Photodegradation of Bexarotene and Its Implication for Cytotoxicity

Bexarotene regulates zebrafish embryonic development by activating Wnt signaling pathway

Bexarotene (Bex) is a selective retinoid X receptor (RXR) agonist and is commonly used as an anti-tumor drug in the clinic to treat patients with cutaneous T-cell lymphoma (CTCL). With the widespread use of this drug, people are increasingly concerned about its side effects and safety of use. At present, the effects of bexarotene drugs on the health of organisms remain uncertain, but retinoid drugs are generally biologically active and may pose potential risks to them. Therefore, in this study, we used a zebrafish model to evaluate the effects of Bex on embryonic development. Six hours after fertilization, we exposed zebrafish embryos to 3 μg/L, 6 μg/L, and 9 μg/L bexarotene. At 96 hpf, compared with the control group, zebrafish embryos exposed to bexarotene showed obvious heart and liver development defects, including reduced hatching rate, pericardial enlargement, heart rate disorder, yolk sac edema, small liver area and abnormal photo-optical motor responses. Transcriptome and qPCR results showed abnormal expression of genes related to heart and liver development was induced by Bexarotene. Mechanistically, bexarotene induced a significant upregulation of the transcriptional expression levels of genes related to the Wnt signaling pathway, and IWR-1 was able to effectively rescue the heart and liver developmental defects of zebrafish caused by bexarotene. Therefore, our study showed that bexarotene may cause zebrafish embryonic developmental defects by upregulating the Wnt signaling pathway, revealing the side effects and associated novel mechanisms of bexarotene, and providing a theoretical basis for its safe and effective use in the treatment of clinically related diseases.

Photodegradation of indomethacin and naproxen contained within commercial products for skin - RAP

Patient can be exposed to the photodegradation products of a drug after skin application of topical formulations. NSAIDs, with analgesic and anti-inflammatory properties, are known for the potential photoinstability, and are applied often in the form of creams, gels or liquids, commonly used among athletes, elderly people, geriatric patients and patients treated with multidrug therapies. Susceptibility to photodegradation hazard of those group arises the need for development of a new approach, with the ability to evaluate the patient safety. We planned to use a rapid assessment procedure (RAP) of safety by testing the photostability of popular skin medicinal products. This method, proposed many years ago by WHO, is now reintroduced to analytical applications in industry, when emergency drugs (e.g. for Covid) are implemented to the market in accelerated procedures. In the health care system, qualitative evaluation of drugs is extremely valuable, therefore we have planned to identify photodegradation using the FTIR method - infrared spectroscopy and DSC - differential scanning calorimetry, whilst the risk of formation of genotoxic products using the Ames test. We have successfully demonstrated that changes in the chemical structure and physical form of both pure APIs and drug products containing the API be assessed in a short time. Another advantage of our work is the combination of the developed results from FTIR/NIR spectra with statistical analysis. As a result, full and quick qualitative assessment of the effects of photoexposure of selected NSAIDs is performed, fortunately showing no mutagenicity. Due to the popularity of NSAIDs applied to the skin, a gel containing naproxen and spray with indomethacin were selected for testing. The analysis carried out for various formulations of both preparations allows us to demonstrate the universality of the applied RAP methods in assessing the risk of hazard to the patient, thus we present research results that expand or widen the knowledge and assessment of risks related to the use of drugs on the skin.

Influence of Storage Conditions on the Stability of Gum Arabic and Tragacanth

Storage conditions should be chosen so that they do not affect the action and stability of the active pharmaceutical substance (API), and excipients used in pharmacy. UV irradiation, increased temperature, and relative humidity can decompose storage substances by photolysis, thermolysis, and hydrolysis process, respectively. The effect of physical factors may be the decomposition of pharmaceutical substances or their inappropriate action, including pharmacological effects. Polymers of natural origin are increasingly used in the pharmaceutical industry. With this in mind, we evaluated the effect of storage conditions on the stability of gum arabic (GA) and tragacanth (GT). The influence of higher temperature, UV irradiation, and relative humidity on GA and GT was tested. Thermogravimetry (TG, c-DTA), colorimetric analysis, UV-Vis spectrophotometry, and optical microscopy were used as research methods. The TGA and c-DTA examination indicated that decomposition of GA starts at a higher temperature compared to GT. This indicate that gum arabic is more resistant to higher temperatures compared to tragacanth. However, the conducted analysis showed that gum arabic is more sensitive to the tested storage conditions. Among the tested physical conditions, both polymers were most sensitive to conditions of increased relative humidity in the environment.

Cytotoxicity and Apoptosis Induction of 6,7-Dehydroroyleanone from Taiwania cryptomerioides Bark Essential Oil in Hepatocellular Carcinoma Cells

The objective of the present study is to evaluate the cytotoxicity of Taiwania cryptomerioides essential oil and its phytochemical on the Hep G2 cell line (human hepatocellular carcinoma). Bark essential oil has significant cytotoxicity to Hep G2 cells, and S3 fraction is the most active fraction in cytotoxicity to Hep G2 cells among the six fractions. The diterpenoid quinone, 6,7-dehydroroyleanone, was isolated from the active S3 fraction by bioassay-guided isolation. 6,7-Dehydroroyleanone exhibited significant cytotoxicity in Hep G2 cells, and the efficacy of 6,7-dehydroroyleanone was better than the positive control, etoposide. Apoptosis analysis of Hep G2 cells with different treatments was characterized via flow cytometry to confirm the cell death situation. Etoposide and 6,7-dehydroroyleanone could induce the apoptosis in Hep G2 cells using flow cytometric assay. Results revealed 6,7-dehydroroyleanone from T. cryptomerioides bark essential oil can be a potential phytochemical to develop the anticancer chemotherapeutic agent for the treatment of the human hepatocellular carcinoma.