Studies on curcumin and curcuminoids. VIII. Photochemical stability of curcumin

Visible light potentiates rapid cell destruction and death by curcumin in vitro

Curcumin, a small molecule derived from the plant Curcuma longa, is a pleiotropic agent with widely varying pharmacological activities attributed to it. In addition to its anti-cancer activity curcumin is also known to be cytotoxic upon photoactivation. Time-lapse DIC and correlative fluorescence microscopy were used to evaluate the effects of curcumin, combined with continuous exposure to visible light, on cellular components of RTG-2 cells. Curcumin combined with visible light resulted in rapid and dramatic destruction of cells. F-actin and microtubule cytoskeletons were drastically altered, both showing fragmentation and overall loss from cells. Nuclei exhibited granulated nucleoplasm, condensed DNA, and physical shrinkage. Mitochondria rapidly fragmented along their length and disappeared from cells. Plasma membrane was breached based on lipophilic dye staining and the entrance of otherwise impermeant small molecules into the cell. Grossly distorted morphology hallmarked by significant swelling and coarse granulation of the cytoplasm was consistently observed. All of these effects were dependent on visible light as the same cellular targets in curcumin-treated cells outside the illuminated area were always unperturbed. The combination of curcumin and continuous exposure to visible light enables rapid and irreversible cellular destruction which can be monitored in real-time. Real-time monitoring of this structural disintegration suggests a new approach to applying curcumin in photodynamic treatments, where the progression of cell and tissue destruction might be simultaneously evaluated through optical means.

Curcumin-Loaded Liposomes in Gel Protect the Skin of Mice against Oxidative Stress from Photodamage Induced by UV Irradiation

Prolonged exposure to ultraviolet (UV) irradiation can cause oxidative stress in the skin, accompanied by rapid immunosuppressive effects, resulting in a peroxidation reaction throughout the body. Curcumin (Cur), as the bioactive compound of turmeric, is a natural polyphenol with potent antioxidant properties but is often overlooked due to its poor solubility and low bioavailability. In this study, curcumin-loaded liposomes in a sodium alginate gel complex preparation were designed to improve the bioavailability of curcumin and to study its preventive effect on photodamage. Cur-loaded liposomes (Cur-L), Cur-loaded gel (Cur-G) based on an alginate matrix, and curcumin-loaded liposomes in gel (Cur-LG) were prepared, and their antioxidant effects and drug diffusion abilities were evaluated. The antioxidant capacity of Cur, Cur-L, Cur-G, and Cur-LG was also studied in a mouse model of photodamage. Cur had the highest antioxidant activity at about 4 mg/mL. Cur-LG at this concentration showed antioxidant effects during 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) and H2O2 experiments. During the UV light damage test, Cur-LG demonstrated the ability to effectively neutralize free radicals generated as a result of lipid peroxidation in the skin, serum, and liver, thereby enhancing the overall activity of superoxide dismutase (SOD). In conclusion, using Cur-LG may protect against epidermal and cellular abnormalities induced by UV irradiation.

The Bright Side of Curcumin: A Narrative Review of Its Therapeutic Potential in Cancer Management

Curcumin, a polyphenolic compound derived from Curcuma longa, exhibits significant therapeutic potential in cancer management. This review explores curcumin's mechanisms of action, the challenges related to its bioavailability, and its enhancement through modern technology and approaches. Curcumin demonstrates strong antioxidant and anti-inflammatory properties, contributing to its ability to neutralize free radicals and inhibit inflammatory mediators. Its anticancer effects are mediated by inducing apoptosis, inhibiting cell proliferation, and interfering with tumor growth pathways in various colon, pancreatic, and breast cancers. However, its clinical application is limited by its poor bioavailability due to its rapid metabolism and low absorption. Novel delivery systems, such as curcumin-loaded hydrogels and nanoparticles, have shown promise in improving curcumin bioavailability and therapeutic efficacy. Additionally, photodynamic therapy has emerged as a complementary approach, where light exposure enhances curcumin's anticancer effects by modulating molecular pathways crucial for tumor cell growth and survival. Studies highlight that combining low concentrations of curcumin with visible light irradiation significantly boosts its antitumor efficacy compared to curcumin alone. The interaction of curcumin with cytochromes or drug transporters may play a crucial role in altering the pharmacokinetics of conventional medications, which necessitates careful consideration in clinical settings. Future research should focus on optimizing delivery mechanisms and understanding curcumin's pharmacokinetics to fully harness its therapeutic potential in cancer treatment.

UV-A-Induced Photoisomerization and Photodimerization of Curcumin: An Ion Mobility Mass Spectrometry Study

Curcumin, the bioactive compound present in spice plant turmeric, has been shown to exhibit selective phototoxic activities toward mammalian cancer cells, and it is being used extensively as a photosensitizer (PS) in photodynamic therapies (PDT). However, so far, the fate of curcumin toward photochemical transformations is not well understood. Here we report our findings of a number of novel photochemical reaction channels of curcumin in water-methanol mixture, like photoisomerization, photodimerization, and photooxidation (H2-loss). The reaction was performed by irradiating the curcumin solution with ultraviolet (UV) light of wavelength 350 nm, which is abundant in the earth's troposphere. Product identification and structure elucidation are done by employing an integrated method of drift tube ion mobility mass spectrometry (DTIMS) in combination with high-performance liquid chromatography (HPLC) and collision-induced dissociation (CID) of the mass-selected molecular ions. Two photoisomers of curcumin produced as a result of trans-cis configurational changes about C═C double bonds in the excited state have been identified, and it has been shown that they could serve as the precursors for formation of isomeric dimers via [2 + 2] cycloaddition and H2-loss products. Comparisons of the experimentally measured collision cross-section (CCS) values of the reactant and product ions obtained by the DTIMS method with those predicted by the electronic structure theory are found to be very effective for the discrimination of the produced photoisomers. The observed photochemical reaction channels are potentially significant toward uses of curcumin as a photosensitizer in photodynamic therapy.

