Estimation of Standards for Gold and Silver Sampling

U protetskoj se terapiji upotrebljava vrlo mnogo plemenitih slitina različita sastava. Plemeniti metali su sinonim za biokompatibilnost. Zlato je jedna od najinertnijih plementih kovina, a srebro jedna od najreaktivnijih. Cilj rada bio je razvijanje i raščlamba kromatografskih mrlja čistoga zlata i srebra (Aurodent, Celje, Slovenija). Kovine su uzorkovane na sobnoj temperaturi otopinom voda-HCl(conc.) (v/v 10:1) tijekom 10 s pri stalnom naponu struje od 4,5 V. Otopine kationa iz čistih kovina i 10 µl standardnih otopina soli nanesene su na HPTLC kromatografske ploče (Merck, Darmstadt, Njemačka) 10 x 10 cm presvučene celulozom. Ploče su razvijene u staklenoj kromatografskoj komori zasićenoj mobilnom fazom izo-amilni alkohol: HCl(conc.) : acetonitril u omjeru 5,4 : 4,3 : 0,3 do visine od približno 8 cm. Kada su razvijene sušene su u struji vrućega zraka, a kationi su vizualizirani prskanjem zasićenim etanolnim otopinama difenilkarbazida, alizarina, kvercetina te 0,1% otopinom ditizona u kloroformu. Nakon prskanja i sušenja ploče su izložene parama amonijaka i učinjena je vizualizacija. Uzorkovano zlato i srebro međusobno se razlikuje bojom kromatografskih mrlja i utvrđenim Rf vrijednostima. Metodom anodnoga uzorkovanja slitina i identifikacijom kationa tankoslojnom kromatogafijom moguće je dokazati postojanje određenih kationa s udjelom mase većim od 1%, ne oštećujući pritom sam uzorak. Metoda se pokazala prikladnom za uzorkovanje kovina zlata i srebra, što je nastavak dosadašnih istraživanja u identifikaciji određenih sastavnica u pojedinim slitinama ili u inkorporiranome protetskom radu.Different precious dental alloys are used in prosthodontic therapy. Precious metals are the synonym for biocompatibility. Gold is one of the most inert and silver the most active presious metals. The purpose of this study was to develop an analyze the chromatographic spots of pure gold and silver (Aurodent, Celje, Slovenia). The sampling was performed in a water-HCl(conc.) solution in a 10 : 1 volume ratio at room temperature using a 4,5 V battery. Dissoluted cations and solutions of standard elements (salts of gold and silver) were applied to HPTLC plates (Mareck, Darmstadt, Germany) 10 x 10 cm precoated with cellulose. Plates were developed in a vertical separating chamber to a height of approximately 8 cm saturated with iso-amyl (3.methyl-1-butanol) - HCl (36,5%) - acetonitrile in a volume ratio 5,4 : 4,3 : 0,3. After development, plates were dried in (a steam of) hot air and the cations were visualized by spraying with the saturated ethanolic solutions of alizarin, diphenylcarbazide, quercetin and 0,1% chlorophorm solution of dithizone. After drying, plates were exposed to NH3 vapor. According to the Rf value and the color of the spots, the difference between gold and silver were obtained. Anodic sampling with thin-layer chromatography is a suitable, nondestructive method for identification of cations presents in different dental alloys. It is possible to identify the cations with their mass ratio W > 1%. The results have shown that the described method is suitable for analysis of gold and silver and it can be used in future work to identify those cations in dental alloys of unknown composition

From functional food to medicinal product: Systematic approach in analysis of polyphenolics from propolis and wine

In the last decade we have been working on standardization of propolis extract and determination of active constituents of wine those are rich in polyphenolics and have nutritional as well as therapeutic value. Here we are summarizing our results and providing overview on systematic approach how to analyse natural products rich in flavonoids and phenolic acids

Antimicrobial activity against oral pathogens and immunomodulatory effects and toxicity of geopropolis produced by the stingless bee Melipona fasciculata Smith

