. This paper reviews the potential role of ginger and its active constituents in cancer chemoprevention. The phytochemistry, bioactivity, and molecular targets of ginger constituents, especially 6-shogaol, are discussed. The content of 6-shogaol is very low in fresh ginger, but significantly higher after steaming. With reported anti-cancer activities, 6-shogaol can be served as a lead compound for new drug discovery. The lead compound derivative synthesis, bioactivity evaluation, and computational docking provide a promising opportunity to identify novel anticancer compounds originating from ginger.

Hexamethoxylated Monocarbonyl Analogues of Curcumin Cause G2/M Cell Cycle Arrest in NCI-H460 Cells via Michael Acceptor-Dependent Redox Intervention

Curcumin, derived from the dietary spice turmeric, holds promise for cancer prevention. This prompts much interest in investigating the action mechanisms of curcumin and its analogues. Two symmetrical hexamethoxy-diarylpentadienones (1 and 2) as cucumin analogues were reported to possess significantly enhanced cytotoxicity compared with the parent molecule. However, the detailed mechanisms remain unclear. In this study, compounds 1 and 2 were identified as the G2/M cell cycle arrest agents to mediate the cytotoxicity toward NCI-H460 cells via Michael acceptor-dependent redox intervention. Compared with curcumin, they could more easily induce a burst of reactive oxygen species (ROS) and collapse of the redox buffering system. One possible reason is that they could more effectively target intracellular TrxR to convert this antioxidant enzyme into a ROS promoter. Additionally, they caused up-regulation of p53 and p21 and down-regulation of redox-sensitive Cdc25C along with cyclin B1/Cdk1 in a Michael acceptor- and ROS-dependent fashion. Interestingly, in comparison with compound 2, compound 1 displayed a relatively weak ability to generate ROS but increased cell cycle arrest activity and cytotoxicity probably due to its Michael acceptor-dependent microtubule-destabilizing effect and greater GST-inhibitory activity, as well as its enhanced cellular uptake. This work provides useful information for understanding Michael acceptor-dependent and redox-mediated cytotoxic mechanisms of curcumin and its active analogues.

Curcumin Prevents Palmitoylation of Integrin β4 in Breast Cancer Cells

Curcumin has been shown to mitigate cancer phenotypes such as invasive migration, proliferation, and survival by disrupting numerous signaling pathways. Our previous studies showed that curcumin inhibits integrin β4 (ITG β4)-dependent migration by blocking interaction of this integrin with growth factor receptors in lipid rafts. In the current study, we investigated the possibility that curcumin inhibits ITG β4 palmitoylation, a post-translational modification required for its lipid raft localization and signaling activity. We found that the levels of ITG β4 palmitoylation correlated with the invasive potential of breast cancer cells, and that curcumin effectively reduced the levels of ITG β4 palmitoylation in invasive breast cancer cells. Through studies of ITG β4 palmitoylation kinetics, we concluded curcumin suppressed palmitoylation independent of growth factor-induced phosphorylation of key ITG β4 Ser and Tyr residues. Rather, curcumin blocked autoacylation of the palmitoyl acyltransferase DHHC3 that is responsible for ITG β4 palmitoylation. Moreover, these data reveal that curcumin is able to prevent the palmitoylation of a subset of proteins, but not indiscriminately bind to and block all cysteines from modifications. Our studies reveal a novel paradigm for curcumin to account for much of its biological activity, and specifically, how it is able to suppress the signaling function of ITG β4 in breast cancer cells.

Anti-proliferative effect and induction of apoptosis in androgen-independent human prostate cancer cells by 1,5-bis(2-hydroxyphenyl)-1,4-pentadiene-3-one