The Anti-Oxidant Curcumin Solubilized as Oil-in-Water Nanoemulsions or Chitosan Nanocapsules Effectively Reduces Helicobacter pylori Growth, Bacterial Biofilm Formation, Gastric Cell Adhesion and Internalization

The bacterium Helicobacter pylori (H. pylori) represents a major risk factor associated with the development of gastric cancer. The anti-oxidant curcumin has been ascribed many benefits to human health, including bactericidal effects. However, these effects are poorly reproducible because the molecule is extremely unstable and water insoluble. Here we solubilized curcumin as either nanoemulsions or chitosan nanocapsules and tested the effects on H. pylori. The nanoemulsions were on average 200 nm in diameter with a PdI ≤ 0.16 and a negative zeta potential (-54 mV), while the nanocapsules were 305 nm in diameter with a PdI ≤ 0.29 and a positive zeta potential (+68 mV). Nanocapsules were safer than nanoemulsions when testing effects on the viability of GES-1 gastric cells. Also, nanocapsules were more efficient than nanoemulsions at inhibiting H. pylori growth (minimal inhibitory concentration: 50 and 75 μM, respectively), whereby chitosan contributed to this activity. Importantly, both formulations effectively diminished H. pylori's adherence to and internalization by GES-1 cells, as well as biofilm formation. In summary, the demonstrated activity of the curcumin nanoformulations described here against H. pylori posit them as having great potential to treat or complement other therapies currently in use against H. pylori infection.

Effect of pulsed light on curcumin chemical stability and antioxidant capacity

Curcumin is the major bioactive component in turmeric with potent antioxidant activity. Little is known about how pulsed light (PL) technology (an emerging non-thermal food processing technology relying on high intensity short duration flashes of light) can affect the chemical stability and antioxidant capacity of curcumin. This study found that PL treatment of fluence levels from 0 to 12.75 J/cm2 produced a fluence-dependent reduction in curcumin content. These results paralleled the production of a tentative curcumin dimer, identified as a potential photochemical transformation product. PL-treated curcumin at relatively higher fluence levels decreased chemical-based ORAC and ABTS antioxidant capacity, relative to control (P < 0.05). This contrasted the effect observed to increase coincidently both intracellular antioxidant capacity (e.g., DCFH-DA (P < 0.05)) and GSH/GSSG ratio (P < 0.05), respectively, in cultured differentiated Caco-2 cells. In conclusion, the application of PL on curcumin results in photochemical transformation reactions, such as dimerization, which in turn, can enhance biological antioxidant capacity in differentiated Caco-2 cells.

Novel green production of natural-like vanilla extract from curcuminoids

The demand for natural vanilla extract, and vanillin in particular, by far exceeds the current production, as both the cultivation of vanilla beans and the extraction of vanillin are laborious. For this purpose, most vanillin used today is produced synthetically, contrary to the general trend toward bio-based products. The present study deals with the synthesis of nature-based vanillin, starting with the more accessible rhizomes of the plant Curcuma longa. Besides vanillin, vanillic acid and p-hydroxybenzaldehyde are synthesized that way, which are also found in the natural vanilla bean. The extraction of the curcuminoids and, finally, their conversion to the flavors are performed using visible light and food-grade chemicals only. A binary mixture of ethanol and triacetin, as well as a surfactant-free microemulsion consisting of water, ethanol, and triacetin, are investigated in this context. The results exceed the literature values for Soxhlet extraction of vanilla beans by a factor > 7.

Enhanced Pharmacokinetics and Anti-inflammatory Activity of Curcumin Using Dry Emulsion as Drug Delivery Vehicle

BACKGROUND AND OBJECTIVE

Many naturally available dietary molecules such as curcumin have not seen the market due to poor solubility, bioavailability, and photodegradability. Successful development of a lipid-based dry emulsion may overcome these issues and help in reaching the markets for natural dietary molecules such as curcumin. The current study aims to develop a dry emulsion formulation of curcumin using natural oil and evaluate its dissolution, photostability, pharmacokinetics, and anti-inflammatory activity.

METHODS

Dry emulsions were prepared using emu oil and corn oil as the lipid phase, Caproyl 90 and Cremophor RH 40 as surfactants, and dextrin as a hydrophilic carrier.

RESULTS

Microscopic studies showed the formation of spherical porous particles, and solid-state characterization using differential scanning calorimetry and powder X-ray diffraction showed the conversion of curcumin to an amorphous form. About 80% drug release was observed from formulation, whereas pure drug showed only 50% drug release in 30 min. In vivo pharmacokinetic studies showed fivefold improvement in the maximum concentration of curcumin in plasma (C_max) and sevenfold improvement in the area under the concentration-time curve of curcumin from emu oil formulation compared with pure curcumin. Significant differences were observed in the anti-inflammatory activity of curcumin dry emulsion and plain curcumin. Emu-oil-based formulations showed synergistic anti-inflammatory activity over corn-oil-based formulations with improved photostability.

CONCLUSION

The present study suggests that the dry emulsion may enhance the bioavailability with synergistic anti-inflammatory activity and photostability of curcumin when given orally.

Inhalation of L-arginine-modified liposomes targeting M1 macrophages to enhance curcumin therapeutic efficacy in ALI

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), characterized by uncontrolled lung inflammation, is one of the most devastating diseases with high morbidity and mortality. As the first line of defense system, macrophages play a crucial role in the pathogenesis of ALI/ARDS. Therefore, it has great potential to selectively target M1 macrophages to improve the therapeutic effect of anti-inflammatory drugs. l-arginine plays a key role in regulating the immune function of macrophages. The receptors mediating l-arginine uptake are highly expressed on the surface of M1-type macrophages. In this study, we designed an l-arginine-modified liposome for aerosol inhalation to target M1 macrophages in the lung, and the anti-inflammatory drug curcumin was encapsulated in liposomes as model drug. Compared with unmodified curcumin liposome (Cur-Lip), l-arginine functionalized Cur-Lip (Arg-Cur-Lip) exhibited higher uptake by M1 macrophages in vitro and higher accumulation in inflamed lungs in vivo. Furthermore, Arg-Cur-Lip showed more potent therapeutic effects in LPS-induced RAW 264.7 cells and the rat model of ALI. Overall, these findings indicate that l-arginine-modified liposomes have great potential to enhance curcumin treatment of ALI/ARDS by targeting M1 macrophages, which may provide an option for the treatment of acute lung inflammatory diseases such as coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome and middle east respiratory syndrome.

Rational design, synthesis, and pharmacological characterisation of dicarbonyl curcuminoid analogues with improved stability against lung cancer via ROS and ER stress mediated cell apoptosis and pyroptosis

Curcumin is a natural medicine with a wide range of anti-tumour activities. However, due to β-diketone moiety, curcumin exhibits poor stability and pharmacokinetics which significantly limits its clinical applications. In this article, two types of dicarbonyl curcumin analogues with improved stability were designed through the calculation of molecular stability by density functional theory. Twenty compounds were synthesised, and their anti-tumour activity was screened. A plurality of analogues had significantly stronger activity than curcumin. In particular, compound B2 ((2E,2'E)-3,3'-(1,4-phenylene)bis(1-(2-chlorophenyl)prop-2-en-1-one)) exhibited excellent anti-lung cancer activity in vivo and in vitro. In addition, B2 could upregulate the level of reactive oxygen species in lung cancer cells, which in turn activated the endoplasmic reticulum stress and led to cell apoptosis and pyroptosis. Taken together, curcumin analogue B2 is expected to be a novel candidate for lung cancer treatment with improved chemical and biological characteristics.

