Ureidopyrazine Derivatives: Synthesis and Biological Evaluation as Anti-Infectives and Abiotic Elicitors.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) has become a frequently deadly infection due to increasing antimicrobial resistance. This serious issue has driven efforts worldwide to discover new drugs effective against Mtb. One research area is the synthesis and evaluation of pyrazinamide derivatives as potential anti-TB drugs. In this paper we report the synthesis and biological evaluations of a series of ureidopyrazines. Compounds were synthesized by reacting alkyl/aryl isocyanates with aminopyrazine or with propyl 5-aminopyrazine-2-carboxylate. Reactions were performed in pressurized vials using a CEM Discover microwave reactor with a focused field. Purity and chemical structures of products were assessed, and the final compounds were tested in vitro for their antimycobacterial, antibacterial, and antifungal activities. Propyl 5-(3-phenylureido)pyrazine-2-carboxylate (compound 4, MICMtb = 1.56 µg/mL, 5.19 µM) and propyl 5-(3-(4-methoxyphenyl)ureido)pyrazine-2-carboxylate (compound 6, MICMtb = 6.25 µg/mL, 18.91 µM) had high antimycobacterial activity against Mtb H37Rv with no in vitro cytotoxicity on HepG2 cell line. Therefore 4 and 6 are suitable for further structural modifications that might improve their biological activity and physicochemical properties. Based on the structural similarity to 1-(2-chloropyridin-4-yl)-3-phenylurea, a known plant growth regulator, two selected compounds were evaluated for similar activity as abiotic elicitors.

Azorella compacta Infusion Activates Human Immune Cells and Scavenges Free Radicals In vitro.

BACKGROUND: Azorella compacta is traditionally used in the form of tea (infusion), in the Andean region of South America, to treat various chronic diseases. However, the health-promoting properties of this herbal tea have not yet been extensively explored. MATERIALS AND METHODS: The free radical scavenging activity of A. compacta infusion (ACI) was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and superoxide anion radical assays. The activation of immune cells by ACI, as determined by cell surface cluster of differentiation 69 expression, was measured by flow cytometry. The qualitative polyphenolic composition of ACI was investigated by HPLC/PDA/ESI-MS, (High-performance liquid chromatography coupled with photodiode array detection and electrospray ionization - mass spectrometry) and the total content of polyphenols was estimated by spectrophotometric methods. RESULTS: Eight polyphenols including chlorogenic acid, 6,8-di-C-hexosyl apigenin, isoorientin, orientin, dicaffeoylquinic acid, biochanin A-O-glucoside, biochanin A-O-(malonyl)-glucoside, and licoisoflavone A were tentatively identified in ACI. The total contents of phenols, flavonoids, and tannins in lyophilized ACI were 5.40 mg/100 mg ACI, 1.79 mg/100 mg ACI, and 1.76 mg/100 mg ACI, respectively. ACI, within the range of 25-400 µg/mL, scavenged DPPH and O2.- by 15-90% and 20-88%, respectively. The human natural killer (NK) cells were substantially activated by ACI, whereas T cells and granulocytes were slightly stimulated. CONCLUSION: Overall, the results demonstrate the free radical scavenging and immune-stimulating properties of ACI, and support, at least in part, its potential utilization as a functional herbal tea. for preventing chronic diseases and as a nonspecific immune stimulator during human immunosenescence. SUMMARY: The total contents of phenols, flavonoids, and tannins in Azorella compacta infusion (ACI) were 5.40 mg/100 mg ACI, 1.79 mg/100 mg ACI, and 1.76 mg/100 mg ACI, respectively.Eight polyphenols including chlorogenic acid, 6,8-di-C-hexosyl apigenin, isoorientin, orientin, dicaffeoylquinic acid, biochanin A-O-glucoside, biochanin A-O-(malonyl)-glucoside, and licoisoflavone A were tentatively identified in ACI by HPLC/PDA/ESI-MS.ACI, within the range of 25-400 µg/ml, scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) and O2. by 15-90% and 20-88%, respectively.The human natural killer (NK) cells were substantially activated by ACI, whereas T cells and granulocytes were slightly stimulated. Abbreviations used: ESI: electrospray ionization, HPLC: high performance liquid chromatography, PDA: photodiode array detector, MS: mass spectrometry, MS/MS: tandem mass spectrometry, MW: molecular weight, m/z: mass-to-charge ratio, FITC: fluorescent isothiocyanate, PE: phycoerythrin.

New Synthetic Pyrazine Carboxamide Derivatives as Potential Elicitors in Production of Secondary Metabolite in In vitro Cultures.

