In the current medical era, the proliferation and dissemination of drug-resistant strains of Mycobacterium tuberculosis continue to pose a significant worldwide health hazard, necessitating the development of new and innovative medications to combat tuberculosis. Decaprenylphosphoryl-β-D-ribose 2'-epimerase (DprE1) is a crucial enzyme for cell wall synthesis in Mycobacterium tuberculosis (Mtb). Its importance is due to its eminent contribution in forming lipoarabinomannan and arabinogalactan. The emergence of the DprE1 enzyme as a druggable target was based on inhibitors discovered in high-throughput screening. Since then, inhibitors with different types of chemical scaffolds have been reported for their activity against it. DprE1 inhibitors can be categorized according to the formation of a covalent or non-covalent bond in the enzyme's active site, causing a loss of its catalytic activity, leading to Mtb's demise. Herein, we describe diverse DprE1 inhibitors that have had anti-tubercular activity reported over the past fifteen years and till the present time.
The possibility to control the effects of drugs in time and space represents an ideal condition for developing safer and more personalized therapies against different disorders. In this context, photopharmacology has paved the way for the use of light in the modulation of drugs activity. Our interest is directed to photo-switchable molecules, capable of interconverting between two different isoforms upon light irradiation. We recently reported compound 1, a donepezil-like based on 2-benzylidenindan-1-one structure, as a dual AChE and MAO-B inhibitor, which can be converted into the E- (active form) and Z- (about tenfold less active form) diastereoisomers by irradiating with UV-vis light. Aiming at identifying compounds with remarkable activity in a physiological conditions, we herein report a fine characterization of compound 1 in PBS solutions. First, we evaluated its ability to act as a photoswitch comparing PBS solution with organic solvents (e.g. methanol), demonstrating that a wavelength in the UV range (330 nm) can convert the E- into the Z-diastereoisomer, while the use of a visible light (400 nm) allows the interconversion from Z to E in both media. Along with its photoinducible behavior, we investigated the passive diffusion across cellular membrane with PAMPA experiments, plasma and microsomal stability, and binding to plasma proteins. Interestingly, the results of such studies suggested that compound 1 could persist in the blood circulation for a long time, which is desirable for application in photopharmacological therapies. Cytotoxicity studies highlighted the potential of our prototypic compound as a lead photodrug against neurodegenerative disorders, deserving to advance in molecular optimization studies and further in vitro and in vivo characterization.
The efficacy of radiation therapy can decrease due to the inherent radioresistance of different tumor cells. Gadolinium shows significant potential as a radiosensitivity enhancer due to its high atomic number. In this study, a novel theranostic nanoprobe based on folic acid-conjugated gadolinium-loaded nanodroplets (FA-Gd-NDs) has been introduced for ultrasound imaging (USI)-guided radiation therapy of hepatocellular carcinoma. The ultrasound echogenicity evaluation of NDs, Gd release studies, biocompatibility test of Gd-NDs, colony assay, cellular uptake of NDs via fluorescence microscopy, and flow cytometry analysis were performed on Hepa1-6 cancer and L929 normal cell lines. Our results showed that synthesized NDs significantly enhanced ultrasound signal intensity in PBS solution and agarose gel phantom. MTT and clonogenic assays indicated that Gd-NDs substantially reduced the cell viability and also surviving fraction of Hepa1-6 cancer cells under US and X-ray exposure. Additionally, FA-Gd-NDs exhibited sensitization enhancement factor (SER) of 1.8 after concurrent exposure to US and X-ray. Fluorescence imaging demonstrated more internalization of FA-Gd-NDs into cancer cells in comparison with normal cells. According to flow cytometry results, the Gd-NDs and FA-Gd-NDs uptake by L929 cell line were 20% and 28%, respectively, while their uptake by Hepa1-6 cells was 60% and 94%, respectively. In conclusion, the synthesized novel theranostic nanoprobe shows great potential for enhancing the efficacy of radiation therapy and enabling ultrasound image-guided radiation therapy of cancers.