Antimicrobial Peptides (Amps) - A Potential Solution Against Microbial Resistance

След въвеждането им за първи път през 50-те години на миналия век, антибиотиците усилено се използват за лечение на микробни инфекции. Много от бактериите обаче стават резистентни към използваните в клиниката антибиотици, което води до необходимостта от търсенето на нови агенти за борба с болестотворните микроорганизми. Тъй като повечето живи организми имат близка структура на молекулно ниво, трудно е да се открият вещества, които да са летални за определени видове и да са безопасни за други.Антимикробните пептиди (AMPs) са получили специално внимание като евентуален алтернативен подход за борба с инфекции, причинени от антибиотично резистентни бактериални щамове. Въведени са като самостоятелна група биологично активни вещества в края на 70-те и началото на 80-те години на миналия век. Към днешно време групата наброява между 2500 и 6000 олигопептида с големина между 10 и 80 аминокиселинни остатъка, с предимно спирална структура. AMPs представляват положително заредени, амфипатични структури с голямо разнообразие и неголяма дължина на молекулата. Проявяват широк спектър на антимикробна активност спрямо грам-положителни и грам-отрицателни бактерии, вируси и паразити в широк диапазон от рН и температури. В природата представляват важна част от вродената имунна защита на животни и насекоми. Счита се, че дори заместват имунния отговор при по-низшите организми – пример за това са изолираните цекропини, дефензини и магенини.AMPs осъществяват бърз бактерициден ефект (in vitro – в рамките на минути). В последните години се определят като „естествени антибиотици“. Настоящият обзор разглежда класификацията на AMPs, тяхната противомикробна активност и механизъм на действие.After introducing them for the first time in the 1950s, antibiotics have been used extensively for the treatment of microbial infections. Many of the bacteria, however, have become resistant to the antibiotics used in the clinic, which has led to the need for new agents to control pathogenic microorganisms. Since most living organisms have a close molecular structure, it is difficult to find substances that are lethal to certain species and are safe for others.Antimicrobial peptides (AMPs) have received special attention as a possible alternative approach to fighting infections caused by antibiotic-resistant bacterial strains. They were introduced as a single group of biologically active substances in the late 1970s and early 1980s. To date, the group is presented by 2500 to 6000 oligopeptides with a size between 10 and 80 amino acid residues, with a predominantly spiral structure. AMPs are positively charged, amphipathic structures of great variety and without a significant molecular length. They exhibit a broad spectrum of antimicrobial activity against Gram-positive and Gram-negative bacteria, viruses and parasites over a wide range of pH and temperatures. In nature they represent an important part of the innate immune protection of animals and insects. It is thought that they even replace the immune response in the lower organisms – an example of this are the isolated cecropins, defensins and maggenes.AMPs perform a rapid bactericidal effect (in vitro – within minutes). In recent years they have been identified as "natural antibiotics". This review is focused on the classification of AMPs, their antimicrobial activity and mechanism of action

