Demethoxycurcumin: A naturally occurring curcumin analogue for treating non-cancerous diseases

Turmeric: from spice to cure. A review of the anti-cancer, radioprotective and anti-inflammatory effects of turmeric sourced compounds

Turmeric (Curcuma longa) has been extensively studied for its diverse pharmacological properties, including its potential role as an anticancer agent, antioxidant, and radioprotector. This review provides an overview of the chemical composition of turmeric, focusing on its main bioactive compounds, such as curcuminoids and volatile oils. Curcumin, the most abundant curcuminoid in turmeric, has been widely investigated for its various biological activities, including anti-inflammatory, antioxidant, and anticancer effects. Numerous in vitro and in vivo studies have demonstrated the ability of curcumin to modulate multiple signaling pathways involved in carcinogenesis, leading to inhibition of cancer cell proliferation, induction of apoptosis, and suppression of metastasis. Furthermore, curcumin has shown promising potential as a radioprotective agent by mitigating radiation-induced oxidative stress and DNA damage. Additionally, turmeric extracts containing curcuminoids have been reported to exhibit potent antioxidant activity, scavenging free radicals and protecting cells from oxidative damage. The multifaceted pharmacological properties of turmeric make it a promising candidate for the development of novel therapeutic strategies for cancer prevention and treatment, as well as for the management of oxidative stress-related disorders. However, further research is warranted to elucidate the underlying mechanisms of action and to evaluate the clinical efficacy and safety of turmeric and its bioactive constituents in cancer therapy and radioprotection. This review consolidates the most recent relevant data on turmeric's chemical composition and its therapeutic applications, providing a comprehensive overview of its potential in cancer prevention and treatment, as well as in radioprotection.

Theoretical studies on the photo protective mechanism of curcuminoids

In this work, the deactivation pathways of curcuminoids after photoexcitation was studied by employing density functional theory to explore their UVA radiation screening capacity. A comprehensive computational characterization of the excited-state processes of curcumin, demethoxycurcumin, and bis-demethoxycurcumin was done. The molecules exist in diketo and enol forms which are in equilibrium and interconvertible through keto-enol tautomerism. The enolic forms of each of the studied molecules have eight geometric cis-trans isomers as a result of torsion rotation about three different carbon-carbon double bonds across the aliphatic chain. For each geometric isomer, sixteen possible rotamers are found to exist due to rotation about five different carbon-carbon single bond rotations, also across the skeleton of the aliphatic chain. Upon photoexcitation, the studied molecules follow three main pathways of radiationless decay: (a) rotamerism and interconversion between rotamers of comparable energies which are in equilibrium, (b) interconversion between the cis-trans geometrical isomers where an efficient vibrational relaxation path is formed at ∼90° during torsion rotation about carbon-carbon double bond, and (c) excited state intramolecular proton transfer in a single O-H stretching vibration through a cyclic intramolecular hydrogen bonded ring formed at the centre of the molecule giving back the original structure. The absorption and emission spectra of the molecules were also simulated where the theoretically obtained absorption and emission maxima are close to the reported experimental values.

Screening of potential phytomolecules against MurG as drug target in nosocomial pathogen Pseudomonas aeruginosa: perceptions from computational campaign

The nosocomial infection outbreak caused by Pseudomonas aeruginosa remains a public health concern. Multi-drug resistant (MDR) strains of P. aeruginosa are rapidly spreading leading to a huge mortality rate because of the unavailability of promising antimicrobials. MurG glycotransferase [UDP-N-acetylglucosamine-N-acetylmuramyl (pentapeptide) pyrophosphoryl-undecaprenol N-acetylglucosamine transferase] is located at the plasma membrane and plays a key role in murein (peptidoglycan) biosynthesis in bacteria. Since MurG is required for bacterial cell wall synthesis and is non-homologous to Homo sapiens; it can be a potential target for the antagonist to treat P. aeruginosa infection. The discovery of high-resolution crystal structure of P. aeruginosa MurG offers an opportunity for the computational identification of its prospective inhibitors. Therefore, in the present study, the crystal structure of MurG (PDB ID: 3S2U) from P. aeruginosa was selected, and computational docking analyses were performed to search for functional inhibitors of MurG. IMPPAT (Indian medicinal plants, phytochemicals and therapeutic) phytomolecule database was screened by computational methods with MurG catalytic site. Docking results identified Theobromine (-8.881 kcal/mol), demethoxycurcumin (-8.850 kcal/mol), 2-alpha-hydroxycostic acid (-8.791 kcal/mol), aurantiamide (-8.779 kcal/mol) and petasiphenol (-8.685 kcal/mol) as a potential inhibitor of the MurG activity. Further, theobromine and demethoxycurcumin were subjected to MDS (molecular dynamics simulation) and free energy (MM/GBSA) analysis to comprehend the physiological state and structural stability of MurG-phytomolecules complexes. The outcomes suggested that these two phytomolecules could act as most favorable natural hit compounds for impeding the enzymatic action of MurG in P. aeruginosa, and thus it needs further validation by both in vitro and in vivo analysis. HIGHLIGHTSThe top phytomolecules such as theobromine, demethoxycurcumin, 2-alpha-hydroxycostic acid, aurantiamide and petasiphenol displayed promising binding with MurG catalytic domain.MurG complexed with theobromine and demethoxycurcumin showed the best interaction and stable by MD simulation at 100 ns.The outcome of MurG binding phytomolecules has expanded the possibility of hit phytomolecules validation.Communicated by Ramaswamy H. Sarma.

