Browsing by discipline "Farmakognosia"

The increasing microbial resistance against conventionally used antibiotics has become a worldwide problem. Plant derived compounds may have different mechanisms of action, which might reduce the resistance problem. The aim of this study was to investigate the antimicrobial activity of three African medicinal plants, Terminalia kaiserana, Terminalia sambesiaca and Combretum psidioides, belonging to the family Combretaceae. All three plant species are used for treatment of bacterial and fungal infections in African traditional medicine, but there is limited, or in the case of Terminalia kaiserana, no research on the chemical composition of these plants. Dried plant material was extracted with methanol and solvent-partition extraction was performed using chloroform, butanol and water. Chemical compositions of the fractions was examined using RP-18 thin layer chromatography. The fractions were screened for antibacterial activity against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa using an agar diffusion method. The most effective fraction against both bacteria was the water soluble fraction of the root bark of T. sambesiaca. A microdilution method was used to determine minimum inhibitory concentration (MIC). This method was used for S. aureus, P. aeruginosa and in addition for Mycobacterium smegmatis. The method was modified for M. smegmatis to contain a smaller inoculum size in the beginning of the experiment than for the two other bacteria. The lowest MIC-values against S. aureus were given by the crude extract and water soluble fraction of the stem bark of C. psidioides and by the butanol fraction of the same plant against P. aeruginosa. The results on the antibacterial effects of the screened extracts were notable and significant. The antimicrobial activity against M. smegmatis was not as obvious as for the other tested bacteria but the choloroform fraction of the root bark of T. kaiserana and the butanol fraction of the stem bark of C. psidioides showed promising preliminary results. Separation of fractions and compounds of the root bark of T. kaiserana was performed using Lobar RP-18 column cromatography in order to investigate which fractions or compounds are responsible for the antimicrobial activity. The antimicrobial activity of the fractions was examined using the microdilution method. The most effective fraction against both S. aureus and P. aeruginosa was the fraction 2F8, which containsthe same compounds as the crude extract, but a higher concentration of polar ellagitannins which are probably responsible for the antimicrobial activity of this fraction. Also fraction 2F9 showed antimicrobial activity against P. aeruginosa. This fractions contains ellagic acid derivatives which are probably responsible for the antimicrobial activity. The crude extract of the root bark of T. kaiserana was also fractionated using RP-18 thin layer chromatography, because this method gave better separation compared to column chromatography. Due to limited time the antimicrobial activity of the TLC-fractions will be investigated in the future.

Estimated 180 million people worldwide are infected by hepatitis C virus. It causes liver diseases which are often asymptomatic. Chronic infections can lead to liver cirrhosis, transplantation and hepatocellular carcinoma. Drug development was slow until 1999 when the first cell culture model with autonomously replicating subgenomic HCV replicon was developed. It expresses the viral proteins that are necessary in HCV replication. The current interest in exploring new medicines is concentrated to the essential viral proteins, such as the NS3/4A protease, NS3 helicase, NS5A and NS5B RNA polymerase. HCV belongs to the Hepacivirus genus. Due to its high variability there are at least seven genotypes and several subtypes. Genotype 1 is the most common and the most difficult to treat. The current standard of care continues 24-48 weeks and consists mainly of pegylated interferon alpha and nucleoside analogue ribavirin, both non-specific HCV medicines with severe adverse effects. In 2011 two new direct-acting antivirals, protease inhibitors telaprevir and boceprevir, were approved for the treatment of HCV. A vaccine against HCV has not yet been developed. The aim of this study was to optimize and validate a robust cell-based assay for screening of replication inhibitors against HCV. Genetically modified Huh-7 cells harbor a subgenomic HCV replicon expressing only the viral proteins needed in viral replication. In addition, the replicon encodes a firefly luciferase as a reporter gene. The amount of expressed luciferase is directly correlated with the amount of HCV replication making the replicon system suitable for HTS. The optimized and validated method was used for screening HCV replication inhibitors from a library containing 113 marine-derived substances. Marine environment has been in recent years a very interesting source for finding new drug candidates. This study was part of international MAREX project which aims to discover new active molecules from marine resources. A total of 37 samples (32.7%) exhibited antiviral activity over 50%. A cytotoxicity evaluation in ATP assay was performed with these samples. 10 samples (27.0%) exhibited cytotoxicity below 20%, of which six were synthetic samples and four were extracts. Compounds with high antiviral activity, low cytotoxicity and clear dose-response in further studies should be tested with a cell line expressing the full-length HCV genome. The structural proteins can exhibit some characteristics which inactivate the compound identified as active in the replicon system.

Rhazya stricta Decne. is a small evergreen shrub belonging to the Apocynaceae family. The plant grows in South Asia and the Middle East, and in these areas it is used in traditional medicine. All parts of the plant are used in different preparations for a variety of purposes such as infections, bowel diseases, itching and diabetes. R. stricta synthesizes about a hundred different alkaloids, of which only a fraction has been studied closer. Some of the analyzed alkaloids have showed some interesting pharmacological properties such as antibacterial and cytotoxic properties. Because it is often both economically and ecologically unsustainable to cultivate or to collect large amounts of medicinal plants from nature, cell cultures have been developed from plants. The properties and synthesized substances of the cell cultures can be analysed and modified in laboratories. In the experimental part of this work, a system was developed for alkaloid extraction, fractionation and isolation from dried cell material from cultured R. stricta hairy root-cells. The goal was to develop a functioning system that eventually enables identification of the alkaloids synthesized by the cultured cells under given conditions. Alkaloids were extracted from 26 g of dried and ground cell mass. The fractionation of the alkaloids was performed with medium pressure liquid chromatography (MPLC) and the fractions were analyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The alkaloids were purified by horizontal TLC and preparative HPLC. Ion-pair chromatography was used for analyzing the extract, fractions and purified alkaloids. Five components from two fractions were eventually isolated. One of the components was tentatively identified as vincanine, but further analyzes have to be performed to identify all components reliably. In total, hairy root-cells seem to synthesize approximately 20 alkaloids with variable polarity.

Numerous scientific studies have revealed the connection between oxidative stress and a wide range of diseases, including cardiovascular, neurodegenerative, inflammatory diseases and cancer. The most probable theory of ageing is based on oxidative stress as well. There exist endogenous and exogenous antioxidants capable of fighting oxidative and nitrosative damage to molecules and tissues of the body. Such compounds may be beneficial in prevention and treatment of different conditions. For example, plant foods contain various amounts of antioxidants. The aim of this thesis is to evaluate the antioxidant-related activities of certain commonly used vegetables (broccoli, brussel sprouts, cauliflower, peas), berries (bilberry, raspberry), herbs (Egyptian basil, oregano, rosemary, thyme) and spices (paprika) and to discuss their role in human health. The sample extracts were tested with four different methods: the determination of total phenols using Folin-Ciocalteu reagent, the DPPH free radical scavenging activity assay, reducing power activity assay and iron (II) chelation. In all assays, with exception of iron (II) chelation, vegetables proved to be less active as a potential source of antioxidants than other samples, while herbs seemed to be the most active samples. Iron chelation potential of samples is approximately the same with exception of paprika (lower than other samples) and bilberry (higher than other samples). The results obtained from different assays are not consistent with each other, and good correlative relationship occurs only between total phenols and iron reduction. On the basis of the results, it can be assumed that herbs and berries may be the main target for the research of pharmaceutically important antioxidants, although in daily diet vegetables and fruits are likely to be the best sources of such compounds. However, the beneficial daily doses of plant foods remain to be considered and further research is needed to provide information on the activity of given samples in vivo.

It is well known that the central nervous system is a highly isolated tissue. Because of this the physico-chemical criteria to be met by an orally administered central nervous system drug are very strict. This work describes methods that can be used to select drug candidates and screening collections that have a higher possibility of being relevant to central nervous system drug development projects. This work also argues that small molecular space is so vast that it is difficult to imagine any progress without focusing screening collections in some way or another. Given that most available commercial compounds are very similar in some respects, it is very much possible that this presents a bottle-neck for the progress of drug development as a whole. Therefore, research on novel methods for compound production are also evaluated. In addition, this work describes the miniaturization and automation of a previously published ELISA-based assay. This assay measures the activation of a tyrosine kinase receptor (TrkB), expressed in a fibroblast cell line. The receptor, and it's endogenous ligand, Brain-derived neurotrophic factor, have been linked to the mechanism of action of previously discovered medical interventions used in the treatment of depression. Such an assay can be used to discover either small molecule agonists or antagonists acting upon the receptor. These molecules could possibly be clinically relevant in the treatment of depressive disorders and anxiety. It is demonstrated that it is indeed possible to miniaturize and automate the method, making it significantly more suitable for high-throughput screening. The original method was carried out in 24-well plates, transferring the samples to another plate for measurement. The new design uses 96-well plates and performs the entire process on the same plate.

Alphaviruses are positive-stranded RNA-viruses and they belong to the family of Togaviridae. Alphaviruses are spread by mosquitoes of family Aedes. Alphaviruses have spread on all continents except Antarctica. So far 29 alphaviral species have been identified and they can be divided in two groups, Old and New world viruses, by their geographical distribution and by diseases they cause. Chikungunya virus (CHIKV) is one of the Old World alphaviruses and it has been found in Africa and Asia. However, due to the global warming, Chikungunya is also spreading to southern Europe. In humans, it causes fever, headache, rash and joint pain, which can last for several years and be very painful. In small children, Chikungunya can cause neurological symptoms such as encephalitis. Genome of alphaviruses encodes for four structural proteins and four non-structural proteins (nsP), of which nsP3 contains a macro domain. Macro domains are conserved in most kingdoms of life but their function has not been elucidated. It has been shown that macro domains bind ADP-ribose and its derivatives and it has been shown that nsP3-protein has an important role in alphavirus replication. The aim of the study was to study the use of compounds which bind to macro domain protein as antiviral agents. 45 compounds were chosen for antiviral studies by molecular modeling. These compounds were expected to bind to macro domain proteins. In a competitive binding assay five compounds inhibited more than 50 % poly-ADP-ribose (PAR) binding to MDO1-macro domain protein, which was the protein on which the molecular modeling was performed. When the competitive binding assay was performed with SFV macro domain (nsP3), only one compound inhibited poly-ADP-ribose binding more than 50 %. In SFV-antiviral assay seven compounds had inhibition percentage higher than 50 %. In a CHIKV replicon assay five compounds had more than 50 % inhibition on replicon expression. We also studied possible inhibition mechanism by studying whether the compounds inhibit the virus to enter the cell. Almost all compounds included in this assay inhibited the virus entry to some extent. In general, the inhibition of PAR binding and antiviral activity did not correlate among the studied compounds. Even though compounds which had antiviral potency did not inhibit PAR binding to macro domains, potential antiviral agents were found which deserve further investigation as virus entry inhibitors.

Ricinus communis L., also known as castor, is a worldwide cultivated plant. Castor seeds are a source of castor oil, an important ingredient in industry. Castor seeds also include one of the most toxic natural compounds - ricin toxin. Ricin toxin has medical purposes, but it can be abused. There is fear that it will be used as a biological weapon or with terrorism. Ricin is listed as a forbidden chemical on Chemical Weapons Convention, CWC. Ricinus is regarded as a monotypic genus, but there is strong variability in its characters. This study concentrates on the taxonomical classification of the Ricinus varieties. Here is represented a taxonomical description of following varieties: "AGF-6", "AGF-M", 'Blue Giant', 'Cambodgensis', 'Carmencita Bright Red', 'Gibsonii', 'Green Giant', 'Impala', 'New Zealand Purple', 'Sanguineus', var. zanzibarensis (mixed), and 'Zanzi Palm'. Also an identification key for varieties is shown. This study is made for VERIFIN (Finnish Institute for Verification of the Chemical Weapons Convention). If the chemical composition especially with the amount of ricin toxin correlates with the morphological characters, the taxonomical classification can provide an important identification tool. This way the monitoring of chemical weapons can be facilitated.

The aim of this study was to explore the functions of T-type calcium channels, and their possible role in neuronal stem cells migration. The role of T-type calcium channel in mature brain is known to be in producing electroencephalographic oscillations. This action in turn is the key factor in some neuronal physiological and pathophysiological functions, like non-REM sleep, memory, learning and absence epilepsy. In addition, T-type calcium channels have peripheral actions, but this study concerns on its neuronal functions. This low-voltage activated channels functions in neurogenesis is less known than its role in mature brain. It is known to promote neuronal proliferation and differentiation, but what comes to its possible actions in neuronal migration, is poorly studied. This study shows some evidence of T-type calcium channel taking part in neuronal migration in mice embryonic subventricular zones progenitor cells. Selective T-type antagonists, ethosuximide, nickelchloride and a scorpion peptide toxin kurtoxin, decreased the rate of migration in differentiating progenitor cells. This study consists of a literature review and an experimental part. Another aim of this study is to consider an alternative approach to stem cell therapies based on invasive transplantation of the cells. This other attempt is non-invasive manipulating of endogenous stem cells to proliferate and migrate to the injured or depleted area in the brain, differentiate into a desired phenotype and stop their division after they have completed their mission. Non-invasive altering of the stem cells is awaiting pharmacological solutions to resolve the problems being faced in this effort. There are some non-invasive therapies already being used successfully to cure pathological conditions such as spinal cord injury. These methods could be used as well in stem cell based therapies in the treatment of neurodegenerative diseases and brain injuries. These methods are still in the beginning of their way and lacking the full understanding of the key factors that affect neuronal development. These factors include some important endogenous inducing and inhibiting substances. One of the most important inducing substances is calcium ion regulating a variety of events in neurogenesis. T-type calcium channel, as being widely expressed during early brain development, and decaying by neuronal maturation, might have a pivotal role in conducting progenitor cells.