Aspects Of The Use Of RGD Peptides

Аминокиселинната последователност L-аргининил-глицил-L-аспарaгинова киселина (L-argininyl-glycyl-L-aspatric acid) – RGD, е присъщa на много екстрацелуларни и вътреклетъчни белтъци. Първоначално пептидът RGD е идентифициран във фибронектин през 1984 г. от E. Ruoslahti, който установява, че тези три аминокиселини са мястото за осъществяване на свързване (адхезия) на клетките към извънклетъчния матрикс или други клетки посредством клетъчни адхезивни молекули като интегрини. В последствие този три-аминокиселинен остатък е открит и в много други белтъци, намиращи се в екстрацелуларния матрикс и в кръвта. Той представлява общ мотив за разпознаване от някои рецептори на клетките. След откриването на RGD последователността като потенциален лиганд за свързване с клетъчните интегрини (най-често αvβ3) RGD-медиираните малки молекули и RGD-съдържащите терапевтични пептиди и белтъци се използват за контролирано лекарствено разпределение и като агенти за клетъчно прицелване и ендозомно доставяне. Поради големия брой интегрини в ендотелиалните клетки и кръвоснабдяването на туморните тъкани RGD-медиираното лекарствено доставяне представлява специален интерес в противораковата терапия. Освен това RGD-интегриновата система се използва за прицелно клетъчно разпознаване и интернализация, което се прилага при създадени от човека структури, които имитират патогените. Поради това си свойство системите се изследват за приложение като диагностици, терапевтици и регенериращи трансплантираните тъкани.Откриването на тумори се отличава с висока специфичност и чувствителност чрез конюгация на маркерите с RGD-пептиди. Тази важна технология се използва широко за ранна диагностика и диференциална диагноза на туморите, както и клиничен анализ и лечение. RGD модифицираните лекарства и агенти за образна диагностика се създават чрез конюгация на RGD-пептидите с носители. Молекулите носители биват натоварени с лекарствени молекули или молекули, генериращи сигнал. RGD-пептидите и RGD-миметиците се прилагат също и за модифициране на липозоми, полимери и пептиди по химичен начин, което повишава биологичните им ефекти като терапевтични агенти.RGD-пептидите са перспективни молекули с голямо бъдещо приложение в терапията като лекарство-доставяща система, в образната диагностика и в тъканното инженерство.The amino acid sequence L-argininyl-glycyl-L-asparaginic acid (RGD) is inherent in many extracellular and intracellular proteins. Initially, the RGD peptide was identified in fibronectin in 1984 by E. Ruoslahti, who found that these three amino acids were the site of adhesion of cells to the extracellular matrix or other cells by cell adhesion molecules as integrins. Subsequently, this tri-amino acid residue was also found in many other proteins in the extracellular matrix and blood. It is a common pattern of recognition by some cell receptors. Following the discovery of the RGD sequence as a potential ligand for binding to cellular integrins (most commonly αvβ3), RGD-mediated small molecules and RGD-containing therapeutic peptides and proteins have been used for controlled drug distribution and as agents for cell targeting and endosomal delivery. Due to the large number of integrins in endothelial cells and blood vessels to tumor tissues, RGD-mediated drug delivery is of a particular interest in cancer therapy. Furthermore, the RGD-integrin system is used for target cell recognition and internalization, which is applied to human-created structures that mimic pathogens. Because of this, the systems are being tested for use as diagnostics, therapeutics, and regenerating transplanted tissues.The detection of tumors is characterized by high specificity and sensitivity by conjugation of markers with RGD peptides. This important technology is widely used for early diagnosis and differential diagnosis of tumors as well as for clinical analysis and treatment. RGD-modified drugs and imaging agents have been created by conjugation of RGD peptides to carriers. The carrier molecules are loaded with drug molecules or signal-generating molecules. RGD peptides and RGD mimetics are also applied to modify liposomes, polymers and peptides in a chemical way that increases their biological effects as therapeutic agents.RGD peptides are promising molecules with great future use in therapy as a drug-delivery system, in imaging diagnostics and in tissue engineering

Sulfo- and Oxy-analogues of Arginine: Synthesis, Analysis and Preliminary Biological Screening

A novel methodology for the synthesis of sulfo- and oxy-modified amino acid analogues of arginine (Arg) has been developed using both conventional and polymer assisted synthesis from ready available amino acid precursor. Introduction of guanidine group was made also by the MWA synthesis. The in vitro inhibitory effect of the amino acid analogues on the growth of murine erythroleukemia cells, clone F4N in culture was also studied. (doi: 10.5562/cca1780

Antiproliferative and apoptogenic effects of myosmine on erythroleukemia and hepatocellular carcinoma cells

Myosmine, 3-(1-pyrroline-2-yl) pyridine is a minor tobacco alkaloid that has also been found in various widely used foods. Recently, this phytochemical has been gaining an increasing interest as a potential risk factor for the development of oesophageal adenocarcinoma. This study aimed to examine the effects of myosmine on the cell viability and proliferative activity of erythroleukemia and hepatocellular carcinoma cells and to obtain additional information about the mechanisms underlying its cytotoxic activity. The in vitro cytotoxic effect of myosmine on the HepG2 and MEL tumour cell lines was assessed by MTT dye reduction and trypan blue dye exclusion assays. The alterations in the tumour cell morphology induced by myosmine were analysed by fluorescent microscopy after staining with acridine orange (AO)/ethidium bromide (EtBr) and 4′,6-diamidine-2′-phenylindole dihydrochloride (DAPI). Annexin V-FITC/propidium iodide (PI) staining was used to assess the apoptosis-inducing ability of myosmine. The modulating action of antioxidant treatment on myosmine-induced cytotoxicity against the HepG2 tumour cell line was also examined. The cell viability tests indicated that myosmine induced a significant dose-dependent reduction of the viability and proliferative activity of both tumour cell lines. Fluorescent microscopy studies revealed marked alterations in the morphology of myosmine-treated tumour cells with signs of cell cycle arrest and apoptosis. The results of the simultaneous treatment with myosmine and vitamin C showed modulating activity of vitamin C on the cytotoxic effect of myosmine with concentration- and time-dependent variations. The presented results could contribute to the assessment of the potential health risks associated with the dietary myosmine exposure. Abbreviations AO: acridine orange; DAPI: 4‘,6-diamidine-2‘-phenylindole dihydrochloride; DMEM: Dulbecco's modified Eagle medium; DMSO: dimethyl sulfoxide; EtBr: ethidium bromide; FITC: fluorescein isothiocyanate; GERD: gastroesophageal reflux disease; MEL: murine erythroleukemia; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NNN: N'-nitrosonornicotine; PBS: phosphate buffered saline; PI: propidium iodid