Lysine-targeting inhibition of amyloid β oligomerization by a green perilla-derived metastable chalcone in vitro and in vivo

Oligomers of amyloid β (Aβ) represent an early aggregative form that causes neurotoxicity in the pathogenesis of Alzheimer's disease (AD). Thus, preventing Aβ aggregation is important for preventing AD. Despite intensive studies on dietary compounds with anti-aggregation properties, some identified compounds are susceptible to autoxidation and/or hydration upon incubation in water, leaving unanswered issues regarding which active structures in metastable compounds are actually responsible for the inhibition of Aβ aggregation. In this study, we observed the site-specific inhibition of 42-mer Aβ (Aβ42) oligomerization by the green perilla-derived chalcone 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC), which was converted to its decomposed flavonoids (dDDC, 1-3) via nucleophilic aromatic substitution with water molecules. DDC suppressed Aβ42 fibrillization and slowed the transformation of the β-sheet structure, which is rich in Aβ42 aggregates. To validate the contribution of dDDC to the inhibitory effects of DDC on Aβ42 aggregation, we synthesized 1-3 and identified 3, a catechol-type flavonoid, as one of the active forms of DDC. ¹H-¹⁵N SOFAST-HMQC NMR revealed that 1-3 as well as DDC could interact with residues between His13 and Leu17, which were near the intermolecular β-sheet (Gln15-Ala21). The nucleation in Aβ42 aggregates involves the rate-limiting formation of low-molecular-weight oligomers. The formation of a Schiff base with dDDC at Lys16 and Lys28 in the dimer through autoxidation of dDDC was associated with the suppression of Aβ42 nucleation. Of note, in two AD mouse models using immunoaffinity purification-mass spectrometry, adduct formation between dDDC and brain Aβ was observed in a similar manner as reported in vitro. The present findings unraveled the lysine-targeting inhibitory mechanism of metastable dietary ingredients regarding Aβ oligomerization.

Curcumin loaded Ag-TiO2-halloysite nanotubes platform for combined chemo-photodynamic therapy treatment of cancer cells

The use of naturally occurring anticancer materials in combination with doped metal oxide has emerged as one of the most promising ways for improving anticancer treatment efficacy. In this study, the anticancer potential of curcumin-loaded Ag-TiO2-halloysite nanotubes (curcumin-loaded Ag-TiO2-HNTs) was examined. Ag-TiO2-HNTs with different wt% of Ag-TiO2 were synthesized and characterized using XRD, TGA, FT-IR, UV-Vis spectroscopy, and SEM-EDX. The XRD results revealed the presence of crystalline TiO2. However, the presence of Ag was detected through the SEM-EDX analysis. Cyclic voltammetry measurements suggested the enhancement of the release of ROS from TiO2 upon deposition with Ag. FT-IR and TGA analysis confirmed the successful loading of curcumin inside the nanotubes of the halloysite. In vitro drug released studies revealed the release of approximately 80-99% curcumin within 48 hours. Kinetic model studies revealed that the release of curcumin from HNT and Ag-TiO2-HNT followed the first-order and Higuchi models, respectively. The light irradiated curcumin-loaded Ag-TiO2-HNTs samples exhibited considerable anticancer potential as compared to the free curcumin, irradiated Ag-TiO2 NPs samples, and unirradiated curcumin loaded Ag-TiO2-HNTs samples. The obtained results revealed that combined chemo- and photodynamic therapy using curcumin-loaded Ag-TiO2-HNTs nanomaterial has the potential as an effective anticancer treatment method.

Supercritical Fluid Extraction with CO2 of Curcuma longa L. in Comparison to Conventional Solvent Extraction

Curcuma longa L. is a traditional medicinal and spice plant containing a variety of lipophilic active substances with promising therapeutic properties. In this work, the solvent properties of supercritical carbon dioxide in a pressure and temperature range of 75–425 bar and 35–75 °C were investigated when Curcuma longa rhizomes were extracted. The three main curcuminoids, namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin, together with the three main constituents of the essential oil, i.e., ar-turmerone, α-turmerone, and β-turmerone, were analyzed in the resulting extracts. For statistical evaluation, experiments were performed employing a full factorial design, in which flow rate, extraction time, and drug load were kept constant. Within the given conditions, the experimental design revealed an optimum yield of all aforementioned substances, when supercritical carbon dioxide extraction was performed at 425 bar and 75 °C. For comparison, solvent extracts using methanol and n-hexane were prepared and their main components were characterized using LC-MS. The stability of the extracts was monitored upon storage for 6 months at 22 and 40 °C under protection from light. The decomposition of individual compounds was mainly observed in the presence of residual water in the extracts.

An Overview of Parkinson's Disease: Curcumin as a Possible Alternative Treatment

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra of the midbrain and basal ganglia, followed by dopamine deficiency in the brain. Dopamine plays a crucial role in motor coordination, memory, and cognition; its decrease in PD leads to dyskinesia, cognitive deficits, and depression. In addition, the formation of alpha-synuclein protein aggregates (Lewy bodies) causes further damage to the CNS. Current treatment options include dopamine precursors, inhibitors of dopamine metabolism, upregulation of autophagy, adenosine A2A antagonists, and surgical intervention as a last resort. A challenge arises from a progressive decrease in treatment efficacy as the disease progresses and this necessitates exploration of adjunctive treatments. Epidemiological studies suggest that the prevalence of PD varies between ethnic groups of Caucasians, Asians, and African Americans. Notably, the prevalence of PD is lower in countries of Southeastern Asia including India. The differences in the diet of various ethnic groups may suggest an origin for this difference in the prevalence of PD. One staple ingredient in traditional Asian cuisine is turmeric. Curcuma longa, popularly known as turmeric, is an orange tuberous rhizome that has been used for centuries in traditional Indian cuisine and traditional medicine. Turmeric contains curcumin, a potent antioxidant that scavenges reactive oxygen species and chelates toxic metals. Curcumin has been proposed to be a neuroprotective agent due to its potent antioxidative properties. Though preliminary studies in animal model systems have suggested a protective effect of curcumin on dopaminergic neurons, the direct benefits of curcumin on the progress of PD remains poorly understood. In this review, we explore the promising use of curcumin as an adjunct to conventional PD treatments in order to enhance treatment and improve outcomes.