The Golden Spice for Life: Turmeric with the Pharmacological Benefits of Curcuminoids Components, Including Curcumin, Bisdemethoxycurcumin, and Demethoxycurcumins

BACKGROUND

Turmeric (Curcuma longa L.), belonging to the Zingiberaceae family, is a perennial rhizomatous plant of tropical and subtropical regions. The three major chemical components responsible for the biological activities of turmeric are curcumin, demethoxycurcumin, and bisdemethoxycurcumin.

METHODS

The literature search included review articles, analytical studies, randomized control experiments, and observations, which have been gathered from various sources, such as Scopus, Google Scholar, PubMed, and ScienceDirect. A review of the literature was carried out using the keywords: turmeric, traditional Chinese medicine, traditional Iranian medicine, traditional Indian medicine, curcumin, curcuminoids, pharmaceutical benefits, turmerone, demethoxycurcumin, and bisdemethoxycurcumin. The main components of the rhizome of the leaf are α-turmerone, β-turmerone, and arturmerone.

RESULTS

The notable health benefits of turmeric are antioxidant activity, gastrointestinal effects, anticancer effects, cardiovascular and antidiabetic effects, antimicrobial activity, photoprotector activity, hepatoprotective and renoprotective effects, and appropriate for the treatment of Alzheimer's disease and inflammatory and edematic disorders.

DISCUSSION

Curcuminoids are phenolic compounds usually used as pigment spices with many health benefits, such as antiviral, antitumour, anti-HIV, anti-inflammatory, antiparasitic, anticancer, and antifungal effects. Curcumin, bisdemethoxycurcumin, and demethoxycurcumin are the major active and stable bioactive constituents of curcuminoids. Curcumin, which is a hydroponic polyphenol, and the main coloring agent in the rhizomes of turmeric, has anti-inflammatory, antioxidant, anti-cancer, and anticarcinogenic activities, as well as beneficial effects for infectious diseases and Alzheimer's disease. Bisdemethoxycurcumin possesses antioxidant, anti-cancer, and anti-metastasis activities. Demethoxycurcumin, which is another major component, has anti-inflammatory, antiproliferative, and anti-cancer activities and is the appropriate candidate for the treatment of Alzheimer's disease.

CONCLUSION

The goal of this review is to highlight the health benefits of turmeric in both traditional and modern pharmaceutical sciences by considering the important roles of curcuminoids and other major chemical constituents of turmeric.

Desmethoxycurcumin aids IFNα's anti-HBV activity by antagonising CRYAB reduction and stabilising IFNAR1 protein

The eradication of chronic hepatitis B (CHB) caused by hepatitis B virus (HBV) infection is a crucial goal in clinical practice. Enhancing the anti-HBV activity of interferon type I (IFNI) is a key strategy for achieving a functional cure for CHB. In this study, we investigated the effect of combined treatment with IFNα and Desmethoxycurcumin (DMC) on HBV replication in HepG2 cells and explored the underlying mechanism. Our results indicated IFNα alone was ineffective in completely inhibiting HBV replication, which was attributed to the virus-induced down-regulation of IFNI receptor 1 (IFNAR1) protein. However, the addition of a low dose of DMC significantly synergized with IFNα, leading to notable enhancement of IFNα anti-HBV activity. This effect was achieved by stabilising the IFNAR1 protein. Further investigation revealed that low dose DMC effectively blocked the ubiquitination-mediated degradation of IFNAR1, which was accomplished by rescuing the protein levels of alphaB-crystallin (CRYAB) and orchestrating the interaction between CRYAB and the E3 ubiquitin ligase, β-Trcp. Importantly, over-expression of CRYAB was found to favour the antiviral activity of IFNα against HBV replication. In conclusion, our study demonstrates that low-dose DMC enhanced the anti-HBV activity of IFNα by counteracting the reduction of CRYAB and stabilising the IFNAR1 protein.

Mechanisms of main components in Curcuma longa L. on hepatic fibrosis based on network pharmacology and molecular docking: A review

BACKGROUND

Hepatic fibrosis is a great concern in public health. While effective drugs for its treatment are lacking, Curcuma longa L. (CL) has been reported as a promising therapeutic. We aimed to uncover the core components and mechanisms of CL against hepatic fibrosis via a network pharmacology approach.

METHODS

The main components of CL were obtained and screened. While targets of components and disease were respectively collected using SwissTargetPrediction and online databases, common targets were assessed. A protein-protein interaction (PPI) network was constructed, and core targets were identified. GO and KEGG pathway enrichment analyses were performed, and molecular docking was conducted to validate the binding of core components in CL on predicted core targets.

