Enhancing Curcumin's therapeutic potential in cancer treatment through ultrasound mediated liposomal delivery.

Improving the efficacy of chemotherapy remains a key challenge in cancer treatment, considering the low bioavailability, high cytotoxicity, and undesirable side effects of some clinical drugs. Targeted delivery and sustained release of therapeutic drugs to cancer cells can reduce the whole-body cytotoxicity of the agent and deliver a safe localized treatment to the patient. There is growing interest in herbal drugs, such as curcumin, which is highly noted as a promising anti-tumor drug, considering its wide range of bioactivities and therapeutic properties against various tumors. Conversely, the clinical efficacy of curcumin is limited because of poor oral bioavailability, low water solubility, instability in gastrointestinal fluids, and unsuitable pH stability. Drug-delivery colloid vehicles like liposomes and nanoparticles combined with microbubbles and ultrasound-mediated sustained release are currently being explored as effective delivery modes in such cases. This study aimed to synthesize and study the properties of curcumin liposomes (CLs) and optimize the high-frequency ultrasound release and uptake by a human breast cancer cell line (HCC 1954) through in vitro studies of culture viability and cytotoxicity. CLs were effectively prepared with particles sized at 81 ± 2 nm, demonstrating stability and controlled release of curcumin under ultrasound exposure. In vitro studies using HCC1954 cells, the combination of CLs, ultrasound, and Definity microbubbles significantly improved curcumin's anti-tumor effects, particularly under specific conditions: 15 s of continuous ultrasound at 0.12 W/cm2 power density with 0.6 × 107 microbubbles/mL. Furthermore, the study delved into curcumin liposomes' cytotoxic effects using an Annexin V/PI-based apoptosis assay. The treatment with CLs, particularly in conjunction with ultrasound and microbubbles, amplified cell apoptosis, mainly in the late apoptosis stage, which was attributed to heightened cellular uptake within cancer cells.

pH-Dependent Thermal Stability of Vibrio cholerae L-asparaginase.

BACKGROUND: pH is one of the decisive macromolecular properties of proteins that significantly affects enzyme structure, stability and reaction rate. Change in pH may protonate or deprotonate the side group of aminoacid residues in the protein, thereby resulting in changes in chemical and structural features. Hence studies on the kinetics of enzyme deactivation by pH are important for assessing the bio-functionality of industrial enzymes. L-asparaginase is one such important enzyme that has potent applications in cancer therapy and food industry. OBJECTIVE: The objective of the study is to understand and analyze the influence of pH on deactivation and stability of Vibrio cholerae L-asparaginase. METHODS: Kinetic studies were conducted to analyze the effect of pH on stability and deactivation of Vibrio cholerae L-asparaginase. Circular Dichroism (CD) and Differential Scanning Calorimetry (DSC) studies have been carried out to understand the pH-dependent conformational changes in the secondary structure of V. cholerae L-asparaginase. RESULTS: The enzyme was found to be least stable at extreme acidic conditions (pH< 4.5) and exhibited a gradual increase in melting temperature from 40 to 81 °C within pH range of 4.0 to 7.0. Thermodynamic properties of protein were estimated and at pH 7.0 the protein exhibited ΔG37of 26.31 kcal mole-1, ΔH of 204.27 kcal mole-1 and ΔS of 574.06 cal mole-1 K-1. CONCLUSION: The stability and thermodynamic analysis revealed that V. cholerae L-asparaginase was highly stable over a wide range of pH, with the highest stability in the pH range of 5.0-7.0.

Glutaminase free l-asparaginase from Vibrio cholerae: Heterologous expression, purification and biochemical characterization.

l-asparaginase is used as a pivotal agent in treatment of lympho proliferative disorders and holds an excessive demand for food processing aids. Most of the l-asparaginases possess glutaminase activity which might lead to side effects during the treatment. The search for new therapeutic enzymes is of great interest in both medical and food applications. In this study, Vibrio cholerael-asparaginase was recombinantly overexpressed in E. coli, purified to homogeneity and molecular size was estimated to be 36.6kDa. Recombinant enzyme showed an optimum pH and temperature of 7.0 and 37°C respectively. The Km and Vmax of the enzyme for l-asparagine was 1.1mM and 1006µM/min respectively. The enzyme is highly specific for l-asparagine and did not show glutaminase activity. The enzyme possessed high half life time and good stability over a wide range of physiological conditions. Tm of the enzyme was found to be 81°C by circular dichroism and differential scanning calorimetric techniques. This enzyme possesses novel properties such as (i) glutaminase free l-asparaginase activity, (ii) very high Vmax value with high affinity and (iii) high stability at 30°C (half-life time of 2.9days).