Vol.3, No 1, 2004 pp. 53 - 60
UDC 669.162.28, 661.8
THE EFFECTS OF DIETARY NITRATE,
pH AND TEMPERATURE ON NITRATE REDUCTION IN THE HUMAN ORAL CAVITY
Danijela V. Bojić, Aleksandar Lj. Bojić, Jelica M. Perović
Department of Chemistry, Faculty of Sciences and Mathematics,
University of Niš, Serbia
Abstract. Dietary nitrate is metabolized to nitrite by bacterial
flora on the posterior surface of the tongue leading to increased salivary
nitrite concentrations. In the acidic environment in the stomach, nitrite
forms nitrous acid, a potent nitrosating agent. The aim of this study was
to examine the effects of dietary nitrate, pH and temperature on nitrate
reduction in the human oral cavity. Nitrate reduction was monitored by
nitrate reduction assay, based on incubation of nitrate test solutions
in the mouth. Results show that all investigated factors significantly
influence the reduction of nitrate in the oral cavity. With increasing
levels of nitrate the amounts of nitrite in reduction assay increased,
but reduction ratio (NO-2 /NO-3
) decreased in this conditions. Influence of pH on nitrate reduction is
specific and in line with nature of nitrite-producing bacteria. The greatest
reduction activity of bacteria is at pH 8. Variations of temperature of
the oral cavity due to outdoor conditions also influence its reduction
activity, which is twice lower in January than in July.
Key words: nitrate, nitrite, oral cavity, reduction, pH, temperature
UTICAJ EGZOGENOG NITRATA, pH I TEMPERATURE
NA REDUKCIJU NITRATA U USNOJ DUPLJI ČOVEKA
Egzogeni nitrati se prevode u nitrite delovanjem bakterija zadnjeg dela
površine jezika, što dovodi do povećanja koncentracije nitrita u ustima.
U kiseloj sredini želuca nitriti formiraju nitritnu kiselinu, potencijalni
nitrozujući agens. Cilj ovog rada je ispitivanje uticaja egzogenog nitrata,
pH i temparature na redukciju nitrata u usnoj duplji čoveka. Redukcija
nitrata je merena redukcionim esejem, koji se bazira na inkubaciji rastvora
nitrata u ustima. Rezulatati pokazuju da svi ispitivani faktori imaju značajan
uticaj na redukciju nitrata u usnoj duplji. Sa povećanjem koncentracije
nitrata količina nitrita u redukcionom eseju raste, međutim, stepen redukcije
(NO-2 /NO-3
) opada u ovim uslovima. Uticaj pH na redukciju nitrata je specifičan i
u skladu je sa prirodom nitrato-redukujućih bakterija. Najveća redukciona
aktivnost bakterija je na pH 8. Oscilacije temperature usne duplje, izazvane
spoljašnjim uticajem, takođe utiču na njenu redukcionu aktivnost, koja
je dvostruko manja u jabnuaru u odnosu na izmerenu vrednost u julu.