Synergistic Antioxidant Activity and Enhanced Stability of Curcumin Encapsulated in Vegetal Oil-Based Microemulsion and Gel Microemulsions

Curcumin, due to its antioxidant, antibacterial, anti-inflammatory, and antitumoral activity, has attracted huge attention in applications in many fields such as pharmacy, medicine, nutrition, cosmetics, and biotechnology. The stability of curcumin-based products and preservation of antioxidant properties are still challenges in practical applications. Stability and antioxidant properties were studied for curcumin encapsulated in O/W microemulsion systems and three related gel microemulsions. Only biodegradable and biocompatible ingredients were used for carriers: grape seed oil as oily phase, Tween 80, and Plurol^® Diisostearique CG as a surfactant mix, and ethanol as a co-solvent. For the gel microemulsions, water-soluble polymers, namely Carbopol^® 980 NF, chitosan, and sodium hyaluronate were used. The influence of UVC irradiation and heat treatment on the degradation kinetics of curcumin in the formulations was studied. Because of the antioxidant character of the microemulsion oily phase, the possibility of a synergistic effect between grape seed oil and curcumin was explored. In this study, the high efficiency of the studied drug delivery systems to ensure protection from external degradative factors was confirmed. Also, the influence of the encapsulation in microemulsion and derived gel microemulsion systems on the antioxidant capacity curcumin was studied, and a synergistic effect with vegetal oil was demonstrated.

Effect of Drying Methods and Processing Conditions on the Quality of Curcuma longa Powder

Turmeric (Curcuma longa) is a spice that has been used for a long time in traditional medicine for its anti-inflammatory properties and recently used in the food industry for its dyeing and flavoring properties. This work studied the effect of different drying methods (convection oven drying, fluidized bed drying, and traditional solar drying) on the quality of Curcuma longa powder. The effect of UV radiation on turmeric powder using different packaging materials (glass, aluminum foil bag, and low-density polyethylene bag), was also studied. Subsequently, the fluidized bed drying method was used to evaluate the effect of drying temperature. The results show that convection and fluidized bed drying had no significant impact on turmeric quality. However, solar drying degraded curcuminoids by 36.5% and the ORAC value decreased by 14%. Regarding the packaging materials, the aluminum bag prevented the deterioration of 14% of the curcuminoids for the powder exposed to UV radiation. Finally, the effect of temperature on fluidized bed drying was evaluated at 50–80 °C, finding that there were no significant differences in the curcuminoid content and antioxidant capacity of turmeric powder. This implies that the range of temperature used in this study is appropriate for drying this material using fluidized bed drying, producing a turmeric powder with a high content of bioactive compounds, when compared to convection oven and solar drying. Therefore, the turmeric powder obtained in this way can be used as an active ingredient in the formulation of different kinds of foods and supplements.

Drying Behavior and Curcuminoids Changes in Turmeric Slices during Drying under Simulated Solar Radiation as Influenced by Different Transparent Cover Materials

Dried turmeric is used as a spice and traditional medicine. The common drying methods for turmeric (Curcuma longa L.) are sun drying and solar drying. In this study, turmeric slices with a thickness of 2 mm were dried at 40, 50, 60, and 70 °C in a laboratory hot-air dryer with a simulated solar radiation applied through transparent polycarbonate cover (UV impermeable) and PMMA cover (UV permeable). Air velocity and relative humidity of drying air were fixed at 1.0 M·s⁻¹ and 25 g H₂O kg⁻¹ dry air, respectively. Light significantly increased the sample temperature under both covers. Page was the best model to predict the drying characteristics of turmeric slices. Drying rate correlated with the effective moisture diffusivity, which increased at higher temperature. The hue angle (h°) of turmeric was distinctly lower at 70 °C under both covers. The dried products were of intensive orange color. Curcumin, demethoxycurcumin, and total curcuminoids were affected by the cumulated thermal load (CTL). The lowest curcumin content was found at 40 °C under PMMA (highest CTL). The optimum drying condition was 70 °C under polycarbonate cover due to shorter drying time and better preservation of color and curcuminoids in the dried product.

Curcumin encapsulation in functional PLGA nanoparticles: A promising strategy for cancer therapies

Nanoparticles have emerged as promising drug delivery systems for the treatment of several diseases. Novel cancer therapies have exploited these particles as alternative adjuvant therapies to overcome the traditional limitations of radio and chemotherapy. Curcumin is a natural bioactive compound found in turmeric, that has been reported to show anticancer activity against several types of tumors. Despite some biological limitations regarding its absorption in the human body, curcumin encapsulation in poly(lactic-co-glycolic acid) (PLGA), a non-toxic, biodegradable and biocompatible polymer, represents an effective strategy to deliver a drug to a tumor site. Furthermore, PLGA nanoparticles can be engineered with targeting moieties to reach specific cancer cells, thus enhancing the antitumor effects of curcumin. We herein aim to bring an up-to-date summary of the recently developed strategies for curcumin delivery to different types of cancer cells through encapsulation in PLGA nanoparticles, correlating their effects with those of curcumin on the biological capabilities acquired by cancer cells (cancer hallmarks). We discuss the targeting strategies proposed for advanced curcumin delivery and the respective improvements achieved for each cancer cell analyzed, in addition to exploring the encapsulation techniques employed. The conjugation of correct encapsulation techniques with tumor-oriented targeting design can result in curcumin-loaded PLGA nanoparticles that can successfully integrate the elaborate network of development of alternative cancer treatments along with traditional ones. Finally, the current challenges and future demands to launch these nanoparticles in oncology are comprehensively examined.

Shedding light on curcumin stability

The stability of molecular curcumin (purcumin, 1a) in solution is strongly light-dependent. Under laboratory artificial light, a relative stability is observed only at neutral pH, while more intense light and/or solar light can trigger degradation via a combination of hydrolytic and oxidative fragmentation of the heptadiendione moiety. Minor curcuminoids in commercial curcumin (purcuminoids) can improve the stability of molecular curcumin, but only under conditions of low irradiation. While confirming earlier observations alerting to the instability of purcumin, our results provide new rationales for unexplained differences between previous studies, question the biological relevance of a non-enzymatic degradation for the bioactivity profiles that have been reported for purcumin, and highlight the need of a better characterization of the degradation of purcuminoids under visible light irradiation.