RESULTS

Nine main components from CL based on high-performance liquid chromatography (HPLC) and 63 anti-fibrosis targets were identified, and a PPI network and a component target-disease target network were constructed. Apigenin, quercetin, demethoxycurcumin, and curcumin are likely to become key phenolic-based components and curcuminoids for the treatment of hepatic fibrosis, respectively. KEGG pathway enrichment analysis revealed that the HIF-1 signaling pathway (hsa04066) was most significantly enriched. Considering core targets of the PPI network and a network of the common targets and pathways enriched, AKT1, MAPK1, EGFR, MTOR, and SRC may be the core potential targets of CL against hepatic fibrosis. Molecular docking was carried out to verify the binding of above core components to core targets.

CONCLUSIONS

The therapeutic effect of CL on hepatic fibrosis may be attributed to multi-components, multi-targets, and multi-pathways.

Processing and Physicochemical Properties of Magnetite Nanoparticles Coated with Curcuma longa L. Extract

In this work, Curcuma longa L. extract has been used in the synthesis and direct coating of magnetite (Fe₃O₄) nanoparticles ~12 nm, providing a surface layer of polyphenol groups (-OH and -COOH). This contributes to the development of nanocarriers and triggers different bio-applications. Curcuma longa L. is part of the ginger family (Zingiberaceae); the extracts of this plant contain a polyphenol structure compound, and it has an affinity to be linked to Fe ions. The nanoparticles' magnetization obtained corresponded to close hysteresis loop M_s = 8.81 emu/g, coercive field H_c = 26.67 Oe, and low remanence energy as iron oxide superparamagnetic nanoparticles (SPIONs). Furthermore, the synthesized nanoparticles (G-M@T) showed tunable single magnetic domain interactions with uniaxial anisotropy as addressable cores at 90-180°. Surface analysis revealed characteristic peaks of Fe 2p, O 1s, and C 1s. From the last one, it was possible to obtain the C-O, C=O, -OH bonds, achieving an acceptable connection with the HepG2 cell line. The G-M@T nanoparticles do not induce cell toxicity in human peripheral blood mononuclear cells or HepG2 cells in vitro, but they can increase the mitochondrial and lysosomal activity in HepG2 cells, probably related to an apoptotic cell death induction or to a stress response due to the high concentration of iron within the cell.

Unlocking the genetic diversity of Indian turmeric (Curcuma longa L.) germplasm based on rhizome yield traits and curcuminoids

Turmeric is an important commercial crop widely grown in Asia due to its pharmacological and nutritional value. India is the centre of turmeric diversity and many turmeric accessions have good rhizome yield, varying curcuminoids content and are well-adapted to various agro-climatic zones. In the present study, we unravel the diversity among 200 Indian turmeric accessions based on rhizome yield traits and curcuminoids content. Clustering and correlation studies were also performed to group the turmeric accessions and to observe the relationship between the traits. Results revealed the presence of large variability among turmeric accessions including the major traits such as yield (24.77 g p^-1 to 667.63 g p^-1), dry recovery percentage (13.42% to 29.18%), curcumin (0.41% to 2.17%), demethoxycurcumin (0.38% to 1.45%), bisdemethoxycurcumin (0.37% to 1.24%) and total curcuminoid content (1.26% to 4.55%). The superior germplasm identified for curcuminoids content were as follows; curcumin (CL 157 - 2.17% and CL 272 - 2.13%), demethoxycurcumin (CL 253 - 1.45% and CL 157 - 1.31%), bisdemethoxycurcumin (CL 216 - 1.24% and CL 57 - 1.11%) and total curcuminoid content (CL 157 - 4.55% and CL 272 - 4.37%). Clustering based on dendrogram, grouped 200 accessions into seven clusters. Among seven clusters, the maximum number of accessions were grouped into cluster II while cluster VII showed maximum mean value for majority of the traits. Correlation analysis revealed a significant relationship between the traits where the total curcuminoid content is significantly and positively correlated with the primary rhizome core diameter and length of the secondary rhizome. The selection of these particular traits may result in the identification of germplasm with high total curcuminoid content. Taken together, it is the first report on the large screening of turmeric accessions for variation in the rhizome yield traits and curcuminoids content. The genetic diversity revealed in this study could be useful for further crop improvement programs in turmeric to develop new varieties with high rhizome yield coupled with high curcuminoids content.

Strategies for Improving Bioavailability, Bioactivity, and Physical-Chemical Behavior of Curcumin

Curcumin (CCM) is one of the most frequently explored plant compounds with various biological actions such as antibacterial, antiviral, antifungal, antineoplastic, and antioxidant/anti-inflammatory properties. The laboratory data and clinical trials have demonstrated that the bioavailability and bioactivity of curcumin are influenced by the feature of the curcumin molecular complex types. Curcumin has a high capacity to form molecular complexes with proteins (such as whey proteins, bovine serum albumin, β-lactoglobulin), carbohydrates, lipids, and natural compounds (e.g., resveratrol, piperine, quercetin). These complexes increase the bioactivity and bioavailability of curcumin. The current review provides these derivatization strategies for curcumin in terms of biological and physico-chemical aspects with a strong focus on different type of proteins, characterization methods, and thermodynamic features of protein–curcumin complexes, and with the aim of evaluating the best performances. The current literature review offers, taking into consideration various biological effects of the CCM, a whole approach for CCM-biomolecules interactions such as CCM-proteins, CCM-nanomaterials, and CCM-natural compounds regarding molecular strategies to improve the bioactivity as well as the bioavailability of curcumin in biological systems.