Newly synthesized neuropeptides with central nervous activity in mice

Aim: Object of present study are two newly synthesized neuropeptides with short chains: analogues of Tyr-MIF – 1 with code P1 and of Nociceptine with code P2. Materials and Methods: On male albino mice we studied the changes in the cognitive functions of animals after 3, 7 and 14-days pretreatment with both compounds (5 mg/kg intraperitoneally- i.p.) via: step through test (for learning and memory), Rot-a-rod test (for muscular coordination) and Hole board test (for exploratory activity). Their potential analgesic effect was evaluated by Acetic acid test and their activity on the cen-tral nervous system (CNS) was evaluated via interaction with hexobarbital (HB- 100 mg/kg i.p). Statistics were performed with Student – Fisher test.Results: On the 3rd day after treatment daily both compounds had no effect on cognitive functions of animals, but on the 7th day the analogue of Tyr- MIF –1 (peptide P1) significantly improved the memory (by 60%) and decreased also the exploratory activity of treated animals. The analogue of Nociceptine-P2 demonstrated significant dose-dependent analgesic effect. On the 14th day both compounds improved neuro-muscular coordination of animals. In single doses two compounds shorten significantly duration of hexobarbital narcosis (Р1 by 40% and Р2 by 50%) via unknown mechanism, probably related to functional antagonism between the neuropeptides and hexobarbital on CNS level. Conclusion: Newly synthesized neuropeptides are promising biological active substances with effect on CNS. The analogue of Tyr-MIF–1 improves cognitive function of animals and the analogue of Nociceptine has significant dose-dependent analgesic effect

In vitro assessment of the cytotoxic effects of novel RGD analogues

The RGD sequence is present in many extracellular matrix proteins and intracellular proteins, including caspases. Synthetic RGD peptides may affect adhesion, migration and tumour metastasis, or directly induce apoptosis. Several RGD peptides were synthesized, and their anti-adhesive and cytotoxic properties were analyzed in vitro. Here we present the cytotoxic activities of RGD, R(NO2)GD, CavGD and RGD-OMe on non-tumour 3T3 cells and tumour cell lines HepG2 and MCF-7. The cell growth inhibitory effects of RGD-OMe are significantly higher than those of RGD on the cell lines used. Evidently the modification in the carboxylic group of RGD with simple esterification increases the cell growth inhibitory effects of the parent compound

Neurotensins and their therapeutic potential: research field study

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 retrieved research articles were analyzed by using the VOSviewer software. The most cited original articles were published between 1973 and 2013. The top-cited article was by Carraway and Leeman reporting the discovery of neurotensin in 1973. The highly cited terms were associated with hypotension and angiotensin-converting-enzyme. The conducted analysis reveals the therapeutic potentials of neurotensin, and further impactful research toward its clinical development is warrantied

Neurotensins and their therapeutic potential: research field study

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 retrieved research articles were analyzed by using the VOSviewer software. The most cited original articles were published between 1973 and 2013. The top-cited article was by Carraway and Leeman reporting the discovery of neurotensin in 1973. The highly cited terms were associated with hypotension and angiotensin-converting-enzyme. The conducted analysis reveals the therapeutic potentials of neurotensin, and further impactful research toward its clinical development is warrantied.MG Georgieva, AA Balacheva, TI Pajpanova, L Milella, AG Atanasov and NT Tzvetkov acknowledge the support by the Bulgarian National Science Found (BNSF) under grant number KP-06-OPR 03/8.info:eu-repo/semantics/publishedVersio