Targeting the ‘garbage-bin’ to fight cancer: HDAC6 inhibitor WT161 has an anti-tumor effect on osteosarcoma and synergistically interacts with 5-FU

An imbalance between protein aggregation and protein degradation may induce ‘stress’ in the functionality of the endoplasmic reticulum (ER). There are quality control (QC) mechanisms to minimize misfolding and to eliminate misfolded proteins before aggregation becomes lethal for the cell. Proper protein folding and maturation is one of the crucial functions of the ER. Chaperones of the ER and folding enzymes guarantee correct conformational maturation of emerging secretory proteins. Histone deacetylase (HDAC) 6 (HDAC6) is a masterpiece coordinating the cell response to protein aggregate formation. The balance between HDAC6 and its partner Valosin-containing protein/p97 determines the fate of polyubiquitinated misfolded proteins. WT161 is a terrific, selective, and bioavailable HDAC6 inhibitor. WT161 selectively inhibits HDAC6 and adequately increases levels of acetylated α-tubulin. This compound induces accumulation of acetylated tubulin and cytotoxicity in multiple myeloma (MM) cells. In this journal, Sun et al. (Biosci. Rep. 41, DOI: 10.1042/BSR20203905) identified that WT161 suppresses the cell growth of osteosarcoma cells. This discovery opens the door to future chemotherapeutic regimens of this bone neoplasm.     

Glipizide matrix transdermal systems for diabetes mellitus: preparation, in vitro and preclinical studies

The aim of the present investigation was to prepare glipizide matrix transdermal systems using the combinations of ethyl cellulose/polyvinylpyrrolidone and Eudragit RL-100/Eudragit RS-100. The systems were evaluated for various in vitro (drug content, drug permeation, scanning electron microscopy and drug-polymer interactions) and in vivo (acute and long-term hypoglycemic activity, biochemical and histopathological studies, skin irritation and pharmacokinetic studies in mice) parameters. Drug content of the patches was found to be more than 98%. Variations in drug permeation profiles were observed among various formulations. The scanning electron microscopy of the patches showed the formation of pores on the surface after in vitro permeation studies. The drug-polymer interaction results suggested no interaction between drug and polymers. The in vivo results revealed that the patches successfully prevented the severe hypoglycemia in the initial hours and they were also effective on chronic application. The transdermal route exhibited negligible skin irritation and produced better improvement with all the tested in vivo parameters compared to oral administration.     

Synthesis, kinetic studies and pharmacological evaluation of mutual azo prodrug of 5-aminosalicylic acid with D-phenylalanine for colon specific drug delivery in inflammatory bowel disease

Mutual azo prodrug of 5-aminosalicylic acid with d-phenylalanine was synthesized by coupling D-phenylalanine with salicylic acid, for targeted drug delivery to the inflamed gut tissue in inflammatory bowel disease. The structure of synthesized prodrug was confirmed by elemental analysis, IR and NMR spectroscopy. In vitro kinetic studies in HCl buffer (pH 1.2) showed negligible release of 5-aminosalicylic acid, whereas in phosphate buffer (pH 7.4) only 15% release was observed over a period of 7h. In rat fecal matter the release of 5-aminosalicylic acid was almost complete (85%), with a half-life of 160.1 min, following first order kinetics. The azo conjugate was evaluated for its ulcerogenic potential by Rainsford's cold stress method. Therapeutic efficacy of the carrier system and the mitigating effect of the azo conjugate were evaluated in trinitrobenzenesulfonic acid-induced experimental colitis model. The synthesized prodrug was found to be equally effective in mitigating the colitis in rats as that of sulfasalazine without the ulcerogenicity of 5-aminosalicylic acid.     

PEGylation of a proprotein convertase peptide inhibitor for vaginal route of drug delivery: In vitro bioactivity,stability and in vivo pharmacokinetics