Potential roles of gut microbes in biotransformation of natural products: An overview

Natural products have been extensively applied in clinical practice, characterized by multi-component and multi-target, many pharmacodynamic substances, complex action mechanisms, and various physiological activities. For the oral administration of natural products, the gut microbiota and clinical efficacy are closely related, but this relationship remains unclear. Gut microbes play an important role in the transformation and utilization of natural products caused by the diversity of enzyme systems. Effective components such as flavonoids, alkaloids, lignans, and phenols cannot be metabolized directly through human digestive enzymes but can be transformed by enzymes produced by gut microorganisms and then utilized. Therefore, the focus is paid to the metabolism of natural products through the gut microbiota. In the present study, we systematically reviewed the studies about gut microbiota and their effect on the biotransformation of various components of natural products and highlighted the involved common bacteria, reaction types, pharmacological actions, and research methods. This study aims to provide theoretical support for the clinical application in the prevention and treatment of diseases and provide new ideas for studying natural products based on gut biotransformation.

Bisdemethoxycurcumin Attenuated Renal Injury via Activation of Keap1/Nrf2 Pathway in High-Fat Diet-Fed Mice

Bisdemethoxycurcumin (BDMC), a principal and active component of edible turmeric, was previously found to have beneficial effects on metabolic diseases. Chronic kidney disease (CKD) may benefit from its potential therapeutic use. Using a high-fat diet (HFD)-fed mouse model, we examined the effects of BDMC on renal injury and tried to determine how its associated mechanism works. A number of metabolic disorders are significantly improved by BDMC, including obesity, hyperglycemia, hyperinsulinemia, hyperlipidemia and inflammation. Further research on renal histopathology and function showed that BDMC could repair renal pathological changes and enhance renal function. Moreover, decreased serum malondialdehyde (MDA), elevated superoxide dismutase (SOD) activity, and the inhibition of renal reactive oxygen species (ROS) overproduction revealed the alleviation of oxidative stress after BDMC administration. In addition, renal Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2 (Keap1/Nrf2) pathway was activated in BDMC-treated mice. In conclusion, these findings demonstrated BDMC as a potential therapy for HFD-induced CKD via the activation of the Keap1/Nrf2 pathway.

Computational approach to decode the mechanism of curcuminoids against neuropathic pain

BACKGROUND

Curcumin (CUR), demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) are the main components of turmeric that commonly used to treat neuropathic pain (NP). However, the mechanism of the therapy is not sufficiently clarified. Herein, network pharmacology, molecular docking and molecular dynamics (MD) approaches were used to investigate the mechanism of curcuminoids for NP treatment.

METHODS

Active targets of curcuminoids were obtained from the Swiss Target database, and NP-related targets were retrieved from GeneCards, OMIM, Drugbank and TTD databases. A protein-protein interaction (PPI) network was built to screen the core targets. Furthermore, DAVID was used for GO and KEGG pathway enrichment analyses. Interactions between potential targets and curcuminoids were assessed by molecular docking and the MD simulations were run for 100ns to validate the docking results on the top six complexes.

RESULTS

CUR, DMC, and BDMC had 100, 99 and 100 targets respectively. After overlapping with NP there were 33, 33 and 31 targets respectively. PPI network analysis of TOP 10 core targets, TNF, GSK3β were common targets of curcuminoids. Molecular docking and MD results indicated that curcuminoids bind strongly with the core targets. The GO and KEGG showed that curcuminoids regulated nitrogen metabolism, the serotonergic synapse and ErbB signaling pathway to alleviate NP. Furthermore, specific targets in these three compounds were also analysed at the same time.

CONCLUSIONS

This study systematically explored and compared the anti-NP mechanism of curcuminoids, providing a novel perspective for their utilization.

Functional characterization of key polyketide synthases by integrated metabolome and transcriptome analysis on curcuminoid biosynthesis in Curcuma wenyujin

Leaf and tuber extracts of Curcuma wenyujin contain a mixture of curcuminoids. However, the curcuminoid constituents and their molecular mechanisms are poorly understood, and the relevant curcumin synthases remain unclear. In this study, we comprehensively compared the metabolite profiles of the leaf and tuber tissues of C. wenyujin. A total of 11 curcuminoid metabolites were identified and exhibited differentially changed contents in the leaf and tuber tissues. An integrated analysis of metabolomic and transcriptomic data revealed the proposed biosynthesis pathway of curcuminoid. Two candidate type Ⅲ polyketide synthases (PKSs) were identified in the metabolically engineering yeasts, indicating that CwPKS1 and CwPKS2 maintained substrate and product specificities. Especially, CwPKS1 is the first type Ⅲ PKS identified to synthesize hydrogenated derivatives of curcuminoid, dihydrocurcumin and tetrehydrocurcumin. Interestingly, the substitution of the glycine at position 219 with aspartic acid (G219D mutant) resulted in the complete inactivation of CwPKS1. Our results provide the first comparative metabolome analysis of C. wenyujin and functionally identified type Ⅲ PKSs, giving valuable information for curcuminoids biosynthesis.

