Long-wave UV Light Research Articles

The use of 1,6-diphenylhexatriene to detect lipids on thin-layer chromatograms

1,6-diphenylhexatriene (DPH) fluoresces violet under long-wave uv light in the presence of lipid on silica gel thin-layer chromatograms. The DPH, sprayed as a solution in a volatile nonpolar solvent, detects submicrogram quantities of all lipid classes. It is a nondestructive marker and can be removed subsequently by elution with a petroleum ether (40–60°C).

The pigmentary response to photochemotherapy

Previous studies on skin topically photosensitized with trimethylpsoralen and subsequently irradiated with long-wave UV light have demonstrated an increase in melanosome size and changes in the distribution patterns of melanosomes, suggesting the possibility of gene derepression or the induction of a somatic mutation of melanocytes. The present investigation was performed to determine whether identical changes are induced by systemic photochemotherapy using 8-methoxypsoralen and UVA (PUVA) under therapeutic conditions. Our results show that PUVA stimulates melanogenesis but does not induce significant changes in the average size of melanosomes nor in their distribution patterns within keratinocytes. Thus they indicate that under therapeutic conditions PUVA does not induce morphologically detectable cytogenetic changes in pigment cells.

Determination of linamarin in biological tissues

A new paper chromatography method for determination of intact cyanogenic glucoside linamarin is based on a reaction with p-anisaldehyde at 85°C; the reaction produces a pink color which is brightly fluorescent under long-wave uv light.

An assessment of the roles of furanocoumarins in Heracleum lanatum

Several naturally occurring furanocoumarins such as xanthotoxin cause cell damage by complexing with DNA in the presence of long-wave UV light. Heracleum lanatum, an Umbellifer, contains high concentrations of such compounds in the leaves but survives in sunlight and is a food source for insects, fungi, and man. Microscopic investigations and feeding experiments carried out in long-wave UV show that although the compounds are normally isolated in the petiolar oil ducts, the plant can tolerate xanthotoxin uptake in the transpiration stream. Aphids living on Heracleum take up and bind xanthotoxin fed via a cut stem but are unaffected over short term. Such tolerance in plant and aphid may be due to limited cell divisions during the test, but the biochemical basis of tolerance in growing Heracleum is not known. Various fungi, including pathogens of Umbellifers, show differing sensitivities to xanthotoxin plus UV, perhaps because of differing uptake rates and growth habits.

8-Methoxypsoralen And Uva Promote Sister-Chromatid Exchanges

8-Methoxypsoralen (8-MOP) and long-wave UV light (UVA 365 nm) are now being use to treat vitiligo and psoriasis. Cultured human lymphocytes exposed to these agents in vitro show an increased infrequency of sister chromatid exchanges, related to 8-MOP-DNA photoadducts. Although these data raise questions regarding the biologic consequences of this therapeutic regimen, it is unknown whether 8-MOP and UVA cause mutations or extracutaneous somatic cell recombinants in vivo. Exchanges may represent cellular repair of DNA damage.

The fate of tetrachlorosalicylanilide in photosensitized guinea pigs

The distribution and fate of 3, 3', 4', 5-tetrachlorosalicylanilide (TCSA) in photosensitized guinea-pig skin following topical application at varying times was investigated by fluorescence microscopy in unfixed, frozen sections. When the site to which TCSA had been applied was irradiated with long-wave UV light, TCSA was detected in the entire epidermis only 3 days after application and in the horny layer up to 10 days. Unless TCSA-treated sites were exposed to light, TCSA was still recognized in the entire epidermis 10 days after application and in the horny layer even at 3 weeks. The irradiated photosensitized guinea pigs in the present study eliminated TCSA more rapidly than normal control animals in our previous work. The mechanism of persistent light reaction was discussed and we concluded that TCSA can remain in the skin for a long time, because it is a prohapten, not a hapten.

