Nikolay T. Tzvetkov

• Assoc. Prof. Dr.
• Professor (Associate) at Bulgarian Academy of Sciences

Ginger ( Zingiber officinale ) has been utilized for medicinal and culinary purposes for thousands of years. Its extensive history showcases diverse uses and health benefits. In this study, we conducted a thorough analysis of the scientific literature landscape surrounding ginger using bibliometric techniques, aiming to explore recurring topics, tr...

Background Cannabis and its derivatives show encouraging therapeutic effects in the treatment of various diseases. However, further studies are needed to better assess their efficacy and safety. A promising base for research in the field of medicine and additional pharmacovigilance is social networks, in which experience and knowledge are exchanged...

In recent years, small peptide and non-peptide AVPI-/Smac-mimetics have been developed as IAP antagonists and are in clinical trials to overcome resistance to apoptosis in various cancer types. In this study, we present molecular modeling studies and in vitro biological evaluation of a set of AVPI-mimetics, including parent AVPI, tetrapeptide AVPI-...

C17H16BrN3, monoclinic, P21/c (no. 14), a = 6.91863(13) Å, b = 7.17190(11) Å, c = 29.6309(5) Å, β = 93.9228(15)∘, V = 1466.83(4) ų, Z = 4, R gt (F) = 0.0201, wR ref (F²) = 0.0392, T = 100.0(1) K.

Ginger (Zingiber officinale Roscoe) is broadly used as a traditional remedy and food ingredient, and numerous preclinical and clinical studies have demonstrated health benefits in a range of age-related disorders. Moreover, longevity-promoting effects have been demonstrated in several (preclinical) research models. With this work, we aimed to compr...

C9H13NO4, orthorhombic, P212121 (no. 19), a = 5.8406(1) Å, b = 7.0840(1) Å, c = 24.3697(3) Å, V = 1,008.29(3) ų, Z = 4, Rgt(F) = 0.0148, wRref(F²) = 0.0381, T = 100.0(1) K.

Multidrug-resistant (MDR) Staphylococcus aureus infections significantly threaten global health. With rising resistance to current antibiotics and limited solutions, the urgent discovery of new, effective, and affordable antibacterials with low toxicity is imperative to combat diverse MDR S. aureus strains. Hence, in this study, we introduce an in...

Citation: Peeva, M.I.; Georgieva, M.G.; Balacheva, A.A.; Ponticelli, M.; Bogdanov, I.P.; Kolev, T.; Milella, L.; Stammler, H.-G.; Tzvetkov, N.T. Crystal Structures, Molecular Docking and In Vitro Investigations of Two 4-Substituted 2-(5,5-dimethyl-3-styrylcyclohex-2-enylidene)malononitrile Derivatives as Potential Topoisomerase II Inhibitors. Cryst...

Aim: This study aimed to identify and analyze the top 100 most cited digital health and mobile health (m-health) publications. It could aid researchers in the identification of promising new research avenues, additionally supporting the establishment of international scientific collaboration between interdisciplinary research groups with demonstrat...

Anthocyanins are water-soluble pigments contained in numerous food plants. This study provides an overall quantitative literature analysis on anthocyanins. Bibliometric data were collected through the search string TOPIC = anthocyan*, which yielded 44,121 publications indexed within the Web of Science Core Collection. Term maps were generated using...

Haberlea rhodopensis Friv., known also as Rhodope silivryak and the Orpheus flower, is a Balkan endemic “resurrecting” plant belonging to the Gesneriaceae family. In folk medicine, the leaves of Haberlea rhodopensis Friv. were widely used to treat wounds and some infectious diseases of stock such as foot-and-mouth disease and hoof rot, while the he...

Withania somnifera (L.) Dunal is a medicinal plant belonging to the traditional Indian medical system, showing various therapeutic effects such as anti-cancer, anti-inflammatory, anti-microbial, anti-diabetic, and hepatoprotective activity. Of great interest is W. somnifera’s potential beneficial effect against neurodegenerative diseases, since the...

Non-alcoholic fatty liver disease (NAFLD) is defined as a clinical syndrome characterized by excessive fat accumulation in liver, predominantly influenced by dietary choices. This study provides an extensive quantitative literature analysis on dietary influences on NAFLD. Bibliometric data were collected through the search string TOPIC = (“NAFLD*”...

