Ivanka Kostadinova

Demyelinating disorders such as multiple sclerosis are characterized by oligodendrocyte loss and insufficient remyelination. The cuprizone model provides a well-established experimental system for studying these processes. The apelinergic system, including the apelin receptor (APLNR), has been implicated in neuroprotection and central nervous system homeostasis. However, its role in white matter demyelination and repair remains incompletely understood. This study aimed to characterize the spatial and temporal dynamics of APLNR expression in relation to oligodendrocyte lineage cells in the corpus callosum (CC) during demyelination and remyelination. Demyelination was induced in 8-week-old C57BL/6 mice by 0.2% cuprizone supplementation in their drinking water for 5 weeks, followed by 5 weeks remyelination phase after toxin withdrawal. Histological assessment using Luxol Fast Blue/Cresyl violet staining was performed to evaluate structural changes in the CC. Immunohistochemistry and confocal microscopy were used to analyze APLNR expression, GST-π⁺ cells, and NG2⁺ cells, including their spatial distribution and co-localization. Quantitative analyses and correlation tests were conducted to assess relationships between cellular markers and CC area. Demyelination resulted in significant reduction in CC area and a marked decrease in GST-π⁺ cells, accompanied by a robust increase in NG2⁺ cells, while remyelination led to partial structural and cellular recovery. APLNR expression increased progressively from control to demyelination and further during remyelination, exhibiting pronounced regional heterogeneity with higher levels in lateral CC regions. Confocal analysis demonstrated increasing co-localization of APLNR with NG2⁺ cells, particularly during remyelination. Correlation analyses identified GST-π⁺ cell density as the strongest predictor of CC area, whereas APLNR showed phase-dependent associations, including a positive correlation with GST-π⁺ cells during remyelination and a negative relationship with NG2⁺ cells during demyelination. APLNR expression is dynamically regulated during cuprizone-induced demyelination and remyelination and is closely associated with oligodendrocyte lineage cell responses. Its increased expression and enhanced co-localization with NG2⁺ cells during remyelination suggest a potential role in endogenous repair processes. However, as the findings are based on descriptive analyses, further functional studies are required to determine the mechanistic contribution of APLNR signaling and its potential as a therapeutic target in demyelinating diseases.

Alpha-lipoic acid (ALA, also known as thioctic acid) was discovered nearly 90 years ago and began to be used in clinical practice in the late 1950s. Numerous nonclinical and clinical studies have investigated ALA for treating diabetic peripheral neuropathy (DPN) and various other diseases. The rising global prevalence of DPN necessitates timely treatment; however, there is currently no effective cure. Current guideline-recommended therapies for DPN provide symptom relief rather than modifying the disease. Among the pathogenesis-oriented therapies, ALA holds a unique position as a universal antioxidant, essential for every cell in the body. This review highlights the ongoing issues and challenges in using ALA to treat DPN. While confronting a complex disease with poorly understood pathophysiology, we also have an endogenous substance with pleiotropic effects on all cells in the human body. It becomes clear that this is a highly multifactorial process that will likely never be precisely defined. This does not diminish the significance of ALA in treating DPN but underscores the need for a deeper understanding of when to start therapy, dosage, duration, and monitoring. In this comprehensive review, we evaluate the achievements of the past 70 years and highlight gaps in ALA’s role in treating DPN.

