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. 2020 Aug 10;10(1):13473.
doi: 10.1038/s41598-020-70370-x.

Performance of a UV-A LED system for degradation of aflatoxins B1 and M1 in pure water: kinetics and cytotoxicity study

Judy Stanley  1 , Ankit Patras  2 , Brahmaiah Pendyala  3 , Matthew J Vergne  4 , Rishipal R Bansode  5
Affiliations

Performance of a UV-A LED system for degradation of aflatoxins B1 and M1 in pure water: kinetics and cytotoxicity study

Judy Stanley et al. Sci Rep. .

Abstract

The efficacy of a UV-A light emitting diode system (LED) to reduce the concentrations of aflatoxin B1, aflatoxin M1 (AFB1, AFM1) in pure water was studied. This work investigates and reveals the kinetics and main mechanism(s) responsible for the destruction of aflatoxins in pure water and assesses the cytotoxicity in liver hepatocellular cells. Irradiation experiments were conducted using an LED system operating at 365 nm (monochromatic wave-length). Known concentrations of aflatoxins were spiked in water and irradiated at UV-A doses ranging from 0 to 1,200 mJ/cm2. The concentration of AFB1 and AFM1 was determined by HPLC with fluorescence detection. LC-MS/MS product ion scans were used to identify and semi-quantify degraded products of AFB1 and AFM1. It was observed that UV-A irradiation significantly reduced aflatoxins in pure water. In comparison to control, at dose of 1,200 mJ/cm2 UV-A irradiation reduced AFB1 and AFM1 concentrations by 70 ± 0.27 and 84 ± 1.95%, respectively. We hypothesize that the formation of reactive species initiated by UV-A light may have caused photolysis of AFB1 and AFM1 molecules in water. In cell culture studies, our results demonstrated that the increase of UV-A dosage decreased the aflatoxins-induced cytotoxicity in HepG2 cells, and no significant aflatoxin-induced cytotoxicity was observed at UV-A dose of 1,200 mJ/cm2. Further results from this study will be used to compare aflatoxins detoxification kinetics and mechanisms involved in liquid foods such as milk and vegetable oils.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
(a) Measured absorption spectra of AFB1 and AFM1 in ultrapure water using Cary100 spectrophotometer (b) Measured spectral irradiance of UV-A LED using Ocean optics QE Pro spectrometer equipped with UV–visible optical fiber.
Figure 2
Figure 2
Degradation kinetics of (a) AFB1 (b) AFM1 in ultrapure water at different UV-A dose levels.
Figure 3
Figure 3
LCMS single ion monitoring (SIM) total ion chromatograms (TIC) of (a) AFB1 and (b) AFM1 samples treated at UV-A dose 1,200 mJ/cm2.
Figure 4
Figure 4
Proposed UV-A light degradation mechanism of (a) AFB1 and (b) AFM1 in ultrapure water.
Figure 5
Figure 5
Cytotoxic effect of untreated and UV-A treated ultrapure water consists of (a) AFB1 (b) AFM1 on human hepatoma HepG2 cells. Results are expressed as mean percentage ± SD of two separate experiments. Levels connected by different letters are significantly different at p < 0.05.
See this image and copyright information in PMC

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