Plant species are a reservoir of natural compounds that can potentially be used to treat different diseases. Citrus medica Linn. belonging to the Rutaceae family, has been used for centuries in medicine for its antioxidant, anti-inflammatory, antimicrobial, antiviral, and antihyperglycemic properties. These activities are ascribable not only to the...

Type 2 diabetes (T2D) accounts for a global health problem. It is a complex disease as a result of the combination of environmental as well as genetic factors. Morbidity is still increasing across the world. One of the possibilities for the prevention and mitigation of the negative consequences of type 2 diabetes is a nutritional diet rich in bioac...

The modulatory interactions between neurotensin (NT) and the dopaminergic neurotransmitter system in the brain suggest that NT may be associated with the progression of Parkinson's disease (PD). NT exerts its neurophysiological effects by interactions with the human NT receptors type 1 (hNTS1) and 2 (hNTS2). Therefore, both receptor subtypes are pr...

Objectives: Digital pills are new technologies that aim to improve healthcare by increasing medication adherence. The aim of the work was a bibliometric analysis of clinical studies of digital pills and an assessment of the level of evidence of their effectiveness, safety, and prospects for the future. Materials and Methods: The studies were conduc...

Background The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled “International Natural Product Sciences Taskforce” (INPST) was established in 2018, to bring...

Background: The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled "International Natural Product Sciences Taskforce" (INPST) was established in 2018, to brin...

The conventional treatment of neurodegenerative diseases (NDDs) is based on the “one molecule—one target” paradigm. To combat the multifactorial nature of NDDs, the focus is now shifted toward the development of small-molecule-based compounds that can modulate more than one protein target, known as “multi-target-directed ligands” (MTDLs), while hav...

Background: The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled “International Natural Product Sciences Taskforce” (INPST) was established in 2018, to brin...

The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled “International Natural Product Sciences Taskforce” (INPST) was established in 2018, to bring together i...

The modern healthcare system is directly related to the development of digital health tools and solutions. Pills with digital sensors represent a highly innovative class of new pharmaceuticals. The aim of this work was to analyze the patent landscape and to systematize the main trends in patent protection of digital pills with ingestible sensors wo...

C10H11N3O6, monoclinic, P21/c (no. 14), a = 7.4928(12) Å, b = 14.860(3) Å, c = 11.0593(18) Å, β = 109.465(5)°, V = 1161.0(4) ų, Z = 4, Rgt(F) = 0.0439, wR ref (F²) = 0.1060, T = 300.0(2) K.

Over the years, the attention towards the role of phytochemicals in dietary natural products in reducing the risk of developing cancer is rising. Cancer is the second primary cause of mortality worldwide. The current therapeutic options for cancer treatment are surgical excision, immunotherapy, chemotherapy, and radiotherapy. Unfortunately, in case...

Lycopene intake from tomatoes and other food sources has multiple potential health benefits. This report aimed to evaluate the current research literature on lycopene concerning human and animal health. The electronic Web of Science Core Collection database was searched with (lycopene*) AND (health* OR illness* OR disease* OR medic* OR pharma* OR d...

C15H16Cl2N4O2, monoclinic, P21/c (no. 14), a = 26.2014(7) Å, b = 7.59320(10) Å, c = 17.9766(4) Å, β = 109.217(3)°, V = 3377.20(14) Å3, Z = 8, R gt(F) = 0.0503, wR ref(F 2) = 0.1411, T = 100.0(1) K.

Numerous investigations on quercetin have revealed that it effectively treats and prevents different diseases, acting as an anti-inflammatory, anti-bacterial, anti-proliferative, anti-atherogenic, anticoagulative, antioxidant, antidiabetic agent, etc. This work aimed to analyze the present research literature on quercetin in the context of human an...

Apples contain substantial amounts of polyphenols, and diverse phenolics – mainly flavonoids and phenolic acids, have been identified in their flesh and skins. This work aimed to analyze the overall landscape of the research literature published to date on apple phenolic compounds in the context of human and animal health. The Web of Science Core C...

The open innovation hub Digital Health and Patient Safety Platform (DHPSP) was recently established with the purpose to invigorate collaborative scientific research and the development of new digital products and personalized solutions aiming to improve human health and patient safety. In this study, we evaluated the effectiveness of a Twitter-base...