Thin-layer chromatographic study of isoquinoline alkaloids with the BN-chamber

Continuous solvent flow thin-layer chromatography with horizontal development using the BN-chamber was successful in the separation of isoquinoline alkaloids on this layers of silica gel H F 254 with acidic and basic solvent systems. Attempts to replace silica gel by other adsorbents did not have a desirable effect. Quantities as low as 1 μg of pure alkaloids were applied and detected by fluorescence under long-wave UV light. The quantity applied was under the detection limit of Dragendorff and iodoplatinate reagents. This procedure is limited to lesser quantities (a maximum of 5 μg of alkaloid per spot) owing to the overlapping of the various spots.

Induction of Respiration-Deficient Mutants in Yeast by Psoralen and Light

4,5', 8-trimethylpsoralen (TMP) and 8-methoxypsoralen (MOP) plus long-wave UV light were found to be potent inducers of respiration-deficient mutants in yeast. TMP was found to be about 100 times as potent as MOP and gave a significant increase in the mutation rate at a concentration of 10 ‒7 ‒10 ‒8 M/Iiter. At concentrations of MOP and TMP that gave 100 % mutants the growth inhibition was rather small.

Rapid Detection of Aflatoxin Contamination in Agricultural Products

Abstract A rapid and simple method, originally designed for detecting aflatoxin contamination in cottonseed products within 15 min, was modified for application to a variety of agricultural products. The modified method involves rapid blender extraction of the sample with aqueous acetonitrile, treatment of an aliquot of the filtrate with lead acetate solution to remove interfering pigments, and rapid partition of aflatoxins in the treated extract into benzene to effect an 8-fold concentration of the aflatoxins. A portion of the benzene extract is adsorbed by capillary attraction onto the bottom of a small column (4 mm × 20 cm) filled with zones of acidic alumina and silica gel and the column is allowed to develop 5 min in chloroform-acetonitrile-2-propanol (93 + 5+2). Aflatoxin contamination is characterized by a sharp blue fluorescent band about 1 cm above the alumina zone when the developed column is viewed under longwave UV light. The total analysis time is about 20 min. The method was successfully applied to the oilseeds cottonseed, soybean, peanut, flax seed, and sunflower seed; to the grains corn, wheat, oats, barley, sorghum, rye, and rice; and to the tree nuts pistachios, almonds, walnuts, brazil nuts, pecans, and filberts. As little as 10 μg aflatoxin/kg can be detected, and approximate contamination levels can be placed in one of 5 categories, based on the observed intensity of the fluorescent aflatoxin band.

Detection of aflatoxin using small columns of florisil.

AbstractThis simplified procedure to detect aflatoxin in cottonseed and cottonseed products can be used at the field level where equipment for thin layer chromatography is not available. Contamination levels as low as 10 ppb can be detected in these columns or tubes using longwave uv light. Development and detection of aflatoxin in these tubes takes ca. 10 min.

2444. The darker side of smelling good: Ippen, H. u. Tesche, Susanne (1971). Zur Photodermatitis pigmentaria Freund (“Berloque-Dermatitis”, “Eau de Cologne Pigmentierung”). Hautarzt22, 535

The antibacterial agent 3,3′,4′,5-tetrachlorosalicylanilide (TCSA) enhanced the sensitivity of erythrocytes to long-wave UV light in vitro. The exposure of TCSA-treated red cells to UV radiation resulted in photohemolysis; the extent of photohemolysis was related to the duration of irradiation. The photohemolytic reaction appeared to be a consequence of UV excitation of TCSA to the triplet state and subsequent reaction of the latter molecule with the erythrocyte membrane. The interaction of the excited TCSA molecule with the red cell membrane was manifested as increased permeability towards Mg2+, K+, or Na+ ions. Photohemolysis was prevented by the UV absorbers urocanic acid and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid. In addition to TCSA, 3,3′,4′,5- and 2′,3,4′,5-tetrabromosalicylanilides caused photohemolysis. Monobromo-, dibromo-, and tribromosalicylanilides failed to induce significant photohemolysis. The results suggest that some instances of photodermatitis due to TCSA may be related to changes in cell permeability and lysis.