Validation of a Quantification Method for Curcumin Derivatives and Their Hepatoprotective Effects on Nonalcoholic Fatty Liver Disease

Curcumin (CM), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) are major curcumin derivatives found in the rhizome of turmeric (Curcuma longa L.), and have yielded impressive properties to halt various diseases. In the present study, we carried out a method validation for curcumin derivatives and analyzed the contents simultaneously using HPLC with UV detection. For validation, HPLC was used to estimate linearity, range, specificity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). Results showed a high linearity of the calibration curve, with a coefficient of correlation (R²) for CM, DMC, and BDMC of 0.9999, 0.9999, and 0.9997, respectively. The LOD values for CM, DMC, and BDMC were 1.16, 1.03, and 2.53 ng/μL and LOQ values were 3.50, 3.11, and 7.67 ng/μL, respectively. Moreover, to evaluate the ability of curcumin derivatives to reduce liver lipogenesis and compare curcumin derivatives’ therapeutic effects, a HepG2 cell model was established to analyze their hepatoprotective properties. Regarding the in vivo study, we investigated the effect of DMC, CM, and BDMC on nonalcoholic fatty liver disease (NAFLD) caused by a methionine choline deficient (MCD)-diet in the C57BL/6J mice model. From the in vitro and in vivo results, curcumin derivatives alleviated MCD-diet-induced lipid accumulation as well as high triglyceride (TG) and total cholesterol (TC) levels, and the protein and gene expression of the transcription factors related to liver adipogenesis were suppressed. Furthermore, in MCD-diet mice, curcumin derivatives suppressed the upregulation of toll-like receptors (TLRs) and the production of pro-inflammatory cytokines. In conclusion, our findings indicated that all of the three curcuminoids exerted a hepatoprotective effect in the HepG2 cell model and the MCD-diet-induced NAFLD model, suggesting a potential for curcuminoids derived from turmeric as novel therapeutic agents for NAFLD.

Design of Hybrid Polymeric-Lipid Nanoparticles Using Curcumin as a Model: Preparation, Characterization, and In Vitro Evaluation of Demethoxycurcumin and Bisdemethoxycurcumin-Loaded Nanoparticles

Polymeric lipid hybrid nanoparticles (PLHNs) are the new generation of drug delivery systems that has emerged as a combination of a polymeric core and lipid shell. We designed and optimized a simple method for the preparation of Pluronic F-127-based PLHNs able to load separately demethoxycurcumin (DMC) and bisdemethoycurcumin (BDM). CUR was used as a model compound due to its greater availability from turmeric and its structure similarity with DMC and BDM. The developed method produced DMC and BDM-loaded PLHNs with a size average of 75.55 ± 0.51 and 15.13 ± 0.014 nm for DMC and BDM, respectively. An FT-IR analysis confirmed the encapsulation and TEM images showed their spherical shape. Both formulations achieved an encapsulation efficiency ≥ 92% and an exhibited significantly increased release from the PLHN compared with free compounds in water. The antioxidant activity was enhanced as well, in agreement with the improvement in water dissolution; obtaining IC₅₀ values of 12.74 ± 0.09 and 16.03 ± 0.55 for DMC and BDM-loaded PLHNs, respectively, while free curcuminoids exhibited considerably lower antioxidant values in an aqueous solution. Hence, the optimized PHLN synthesis method using CUR as a model and then successfully applied to obtain DMC and BDM-loaded PLHNs can be extended to curcuminoids and molecules with a similar backbone structure to improve their bioactivities.

A Promising Anticancer Agent Dimethoxycurcumin: Aspects of Pharmacokinetics, Efficacy, Mechanism, and Nanoformulation for Drug Delivery

Curcumin is a well-known anticancer natural product with various significant bioactivities that has been well documented, but its widespread use is mainly hindered by insufficient ADME properties such as poor solubility and low metabolic stability. Dimethoxycurcumin (DiMC) is a kind of lipophilic compound derived from curcumin that maintains its anticancer potency and has greatly improved systematic bioavailability. Therefore, DiMC is regarded as a promising plant-derived anticancer agent that deserves to be well developed. Herein, we concentrate on the published work by those from original research groups concerned with the pharmacokinetics, efficacy, and mechanism of DiMC involved in the treatment of various tumors, as well as the nanoformulations for effective drug delivery.