Natural products and their structural analogues have historically made a major contribution to pharmacotherapy, especially for cancer and infectious diseases. Nevertheless, natural products also present challenges for drug discovery, such as technical barriers to screening, isolation, characterization and optimization, which contributed to a declin...

Ginger (Zingiber officinale Roscoe) is a common and widely used spice. It is rich in various chemical constituents, including phenolic compounds, terpenes, polysaccharides, lipids, organic acids, and raw fibers. Herein, we reviewed its effects on the vascular system. Studies utilizing cell cultures or animal models showed that ginger constituents a...

Background Substances present in nature have been a continuous source for the development of drugs for cardiovascular and infectious diseases, cancer, and many other diseases. As the literature concerning these natural products grows, it becomes more difficult for a reader to quickly grasp the essential facts and develop a well-informed impression...

The decreased hepatic drug metabolism (predominately first phase) is one of the essential reasons for numerous side effects and for increased drug toxicity during influenza virus infection (IVI). The present study aims to investigate some mechanisms of the preventive effect of a standardized polyphenol complex from the medicinal plant Geranium sang...

The current study aimed to identify which natural products and which research directions are related to the major contributors to academic journals for diabetes therapy. Bibliometric data were extracted from the Web of Science online database using the search string TOPIC = (‘‘natural product*’ OR ‘‘natural compound*’ OR ‘‘natural molecule*’ OR ‘ph...

The natural tridecapeptide neurotensin has been emerged as a promising therapeutic scaffold for the treatment of neurological diseases and cancer. In this work, we aimed to identify the top 100 most cited original research papers as well as recent key studies related to neurotensins. The Web of Science Core Collection database was searched and the...

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To date, there have been more than 10 million reported cases, more than 517,000 deaths in 215 countries, areas or territories. There is no effective antiviral medicine to prevent or treat COVID-19. Natural products and traditional medicine...

Excessive alcohol consumption is the cause of several diseases and thus is of a major concern for society. Worldwide alcohol consumption has increased by many folds over the past decades. This urgently calls for intervention and relapse counteract measures. Modern pharmacological solutions induce complete alcohol self-restraint and prevent relapse,...

Significance: Excessive production of reactive oxygen species (ROS) has been linked to neurodegenerative diseases (NDs), and therefore, many scientific works were published on the impact of ROS on the development of prevalent NDs, such as Alzheimer's (AD) and Parkinson's disease (PD). Since quantitative and qualitative bibliometric analyses on thi...

The current study provides a comprehensive overview and analysis of the lignan literature. Data for the current study were extracted from the electronic Web of Science Core Collection database via the search string TOPIC = (“lignan*”) and processed by the VOSviewer software. The search yielded 10,742 publications. The ratio of original articles to...

Scavenger receptor class B type I (SR-BI) protein is an integral membrane glycoprotein. SR-BI is emerging as a multifunctional protein, which regulates autophagy, efferocytosis, cell survival and inflammation. It is well known that SR-BI plays a critical role in lipoprotein metabolism by mediating cholesteryl esters selective uptake and the bi-dire...

We compared the neuroprotective action of three natural bio-antioxidants (AOs): ellagic acid (EA), α-lipoic acid (LA), and myrtenal (Myrt) in an experimental model of Parkinson's disease (PD) that was induced in male Wistar rats through an intrastriatal injection of 6-hydroxydopamine (6-OHDA). The animals were divided into five groups: the sham-ope...

Berberine is an alkaloid with a wide range of reported beneficial health effects. The current work provides an extensive literature analysis on berberine. Bibliometric data were identified by means of the search string TOPIC=(“berberin*” OR “umbellatine*”), which yielded 5,547 publications indexed in the Web of Science Core Collection electronic da...

Ethnopharmacological relevance: The research into bioactive natural products originating from medicinal plants, fungi and other organisms has a long history, accumulating abundant and diverse publications. However no quantitative literature analysis has been conducted. Aim of the study: Here we analyze the bibliometric data of ethnopharmacology...

Biotechnology is an evolving research field that covers a broad range of topics. Here we aimed to evaluate the latest research literature, to identify prominent research themes, major contributors in terms of institutions, countries/regions, and journals. The Web of Science Core Collection online database was searched to retrieve biotechnology arti...

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 interr...

Biotechnology is an evolving research field that covers a broad range of topics. Here we aimed to evaluate the latest research literature, to identify prominent research themes, major contributors in terms of institutions, countries/regions, and journals. The Web of Science Core Collection online database was searched to retrieve biotechnology arti...

A comprehensive study was performed for the first time to compare two structurally related substance classes, namely indazole-5-carboxamides (11e16) and (indazole-5-yl)methanimines (17e22). Both chemical entities are potent, selective and reversible MAO-B inhibitors and, therefore, may serve as promising lead structures for the development of drug...

Resveratrol is a stilbene-type bioactive molecule with a broad spectrum of reported biological effects. In this sense, the current work provides a comprehensive literature analysis on resveratrol, representing a highly-researched commercially available dietary ingredient. Bibliometric data were identified by means of the search string TOPIC=(“resve...

Background: Cannabis, cannabinoids and endocannabinoids are heavily investigated topics with many articles published every year. We aimed to identify the 100 most cited manuscripts among the vast literature and analyze their contents. Methods: Web of Science (WoS) Core Collection was searched to identify the 100 most cited relevant manuscripts,...

A comprehensive study was performed for the first time to compare two structurally related substance classes, namely indazole-5-carboxamides (11-16) and (indazole-5-yl)methanimines (17-22). Both chemical entities are potent, selective and reversible MAO-B inhibitors and, therefore, may serve as promising lead structures for the development of drug...

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 candid...

Total-scale quantitative research literature analysis on the food toxicology scientific field has yet to be conducted. In this work, we identified and analysed food toxicology publications in the existing scientific literature. A literature search was performed with the online Web of Science database. Full records and cited references of the 73,099...

The current study aimed to provide a comprehensive bibliometric overview of the literature on curcumin, complementing the previous reviews and meta-analyses on its potential health benefits. Bibliometric data for the current analysis were extracted from the Web of Science Core Collection database, using the search string TOPIC=(“curcumin*”), and an...

Antioxidants are abundant in natural dietary sources and 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 aimed to identify and analyse the antioxidant publications in the existing scientific literature...

BACKGROUND Berries are important sources of crucial dietary components such as vitamins and minerals, as well as various phytonutrients that may be potentially beneficial to human health and could be used against chronic diseases including cancer and cardiovascular disorders. OBJECTIVE The current study aimed to identify and analyze the 100 most c...

Background: Considering the enormous progress in the field of neuropharmacology and its global importance, as well as the lack of bibliometric studies examining this field as a whole, it is a high time to assess the prevailing topics and citation performances of its research works. Methods: Web of Science (WoS) was searched to identify relevant neu...

A supplementary data sheet (XLSX) includes 1,659 terms that occurred in at least 100 of all studied 43,354 manuscripts and their citations per manuscript.

DEVELOPMENT OF NEW HIGHLY POTENT DRUG LEADS FOR DISORDERS OF THE CENTRAL NERVOUS SYSTEM NTZ Lab Ltd. has developed new promising brain-penetrant compounds, the discovery of which is described in our latest publication in the European Journal of Medicinal Chemistry. We develop a series of promising BBB permeable derivatives combining both high pot...

Alzheimer´s disease (AD) belongs to the most intensively investigated and discussed disorders in modern medicine and community worldwide. Only few clinical diagnoses evoke greater consternation among affected people than AD [1,2]. Despite enormous research efforts in the past decades, the root causes and risk factors for AD are not fully understood...

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...

Many natural products have been so far tested regarding their potency to inhibit vascular smooth muscle cell proliferation, a process involved in atherosclerosis, pulmonary hypertension and restenosis. Compounds studied in vitro and in vivo as VSMC proliferation inhibitors include, for example indirubin-3'-monoxime, resveratrol, hyperoside, plumeri...

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules a...

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). In this poster we highlight fiv...

The dysregulation of autophagy is involved in the pathogenesis of a broad range of diseases, and accordingly universal research efforts have focused on exploring novel compounds with autophagy-modulating properties. While a number of synthetic autophagy modulators have been identified as promising cancer therapy candidates, autophagy-modulating phy...

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 dis...

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...

https://www.frontiersin.org/articles/10.3389/fnagi.2018.00004/full

The tautomeric properties of an N-(3,4-dichlorophenyl)-1H-indazole-5-carboxamide (NTZ-1006, 2) derivative, developed as highly potent, reversible and selective MAO-B inhibitor useful for the treatment of Parkinson's disease (PD) and other neurological disorders, have been studied both experimentally and theoretically. The theoretical data (M06–2X,...

Pharmacological and physicochemical studies of N-unsubstituted indazole-5-carboxamides (subclass I) and their structurally optimised N1-methylated analogues (subclass II), initially developed as drug and radioligand candidates for the treatment and diagnosis of Parkinson’s disease (PD), are presented. The compounds are highly brain permeable, selec...

The pharmacological and physicochemical analysis of structurally optimized N-alkyl-substituted indazole-5-carboxamides, developed as potential drug and radioligand candidates for the treatment and diagnosis of Parkinson's disease (PD) and other neurological disorders, is reported. Recent efforts have been focused on the development of subnanomolar...

C16H20N4O2, triclinic, P1̅ (no. 2), a = 9.0959(5) Å, b = 9.1993(5) Å, c = 18.5825(9) Å, α = 100.534(4)°, β = 94.120(4)°, γ = 94.752(4)°, V = 1517.44(13) ų, Z = 4, Rgt(F) = 0.0801, wRref(F²) = 0.2371, T = 100(1) K.

A simple approach for the synthesis of multifunctionalized N1-alkyl 7-amino-6-azaoxindole derivatives was developed and investigated. Formation of 5-amino- and 7-amino-6-aza-2-oxindoles 12a and 13a, respectively, was achieved using an intramolecular reductive cyclization as a key step. Subsequent alkylation of the pyrrole N1 atom in 12a led to the...

Bielefeld, Universiẗat, Diss., 2004 (Nicht für den Austausch).

Indazole- and indole-carboxamides were discovered as highly potent, selective, competitive and reversible inhibitors of monoamine oxidase B (MAO-B). The compounds are easily accessible by standard synthetic procedures with high overall yields. The most potent derivatives were N-(3,4-dichlorophenyl)-1-methyl-1H-indazole-5-carboxamide (38a, IC50 huma...

C14H18O2, monoclinic, P121/c1 (no. 14), a = 15.399(1) Å, b = 11.646(1) Å, c = 14.849(1) Å, β= 117.659(4)°, V = 2358.7 Å3, Z = 8, R gt(F) = 0.068, wRref(F2) = 0.206, T = 100 K.

C12H14N2O2, monoclinic, P121/n1 (no. 14), a = 13.0062(3) Å, b = 6.0105(1) Å, c = 15.6960(4) Å, β = 108.359(1)°, V = 1164.6 Å3, Z = 4, Rgt(F) = 0.043, wRref(F2) = 0.121, T=295K.

The enzyme monoamine oxidase B (MAO-B) catalyses the oxidative degradation of monoamine neurotransmitters and xenobiotic arylalkylamines. Selective inhibition of MAO-B in the human brain is considered an attractive concept for treatment of several neurodegenerative conditions, including Parkinson's and Alzheimer's diseases. We have recently reporte...

An efficient approach for the formation of 5-amino- and 7-amino-6-azaoxindole derivatives was developed. 2-Amino-4-chloro-3-nitropyridine (8), and its 5-nitro-substituted regioisomer (9), respectively, were obtained by reaction with ethyl malonate. The resulting 2-amino-3/5-nitropyridine derivatives substituted in the 4-position with malonic acid d...

Dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives were prepared by successive N3- and N1-alkylation of hydantoins, followed by regioselective thionation and subsequent cyclization under mild conditions. In a final alkylation step a further substituent may be introduced. The synthetic strategy allows broad structural variation of thi...

C12H14N2O2, monoclinic, P121/n1 (no. 14), a = 13.0062(3) Å, b = 6.0105(1) Å, c = 15.6960(4) Å, β = 108.359(1)°, V= 1164.6 ų, Z = 4, Rgt(F) = 0.043, wRref(F²) = 0.121, T = 295 K. © 2014 Oldenbourg Wissenschaftsverlag GmbH, Rosenheimer Str. 145, 81671 München. All rights reserved.