Evaluation of Reflectance Fluorodensitometry for Measuring Aflatoxins on Thin Layer Plates

Abstract A reflectance fluorodensitometer employing illumination of chromatograms with longwave UV light at 45° angles to the plate surface and measurement of reflected fluorescence at 90° was found to be suitable for measuring aflatoxins on silica gel-coated thin layer plates. The relationship of peak area vs. concentration was linear for 1–20 ng aflatoxins B1 and G1/ spot. Degradation of aflatoxins was slight. Five repetitive scans of the same chromatogram containing 5 ng each of B1 and G1 reduced the recorded areas an average of 1% per scan. Consecutive scans of 8 identical standard chromatograms containing 5 ng each of B1 and G1 and 1.5 ng each of B2 and G2 showed a reproducibility, as measured by coefficients of variation, of ±4–5% (B1 and G1) and ±5–9% (B2 and G2), representing the combined errors of standard application, TLC development, and scanning. Analysis of aflatoxins in purified sample extracts from 6 contaminated oilseed meals, 3–500 μg afla toxins/kg, in which the same TLC plates were scanned by a transmission densitometer and the reflectance densitometer yielded essentially equivalent values.

An improved spray reagent for detection of bile acids on thin-layer chromatoplates

A spray reagent containing 8-hydroxy-1,3,6-pyrenetrisulfonic acid sodium salt is described, which allows detection of as little as 1 micro g of bile acids under long-wave UV light. The bile acids can be eluted directly from the sprayed plates with acetone without eluting the spray reagent.

Induction of Photohemolysis by Tetrachlorosalicylanilide

The antibacterial agent 3,3′,4′,5-tetrachlorosalicylanilide (TCSA) enhanced the sensitivity of erythrocytes to long-wave UV light in vitro. The exposure of TCSA-treated red cells to UV radiation resulted in photohemolysis; the extent of photohemolysis was related to the duration of irradiation. The photohemolytic reaction appeared to be a consequence of UV excitation of TCSA to the triplet state and subsequent reaction of the latter molecule with the erythrocyte membrane. The interaction of the excited TCSA molecule with the red cell membrane was manifested as increased permeability towards Mg2+, K+, or Na+ ions. Photohemolysis was prevented by the UV absorbers urocanic acid and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid. In addition to TCSA, 3,3′,4′,5- and 2′,3,4′,5-tetrabromosalicylanilides caused photohemolysis. Monobromo-, dibromo-, and tribromosalicylanilides failed to induce significant photohemolysis. The results suggest that some instances of photodermatitis due to TCSA may be related to changes in cell permeability and lysis.

PHOTOSENSITIZATION OF HUMAN CELL CULTURES BY DEMETHYLCHLORETETRACYCLINE.

SummaryExposure of cultured human amnion cells to some tetracycline compounds produced slight suppression of growth. When drug treated cells were subjected to irradiation with short-wave (2537A) UV light, those to which demethylchlortetracycline had been added were severely damaged, the effect being moderate at a concentration of 1.6 μg per ml of the drug and marked at a level of 6.4 μg per ml. Methacycline and tetracycline were without significant effect. Exposure to long-wave (3960A) UV light did not increase the slight damaging effects of the antibiotics on cells. The phenomenon was observed at concentrations of demethylchlortetracycline commonly present in the serum of patients treated with this agent and appears to be due to cellular injury produced by irradiation on cells which have been sensitized by exposure to drug.

Studies in polymer synthesis—IX. Polymerization of acrylonitrile under the action of visible light in the presence of chloride

PHOTOSENSITIZED polymerization is one of the methods making it possible to use visible and long-wave UV light for the synthesis of polymers. I t has been shown that organic compounds belonging to various classes may be used as sensitizing additives. However, the action of some simple substances such as the halogens on the photopolymerization of vinyl monomers has not been investigated. I t is known that when halogens are irradiated with visible light, they are decomposed into free atoms. On this phenomenon are based the photo-reactions of halogens with organic compounds [1]. I t may be assumed that under certain conditions and ratios of the reactivities of an unsaturated compound and a free halogen atom, the latter will initiate a polymerization reaction by the scheme: