Nikolay T. Tzvetkov

Prof. Dr. Nikolay T. Tzvetkov

Institute of Molecular Biology, Bulgarian Academy of Sciences
orcid

Research Focus & Metrics

Academic Career Length

24Years (2003-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 January 2018 in Frontiers in Aging Neuroscience
Verified
Journal Article
Open access
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SUSahab Uddin
Sahab Uddin
ASAnna Stachowiak
Anna Stachowiak
AMAbdullah Al Mamun
Abdullah Al Mamun
NTNikolay T. Tzvetkov
Nikolay T. Tzvetkov
STShinya Takeda
Shinya Takeda
ASAdrian Mateusz Stankiewicz
Adrian Mateusz Stankiewicz
Alzheimer’s disease (AD) is the most common cause of progressive dementia in the elderly. It is characterized by a progressive and irreversible loss of cognitive abilities and formation of senile plaques, composed mainly of amyloid β (Aβ), and neurofibrillary tangles (NFTs), composed of tau protein, in the hippocampus and cortex of afflicted humans. In brains of AD patients the metabolism of Aβ is dysregulated, which leads to the accumulation and aggregation of Aβ. Metabolism of Aβ and tau proteins is crucially influenced by autophagy. Autophagy is a lysosome-dependent, homeostatic process, in which organelles and proteins are degraded and recycled into energy. Thus, dysfunction of autophagy is suggested to lead to the accretion of noxious proteins in the AD brain. In the present review, we describe the process of autophagy and its importance in AD. Additionally, we discuss mechanisms and genes linking autophagy and AD, i.e., the mTOR pathway, neuroinflammation, endocannabinoid system, ATG7, BCL2, BECN1, CDK5, CLU, CTSD, FOXO1, GFAP, ITPR1, MAPT, PSEN1, SNCA, UBQLN1, and UCHL1. We also present pharmacological agents acting via modulation of autophagy that may show promise in AD therapy. This review updates our knowledge on autophagy mechanisms proposing novel therapeutic targets for the treatment of AD.

1 October 2019 in Pharmacological Reviews
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Journal Article
Closed access
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DWDongdong Wang
Dongdong Wang
YYYang Yang
Yang Yang
YLYingnan Lei
Yingnan Lei
NTNikolay T. Tzvetkov
Nikolay T. Tzvetkov
XLXingde Liu
Xingde Liu
Atanas G. AtanasovAtanas G. Atanasov
Atanas G. Atanasov
Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

24 May 2018 in Frontiers in Pharmacology
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Journal Article
Open access
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DWDongdong Wang
Dongdong Wang
CÖCigdem Özen
Cigdem Özen
Ibrahim Abu-ReidahIbrahim Abu-Reidah
Ibrahim Abu-Reidah
SCSridevi Chigurupati
Sridevi Chigurupati
Jayanta Kumar PatraJayanta Kumar Patra
Jayanta Kumar Patra
Atanas G. AtanasovAtanas G. Atanasov
Atanas G. Atanasov
Pomegranate (Punica granatum L.), one of the oldest known edible fruits, is nowadays broadly consumed throughout the world. Its fruits and seeds as well as other anatomical compartments (e.g., flowers and leaves) are rich in numerous bioactive compounds and therefore, the scientific interest in this plant has been constantly growing in recent years. It has been shown that pomegranate and its extracts exhibit potent antioxidative, antimicrobial, and anticarcinogenic properties. The present review summarizes some recent studies on pomegranate, highlighting mainly its vasculoprotective role attributed to the presence of hydrolyzable tannins ellagitannins and ellagic acid, as well as other compounds (e.g., anthocyanins and flavonoids). These in vitro and in vivo studies showed that substances derived from pomegranate reduce oxidative stress and platelet aggregation, diminish lipid uptake by macrophages, positively influence endothelial cell function, and are involved in blood pressure regulation. Clinical studies demonstrated that daily intake of pomegranate juice lessens hypertension and attenuates atherosclerosis in humans. Altogether, the reviewed studies point out the potential benefits of a broader use of pomegranate and its constituents as dietary supplements or as adjuvants in therapy of vascular diseases, such as hypertension, coronary artery disease, and peripheral artery disease.

8 January 2019 in Oxidative Medicine and Cellular Longevity
Verified
Journal Article
Open access
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AYAndy Wai Kan Yeung
Andy Wai Kan Yeung
NTNikolay T. Tzvetkov
Nikolay T. Tzvetkov
OEOsama S. El-Tawil
Osama S. El-Tawil
Simona BungăuSimona Bungău
Simona Bungău
Mohamed Abdel-DaimMohamed Abdel-Daim
Mohamed Abdel-Daim
Atanas G. AtanasovAtanas G. Atanasov
Atanas G. Atanasov
Antioxidants are abundant in natural dietary sources, and the consumption of antioxidants has a lot of potential health benefits. However, there has been no literature analysis on this topic to evaluate its scientific impact in terms of citations. This study is aimed at identifying and analysing the antioxidant publications in the existing scientific literature. In this context, a literature search was performed with the Web of Science database. Full records and cited references of the 299,602 identified manuscripts were imported into VOSviewer for bibliometric analysis. Most of the manuscripts were published since 1991. The publications were mainly related to the categories biochemistry/molecular biology, food science technology, and pharmacology/pharmacy. These topics have been prolific since 1990 and before. Polymer science was prolific before, but its publication share declined in the recent two decades. Brazil, China, India, and South Korea have emerged as upcoming major contributors besides USA. Most prolific journals were Food Chemistry, Journal of Agricultural and Food Chemistry, Free Radical Biology and Medicine, and PLOS One. Clinical conditions with high citations included Alzheimer’s disease, cancer, cardiovascular disease, and Parkinson’s disease. Chemical terms and structures with high citations included alpha-tocopherol, anthocyanin, ascorbate, beta-carotene, carotenoid, curcumin, cysteine, flavonoid, flavonol, hydrogen peroxide, kaempferol, N-acetylcysteine, nitric oxide, phenolic acid, uric acid, vitamin C, vitamin E, selenium, and resveratrol. Citation patterns temporal analysis revealed a transition of the scientific interest from research focused on antioxidant vitamins and minerals into stronger attention focus on antioxidant phytochemicals (plant secondary metabolites).