Optical spectroscopy study of the interaction between curcumin and acrylic polymers

This paper presents the results of a study conducted on the interaction between curcumin, a compound with several biomedical applications in traditional and modern medicine, and the acrylic polymers poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n-butyl methacrylate), through photophysical experiments in curcumin/acrylic polymers casting films. Optical absorption intensity at ~340 nm increases relatively to its maximum at ~417 nm when the amount of curcumin in the polymeric film decreases, due to a significant change in the concentration of the isomers cis- or trans-form of curcumin, regardless of the acrylic polymer. Fluorescence (FL) spectra of the films depend on the curcumin concentration in the matrix with well-resolved line shape. They show two distinct bands, one at ~525 nm, for higher curcumin concentration (5.00 mmol.L^-1), related to the aggregated curcumin species, and another at ~465 nm, for lower concentration of curcumin (0.10 mmol.L^-1), related to the effects of the solvent on the conformational structure of the curcumin molecule and the presence of the trans-form of curcumin. The parameter K_agg, related to the contribution of the aggregated curcumin, shows the influence of the polymeric lateral chain length of the matrix in the de-aggregation of the curcumin. The Huang-Rhys factor indicates that curcumin aggregated species are conformationally more stable, and that the isolate species depends on the chemical environment and the matrix/curcumin interaction, decreasing its conformational degrees of freedom. Arrhenius plots, obtained via FL experiment in function of the sample temperature, show that, for higher curcumin concentration, the value for the relaxation energy process is not well defined, due the decrease in the interaction between the matrix and the curcumin molecules. With these results, it is possible to infer that the interaction matrix/curcumin must occur via lateral chemical alkyl groups.

Turmeric and its bioactive constituents trigger cell signaling mechanisms that protect against diabetes and cardiovascular diseases

Turmeric, the rhizome of Curcuma longa plant belonging to the ginger family Zingiberaceae, has a history in Ayurvedic and traditional Chinese medicine for treatment of chronic diseases, including metabolic and cardiovascular diseases (CVD). This parallels a prevalence of age- and lifestyle-related diseases, especially CVD and type 2 diabetes (T2D), and associated mortality which has occurred in recent decades. While the chemical composition of turmeric is complex, curcuminoids and essential oils are known as two major groups that display bioactive properties. Curcumin, the most predominant curcuminoid, can modulate several cell signaling pathways involved in the etiology and pathogenesis of CVD, T2D, and related morbidities. Lesser bioactivities have been reported from other curcuminoids and essential oils. This review examines the chemical compositions of turmeric, and related bioactive constituents. A focus was placed on the cellular and molecular mechanisms that underlie the protective effects of turmeric and turmeric-derived compounds against diabetes and CVD, compiled from the findings obtained with cell-based and animal models. Evidence from clinical trials is also presented to identify potential preventative and therapeutic efficacies. Clinical studies with longer intervention durations and specific endpoints for assessing health outcomes are warranted in order to fully evaluate the long-term protective efficacy of turmeric.

Curcumin in Osteosarcoma Therapy: Combining With Immunotherapy, Chemotherapeutics, Bone Tissue Engineering Materials and Potential Synergism With Photodynamic Therapy

Osteosarcoma is a dominating malignant bone tumor with high mortality due to pulmonary metastases. Furthermore, because of the cancer cell erosion and surgery resection, osteosarcoma always causes bone defects, which means dysfunction and disfigurement are seldom inevitable. Although various advanced treatments (e.g. chemotherapy, immunotherapy, radiotherapy) are coming up, the 5-year survival rate for osteosarcoma with metastases is still dismal. In line with this, the more potent treatments for osteosarcoma are in high demand. Curcumin, a perennial herb, has been reportedly applied in the therapy of various types of tumors via different mechanisms. In vitro, it has also been reported that curcumin can inhibit the proliferation of osteosarcoma cell lines and can be used to repair bone defects. This seems curcumin is a promising candidate in osteosarcoma treatment. However, due to its congenital property like hydrophobicity, and low bioavailability, affecting its anticancer effect, clinical applications of curcumin are highly limited. To enhance its performance in cancer therapies, some synergist approaches with curcumin have emerged. The present review presents some prospective ones (i.e. combinations with immunotherapy, chemotherapeutics, bone tissue engineering, and biomaterials) applied in osteosarcoma treatment. Additionally, with the advancements of photodynamic therapy in cancer therapy, this review also prospects the combination of curcumin with photodynamic therapy in osteosarcoma treatment.

Virtual screening of curcumin analogues as DYRK2 inhibitor: Pharmacophore analysis, molecular docking and dynamics, and ADME prediction

Background: Curcumin reduces the proliferation of cancer cells through inhibition of the DYRK2 enzyme, which is a positive regulator of the 26S proteasome. Methods: In the present work, curcumin analogues have been screened from the MolPort database using a pharmacophore model that comprised a ligand-based approach. The result of the screening was then evaluated by molecular docking and molecular dynamics based on binding the free energy of the interaction between each compound with the binding pocket of DYRK2. The hit compounds were then confirmed by absorption, distribution, metabolism, and excretion (ADME) prediction. Results: Screening of 7.4 million molecules from the MolPort database afforded six selected hit compounds. By considering the ADME prediction, three prospective curcumin analogues have been selected. These are:  2‐[2‐(1‐methylpyrazol‐4‐yl)ethyl]‐1H,5H,6H,7H,8H‐imidazo[4,5‐c]azepin‐4‐one (Molport-035-369-361), methyl 4‐(3‐hydroxy‐1,2‐oxazol‐5‐yl)piperidine‐1‐carboxylate (Molport-000-004-273) and (1S)‐1‐[5‐(furan‐3‐carbonyl)‐4H,6H,7H‐pyrazolo[1,5‐a]pyrazin‐2‐yl]ethanol (MolPort-035-585-822). Conclusion: Pharmacophore modelling, combined with molecular docking and molecular dynamics simulation, as well as ADME prediction were successfully applied to screen curcumin analogues from the MolPort database as DYRK2 inhibitors. All selected compounds that have better predicted pharmacokinetic properties than that of curcumin are considered for further study.

