Influence of clay minerals on curcumin properties: Stability and singlet oxygen generation

Incorporation of Different Metal Ion for Tuning Color and Enhancing Antioxidant Activity of Curcumin/Palygorskite Hybrid Materials

Curcumin is one of the dietary dyes extracted from turmeric and used for prevention and treatment of various illnesses. However, the low bioavailability and poor stability of curcumin limits its relevant applications. Therefore, different metal ions including Cu²⁺, Zn²⁺, Mg²⁺, Al³⁺, or Fe³⁺ were incorporated to tune the color, enhance the environmental stability and antioxidant activity of curcumin in the presence of palygorskite in this study. The as-prepared samples were studied using X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Zeta potential, and transmission electron microscopy. In addition, the density functional theory calculation was also performed to explore the possible interaction among metal ions, curcumin and palygorskite. It was found that the color changing and stability enhancing were ascribed to the curcumin-metal ions coordination as well as chemical interactions between curcumin-metal complex and palygorskite. Moreover, the as-prepared composites showed more excellent color, thermal stability, antioxidant activity, and fluorescence properties than that of the curcumin/palygorskite composites due to the presence of metal ions. The finding of this investigation may contribute to developing the multifunctional composites with different colors and good antioxidant activity for relevant applications based on curcumin and palygorskite.

Synthesis of New Water Soluble β-Cyclodextrin@Curcumin Conjugates and In Vitro Safety Evaluation in Primary Cultures of Rat Cortical Neurons

Self-aggregation of Curcumin (Cur) in aqueous biological environment decreases its bioavailability and in vivo therapeutic efficacy, which hampers its clinical use as candidate for reducing risk of neurodegenerative diseases. Here, we focused on the design of new Cur- β-Cyclodextrin nanoconjugates to improve the solubility and reduce cell toxicity of Cur. In this study, we described the synthesis, structural characterization, photophysical properties and neuron cell toxicity of two new water soluble β-CD/Cur nanoconjugates as new strategy for reducing risks of neurodegenerative diseases. Cur was coupled to one or two β-CD molecules via triazole rings using CuAAC click chemistry strategy to yield β-CD@Cur and (β-CD)₂@Cur nanoconjugates, respectively. The synthesized nanoconjugates were found to be able to self-assemble in aqueous condition and form nano-aggregates of an average diameter size of around 35 and 120 nm for β-CD@Cur and (β-CD)₂@Cur, respectively. The photophysical properties, water solubility and cell toxicity on rat embryonic cortical neurons of the designed nanoconjugates were investigated and compared to that of Cur alone. The findings revealed that both new nanoconjugates displayed better water solubility and in vitro biocompatibility than Cur alone, thus making it possible to envisage their use as future nano-systems for the prevention or risk reduction of neurodegenerative diseases.