Curcumin: A review of experimental studies and mechanisms related to periodontitis treatment

Curcumin is the main active ingredient of turmeric, which has a wide range of pharmacological effects, including antitumor, antibacterial, anti-inflammatory, anti-oxidation, immune regulation, and so on. Periodontitis is a prevalent oral inflammatory disease caused by a variety of factors. In recent years, many studies have shown that curcumin has a potential role on the treatment of periodontitis. Curcumin has been used in research related to the treatment of periodontitis in the form of solution, chip, gel, and capsule. Combined with other periodontitis treatment methods, such as scaling and root planing (SRP) and photodynamic therapy (PDT), can enhance curcumin's efficacy in treating periodontitis. In addition to natural curcumin, chemically modified curcumin, such as 4-phenylaminocarbonyl bis-demethoxy curcumin (CMC 2.24) and 4-methoxycarbonyl curcumin (CMC 2.5), have also been used in animal models of periodontitis. Here, this paper reviews the research progress of curcumin on the treatment of periodontitis and its related mechanisms.

Existence of β-diketone form of curcuminoids revealed by NMR spectroscopy

Curcumin (CUR), demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDMC) - the class of natural compound derived from turmeric can exist as keto-enol and β-diketone tautomer form. The structure and dynamics of particular relevance CUR is reported in prior studies, whereas DMC and BDMC, by far, have not been scrutinized. In the present studies, we have investigated the detailed molecular structure of CUR, DMC and BDMC by employing NMR spectroscopy as a key tool. The bridging carbon as methylene in β-diketone form and methine in keto-enol form shows significant difference in NMR spectrum. The results justified that Curcuminoids (CC) has nearly 3% of β-diketone tautomer in DMSO solvent at 298 K. Further, results revealed that β-diketone form was favoured in alkaline pH condition whereas acidic and neutral pH conditions favour keto-enol tautomer. However, at higher temperature equilibrium shift towards β-diketone tautomer. Moreover, this is the first report by NMR for observing the presence of β-diketone tautomer.

Study on Demethoxycurcumin as a Promising Approach to Reverse Methicillin-Resistance of Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has always been a threatening pathogen. Research on phytochemical components that can replace antibiotics with limited efficacy may be an innovative method to solve intractable MRSA infections. The present study was devoted to investigate the antibacterial activity of the natural compound demethoxycurcumin (DMC) against MRSA and explore its possible mechanism for eliminating MRSA. The minimum inhibitory concentrations (MICs) of DMC against MRSA strains was determined by the broth microdilution method, and the results showed that the MIC of DMC was 62.5 μg/mL. The synergistic effects of DMC and antibiotics were investigated by the checkerboard method and the time–kill assay. The ATP synthase inhibitors were employed to block the metabolic ability of bacteria to explore their synergistic effect on the antibacterial ability of DMC. In addition, western blot analysis and qRT-PCR were performed to detect the proteins and genes related to drug resistance and S. aureus exotoxins. As results, DMC hindered the translation of penicillin-binding protein 2a (PBP2a) and staphylococcal enterotoxin and reduced the transcription of related genes. This study provides experimental evidences that DMC has the potential to be a candidate substance for the treatment of MRSA infections.

A supramolecular complex of hydrazide-pillar[5]arene and bisdemethoxycurcumin with potential anti-cancer activity

Pillar[5]arene complexes of the naturally occurring compound bisdemethoxycurcumin (BDMC) were acquired for improving the water solubility and stability of BDMC. As a family member of curcuminoid compounds, BDMC has many interesting therapeutic properties. However, its low aqueous solubility and stability resulted in poor availability and restricted the clinical efficacy. Pillar[5]arenes with hydrophilic ends and a hydrophobic cavity could include with BDMC based on size matching. The synthesized hydrazide-pillar[5]arene (HP5A) and BDMC had a strong host-guest interaction with a 1:1 binding stoichiometry. Furthermore, the HP5A ⊃ BDMC complex could self-assemble into well-defined fibers in water/ethanol solution. This supramolecular complex worked well in vitro for inhibiting the proliferation of hepatoma carcinoma cells HepG2. Remarkably, this method of complexation with pillar[5]arenes visibly reduced the undesirable side effects on normal cells without weakening the anti-cancer activity of the drugs. We expected that the obtained host-guest complex and fibrous assembly would provide a promising platform for delivering drugs with low water solubility.

Demethoxycucumin protects MDA-MB-231 cells induced bone destruction through JNK and ERK pathways inhibition

Bone is the most common late metastasis of breast cancer. Bone metastasis causes not only severe bone pain, but also bone-related diseases such as pathological fractures, which are closely related to osteoclasts. The effects of demethoxycurcumin (DMC) on osteoclast biology has not been investigated. In this study, we explored the effects of DMC on MDA-MB-231 cells, MCF-7 cells, and osteoclasts induced by RANKL in vitro, as well as the protective effect on bone destruction of tumor bone metastasis in vivo. DMC showed inhibitory effect on the migration and promotes the apoptosis of MDA-MB-231 and MCF-7 cells. At the same time, DMC inhibited osteoclast maturation and mature osteoclast bone resorption in a dose-dependent manner, and suppressed the expression of osteoclast marker genes TRAP, CTSK, MMP9, V-ATPase-d2 and DC-STAMP significantly. Biochemical data showed that DMC inhibited tumor cells and osteoclasts by inhibiting the early activation of ERK and JNK MAPK pathway. Consistent with the results in vitro, we confirmed that DMC protects bone destruction caused by tumor metastasis in vivo. In short, our study confirmed that DMC could be used as a potential drug for the treatment of tumor bone destruction.

