Controlled Release of Curcumin and Hypocrellin A from Electrospun Poly(l-Lactic Acid)/Silk Fibroin Nanofibers for Enhanced Cancer Cell Inhibition

Nanofibers have emerged as a highly effective method for drug delivery, attributed to their remarkable porosity and ability to regulate drug release rates while minimizing toxicity and side effects. In this study, we successfully loaded the natural anticancer drugs curcumin (CUR) and hypocrellin A (HA) into pure poly(l-lactic acid) (PLLA) and PLLA-silk protein (PS) composite nanofibers through electrospinning technology. This result was confirmed through comprehensive analysis involving SEM, FTIR, XRD, DSC, TG, zeta potential, and pH stability analysis. The encapsulation efficiency of all samples exceeded 85%, demonstrating the effectiveness of the loading process. Additionally, the drug release doses were significantly higher in the composites compared to pure PLLA, owing to the enhanced crystallinity and stability of the silk proteins. Importantly, the composite nanofibers exhibited excellent pH stability in physiological and acidic environments. Furthermore, the drug-loaded composite nanofibers displayed strong inhibitory effects on cancer cells, with approximately 28% (HA) and 37% (CUR) inhibition of cell growth and differentiation within 72 h, while showing minimal impact on normal cells. This research highlights the potential for controlling drug release through the manipulation of fiber diameter and crystallinity, paving the way for wider applications of electrospun green nanomaterials in the field of medicine.

Heteroleptic cobalt complex augments antifungal activity with fluconazole and causes membrane disruption in Candida albicans

Heteroleptic metal complexes containing CuII, CoII, and ZnII, incorporating curcumin and a Schiff base ligand (L), were synthesized and characterized, and their antifungal activity was evaluated. Their antifungal activities were investigated individually and in combination with fluconazole. Utilizing various analytical techniques such as UV-Vis, FT-IR, NMR, ESI-MS, TGA-DTG, elemental analyses, conductance, and magnetic susceptibility measurements, complex C1 ([Cu(Cur)LCl(H2O)]) was assigned a distorted octahedral geometry, while complexes C2 ([Co(Cur)LCl(H2O)]) and C3 ([Zn(Cur)LCl(H2O)]) were assigned octahedral geometries. Among these complexes, C2 exhibited the highest inhibitory activity against both FLC-susceptible and resistant strains of Candida albicans. Furthermore, C2 demonstrated candidicidal activity and synergistic interactions with fluconazole, effectively inhibiting the growth and survival of both FLC-resistant and FLC-sensitive C. albicans strains. The complex displayed a dose-dependent inhibition of drug efflux pumps in FLC-resistant C. albicans strains, indicating its potential to disrupt the cell membrane of these strains. The significant role of membrane efflux transporters in the development of antifungal drug resistance within Candida species has been extensively documented and our findings indicate that complex C2 specifically targets this crucial factor, thereby playing a pivotal role in mitigating drug resistance in C. albicans.

Curcumin Inhibits α-Synuclein Aggregation by Acting on Liquid-Liquid Phase Transition

Parkinson's disease (PD), the second most common neurodegenerative disorder, is linked to α-synuclein (α-Syn) aggregation. Despite no specific drug being available for its treatment, curcumin, from the spice turmeric, shows promise. However, its application in PD is limited by a lack of understanding of its anti-amyloidogenic mechanisms. In this study, we first reconstructed the liquid-liquid phase separation (LLPS) of α-Syn in vitro under different conditions, which may be an initial step in entraining the pathogenic aggregation. Subsequently, we evaluated the effects of curcumin on the formation of droplets, oligomers, and aggregated fibers during the LLPS of α-synuclein, as well as its impact on the toxicity of aggregated α-synuclein to cultured cells. Importantly, we found that curcumin can inhibit amyloid formation by inhibiting the occurrence of LLPS and the subsequent formation of oligomers of α-Syn in the early stages of aggregation. Finally, the molecular dynamic simulations of interactions between α-Syn decamer fibrils and curcumin showed that van der Waal's interactions make the largest contribution to the anti-aggregation effect of curcumin. These results may help to clarify the mechanism by which curcumin inhibits the formation of α-Syn aggregates during the development of PD.