29 May 2019 in Frontiers in Molecular Neuroscience
Verified
Journal Article
Open access
AYAndy Wai Kan Yeung
Andy Wai Kan Yeung
MGMaya G. Georgieva
Maya G. Georgieva
Atanas G. AtanasovAtanas G. Atanasov
Atanas G. Atanasov
NTNikolay T. Tzvetkov
Nikolay T. Tzvetkov
Background: Monoamine oxidases (MAOs) were discovered nearly a century ago. This article aims to analyze the research literature landscape associated with MAOs as privileged class of neuronal enzymes (neuroenzymes) with key functions in the processes of neurodegeneration, serving as important biological targets in neuroscience. With the accumulating publications on this topic, we aimed to evaluate the publication and citation performance of the contributors, reveal the popular research themes, and identify its historical roots. Methods: The electronic database of Web of Science (WoS) Core Collection was searched to identify publications related to MAOs, which were analyzed according to their publication year, authorship, institutions, countries/regions, journal title, WoS category, total citation count, and publication type. VOSviewer was utilized to visualize the citation patterns of the words appearing in the titles and abstracts, and author keywords. CRExplorer was utilized to identify seminal references cited by the MAO publications. Results: The literature analysis was based on 19,854 publications. Most of them were original articles (n = 15,148, 76.3%) and reviews (n = 2,039, 10.3%). The top five WoS categories of the analyzed MAO publications were Pharmacology/Pharmacy (n = 4,664, 23.5%), Neurosciences (n = 4,416, 22.2%), Psychiatry (n = 2,906, 14.6%), Biochemistry/Molecular Biology (n = 2,691, 13.6%), and Clinical Neurology (n = 1,754, 8.8%). The top 10 institutions are scattered in the United States, UK, France, Sweden, Canada, Israel, and Russia, while the top 10 countries/regions with the most intensive research on the field of MAOs are the United States, followed by European and Asian countries. More highly cited publications generally involved neurotransmitters, such as dopamine (DA), serotonin, and norepinephrine (NE), as well as the MAO-A inhibitors moclobemide and clorgyline, and the irreversible MAO-B inhibitors selegiline and rasagiline. Conclusion: Through decades of research, the literature has accumulated many publications investigating the therapeutic effects of MAO inhibitors (MAOIs) on various neurological conditions, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and depression. We envision that MAO literature will continue to grow steadily, with more new therapeutic candidates being tested for better management of neurological conditions, in particular, with the development of multi-target acting drugs against neurodegenerative diseases.

12 February 2018 in Frontiers in Aging Neuroscience
Verified
Journal Article
Open access
DTDevesh Tewari
Devesh Tewari
ASAdrian Mateusz Stankiewicz
Adrian Mateusz Stankiewicz
Andrei-Marius MocanAndrei-Marius Mocan
Andrei-Marius Mocan
ASArchana N. Sah
Archana N. Sah
NTNikolay T. Tzvetkov
Nikolay T. Tzvetkov
Atanas G. AtanasovAtanas G. Atanasov
Atanas G. Atanasov
Dementia is a clinical syndrome wherein gradual decline of mental and cognitive capabilities of an afflicted person takes place. Dementia is associated with various risk factors and conditions such as insufficient cerebral blood supply, toxin exposure, mitochondrial dysfunction, oxidative damage, and often coexisting with some neurodegenerative disorders such as Alzheimer’s disease (AD), Huntington’s disease (HD), and Parkinson’s disease (PD). Although there are well-established (semi-)synthetic drugs currently used for the management of AD and AD-associated dementia, most of them have several adverse effects. Thus, traditional medicine provides various plant-derived lead molecules that may be useful for further medical research. Herein we review the worldwide use of ethnomedicinal plants in dementia treatment. We have explored a number of recognized databases by using keywords and phrases such as “dementia”, “Alzheimer’s”, “traditional medicine”, “ethnopharmacology”, “ethnobotany”, “herbs”, “medicinal plants” or other relevant terms, and summarized 91 medicinal plants that are traditionally used to treat dementia. Moreover, we highlight five medicinal plants or plant genera of prime importance and discuss the physiological effects, as well as the mechanism of action of their major bioactive compounds. Furthermore, the link between mitochondrial dysfunction and dementia is also discussed. We conclude that several drugs of plant origin may serve as promising therapeutics for the treatment of dementia, however, pivotal evidence for their therapeutic efficacy in advanced clinical studies is still lacking.