ABSTRACT
Ethyl-4-aminobenzoate (Et-PABA) is currently used as a substitute for 4-aminobenzoate (PABA) in sunscreens and anesthetic ointments. Despite its widespread use and hydrophilicity, Et-PABA has never been found in environmental waters. This study, probed the occurrence of Et-PABA in both seawater and drinking water sources in Hong Kong, and evaluated its transformation products (TPs) and environmental fate via cumulative potency and photocatalytic profile analyses. Another 11 UV filters used in skin-care products were also studied. Et-PABA was not detected in any water sample. Four other UV filters were dominant at ng/L level in both seawater and drinking water sources. UHPLC-QTOF-MS was used to elucidate the structure of TPs. With high resolution accurate mass data and fragment rationalization, 11 Et-PABA TPs were characterized, including seven intermediates firstly proposed as TPs; two compounds were reported for the first time. It is proposed that photocatalysis induces transformation pathways of (de)hydroxylation, demethylation and molecular rearrangement. Luminescent bacteria tests showed decreasing toxicity with increasing irradiation of Et-PABA, suggesting that irradiation TPs are less toxic than the parent compound. Transformation of Et-PABA appears to explain why Et-PABA has not been detected in the natural environment.
Subject(s)
Benzocaine/chemistry , Sunscreening Agents/chemistry , Ultraviolet Rays , Water Pollutants, Chemical/chemistry , Aliivibrio fischeri/drug effects , Aliivibrio fischeri/metabolism , Benzocaine/isolation & purification , Benzocaine/toxicity , Catalysis , Chromatography, High Pressure Liquid/methods , Drinking Water/chemistry , Hong Kong , Hydroxylation , Limit of Detection , Luminescence , Mass Spectrometry/methods , Photolysis , Seawater/chemistry , Sunscreening Agents/isolation & purification , Sunscreening Agents/toxicity , Water Pollutants, Chemical/isolation & purification , Water Pollutants, Chemical/toxicityABSTRACT
A new heteroleptic iridium complex demonstrated low cytotoxicity and near-infrared excitation (via two-photon absorption) for target-specific in vitro Golgi imaging in various cell lines (HeLa and A549 cells) with two-photon absorption cross section (~350 GM) in DMSO.
Subject(s)
Golgi Apparatus/metabolism , Iridium/chemistry , Luminescent Agents/chemistry , Luminescent Agents/metabolism , Organometallic Compounds/chemistry , Organometallic Compounds/metabolism , Photons , Golgi Apparatus/drug effects , HeLa Cells , Humans , Luminescent Agents/chemical synthesis , Luminescent Agents/toxicity , Organometallic Compounds/chemical synthesis , Organometallic Compounds/toxicityABSTRACT
Oxidative stress has been implicated in the pathogenesis of diabetic complications. We have previously demonstrated the occurrence of oxidative stress in the eye and aorta but not in the kidney of diabetic rats. In the present study we have investigated the effects of danshen, a herb used in traditional Chinese medicine to treat ailments related to diabetic complications, on the onset of oxidative stress in the above tissues. Diabetic rats were treated with 3 g/kg of danshen via oral intubation for 7 weeks. Afterwards, the tissue levels of glutathione (GSH), the primary endogenous antioxidant, and malondialdehyde (MDA), a marker of oxidative stress, were measured. Our results showed that danshen treatment did not alter the hyperglycemic status of the diabetic animals. However, the GSH levels were normalized in both the eye and aorta of the diabetic rats when these rats were administered with danshen. Administration with danshen also restored the level of MDA in the eye and aorta of the diabetic rats to that found in the control rats. These changes, however, were not observed in the kidney where oxidative stress did not occur. These results suggested that oral administration of danshen can effectively prevent the occurrence of oxidative stress in the eye and aorta of the diabetic rats. Furthermore, danshen treatment did not affect the blood glucose concentration of the animals irrespective of their diabetic state. These data therefore provide important information on mode of action of danshen, thereby establishing a basis for this herb to be used as a supportive treatment regime to ameliorate the severity of diabetic complications.