Sodium fusidate prevents protein aggregation of silk fibroin and offers new perspectives for human lens material disaggregation

Silk fibroin (SF) is a non-pathological amyloidogenic protein prone, in solution, to the formation of amyloid-like aggregated species, displaying similarities in fibrillation kinetics with pathological amyloids, as widely reported in the literature. We show here, on the basis of different biophysical approaches (turbidity, Congo Red assays, CD, DLS and fluorescence), that fusidic acid (FA), a well-known antibiotic, acts on SF as an anti-aggregating agent in a dose-dependent manner, being also able to revert SF aggregation. FA binds to SF inducing changes in the environment of SF aromatic residues. We further provide the proof of principle that FA, already approved as drug on humans and used in ophthalmic preparations, displays its anti-aggregation properties also on lens material derived from cataract surgery and is capable of reducing aggregation. Thus it is suggested that FA can be foreseen as a therapeutic treatment for cataract and other protein aggregation disorders.

Metal-Curcumin Complexes in Therapeutics: An Approach to Enhance Pharmacological Effects of Curcumin

Curcumin, an active component of the rhizome turmeric, has gained much attention as a plant-based compound with pleiotropic pharmacological properties. It possesses anti-inflammatory, antioxidant, hypoglycemic, antimicrobial, neuroprotective, and immunomodulatory activities. However, the health-promoting utility of curcumin is constrained due to its hydrophobic nature, water insolubility, poor bioavailability, rapid metabolism, and systemic elimination. Therefore, an innovative stride was taken, and complexes of metals with curcumin have been synthesized. Curcumin usually reacts with metals through the β-diketone moiety to generate metal–curcumin complexes. It is well established that curcumin strongly chelates several metal ions, including boron, cobalt, copper, gallium, gadolinium, gold, lanthanum, manganese, nickel, iron, palladium, platinum, ruthenium, silver, vanadium, and zinc. In this review, the pharmacological, chemopreventive, and therapeutic activities of metal–curcumin complexes are discussed. Metal–curcumin complexes increase the solubility, cellular uptake, and bioavailability and improve the antioxidant, anti-inflammatory, antimicrobial, and antiviral effects of curcumin. Metal–curcumin complexes have also demonstrated efficacy against various chronic diseases, including cancer, arthritis, osteoporosis, and neurological disorders such as Alzheimer’s disease. These biological activities of metal–curcumin complexes were associated with the modulation of inflammatory mediators, transcription factors, protein kinases, antiapoptotic proteins, lipid peroxidation, and antioxidant enzymes. In addition, metal–curcumin complexes have shown usefulness in biological imaging and radioimaging. The future use of metal–curcumin complexes may represent a new approach in the prevention and treatment of chronic diseases.

Modulation of aggregation of silk fibroin by synergistic effect of the complex of curcumin and β-cyclodextrin

Amyloid aggregation has been associated with numerous human pathological diseases. A recent study has demonstrated that silk fibroin intermittently endorses amyloidogenesis in vivo. In the current study, we explored the propensity of silk fibroin to undergo amyloid-like aggregation and its prevention using an optimized concoction of curcumin with β-cyclodextrin. Aggregation of silk fibroin resulted in the formation of fibrils with a diameter of ~3.2 nm. However, addition of the optimized concentration of curcumin and β-cyclodextrin to silk fibroin inhibited aggregation and preserved the random coil conformation even under aggregation inducing conditions, as demonstrated by CD and FTIR spectroscopy. Benzene rings of curcumin interact with the aromatic residues of fibroin via hydrophobic interactions. However, β-cyclodextrin preferentially interacts with the non-polar residues, which are the core components for nucleation dependent protein aggregation. The present study demonstrates the ability of the concoction of curcumin and β-cyclodextrin in tuning the self assembly process of fibroin. It also provides a platform to explore the assembly process of nano-fibril and hierarchical structures in vitro along with a novel insight for designing clinically relevant silk-based functional biomaterials.

Dual-loaded, long-term sustained drug releasing and thixotropic hydrogel for localized chemotherapy of cancer

A thixotropic injectable regenerated silk fibroin/hydroxypropylcellulose (RSF/HPC) hydrogel for highly sustainable dual-drug release with improved anticancer therapy and alleviated side effects.

Al cation induces aggregation of serum proteins

Al cation is known to induce protein fibrillation and causes several neurodegenerative disorders. We report the spectroscopic, thermodynamic analysis and AFM imaging for the Al cation binding process with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. Hydrophobicity played a major role in Al-protein interactions with more hydrophobic b-LG forming stronger Al-protein complexes. Thermodynamic parameters ΔS, ΔH and ΔG showed Al-protein bindings occur via hydrophobic and H-bonding contacts for b-LG, while van der Waals and H-bonding interactions prevail in HSA and BSA adducts. AFM clearly indicated that aluminum cations are able to force BSA and b-LG into larger or more robust aggregates than HSA, with HSA 4±0.2 (SE, n=801) proteins per aggregate, for BSA 17±2 (SE, n=148), and for b-LG 12±3 (SE, n=151). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced major alterations of protein conformations with the order of perturbations b-LG>BSA>HSA.