Application of starch nanoparticles as host materials for encapsulation of curcumin: Effect of citric acid modification

To encapsulate curcumin, absolute ethanolic curcumin solution with various content (300-1200 μg) was added to aqueous dispersion of citric acid-modified starch nanoparticles (M.SNPs) with various contents (0.5-2.5%), and then ethanol of the mixture was evaporated by nitrogen gas purge for 40 min (ethanol content decreased to 1%). SNPs (100 mg) could encapsulate 75.7 μg of curcumin in matrices of the composite, while 100 mg of M.SNPs could encapsulate 144.9 μg of curcumin. The XRD results revealed that curcumin was amorphously encapsulated in the composite, and hydrogen bond formation between M.SNPs and curcumin was one of the major driving forces for encapsulation as suggested by FT-IR. The composites had a spherical shape and mean particle size of the composites was increased from 136.3 to 255.3 nm with higher curcumin content in the matrices of composites. UV, pH, and thermal stability of curcumin significantly enhanced by the encapsulation, which was further increased when using M.SNPs and/or higher content of host materials. For the release of curcumin in simulated intestinal fluid digestion, release mechanism explained by Korsmeyer-Peppas model. For M.SNPs, k value was decreased from 13.097 to 2.938 as addition level of host material increased from 0.5 to 2.5%.

Transferrin-functionalized lipid nanoparticles for curcumin brain delivery

Curcumin is an anti-inflammatory and antioxidant compound with potent neuroprotective activity. Due to its poor water solubility, low bioavailability, rapid elimination and the challenges for crossing and transposing the blood-brain barrier (BBB), solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) loaded with curcumin were successfully produced and functionalized with transferrin, in order to mediate the transport of these particles through the BBB endothelium to the brain. The nanosystems revealed Z-averages under 200 nm, polydispersity index below 0.2 and zeta potential around -30 mV. Curcumin encapsulation around 65 % for SLNs and 80 % for NLCs was accomplished, while the functionalized nanoparticles presented a value around 70-75 %. A stability study revealed these characteristics remained unchanged for at least 3 months. hCMEC/D3 cells viability was firstly analysed by MTT and LDH assays, respectively, and a concentration of 10 μM of curcumin-loaded nanoparticles were then selected for the subsequent permeability assay. The permeability study was conducted using transwell devices with hCMEC/D3 cells monolayers and a 1.5-fold higher permeation of curcumin through the BBB was verified. Both SLNs and NLCs are promising for curcumin brain delivery, protecting the incorporated curcumin and targeting to the brain by the addition of transferrin to the nanoparticles surface.

Isocratic high-performance liquid chromatography (HPLC) for simultaneous quantification of curcumin and piperine in a microparticle formulation containing Curcuma longa and Piper nigrum

Poor bioavailability has been reported as a major challenge in the development of curcumin as a pharmaceutical agent. However, co-administration of curcumin with piperine has been shown to improve curcumin bioavailability. Therefore, to assure product control quality, an analytical method needs to be developed for the determination of curcumin and piperine content in a dosage form formulation. The objective of this study was to develop a simple isocratic reversed-phase HPLC (RP-HPLC) method to simultaneously quantify curcumin and piperine content in solid dispersion based microparticle formulation containing Curcuma longa and Piper nigrum extracts. The method was validated according to the International Council for Harmonization (ICH) guideline. Chromatographic separation of three curcuminoids and piperine could be achieved using acetonitrile-methanol-water of 65:5:35 %, at a flow rate of 1 mL/min and a wavelength of 353 nm for detection. Resolution (Rs) of 3.57 and 1.68 for piperine and curcumin, respectively, a theoretical plate number (N) > 8000 and a tailing factor (T) < 1.5 indicate a satisfactory separation of the compounds. The calibration curve was linear from 1.25-15 μg/mL and 2.5-30 μg/mL for piperine and curcumin, respectively, with the correlation coefficient of >0.999. The intra-day/inter-day accuracy and precision demonstrated a recovery of 99.54-101.50%/99.38-99.89% and 100.78-102.51%/101.15-102.47% with a Relative Standard Deviation (RSD) of 0.53-0.95%/0.13-1.44 % and 0.28-1.62%/0.46-1.14% for piperine/curcumin. The limit of detection (LOD) were 0.27 and 0.42 μg/mL, for piperine and curcumin, which reveals an adequate sensitivity. A solid dispersion based microparticle formulation containing C. longa and P. nigrum extracts confirmed the validity of the developed method as a recovery of 91.14% and 99.14% for piperine and curcumin, respectively. In conclusion, all the tested parameters confirm the precision, accuracy, and reliability of the method for the simultaneous analysis of curcumin and piperine within a microparticle formulation containing C. longa and P. nigrum extracts.

Improving the Stability and Curcumin Retention Rate of Curcumin-Loaded Filled Hydrogel Prepared Using 4αGTase-Treated Rice Starch

In this study, 4-α-glucanotransferase (4αGTase)-treated rice starch (GS) was added after 1-h (1 GS) and 96-h (96 GS) treatments to the aqueous phase of a curcumin-loaded emulsion to produce filled hydrogels (1 GS-FH and 96 GS-FH, respectively). The relative protective effects of the FH system, native rice starch-based filled hydrogel (RS-FH), and emulsion without starch (EM), on curcumin were evaluated based on ultraviolet (UV) stability and simulated gastrointestinal studies. The UV stability and curcumin retention after in vitro digestion of the filled hydrogels (FH) samples were greater than those of the EM samples. RS-FH showed a 2.28-fold improvement in UV stability over EM due to the higher viscosity of RS. 1 GS-FH and 96 GS-FH increased curcumin retention by 2.31- and 2.60-fold, respectively, and the microstructure of 96 GS-FH, determined using confocal laser microscopy, remained stable even after the stomach phase. These effects were attributed to the molecular structure of GS, with decreased amylopectin size and amylose content resulting from the enzyme treatment. The encapsulation of lipids within the GS hydrogel particles served to protect and deliver the curcumin component, suggesting that GS-FH can be applied to gel-type food products and improve the chemical stability of curcumin.

A multi-responsive self-healing hydrogel for controlled release of curcumin

A multi-responsive self-healing hydrogel for the controlled release of curcumin has been developed using dynamic boronic acid ester linkages.

The Hantzsch Reaction in Polymer Chemistry: From Synthetic Methods to Applications

The Hantzcsh reaction is a robust four-component reaction for the efficient generation of 1,4-dihydropyridine (1,4-DHP) derivatives. Recently, this reaction has been introduced into polymer chemistry in order to develop polymers having 1,4-DHP structures in the main and/or side chains. The 1,4-DHP groups confer new properties/functions to the polymers. This mini-review summarizes the recent studies on the development of new functional polymers by using the Hantzsch reaction. Several synthetic approaches, including polycondensation, post-polymerization modification (PPM), monomer to polymer strategy, and one-pot strategy are introduced; different applications (protein conjugation, formaldehyde detection, drug carrier, and anti-bacterial adhesion) of the resulting polymers are emphasized. Meanwhile, the future development of the Hantzsch reaction in exploring new functional polymers is also discussed.