Curcumin has poor in vivo absorption and bioavailability, highlighting a need for new curcumin analogues with better characteristics in these aspects. The aim of this study is to determine the anti-cancer properties of four selected curcumin analogues, on the cytotoxicity, proliferative and apoptotic effects on androgen-independent human prostate cancer cells (PC-3 and DU 145). Initial cytotoxicity screening showed MS17 has the highest cell inhibitory effect, with EC50 values of 4.4 ± 0.3 and 4.1 ± 0.8 µM, followed by MS13 (7.5 ± 0.1 and 7.4 ± 2.6 µM), MS49 (14.5 ± 1.2 and 12.3 ± 2.3 µM) and MS40E (28.0 ± 7.8 and 30.3 ± 1.9 µM) for PC-3 and DU 145 cells, respectively. Time-dependent analysis also revealed that MS13 and MS17 displayed a greater anti-proliferative effect than the other compounds. MS17 was chosen based on the high selectivity index value for further analysis on the morphological and biochemical hallmarks of apoptosis. Fluorescence microscopy analysis revealed apoptotic changes in both treated prostate cancer cells. Relative caspase-3 activity increased significantly at 48 h in PC-3 and 12 h in DU 145 cells. Highest enrichment of free nucleosomes was noted at 48 h after treatment with MS17. In conclusion, MS17 demonstrated anti-proliferative effect and induces apoptosis in a time and dose-dependent manner suggesting its potential for development as an anti-cancer agent for androgen-independent prostate cancer.

Synthesis and assessment of the antioxidant and antitumor properties of asymmetric curcumin analogues

In this study, 12 asymmetric curcumin (CUR) analogues and 5 symmetric curcumin derivatives were synthesized, the antioxidant activity of these derivatives were evaluated by radicals 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay, 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assay, ROO (TRAP) assay and O(2-) (NET) assay and anti-proliferative activities of these analogues were assessed against the human hepatoma cell line (SMMC-7721), the human breast cancer cell line (MCF-7) and the human prostate cancer cell lines (PC-3). Most of the asymmetric compounds showed stronger antioxidant activities than Vitamin C (Vc). Curcumin analogues reducing free radicals contain two reaction mechanisms: H-atom and electron transfer mechanisms. Compound 14 showed the most significant antioxidant activity compared with curcumin and other derivatives. Shorted the carbon chain of 14 can reduce the O-H bond dissociation enthalpy (BED) to improve the antioxidant activity. The antioxidant activity of 25 was similar to curcumin. All of the compounds performed better in an anti-proliferate assay than curcumin, especially compound 25, which exhibited the preferential cytotoxic activity against MCF-7 cells(25, IC50 = 9.11 μM, curcumin, IC50 = 70.2 μM). Considering these data, future studies should be performed to assess the therapeutic values of these asymmetric curcumin analogues.

Eliminating the heart from the curcumin molecule: monocarbonyl curcumin mimics (MACs)

Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs). A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK) profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria.

Hybrid curcumin compounds: a new strategy for cancer treatment

Cancer is a multifactorial disease that requires treatments able to target multiple intracellular components and signaling pathways. The natural compound, curcumin, was already described as a promising anticancer agent due to its multipotent properties and huge amount of molecular targets in vitro. Its translation to the clinic is, however, limited by its reduced solubility and bioavailability in patients. In order to overcome these pharmacokinetic deficits of curcumin, several strategies, such as the design of synthetic analogs, the combination with specific adjuvants or nano-formulations, have been developed. By taking into account the risk-benefit profile of drug combinations, as well as the knowledge about curcumin's structure-activity relationship, a new concept for the combination of curcumin with scaffolds from different natural products or components has emerged. The concept of a hybrid curcumin molecule is based on the incorporation or combination of curcumin with specific antibodies, adjuvants or other natural products already used or not in conventional chemotherapy, in one single molecule. The high diversity of such conjugations enhances the selectivity and inherent biological activities and properties, as well as the efficacy of the parental compound, with particular emphasis on improving the efficacy of curcumin for future clinical treatments.

Synthesis and biological evaluation of novel curcuminoid derivatives

Curcuminoids have been reported to possess multiple bioactivities, such as antioxidant, anticancer and anti-inflammatory properties. Three novel series of curcuminoid derivatives (11a-h, 15a-h and 19a-d) with enhanced bioactivity have been synthesized. Among the synthesized compounds, 11b exhibited the most significant activity with an MIC of 0.5 µM /mL against selected medically important Gram-positive cocci (S. aureus and S. viridans) and Gram-negative bacilli (E. coli and E. cloacae). The derivatives exhibited remarkable results in an antioxidant test with an IC50 2.4- to 9.3-folder smaller than curcuminoids. With respect to antiproliferative activity against Hep-G2, LX-2, SMMC7221 and MDA-MB-231, the derivatives exhibited an effect stronger than curcuminoids with an IC50 ranging from 0.18 to 4.25 µM.