Table 1.
Main spectra of light source.
Figure 1.
Variation in the quantity of native mycolactones after exposure to UV irradiation in quartz and glass tubes.
(A) Remaining native mycolactones after different exposure times and UV wavelengths in quartz tubes. (B) Representation of the linear relationship between mycolactones and time irradiation to calculate half-life time in quartz tubes. (C) Remaining native mycolactones after different exposure times and UV wavelengths in glass tubes. (D) Representation of the linear relationship between mycolactones and time irradiation to calculate half-life time in glass tubes. Results in (A) and (C) represent mean values of triplicate experiments. Standard deviations represent less than 2.5% of the obtained mean values. C0 and Ct are the concentration at times 0 and t, t is the irradiation time.
Table 2.
Kinetic parameters of mycolactone degradation at different UV wavelengths.
Figure 2.
Photodegradation of mycolactones after exposure to natural and artificial lights.
Results represent mean values of triplicate experiments. Standard deviations represent less than 2.5% of the obtained mean values. C0 and Ct are the concentration at times 0 and t, t is the irradiation time.
Figure 3.
Variation in the quantity of native mycolactones after exposure to UV at 312 nm in different solvents and in amber tubes.
Results represent mean values of triplicate experiments. Standard deviations represent less than 2.5% of the obtained mean values. C0 and Ct are the concentration at times 0 and t, t is the irradiation time.
Figure 4.
LC-MS and NMR analysis of mycolactones after 12-h UV irradiation.
(A) Extracted ion current chromatogram for the mycolactone control shows a 26.19-min retention time and (B) for the mycolactones after UV exposure. (C) Positive ESI mass spectrum at 26.19 min revealing the presence of mycolactones A/B [M+H]+ at m/z : 743.5092 for the control and (D) its absence UV exposure. (E) 1H NMR spectrum (Acetone-d6, 298 K, 400 MHz) of mycolactone control and (F) mycolactones after exposure.
Figure 5.
Key 1H-1H COSY (COrrelation SpectroscopY) and 1H-13C HMBC (Heteronuclear Multiple-Bond Correlation) correlations for one fragment.
Figure 6.
Cytotoxic evaluation of mycolactones after irradiation.
(A) Cytotoxic effect of mycolactones: a dose response. Raw 264.7 cells were incubated with mycolactones during 24 hours. (B) Cytotoxic effect evaluation of mycolactones after light and UV exposure. Medium is a culture medium containing 1% of acetonitrile. Asterisks indicate significant (p<0.05) effect of exposure to light on mycolactone cytotoxic effect.