Multiple sclerosis (MS) is a chronic neurodegenerative disorder involving demyelination. The cuprizone model is commonly used to study MS by inducing oligodendrocyte stress and demyelination. The subventricular zone (SVZ) plays a key role in neurogenesis, while the neuronal/glial antigen 2 (NG2) is a marker for immature glial cells, involved in oligodendrocyte differentiation. The apelin receptor (APLNR) is linked to neurogenesis and behavior modulation. This study explores the role of APLNR in NG2-positive cells during de- and remyelination phases in the experimental cuprizone mouse model. Thirty male C57BL/6 mice were divided into control (not treated), demyelination (5 weeks cuprizone administration), and remyelination (5 weeks cuprizone administration + 5 weeks recovery) groups. Histological examinations, immunohistochemistry, and immunofluorescence on serial coronal sections were conducted to evaluate corpus callosum (CC) morphology and APLNR and NG2 expression in the SVZ, in addition to behavioral assessments. The histological analysis showed a significant reduction in the CC’s thickness and area after five weeks of cuprizone exposure, followed by recovery five weeks post-exposure. During the demyelination phase, APLNR-expressing cells peaked while NG2-positive cells decreased. In the remyelination phase, APLNR-expressing cells declined, and NG2-positive cells increased. Confocal microscopy confirmed the co-localization of NG2 and APLNR markers. Statistically significant differences were observed across experimental groups. Correlation analyses highlighted associations between APLNR/NG2 cell counts and CC changes. Behavioral tests revealed impaired motor coordination and memory during demyelination, with gradual recovery during remyelination. Significant changes in the CC structure and the number of APLNR and NG2-positive cells were observed during de- and remyelination, suggesting that NG2-positive cells expressing APLNR may play a key role in remyelination.

Targeting the inflammation-related molecules with nonsteroidal anti-inflammatory drugs (NSAIDs) represents a promising approach for cancer prevention/therapy. We evaluated the in vitro anticancer effects of meloxicam, lornoxicam, ketoprofen, and dexketoprofen on the proliferation, migration, and apoptosis of human cervical, colorectal, and mammary carcinoma cells. The antiproliferative activity and cytotoxicity of tested NSAIDs on HeLa, HT-29, and MCF-7 cell lines were assessed by the MTT test. The apoptosis-inducing potential was analyzed by fluorescent staining with acridine orange/ethidium bromide and DAPI. Migration activity was assessed by a wound-healing scratch assay. The tested NSAIDs reduced the viability of the used tumor cell lines. The cytomorphological analysis revealed reduced cell density and mitotic activity and the presence of cells with morphological features of early and late apoptosis. Significant inhibition of the migration capacity was established as well. In conclusion, NSAIDs could be candidates for the development of new pharmacological strategies for the treatment and prevention of cancer.

In the current study, we investigated the effect of creatine monohydrate (CrM) and newly synthesized creatine lysinate (CrLys) in tail suspension (TST) and rotarod tests and their influence on the histology of the skeletal muscles. In the TST, a slight decrease in the immobility time from the 1st to the 3rd week was observed in the group treated with CrM at a dose of 1.5 g/kg/day and CrLys at a dose of 6 g/kg/day. The rotarod test revealed that CrM (1.5 g/kg/day) and CrLys (3 g/kg/day) lead to a significant improvement in motor coordination in the 3rd week. The results from histology showed an increase in the muscle fiber diameter of soleus muscle in animals treated with CrM (3 g/kg/day) and CrLys (6 g/kg/day). The results showed that supplementation with creatine derivatives appears to be a generally effective nutritional ergogenic aid for an improvement of physical performance.

In our study we investigated the acute toxicity of а newly synthesized creatine lysinate as well as its effect on the biochemical parameters in mice. Creatine lysinate exerts better solubility in water (3.3%) in comparison to creatine monohydrate (1.4%) at 20 °C and it is determined as a non-toxic after intraperitoneal (LD50 – 4543 mg/kg) and oral administration (LD50 > 8000 mg/kg). Oral administration of creatine lysinate at doses of 3 g/kg/day and 6 g/kg/day for 2 weeks reduced the creatine kinase levels, which indicates muscle protection. An increased levels of liver enzymes like alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) was observed after the supplementation with creatine lysinate at both administered doses and the level of lactate was comparable both in the studied and the control group.