<p>Abstract</p> <p>Background</p> <p>Native bees of the tribe Meliponini produce a distinct kind of propolis called geopropolis. Although many pharmacological activities of propolis have already been demonstrated, little is known about geopropolis, particularly regarding its antimicrobial activity against oral pathogens. The present study aimed at investigating the antimicrobial activity of <it>M. fasciculata </it>geopropolis against oral pathogens, its effects on <it>S. mutans </it>biofilms, and the chemical contents of the extracts. A gel prepared with a geopropolis extract was also analyzed for its activity on <it>S. mutans </it>and its immunotoxicological potential.</p> <p>Methods</p> <p>Antimicrobial activities of three hydroalcoholic extracts (HAEs) of geopropolis, and hexane and chloroform fractions of one extract, were evaluated using the agar diffusion method and the broth dilution technique. Ethanol (70%, v/v) and chlorhexidine (0.12%, w/w) were used as negative and positive controls, respectively. Total phenol and flavonoid concentrations were assayed by spectrophotometry. Immunotoxicity was evaluated in mice by topical application in the oral cavity followed by quantification of biochemical and immunological parameters, and macro-microscopic analysis of animal organs.</p> <p>Results</p> <p>Two extracts, HAE-2 and HAE-3, showed inhibition zones ranging from 9 to 13 mm in diameter for <it>S. mutans </it>and <it>C. albicans</it>, but presented no activity against <it>L</it>. <it>acidophilus</it>. The MBCs for HAE-2 and HAE-3 against <it>S. mutans </it>were 6.25 mg/mL and 12.5 mg/mL, respectively. HAE-2 was fractionated, and its chloroform fraction had an MBC of 14.57 mg/mL. HAE-2 also exhibited bactericidal effects on <it>S. mutans </it>biofilms after 3 h of treatment. Significant differences (p < 0.05) in total phenol and flavonoid concentrations were observed among the samples. Signs toxic effects were not observed after application of the geopropolis-based gel, but an increase in the production of IL-4 and IL-10, anti-inflammatory cytokines, was detected.</p> <p>Conclusions</p> <p>In summary, geopropolis produced by <it>M. fasciculata </it>can exert antimicrobial action against <it>S. mutans </it>and <it>C. albicans</it>, with significant inhibitory activity against <it>S. mutans </it>biofilms. The extract with the highest flavonoid concentration, HAE-2, presented the highest antimicrobial activity. In addition, a geopropolis-based gel is not toxic in an animal model and displays anti-inflammatory effect.</p

Picoplankton community structure before, during and after convection event in the offshore waters of the Southern Adriatic Sea

This paper documents the picoplankton community's response to changes in oceanographic conditions in the period between October 2011 and September 2012 at two stations belonging to the South Adriatic Pit (SAP). The recorded data include the community's abundance, composition, prokaryotic production rates and bacterial metabolic capacity. The sampling period included an intense sea cooling with formation of exceptional, record-breaking dense water. We documented an especially intense winter convection episode that completely diluted the core of Levantine intermediate waters (LIW) in a large area encompassing the SAP's center and its margin. During this convection event the whole picoplankton community had significantly higher abundances with a recorded picoeukaryotic peak at the SAP margin. In the post-convection phase in March, prokaryotic heterotrophic production strongly increased in the entire SAP area (up to 50 times; 456.8 nM C day⁻¹). An autotrophic biomass increase (up to 5 times; 4.86 μg L⁻¹) and a disruption of a close correspondence between prokaryotic heterotrophic biomass production and cell replication rates were observed only in the center of the SAP, which was not under the influence of LIW. At the SAP's margin such an effect was attenuated by LIW, since the waters affected by LIW were characterized by decreased concentrations of dissolved inorganic nitrogen, decreased autotrophic biomasses, and by increased bacterial biomass production balanced with cell replication rates as well as by the domination of <i>Synechococcus</i> among autotrophic picoplankton. The metabolic capacity was lowest in spring when autotrophic biomass largely increased, while the highest levels found in the pre-convection phase (October 2011) suggest that the system was more oligotrophic before than after the convection event. Furthermore, we showed that metabolic capacity is a trait of bacterial community independent of environmental conditions and tightly linked to cell replication and substrate availability. In contrast, the bacterial community composition appears to be strongly influenced by physico-chemical characteristics of waters (e.g., temperature and nutrients) and environmental forcing (e.g., convection and LIW). Our results showed that the two oceanographic phenomena of the Southern Adriatic, strongly relevant for the total production of the Adriatic Sea, winter convection and LIW intrusion, regulate the changes in picoplankton community structure and activities