Evaluation of glycyl-arginine and lysyl-aspartic acid dipeptides for their antimicrobial, antibiofilm, and anticancer potentials.

Antibacterial resistance and cancer are worldwide challenges and have been defined as major threats by international health organizations. Peptides are produced naturally by all organisms and have a variety of immunomodulatory, physiological, and wound-healing properties. They can also provide protection against microorganisms and tumor cells. Therefore, we aimed to determine the antimicrobial, antibiofilm, and anticancer potentials of Glycyl-Arginine and Lysyl-Aspartic acid dipeptides. The Broth Dilution and Crystal Violet Binding assays assessed the antimicrobial tests and biofilm inhibitory effects. The MTT assay was used to measure the cytotoxic effects of dipeptides on HeLa cell viability. According to our results, Candida tropicalis T26 and Proteus mirabilis U15 strains were determined as more resistant to Staphylococcus epidermidis W17 against Glycyl-Arginine and Lysyl-Aspartic acid dipeptides with MICs higher than 2 mM (1 mg/mL). Sub-MICs of Glycyl-Arginine caused inhibitions against biofilm formation of all the tested clinical isolates, with the highest inhibition observed against S. epidermidisW17. Lysyl-Aspartic acid exhibited zero to no effect against biofilm formation of P. mirabilisU15, and S. epidermidisW17, whereas it exhibited 52% inhibition of biofilm formation of C. tropicalisT26. Cell viability results revealed that HeLa cell viability decreases with increasing concentration of both dipeptides. Also, parallel to antimicrobial tests, Glycyl-Arginine has a greater cytotoxic effect compared to Lysyl-Aspartic acid. The findings from this study will contribute to the advancement of novel strategies involving dipeptide-based synthesizable molecules and drug development studies. However, it is essential to note that there are still challenges, including the need for extensive experimental and clinical trials.

Mineral status of COPD patients under long-term inhaled corticosteroid therapy.

PURPOSE: The aim of this study was to determine the mineral status of mandibles, femurs, and spines in chronic obstructive pulmonary disease (COPD) patients under long-term inhaled corticosteroid therapy. MATERIALS AND METHODS: Pulmonary function tests were conducted on patients (n = 30) with COPD under inhaled corticosteroid therapy for at least 1 year. The results were compared to sex- and age-matched controls (n = 30). Analyses of blood gases were also carried out relative to COPD, and bone mineral densities (BMD) of the mandible, lumbar spine, femoral neck, trochanter, and Ward's triangle were also measured by dual-energy X-ray absorptiometry (DEXA). Levels of serum osteocalcin, alkaline phosphatase, calcium, phosphorus, and cortisol were also assessed. RESULTS: In accordance with the Global Initiative for Chronic Obstructive Lung Disease criteria, 8 of the COPD patients had moderate, 11 patients had severe, and 11 patients had very severe forms of the disease. All BMD measurements were lower in the COPD patients than in the control group. The serum osteocalcin levels in COPD patients were significantly lower than those in the control group (p < 0.0001). Serum calcium (p < 0.004) and cortisol levels (p < 0.026) in the COPD patients were also significantly lower than those in the control subjects. Although serum alkaline phosphatase level was higher and the phosphorus level was lower in the treatment group than in the control group, the differences were not statistically significant. CONCLUSION: Regular evaluation of the biochemical markers of bone metabolism and BMD would be helpful for detecting any detrimental changes of bone in COPD patients under long-term inhaled corticosteroid therapy. In this study, mandibular BMD was observed to be lower in COPD patients under long-term inhaled corticosteroid therapy than in healthy subjects. Thus, dental implant treatment may require preventive measures in COPD patients under long-term inhaled corticosteroid therapy.