Photosensitive inhibition of sodium pheophorbide a against Pestalotiopsis neglecta under different light conditions

Sodium pheophorbide a (SPA) is a water-soluble sodium salt of pheophorbide a, an intermediate product of chlorophyll metabolism, which has good photoactivated antimicrobial activity. To investigate the effects of illumination conditions on its antifungal activity, the mycelial growth rate method was used to study the photoactivated inhibitory effect of SPA on Pestalotiopsis neglecta under different light intensities, light wavelengths and light durations. The results showed that, when treated by 20 mg/mL SPA, the inhibition rate of mycelial growth was 83.7% under white light with an illuminance of 2 000 lx, and the inhibition rate was 77.0% under dark conditions, which indicated that light had a significant effect on the antifungal activity of SPA (P < 0.05), and the effect of white light was better than that of the monochromatic light. In addition, light intensity and duration also had significant effects on the antifungal activity of SPA, and the strongest effect was observed when the light intensity was 16 000 lx and the light duration was 24 h.