Curcumin extracts from Curcuma Longa - Improvement of concentration, purity, and stability in food-approved and water-soluble surfactant-free microemulsions

Curcumin was extracted from Curcuma Longa employing a green, bio-based, and food-agreed surfactant-free microemulsion (SFME) consisting of water, ethanol, and triacetin. Concerning the high solubility of curcumin in the examined ternary mixtures, it was attempted to produce highly concentrated tinctures of up to a total of ~130 mg/mL curcuminoids in the solvent by repeatedly extracting fresh rhizomes in the same extraction mixture. The amount of water had a significant influence on the number of cycles that could be performed as well as on the extraction of the different curcuminoids. In addition, the purity of single extracts was enhanced to 94% by investigating several purification steps, e.g. vacuum distillation and lyophilization. Through purification before extraction, the water insoluble curcumin extract could be solubilized indefinitely in an aqueous environment. Additional stability tests showed that solutions of curcumin can be stable up to five months when concealed from natural light.

Solubilization and extraction of curcumin from Curcuma Longa using green, sustainable, and food-approved surfactant-free microemulsions

Curcumin is a powerful coloring agent widely used in the food industry. Its extraction from the plant Curcuma longa is commonly done with aqueous solvent solutions. In contrast to the conventional extraction methods, the present study aimed to compare two different green and bio-based surfactant-free microemulsion (SFME) extraction systems, which are approved for food and yield a higher extracting power of curcuminoids. Two SFMEs, water/ethanol/triacetin and water/diacetin/triacetin, were investigated via dynamic light scattering. Curcumin solubility in binary mixtures consisting of ethanol/triacetin or diacetin/triacetin was studied both experimentally and theoretically using UV-Vis measurements and COSMO-RS. The SFMEs were further examined and compared to a common ethanol/water (80/20) extraction mixture with respect to their extracting ability using high performance liquid chromatography. The SFMEs containing ethanol were found to extract ~18% more curcuminoids than the SFMEs containing diacetin and ~53% more than the ordinary ethanol/water mixture.

Effect of curcumin and cosolvents on the micellization of Pluronic F127 in aqueous solution

The drug solubilization capacity of poloxamers like Pluronic F127 (PF127, poloxamer 407) is dependent on the physical form of the polymer; i.e. the distribution between unimers, aggregates, and micelles. Further, the formation of micelles can alter the stability and pharmacological activity of a drug molecule. It is therefore important to understand how the micellization process is influenced by the addition of excipients and drug molecules. Curcumin is considered a photosensitizer in antimicrobial photodynamic therapy (aPDT). The aPDT effect is optimized at a poloxamer concentration just below the critical micellar concentration (CMC). We aimed to evaluate the effect of curcumin in the presence of 1% ethanol (EtOH) or dimethyl sulfoxide (DMSO) on PF127 micellization. These organic solvents are commonly used in topical preparations as a cosolvent or penetration enhancer (in the case of DMSO). The micellization process was investigated by UV-vis spectroscopy, dynamic light scattering (DLS), and differential scanning calorimetry (DSC). The micellization process of PF127 was slightly influenced by the addition of 1% EtOH or DMSO; however, the presence of 20 μM curcumin enhanced the effect. Micellization was favored in PBS compared to MilliQ water. Structures were formed between PF127 and curcumin at poloxamer concentrations ≥0.3 μM which facilitated solubilization of the photosensitizer. The optimal PF127 concentration required to solubilize 20 μM curcumin but avoid micellization was in the range 0.3 μM-0.04 mM in PBS in the presence of 1 % EtOH or DMSO. A careful consideration of the curcumin, cosolvents, and PF127 concentrations is required to enhance the curcumin solubility and prevent the PF127 micellization.

An insight into curcumin-based photosensitization as a promising and green food preservation technology

Consumer awareness on the side effects of chemical preservatives has increased the demand for natural preservation technologies. An efficient and sustainable alternative to current conventional preservation techniques should guarantee food safety and retain its quality with minimal side effects. Photosensitization, utilizing light and a natural photosensitizer, has been postulated as a viable and green alternative to the current conventional preservation techniques. The potential of curcumin as a natural photosensitizer is reviewed in this paper as a practical guide to develop a safe and effective decontamination tool for industrial use. The fundamentals of the photosensitization mechanism are discussed, with the main emphasis on the natural photosensitizer, curcumin, and its application to inactivate microorganisms as well as to enhance the shelf life of foods. Photosensitization has shown promising results in inactivating a wide spectrum of microorganisms with no reported microbial resistance due to its particular lethal mode of targeting nucleic acids. Curcumin as a natural photosensitizer has recently been investigated and demonstrated efficacy in decontamination and delaying spoilage. Moreover, studies have shown the beneficial impact of an appropriate encapsulation technique to enhance the cellular uptake of photosensitizers, and therefore, the phototoxicity. Further studies relating to improved delivery of natural photosensitizers with inherent poor solubility should be conducted. Also, detailed studies on various food products are warranted to better understand the impact of encapsulation on curcumin photophysical properties, photo-driven release mechanism, and nutritional and organoleptic properties of treated foods.

Effects of curcumin complexes on MDA‑MB‑231 breast cancer cell proliferation

Curcumin displays anticancer properties; however, some issues with the drug delivery mode limit its therapeutic use. Although reformulation and derivatization of curcumin have improved its bioavailability, curcumin derivatives may not retain the same anticancer properties as the parent compound. The present study investigated the anticancer properties of two curcumin complexes, the iron‑curcumin [Fe(Cur)3] and boron‑curcumin [B(Cur)2] complexes, in the MDA‑MB‑231 breast cancer cell line. The cellular localization of curcumin, B(Cur)2 and Fe(Cur)3 was determined by fluorescence microscopy. Cell proliferation, migration and invasion were also analysed. Furthermore, apoptosis‑associated proteins were detected by using a proteome profiler array, and ion channel gene expression was analysed by reverse transcription‑quantitative PCR. The results demonstrated that the three compounds were localized in the perinuclear and cytoplasmic regions of the cell, and displayed cytotoxicity with IC50 values of 25, 35 and 8 µM for curcumin, B(Cur)2 and Fe(Cur)3, respectively. In addition, the three compounds inhibited cell invasion, whereas only curcumin and B(Cur)2 inhibited cell migration. Furthermore, cell exposure to curcumin resulted in an increase in the relative expression of the two key proapoptotic proteins, cytochrome c and cleaved caspase‑3, as well as the antiapoptotic protein haem oxygenase‑1. In addition, curcumin increased the expression levels of the voltage‑gated potassium channels Kv2.1 and Kv3.2. Similarly, the expression levels of the chloride channel bestrophin‑1 and the calcium channel coding gene calcium voltage‑gated channel auxiliary subunit γ4 were increased following exposure to curcumin. Taken together, these results indicated that Fe(Cur)3 and B(Cur)2 may display similar anticancer properties as curcumin, suggesting that chemical complexation may be considered as a strategy for improving the potency of curcumin in the treatment of breast cancer.

