UV synchrotron radiation linear dichroism spectroscopy of the anti-psoriatic drug anthralin

Abstract

Anthralin (1,8-dihydroxyanthrone, 1,8-dihydroxy-9(10H)-anthracenone), also known as dithranol and cignolin, is one of the most efficient drugs in the treatment of psoriasis and other skin diseases. The precise mode of biochemical action is not fully understood, but the activity of the drug is increased by the influence of UV radiation. In the present investigation, the UV absorption of anthralin is studied by synchrotron radiation linear dichroism (SRLD) spectroscopy on molecular samples partially aligned in stretched polyethylene, covering the near and vacuum UV regions with wavenumbers ranging from 23,000 to 58,000 cm–1(430–170 nm). The observed polarization spectra are well predicted by quantum chemical calculations using time-dependent density functional theory (TD–DFT). About a dozen spectral features are assigned to computed electronic transitions. The calculations support interpretation of the anomalous fluorescence of anthralin as a result of barrier-less excited state intramolecular proton transfer (ESIPT) to the tautomer 8,9-dihydroxy-1(10H)-anthracenone.

Effect of turbidity on ultraviolet disinfection of domestic wastewater for agricultural reuse

“…Figure 2 shows that UV transmittance decreased exponentially with turbidity; therefore, transmittance differences between samples with 5 and 50 NTU were greater than those of samples with 200 and 300 NTU. Similar results were obtained by Nguyen et al (2019), wherein treatments that reduced effluent turbidity increased UV transmittance.…”

“…Transmittance is the amount of radiation passing through a sample relative to the emitted radiation. The lower the transmittance, the greater the amount of particles impairing disinfection (Nguyen et al, 2019). Transmittance decreased as turbidity increased (Figure 3).…”

“…In our study, heterotrophic bacteria counts were reduced by 3.0 logs at a dose of 20 mWs cm -2 and by 5 logs at a dose of 28.8 mWs cm -2 in samples with a turbidity of 5 NTU. Nguyen et al (2019) reported that the total count of E. coli was reduced by 5 logs in domestic wastewater pretreated with a UV dose of 69.4 mWs cm -2 in samples with an initial turbidity of 4 NTU.…”