Turmeric and Curcumin: From Traditional to Modern Medicine

The rhizome of turmeric (Curcuma longa L.) has been used as an herbal medicine, coloring agent, spice, and food additive for thousands of years in different parts of the world particularly in Asian countries. It has been used for a range of diseases in many traditional medical schools, including Islamic traditional medicine, Chinese traditional medicine, and Ayurveda. It has been used mainly for digestive problems, as a cardio-, hepato-, and neuroprotective agent as well as in many inflammatory conditions such as arthritis and for enhancing immune system. Curcumin, a diarylheptanoid derivative found in turmeric, has anti-inflammatory, antioxidant, and anticancer properties; controls obesity and metabolic problems; and improves memory and mood disorders. Therapeutically, curcumin exhibits promising potential in preclinical and clinical studies and is currently in human trials for a variety of conditions, including metabolic syndrome, nonalcoholic fatty liver disease, rheumatoid arthritis, migraine, premenstrual syndrome, ulcerative colitis, knee osteoarthritis, polycystic ovarian syndrome, atherosclerosis, liver cirrhosis, amyotrophic lateral sclerosis, depression, psoriasis, and Alzheimer's disease. Among all beneficial activities reported for curcumin, the research toward the obesity and metabolic-preventing/suppressing aspects of curcumin is growing. These findings emphasize that most of the traditional applications of turmeric is due to the presence of its key constituent, curcumin. According to the traditional background of turmeric use and clinical values of curcumin, further preclinical studies for unstudied properties and clinical studies with larger sample sizes for confirmed activities are expected.

Facile NMR approach for profiling curcuminoids present in turmeric

Curcumin, together with demethoxycurcumin and bisdemethoxycurcumin as a whole called curcuminoids, is an active phytochemical constituent present in the turmeric. When it comes to their analysis, most will rely on UV-Visible spectroscopy, HPLC and LC-MS methods. Looking to improve productivity, time and simplicity, we are proposing a ¹H NMR based approach for curcuminoids analysis and its applications to different geographical regions. In the present work, sample preparation protocol is reported for the simultaneous determination of curcuminoids using ¹H NMR. For the quantification of curcuminoids, 6-7 ppm vinylic proton region in the ¹H NMR spectrum was used, where acetone was observed as the suitable solvent in terms of curcuminoids solubility and proper resolution of peak. The result shows that curcumin (46.8-59.50%) was major among all varieties, followed by DMC (22.15-27.70%) and BDMC (17.52-30.29%) except in Andhrapradesh variety, where BDMC (30.29%) was more than DMC (22.89%). These studies were further supported by HPLC analysis.

Plants as source of new therapies for endometriosis: a review of preclinical and clinical studies

BACKGROUND

Given the disadvantages and limitations of current endometriosis therapy, there is a progressive increase in studies focusing on plant-derived agents as a natural treatment option with the intention of achieving high efficiency, avoiding adverse effects and preserving the chance for successful pregnancy. The heterogeneity of these studies in terms of evaluated agents, applied approaches and outcomes illustrates the need for an up-to-date summary and critical view on this rapidly growing field in endometriosis research.

OBJECTIVE AND RATIONALE

This review provides a comprehensive overview of plant-derived agents and natural treatment strategies that are under preclinical or clinical investigation and critically evaluates their potential for future endometriosis therapy.

SEARCH METHODS

An English language PubMed literature search was performed using variations of the terms 'endometriosis', 'natural therapy', 'herb/herbal', 'plant', 'flavonoid', 'polyphenol', 'phytochemical', 'bioactive', 'Kampo' and 'Chinese medicine'. It included both animal and human studies. Moreover, the Clinicaltrials.gov database was searched with the term 'endometriosis' for clinical trials on plant-derived agents. No restriction was set for the publication date.

OUTCOMES

Natural therapies can be assigned to three categories: (i) herbal extracts, (ii) specific plant-derived bioactive compounds and (iii) Chinese herbal medicine (CHM). Agents of the first category have been shown to exert anti-proliferative, anti-inflammatory, anti-angiogenic and anti-oxidant effects on endometrial cells and endometriotic lesions. However, the existing evidence supporting their use in endometriosis therapy is quite limited. The most studied specific plant-derived bioactive compounds are resveratrol, epigallocatechin-3-gallate, curcumin, puerarin, ginsenosides, xanthohumol, 4-hydroxybenzyl alcohol, quercetin, apigenin, carnosic acid, rosmarinic acid, wogonin, baicalein, parthenolide, andrographolide and cannabinoids, with solid evidence about their inhibitory activity in experimental endometriosis models. Their mechanisms of action include pleiotropic effects on known signalling effectors: oestrogen receptor-α, cyclooxygenase-2, interleukin-1 and -6, tumour necrosis factor-α, intercellular adhesion molecule-1, vascular endothelial growth factor, nuclear factor-kappa B, matrix metalloproteinases as well as reactive oxygen species (ROS) and apoptosis-related proteins. Numerous studies suggest that treatment with CHM is a good choice for endometriosis management. Even under clinical conditions, this approach has already been shown to decrease the size of endometriotic lesions, alleviate chronic pelvic pain and reduce postoperative recurrence rates.

