Comprehensive study on the degradation of ochratoxin A in water by spectroscopic techniques and DFT calculations

Abstract

The OTA degradation process becomes irreversible only if, following hydrolyzation of the lactone ring, the molecule fragments.

Insights into the Ochratoxin A/Aptamer Interactions on a Functionalized Silicon Surface by Fourier Transform Infrared and UV–Vis Studies

“…At intermediate pH, the band at 380 nm overlaps with a second band centered at 340 nm. The decrease in intensity of the 380 nm band suggested that di-anionic OTA 2– coexists with mono-anionic OTA – in solution and that the band at 340 nm may be assigned to the latter . In strongly alkaline solution (pH 14), there is a blue shift and a broadening of the 380 nm band, suggesting the coexistence of a second band at high energy (∼350 nm).…”

“…mono-anionic OTAin solution and that the band at 340 nm may be assigned to the later. 7 In strongly alkaline solution pH (14) there is a blue shift and a broadening of the 380 nm band, suggesting the coexistence of a second band at high energy (~350 nm). The interpretation of the later remains uncertain.…”

“…The existence of a fourth form corresponding to the ring-opened form of OTA (OP-OTA) is suggested at pH higher than 8-8.5 4,5 even though pH higher than 12 is necessary to hydrolyze the lactone ring. 6,7 Figure 1. Chemical structures of OTA as a function of pH: acidic (1), close to neutral (2)(3) and alkaline (4) media.…”

“…However, when the carboxylic acid group on C22 (p K a1 = 4.4) and the phenolic group on C9 (p K a2 = 7.3) deprotonate in physiological buffer, forms (2) and (3), respectively, called OTA – and OTA 2– in the following, co-exist. The existence of a fourth form corresponding to the ring-opened form of OTA (OP-OTA) is suggested at pH higher than 8–8.5, , although pH higher than 12 is necessary to hydrolyze the lactone ring. , …”

“…The existence of a fourth form corresponding to the ring-opened form of OTA (OP-OTA) is suggested at pH higher than 8−8.5, 4,5 although pH higher than 12 is necessary to hydrolyze the lactone ring. 6,7 Mycotoxins such as OTA may be detected using biosensors 8−12 as it is a rapid and simple method with high specificity and sensitivity at relatively low cost compared to conventional chromatographic and immunoassay techniques. 13,14 In these devices, a specific probe is anchored on a solid surface to recognize the mycotoxin.…”