BACKGROUND: Silymarin, an active polyphenolic fraction of Silybum marianum, and high flavonoid content of Fagopyrum possess various interesting biological activities. The substituted pyrazine-2-carboxamides were previously used as effective elicitors of studied secondary metabolites. OBJECTIVE: To study the effect of new synthetic pyrazine carboxamide derivatives, N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide (1) and 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide (2), on flavonolignan and flavonoid production in S. marianum and Fagopyrumes culentum in vitro cultures. MATERIALS AND METHODS: Callus and suspension cultures were cultured on MS medium containing α-naphtaleneacetic acid or 2,4-D. Three elicitor concentrations for different exposure times were tested. Dried and powdered samples of callus and suspension cultures were extracted with methanol and analyzed by DAD-HPLC. RESULTS: Compound 1 showed as a good elicitor of taxifolin production. The effect on silymarin complex was less visible with a maximum between 24 and 48 h after 3.292 ×10(-4) mol/L concentration. The detailed analysis showed that silychristin was the most abundant. Compound 2 was effective in rutin production only in callus culture with maximum 24 h and 168 h after application of 3.3756 ×10(-3) mol/L concentration and 48 and 72 h after 3.3756 ×10(-4) mol/L concentration. CONCLUSION: From the results of the performed experiments, it can be concluded that compound 1 shows to be suitable elicitor for enhanced production of taxifolin and silychristin in S. marianum, mainly when 3.292 ×10(-4) mol/L concentration was used, and compound 2 is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum. SUMMARY: The influence of two new synthetic pyrazine-2-carboxamidesderivatives on secondary metabolite content of Silybum marianum and Fagopyrum esculentum in vitro cultures was tested.In S. marianum, the derivate N-(4-chlorobenzyl)-5-tert-butylpyrazine-2-carboxamide showed as a good elicitor of taxifolin production and less effective for silymarin complex production with silychristin as the most abundant.The derivate 3-(3-((trifluoromethyl) benzyl) amino) pyrazine-2-carboxamide is suitable for increase rutin production in callus cultures and less appropriate for suspension cultures of F. esculentum.

Hydrogen sulfide donor protects porcine oocytes against aging and improves the developmental potential of aged porcine oocytes.

Porcine oocytes that have matured in in vitro conditions undergo the process of aging during prolonged cultivation, which is manifested by spontaneous parthenogenetic activation, lysis or fragmentation of aged oocytes. This study focused on the role of hydrogen sulfide (H2S) in the process of porcine oocyte aging. H2S is a gaseous signaling molecule and is produced endogenously by the enzymes cystathionine-ß-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MPST). We demonstrated that H2S-producing enzymes are active in porcine oocytes and that a statistically significant decline in endogenous H2S production occurs during the first day of aging. Inhibition of these enzymes accelerates signs of aging in oocytes and significantly increases the ratio of fragmented oocytes. The presence of exogenous H2S from a donor (Na2S.9H2O) significantly suppressed the manifestations of aging, reversed the effects of inhibitors and resulted in the complete suppression of oocyte fragmentation. Cultivation of aging oocytes in the presence of H2S donor positively affected their subsequent embryonic development following parthenogenetic activation. Although no unambiguous effects of exogenous H2S on MPF and MAPK activities were detected and the intracellular mechanism underlying H2S activity remains unclear, our study clearly demonstrates the role of H2S in the regulation of porcine oocyte aging.

[Bergenia genus - content matters and biological activity]. / Rod Bergenia - obsahové látky a biologická aktivita.

Bergenia, a genus included in the family Saxifragaceae, is a valuable source of healing matters. About 30 Bergenia species are known all over the world. Scientific research is focused on five species mainly distributed in the mountains of Central and East Asia: Bergenia ciliata (Haw.) Sternb., Bergenia stracheyi Engl., Bergenia crassifolia (L.) Fritsch, Bergenia ligulata (Wall.) Engl. and Bergenia himalaica Boriss. These taxons belong to the widely used medicinal herbs in the traditional Chinese, Nepalese and Indian medicine, for therapy of cough and pulmonary diseases, to stop bleeding, to increase immunity and to dissolve kidney or bladder stones. Bergenia consists of many different active compounds including bergenin, norbergenin, catechin, gallic acid, arbutin and other polyphenols. In the Czech Republic this species is commonly grown but it is not used for medical therapy. Individual parts of this plant demonstrate an interesting biological activity, and antibacterial, antiviral, cytoprotective and antioxidant effects.

Substituted pyrazinecarboxamides as abiotic elicitors of flavolignan production in Silybum marianum (L.) gaertn cultures in vitro.

Substituted pyrazinecarboxamides markedly influenced production of flavonolignans in Silybum marianum callus and suspension cultures. In this study the effect of two compounds, N-(3-iodo-4-methylphenyl)pyrazine-2-carboxamide (1) and N-(3-iodo-4-methylphenyl)-5-tert-butyl-pyrazine-2-carboxamide (2), as abiotic elicitors on flavono-lignan production in callus culture of S. marianum was investigated. Silymarin complex compounds have hepatoprotective, anticancer and also hypocholesterolemic activity. In vitro flavonolignan concentration in cells is very low and the elicitation is one of the methods to increase production. Elicitors were tested at three concentrations and at different culture times. In the case of elicitation with 1, the greatest increase of flavonolignan and taxifoline production was observed at concentration c(1a) after 6-hours of elicitation and after 24 and 72-hours at concentration c(1b). However, increased production of silychristin, one of the compounds in the silymarin complex, was achieved after only 6-hours elicitation with c(1a) (2.95 x 10(-4) mol/L). The content of silychristin was 2-times higher compared to the control sample. An increased production of silychristin was reached with compound 2 at the concentration c(2) (2.53 x 10(-3) mol/L) after 72 h of elicitation. The production of silychristin in this case was increased 12-times compared to control.