WIDER IMPLICATIONS

The necessity to manage endometriosis as a chronic disease highlights the importance of identifying novel and affordable long-term safety therapeutics. For this purpose, natural plant-derived agents represent promising candidates. Many of these agents exhibit a pleiotropic action profile, which simultaneously inhibits fundamental processes in the pathogenesis of endometriosis, such as proliferation, inflammation, ROS formation and angiogenesis. Hence, their inclusion into multimodal treatment concepts may essentially contribute to increase the therapeutic efficiency and reduce the side effects of future endometriosis therapy.

Berberine Administration in Treatment of Colitis: A Review

Berberine (Brb) is one of the well-known naturally occurring compounds exclusively found in Berberis vulgaris and other members of this family, such as Berberis aristata, Berberis aroatica, and Berberis aquifolium. This plant-derived natural compound has a variety of therapeutic impacts, including anti-oxidant, anti-inflammatory, anti-diabetic, and anti-tumor. Multiple studies have demonstrated that Brb has great anti-inflammatory activity and is capable of reducing the levels of proinflammatory cytokines, while it enhances the concentrations of anti-inflammatory cytokines, making it suitable for the treatment of inflammatory disorders. Colitis is an inflammatory bowel disease with chronic nature. Several factors are involved in the development of colitis and it appears that inflammation and oxidative stress are the most important ones. With respect to the anti-inflammatory and antioxidant effects of Brb, its administration seems to be beneficial in the treatment of colitis. In the present review, the protective effects of Brb in colitis treatment and its impact on molecular pathways are discussed.

Demethoxycurcumin increases the sensitivity of cisplatin-resistant non-small lung cancer cells to cisplatin and induces apoptosis by activating the caspase signaling pathway

Patients with non-small cell lung cancer (NSCLC) can develop strong drug resistance following long-term treatment with platinum-based drugs. Increasing doses of chemotherapeutic drugs fail to obtain better results, and serious complications occur. It has been demonstrated that upregulation of excision repair cross-complementary 1 (ERCC1) in lung cancer cells is closely associated with cell resistance to platinum-based chemotherapy. In addition, curcumin (CMN) enhances antitumor effects in NSCLC by downregulating ERCC1. The aim of the present study was to investigate the effects of demethoxycurcumin (DMC), a curcuminoid, on the reversal of resistance of NSCLC cells in vitro and in vivo. The present study demonstrated that DMC significantly increased the sensitivity of DDP in DDP-resistant A549 (A549/DDP) cells. The results from an MTT assay demonstrated that DMC combined with DDP significantly attenuated the proliferation of A549/DDP cells. Furthermore, DMC exhibited decreased toxicity in normal lung fibroblast MRC-5 cells. In addition, following treatment of A549/DDP cells with a combination of DMC and DDP, the expression of ERCC1 was reduced, the protein levels of Bcl-2 and Bax were decreased and increased, respectively, whereas caspase-3 was activated, according to results from western blotting. Finally, DDP combined with DMC significantly attenuated A549/DDP cell-derived tumor growth in vivo. Taken together, the findings from the present study suggested that DMC in combination with DDP may be considered as a novel combination regimen for restoring DDP sensitivity in DDP-resistant NSCLC cells.

Dual Targeting of the p38 MAPK-HO-1 Axis and cIAP1/XIAP by Demethoxycurcumin Triggers Caspase-Mediated Apoptotic Cell Death in Oral Squamous Cell Carcinoma Cells

Demethoxycurcumin (DMC) is a curcumin analogue with better stability and higher aqueous solubility than curcumin after oral ingestion and has the potential to treat diverse cancers, including oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the anticancer effects and underlying mechanisms of DMC against OSCC. We found that DMC suppressed cell proliferation via simultaneously inducing G2/M-phase arrest and cell apoptosis. Mechanistic investigations found that the downregulation of cellular IAP 1 (cIAP1)/X-chromosome-linked IAP (XIAP) and upregulation of heme oxygenase-1 (HO-1) were critical for DMC-induced caspase-8/-9/-3 activation and apoptotic cell death. Moreover, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK)1/2 were activated by DMC treatment in OSCC cells, and only the inhibition of p38 MAPK significantly abolished DMC-induced HO-1 expression and caspase-8/-9/-3 activation. The analyses of clinical datasets revealed that patients with head and neck cancers expressing high HO-1 and low cIAP1 had the most favorable prognoses. Furthermore, a combinatorial treatment of DMC with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, gefitinib, significantly enhanced the inhibitory effect of gefitinib on the proliferation of OSCC cells. Overall, the current study supported a role for DCM as part of a therapeutic approach for OSCC through suppressing IAPs and activating the p38-HO-1 axis.