Improving the Solubility and Oral Bioavailability of a Novel Aromatic Aldehyde Antisickling Agent (PP10) for the Treatment of Sickle Cell Disease

Ferroptosis as an emerging target in sickle cell disease

Sickle cell disease (SCD) is an inherited hemoglobin disorder marked by red blood cell sickling, resulting in severe anemia, painful episodes, extensive organ damage, and shortened life expectancy. In SCD, increased iron levels can trigger ferroptosis, a specific type of cell death characterized by reactive oxygen species (ROS) and lipid peroxide accumulation, leading to damage and organ impairments. The intricate interplay between iron, ferroptosis, inflammation, and oxidative stress in SCD underscores the necessity of thoroughly understanding these processes for the development of innovative therapeutic strategies. This review highlights the importance of balancing the complex interactions among various factors and exploitation of the knowledge in developing novel therapeutics for this devastating disease.

Design, Synthesis, and Antisickling Investigation of a Thiazolidine Prodrug of TD-7 That Prolongs the Duration of Action of Antisickling Aromatic Aldehyde

The synthetic allosteric effector of hemoglobin, TD-7 has been investigated as a potential therapeutic agent for the treatment of sickle cell disease. The pharmacologic activity of TD-7 is due to formation of a Schiff-base interaction between its aldehyde group and the two N-terminal αVal1 amines of hemoglobin, effectively inhibiting sickling of red blood cells. However, TD-7 faces a challenge in terms of poor oral bioavailability due to rapid in-vivo oxidative metabolism of its aldehyde functional group. To address this shortcoming, researches have explored the use of a L-cysteine ethyl ester group to cap the aldehyde group to form a thiazolidine aromatic aldehyde prodrug complex, resulting in the improvement of the metabolic stability of this class of compounds. This report details the synthesis of a thiazolidine prodrug of TD-7, referred to as Pro-7, along with a comprehensive investigation of Pro-7 functional and biological properties. In an in-vitro Hb modification and Hb oxygen affinity studies using normal whole blood, as well as erythrocyte sickling inhibition using sickle whole blood, Pro-7 exhibited a gradual onset but progressive increase in all activities. Additionally, in-vivo pharmacokinetic studies conducted with Sprague Dawley rats demonstrated that Pro-7 can undergo hydrolysis to release TD-7. However, the blood concentration of TD-7 did not reach the desired therapeutic level. These findings suggest that the incorporation of the L-cysteine ethyl ester group to TD-7 represents a promising strategy to enhance the metabolic stability of aromatic aldehydes that could lead to the development of a more effective drug for the treatment of sickle cell disease.

p97 dysfunction underlies a loss of quality control of damaged membrane proteins and promotes oxidative stress and sickling in sickle cell disease

Sickling is the central pathogenic process of sickle cell disease (SCD), one of the most prevalent inherited hemolytic disorders. Having no easy access to antioxidants in the cytosol, elevated levels of reactive oxygen species (ROS) residing at the plasma membrane in sickle red blood cells (sRBCs) easily oxidize membrane proteins and thus contribute to sickling. Although the ubiquitin-proteasome system (UPS) is essential to rapidly clear ROS-damaged membrane proteins and maintain cellular homeostasis, the function and regulatory mechanism of the UPS for their clearance in sRBCs remains unidentified. Elevated levels of polyubiquitinated membrane-associated proteins in human sRBCs are reported here. High throughput and untargeted proteomic analyses of membrane proteins immunoprecipitated by ubiquitin antibodies detected elevated levels of ubiquitination of a series of proteins including cytoskeletal proteins, transporters, ROS-related proteins, and UPS machinery components in sRBCs. Polyubiquitination of membrane-associated catalase was increased in sRBCs, associated with decreased catalase activity and elevated ROS. Surprisingly, shuttling of p97 (ATP-dependent valosin-containing chaperone protein), a key component of the UPS to shuttle polyubiquitinated proteins from the membrane to cytosol for proteasomal degradation, was significantly impaired, resulting in significant accumulation of p97 along with polyubiquitinated proteins in the membrane of human sRBCs. Functionally, inhibition of p97 directly promoted accumulation of polyubiquitinated membrane-associated proteins, excessive ROS levels, and sickling in response to hypoxia. Overall, we revealed that p97 dysfunction underlies impaired UPS and contributes to oxidative stress in sRBCs.

Development of Multi-Compartment 3D-Printed Tablets Loaded with Self-Nanoemulsified Formulations of Various Drugs: A New Strategy for Personalized Medicine

This work aimed to develop a three-dimensional printed (3DP) tablet containing glimepiride (GLMP) and/or rosuvastatin (RSV) for treatment of dyslipidemia in patients with diabetes. Curcumin oil was extracted from the dried rhizomes of Curcuma longa and utilized to develop a self-nanoemulsifying drug delivery system (SNEDDS). Screening mixture experimental design was conducted to develop SNEDDS formulation with a minimum droplet size. Five different semi-solid pastes were prepared and rheologically characterized. The prepared pastes were used to develop 3DP tablets using extrusion printing. The quality attributes of the 3DP tablets were evaluated. A non-compartmental extravascular pharmacokinetic model was implemented to investigate the in vivo behavior of the prepared tablets and the studied marketed products. The optimized SNEDDS, of a 94.43 ± 3.55 nm droplet size, was found to contain 15%, 75%, and 10% of oil, polyethylene glycol 400, and tween 80, respectively. The prepared pastes revealed a shear-thinning of pseudoplastic flow behavior. Flat-faced round tablets of 15 mm diameter and 5.6–11.2 mm thickness were successfully printed and illustrated good criteria for friability, weight variation, and content uniformity. Drug release was superior from SNEDDS-based tablets when compared to non-SNEDDS tablets. Scanning electron microscopy study of the 3DP tablets revealed a semi-porous surface that exhibited some curvature with the appearance of tortuosity and a gel porous-like structure of the inner section. GLMP and RSV demonstrated relative bioavailability of 159.50% and 245.16%, respectively. Accordingly, the developed 3DP tablets could be considered as a promising combined oral drug therapy used in treatment of metabolic disorders. However, clinical studies are needed to investigate their efficacy and safety.