Encapsulation of curcumin into layered double hydroxides improve their anticancer and antiparasitic activity

Objectives

Curcumin (CUR) has well-known activity against cancer cells and parasites; however, its applications are limited since this is an unstable molecule, which may suffer degradation by light and temperature, also, the low water solubility reduce its bioavailability. Layered double hydroxides (LDH) are well-known materials owing to the excellent anion exchange capacity, good biocompatibility and low toxicity.

Methods

Layered double hydroxides nanoparticles prepared with zinc and magnesium cations were used as a vehicle for CUR in Caco-2, Giardia lamblia and Entamoeba histolytica cultures. The physicochemical properties of Mg-LDH-CUR and Zn-LDH-CUR were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and X-ray powder diffraction (XRD). Additionally, the load efficiency, release profiles and photostability of CUR were quantified by high-performance liquid chromatography (HPLC) and UV-Vis spectrometry. Then, Mg-LDH-CUR and Zn-LDH-CUR were tested on Caco-2, G. lamblia and E. histolytica cultures.

Key findings

The experiments demonstrated that Zn-LDH-CUR protects better against photodegradation by UV light, while Mg-LDH-CUR showed increased toxicity against Caco-2 cell, G. lamblia and E. histolytica, in comparison with free CUR.

Conclusions

Layered double hydroxides are good vehicles to improve stability, resistance to degradation of CUR, also they are useful to improve solubility, provide a controlled release and improve the cytotoxic activity. Additionally, it was shown that the composition of the M+2 cation of LDH affects its properties and structure and that this directly influences its biological activity. The findings are important to select the composition of the encapsulation vehicle for a specific activity.

Fabrication of Polydopamine-Based Curcumin Nanoparticles for Chemical Stability and pH-Responsive Delivery

Polydopamine (PDA) possesses high aqueous dispersibility, strong optical absorption, and a zwitterionic property, which give it multitudes of advantages to coat light-sensitive hydrophobic curcumin (Cur) for pH-responsive release. However, PDA is formed in alkaline conditions, which hinders its potential application for alkali-sensitive curcumin coating. Here, we developed a method to prepare PDA-coated Cur nanoparticles (NPs), which reduced chemical degradation of Cur in alkaline conditions. Encapsulation efficiency and loading capacity decreased to 73.69% and 51.80%, as the time for dopamine polymerization went on. PDA could protect Cur from light-induced degradation in powder and solution forms. Controlled release and pH-responsive delivery of PDA-coated Cur were observed under stomach and intestinal conditions compared to free Cur, which resulted from the coverage and thickness of the PDA shell and the electrostatic attraction between PDA and Cur. PDA-coated Cur NPs could be a promising way for the application of Cur in the beverage and food industry.

Curcumin–polymer conjugates with dynamic boronic acid ester linkages for selective killing of cancer cells

A phenylboronic acid (PBA)-containing copolymer was synthesized via the Hantzsch reaction and radical polymerization. Curcumin was dynamically included in this PBA-containing polymer to selectively kill cancer cells.

Curcumin-loaded Pickering emulsion stabilized by insoluble complexes involving ovotransferrin-gallic acid conjugates and carboxymethyldextran

The present work aimed to fabricate antioxidant particle-stabilized Pickering emulsions with outstanding protection of encapsulated nutraceuticals. Antioxidant ovotransferrin-gallic acid conjugates (OTGCONJ) were prepared using the alkaline method, and the electrostatic assembly technique was utilized to construct OTGCONJ-CMD particles with OTGCONJ and carboxymethyldextran (CMD) as the building blocks. After the investigation of the particle size, insoluble nature and intermediate wettability of the OTGCONJ-CMD particles, the OTGCONJ-CMD particles were verified as eligible Pickering stabilizers. Visual observation showed that the stable OTGCONJ-CMD particle-stabilized Pickering emulsion consisted of the emulsified phase alone. Rheological analysis revealed that the Pickering emulsion had a high viscosity and a gel-like structure. In terms of the protective effect, the OTGCONJ-CMD particle-stabilized Pickering emulsion could significantly retard curcumin degradation under UV light. An in vitro digestion study revealed that the OTGCONJ-CMD particle-stabilized Pickering emulsion improved both the extent of lipolysis and curcumin bioaccessibility remarkably, suggesting that the OTGCONJ-CMD particle-stabilized Pickering emulsion was an excellent nutraceutical delivery vehicle. The novel findings in this work could have important implications for the design of nutraceutical-loaded Pickering emulsions with an excellent protective effect and nutraceutical delivery efficiency.

Crucial successes in drug delivery systems using multivariate chemometric approaches: challenges and opportunities

Applying multivariate chemometric methods for thorough investigation of three processes in drug delivery systems: loading, release and photo-degradation.

Curcumin-based photosensitization inactivates Aspergillus flavus and reduces aflatoxin B1 in maize kernels

Different methods have been applied in controlling contamination of foods and feeds by the carcinogenic fungal toxin, aflatoxin, but nevertheless the problem remains pervasive in developing countries. Curcumin is a natural polyphenolic compound from the spice turmeric (Curcuma longa L.) that has been identified as an efficient photosensitiser for inactivation of Aspergillus flavus conidia. Curcumin mediated photoinactivation of A. flavus has revealed the potential of this technology to be an effective method for reducing population density of the aflatoxin-producing fungus in foods. This study demonstrates the influence of pH and temperature on efficiency of photoinactivation of the fungus and how treating spore-contaminated maize kernels affects aflatoxin production. The results show the efficiency of curcumin mediated photoinactivation of fungal conidia and hyphae were not affected by temperatures between 15 and 35 °C or pH range of 1.5-9.0. The production of aflatoxin B₁ was significantly lower (p < 0.05), with an average of 82.4 μg/kg as compared to up to 305.9 μg/kg observed in untreated maize kept under similar conditions. The results of this study indicate that curcumin mediated photosensitization can potentially be applied under simple environmental conditions to achieve significant reduction of post-harvest contamination of aflatoxin B₁ in maize.