Uterine proprotein convertase (PC) 6 is critical for embryo implantation in mice and women. It is also one of the PC family members that play a vital role in HIV infectivity. We hypothesized that inhibiting PC6 in the female reproductive tract (vagina, cervix and uterus), may protect women from both pregnancy and HIV infection. One key requirement to prove this concept in an animal model is a vaginally deliverable PC6 inhibitor. Nona-d-arginine (Poly R) is a potent peptide PC inhibitor and is able to inhibit HIV in cell culture. We modified Poly R by PEGylation with different strategies and determined their biochemical properties in vitro and in vivo. PEGylation at the C-terminus, regardless of the PEG size (30 kDa or 1239 Da) did not compromise the inhibitory potency of Poly R. In contrast, PEGylation at both termini (1239 Da) dramatically reduced its inhibitory activity. Poly R and C-PEGylated Poly Rs also showed equal potency in inhibiting a PC6-dependent cellular process critical for embryo implantation. Poly R and the equipotent C-PEGylated Poly Rs were further tested for their serum stability in vitro and pharmacokinetics in vivo following vaginal administration in mice. All Poly Rs were equally stable in mouse serum in vitro for 24 h; C-PEGylated Poly Rs showed enhanced vaginal absorption and penetration across the vaginal mucosa/epithelium. This is the first report that C-terminal PEGylation significantly enhances the therapeutic properties of Poly R for vaginal drug delivery. Our findings also provide important insights into future design of Poly R derivatives.     

Design and development of a proniosomal transdermal drug delivery system of caffeine for management of migraine: In vitro characterization, 131I-radiolabeling and in vivo biodistribution studies

Caffeine is a naturally occurring alkaloid compound which is widely used alone or in combination in the treatment of migraine. The short elimination half life of caffeine (3−5 h) and the relationship between its absorption from gastrointestinal tract and gastric emptying are the major obstacles toward its effective oral delivery. To surmount such limitations, transdermal proniosomal systems of caffeine were developed. A full 3² factorial design was employed using Design-Expert® software to study the effect of different parameters and to select the optimal proniosomal system (PNS-4). Skin irritation study and in vivo histopathological examination confirmed the safety of transdermal application of PNS-4. Radioiodination of caffeine using iodine-131 (¹³¹I) was performed via direct electrophilic substitution reaction. Insilco docking results showed almost the same binding affinity of caffeine and ¹³¹I-Caffeine against adenosine A_2A receptor. Biodistribution results showed that, transdermal ¹³¹I-Caffeine loaded PNS-4 (patch) significantly increased the residence of ¹³¹I-Caffeine in the blood with higher brain targeting than oral suspension. The obtained results proved that, PNS-4 represents a promising transdermal drug delivery system capable of overcoming challenges facing oral delivery of caffeine.     

Ligands of the asialoglycoprotein receptor for targeted gene delivery, part 1: Synthesis of and binding studies with biotinylated cluster glycosides containing N-acetylgalactosamine

In order to develop the non-viral Bioplex vector system for targeted delivery of genes to hepatocytes, we have evaluated the structure-function relationship for a number of synthetic ligands designed for specific interaction with the hepatic lectin ASGPr. Biotinylated ligand derivatives containing two, three or six beta-linked N-acetylgalactosamine (GalNAc) residues were synthesized, bound to fluorescent-labeled streptavidin and tested for binding and uptake to HepG2 cells using flow cytometry analysis (FACS). Uptake efficiency increased with number of displayed GalNAc units per ligand, in a receptor dependent manner. Thus, a derivative displaying six GalNAc units showed the highest uptake efficacy both in terms of number of internalizing cells and increased amount of material taken up per each cell. However, this higher efficiency was shown to be due not so much to higher number of sugar units, but to higher accessibility of the sugar units for interaction with the receptor (longer spacer). Improving the flexibility and accessibility of a trimeric GalNAc ligand through use of a longer spacer markedly influenced the uptake efficiency, while increasing the number of GalNAc units per ligand above three only provided a minor contribution to the overall affinity. We hereby report the details of the chemical synthesis of the ligands and the structure-function studies in vitro.     

Continued optimization of the M5 NAM ML375: Discovery of VU6008667, an M5 NAM with high CNS penetration and a desired short half-life in rat for addiction studies

This letter describes the continued optimization of M₅ NAM ML375 (VU0483253). While a valuable in vivo tool compound, ML375 has an excessively long elimination half-life in rat (t_1/2 = 80 h), which can be problematic in certain rodent addiction paradigms (e.g., reinstatement). Thus, we required an M₅ NAM of comparable potency to ML375, but with a rat t_1/2 of less than 4 h. Steep SAR plagued this chemotype, and here we detail aniline replacements that offered some improvements over ML375, but failed to advance. Ultimately, incorporation of a single methyl group to the 9b-phenyl ring acted as a metabolic shunt, providing (S)-11 (VU6008667), an equipotent M₅ NAM, with high CNS penetration, excellent selectivity versus M_1–4 and the desired short half-life (t_1/2 = 2.3 h) in rat.