Influence of reaction conditions on the self-assembly of the natural silk sericin protein

In the past years, the self-assembly of specific proteins has been paid more and more attention due to their significant role in human health and fabrication of new materials. In this article, we explore the effect of reaction conditions on the self-assembly of natural silk sericin protein, including the molecular weight and the concentration of sericin, pH, and metal ions in the reaction system. The results indicate that all these factors, especially species and concentration of metal ions, could influence the self-assembly process of the silk sericin protein. A series of assemblies with various morphologies can be fabricated by modulating the reaction condition. The article may provide some clue for the understanding of the protein self-assembly in the body and a method to fabricate new organic materials with different morphology. Microsc. Res. Tech. 80:298-304, 2017. © 2016 Wiley Periodicals, Inc.

Aggregation of trypsin and trypsin inhibitor by Al cation

Al cation may trigger protein structural changes such as aggregation and fibrillation, causing neurodegenerative diseases. We report the effect of Al cation on the solution structures of trypsin (try) and trypsin inhibitor (tryi), using thermodynamic analysis, UV-Visible, Fourier transform infrared (FTIR) spectroscopic methods and atomic force microscopy (AFM). Thermodynamic parameters showed Al-protein bindings occur via H-bonding and van der Waals contacts for trypsin and trypsin inhibitor. AFM showed that Al cations are able to force trypsin into larger or more robust aggregates than trypsin inhibitor, with trypsin 5±1 SE (n=52) proteins per aggregate and for trypsin inhibitor 8.3±0.7 SE (n=118). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced more alterations of trypsin inhibitor conformation than trypsin.

Influence of trehalose on human islet amyloid polypeptide fibrillation and aggregation

A lower dose of trehalose inhibits or delays, while higher dose of trehalose promotes the hIAPP fibrillation and aggregation.

Curcumin Protects β-Lactoglobulin Fibril Formation and Fibril-Induced Neurotoxicity in PC12 Cells

In this study the β-lactoglobulin fibrillation, in the presence or absence of lead ions, aflatoxin M1 and curcumin, was evaluated using ThT fluorescence, Circular dichroism spectroscopy and atomic force microscopy. To investigate the toxicity of the different form of β-Lg fibrils, in the presence or absence of above toxins and curcumin, we monitored changes in the level of reactive oxygen species and morphology of the differentiated neuron-like PC12 cells. The cell viability, cell body area, average neurite length, neurite width, number of primary neurites, percent of bipolar cells and node/primary neurite ratios were used to assess the growth and complexity of PC12 cells exposed to different form of β-Lg fibrils. Incubation of β-Lg with curcumin resulted in a significant decrease in ROS levels even in the presence of lead ions and aflatoxin M1. The β-Lg fibrils formed in the presence of lead ions and aflatoxin M1 attenuated the growth and complexity of PC12 cells compared with other form of β-Lg fibrils. However, the adverse effects of these toxins and protein fibrils were negated in the presence of curcumin. Furthermore, the antioxidant and inhibitory effects of curcumin protected PC12 cells against fibril neurotoxicity and enhanced their survival. Thus, curcumin may provide a protective effect toward β-Lg, and perhaps other protein, fibrils mediated neurotoxicity.

Metal complexes of curcumin--synthetic strategies, structures and medicinal applications

This Tutorial Review presents an overview on the synthesis, characterization and applications of metal complexes containing curcumin (=1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) and its derivatives as ligands. Innovative synthetic strategies leading to soluble and crystallizable metal curcumin complexes are outlined in detail. Special emphasis is placed on the highly promising and exciting medicinal applications of metal curcumin complexes, with the three most important areas being anticancer activity and selective cytotoxicity, anti-Alzheimer's disease activity, and antioxidative/neuroprotective effects. Overall, this Tutorial Review provides the first general overview of this emerging and rapidly expanding field of interdisciplinary research.

Modulation of stability and functionality of a phyto-antioxidant by weakly interacting metal ions: curcumin in aqueous solution

Metal exchange process in metallo–curcumin leading to duality in action: enhancement of both aqueous stability and anti-oxidant property.

Effect of Al(iii) and curcumin on silk fibroin conformation and aggregation morphology

Al(iii) can accelerate the conformation transition of silk fibroin from random coils into β-sheets, and curcumin can reverse the transition.