This study aimed at the evaluation of the antioxidant and cognitive-enhancing effect of methanol–aqueous extract from Helichrysum italicum ssp. italicum aerial parts. Significant radical scavenging activity (110.33 ± 3.47 and 234.70 ± 5.21 mg TE/g for DPPH and ABTS) and reducing power (354.23 ± 17.51 and 210.24 ± 8.68 mg TE/g for CUPRAC and FRAP) were observed. The extract showed average acetylcholinesterase and low butyrylcholinesterase inhibitory potential. H. italicum extract (200 mg/kg/po) administered in combination with galantamine (3 mg/kg/po) for 12 days significantly improved the memory and learning process compared with galantamine alone in the passive avoidance test. The effect was comparable to that of Ginkgo biloba extract (100 mg/kg/po). In deep secondary metabolite annotation of the extract by UHPLC-HRMS, more than 90 hydroxybenzoic and hydroxicinnamic acid-glycosides, phenylethanoid glycosides, a series of acylquinic and caffeoylhexaric acids, methoxylated derivatives of scutellarein, quercetagetin and 6-hydroxyluteolin, and prenylated phloroglucinol-α-pyrones were reported for the first time in H. italicum. Fragmentation patterns of four subclasses of heterodimer-pyrones were proposed. In-depth profiling of the pyrones revealed 23 compounds undescribed in the literature. Pyrones and acylphloroglucinols together with acylquinic acids could account for memory improvement. The presented research advanced our knowledge of H. italicum, highlighting the species as a rich source of secondary metabolites with cognitive-enhancing potential.

Oxidative stress is one of the key factors responsible for many diseases–neurodegenerative (Parkinson and Alzheimer) diseases, diabetes, atherosclerosis, etc. Creatine, a natural amino acid derivative, is capable of exerting mild, direct antioxidant activity in cultured mammalian cells acutely injured with an array of different reactive oxygen species (ROS) generating compounds. The aim of the study was in vitro (on isolated rat brain sub-cellular fractions–synaptosomes, mitochondria and microsomes) evaluation of newly synthetized creatine derivatives for possible antioxidant and neuroprotective activity. The synaptosomes and mitochondria were obtained by multiple centrifugations with Percoll, while microsomes–only by multiple centrifugations. Varying models of oxidative stress were used to study the possible antioxidant and neuroprotective effects of the respective compounds: on synaptosomes–6-hydroxydopamine; on mitochondria–tert-butyl hydroperoxide; and on microsomes–iron/ascorbate (non-enzyme-induced lipid peroxidation). Administered alone, creatine derivatives and creatine (at concentration 38 µM) revealed neurotoxic and pro-oxidant effects on isolated rat brain subcellular fractions (synaptosomes, mitochondria and microsomes). In models of 6-hydroxydopamine (on synaptosomes), tert-butyl hydroperoxide (on mitochondria) and iron/ascorbate (on microsomes)-induced oxidative stress, the derivatives showed neuroprotective and antioxidant effects. These effects may be due to the preservation of the reduced glutathione level, ROS scavenging and membranes’ stabilizers against free radicals. Thus, they play a role in the antioxidative defense system and have a promising potential as therapeutic neuroprotective agents for the treatment of neurodegenerative disorders, connected with oxidative stress, such as Parkinson’s disease.

In this study, the cytotoxic potential of newly synthesized peptide esters of Galantamine, namely GAL-VAL and GAL-LEU, was investigated against the human cervical adenocarcinoma cell line (HeLa) across a range of concentrations spanning from 1.875µM to 30µM. Notably, GAL-LEU demonstrated significant efficacy in suppressing HeLa cells, particularly at a concentration of 30 µM, where it elicited an impressive 86.81% reduction in cell viability. This effect was corroborated by a c

The current work's objective was to examine the cytotoxic activity of recently created peptide esters of Galantamine: GAL-LEU and GAL-VAL on prostate cancer PC3 cell lines. For the estimation of the cytotoxic effect of Galantamine derivatives, the MTT reduction assay was applied. PC3 cells were triplicate exposed separately to each of the peptide esters, applied in different concentrations (1.875 m М ÷ 30 m М). In the MTT test, the reduction of tetrazolium salt MTT resulted in the cre