Dimethyl sulfoxide test

This is the general procedure used with top agar in the Ames test (Maron and Ames 1983), although dimethyl sulfoxide is generally used as the water-miscible solvent. 

Caco-2 model is easily affected by commonly used organic solvents or co-solvents [e.g., methanol, ethanol, polyethylene glycol (PEG), dimethyl sulfoxide (DMSO)] at relatively low concentrations (<1% v/v). Therefore, NCEs with poor aqueous solubility may not be adequately evaluated by this model. It has become a common practice in the pharmaceutical industry to test solubility of compounds before performing any other in vitro screens and eliminate NCEs with poor aqueous solubility, thus preventing false negatives due to this issue. 

The cells are permitted to "plant" to the ECM and adjust to the incubator temperature (37°C) and C02 concentration. Then test compounds or controls (both in 0.1% dimethyl sulfoxide, DMSO) are added to the test wells. The cells are then incubated overnight, and the indicator dye Alamar blue10 is added. This noncytotoxic dye reacts to mitochondrial redox reactions and is measured fluorometrically. Cell metabolic activity is determined starting at 3 h after the dye is added and daily thereafter. 

A qualitative test for the interaction between superoxide and the reduced form of a potential SOD mimetic is an electrochemical experiment, where the reduced form of a complex and superoxide are generated in situ in aprotic solvent (most appropriate in DMSO — dimethyl sulfoxide). Aprotic solvent is needed to stabilize superoxide. 

Drug Treatment for Inhibition of Tumor Cell Migration 1. Drug or inhibitor to be tested. Here we use cisplatin cis-diammineplatinum(ll) dichloride), stored in aliquots of 100 mM in dimethyl sulfoxide (DMSO) at -20°C for up to 4 weeks. 2. DMSO or appropriate solvent for the agent under test. 

Figure 10.14 is a simplified diagram of the test procedure. A suitable organic solvent, e.g., dichloromethane, or solvent mixture (see Nielsen, 1992) is used to extract the POM from the environmental sample, the solvent is evaporated, and the residual POM is redissolved in dimethyl sulfoxide (DMSO). Serial dilutions of this DMSO solution are then added to a series of tubes, each containing agar and one of the several his test strains of bacteria, e.g., TA98, which is widely used for frameshift mutagens. 

Iodine Pentafluoride. The controlled reaction of IF5 with dimethyl sulfoxide, Me2SO, was found to be quite violent. Although small scale tests in the cold (0°) proceeded without incident, delayed violent explosions occurred upon scale-up or upon allowing the temp to rise to 10-15°... 

Bacterial mutagenesis tests have been conducted with distilled water solutions of the freeze-dried residues [concentrated up to 3000-fold (7)] and partially freeze-dried samples [concentrated 10-fold (49)]. High salt concentrations in such concentrates may cause toxicity problems in the bacterial tests. The use of dimethyl sulfoxide, methanol, or supercritical carbon dioxide to extract the organics from the freeze-dried residues for mutagenicity test purposes should be investigated. 

Concentration Plus Solvent Transfer. Concentration of the organic solutes is essential to the determination of many organic contaminants present in water at very trace levels. The solvent transfer is needed for implementation of the separation and detection schemes that do not tolerate the water matrix. For bioassay work, concentration and solvent transfer are also needed because the amounts are too low for direct testing of the water solutions, and dimethyl sulfoxide. (DMSO) is the preferred solvent. In bioassay studies that involve animal exposure, the concentration scheme must accommodate very large volumes of water. Theoretically and practically, these elements of the analytical and bioassay methodologies can be achieved by using solid adsorbents, especially synthetic polymers. 

For the highly inhibitive compounds in the TPA-induced inflammatory assay, we evaluated their antitumor-promoting activity by a standard initiation-promotion protocol [Fig. (3)] [37,40]. Initiation was achieved by a single application of 50 pg of DMBA (2), a well known tumor initiator, to the skin of backs of 8-week-old female ICR mice. From one week after initiation, 1 pg of TPA (1) was applied twice a week until week 20. The test compound (2.0 or 0.2 pM) dissolved in acetone-dimethyl sulfoxide (DMSO) (9 1, 100 pi) was applied 30 min before each TPA treatment. Groups of 15 mice were used. The number of tumors was counted weekly. 

During some couplings of nucleosides, promoted by dicyclohexylcarbodii-mide (DCC), Pfitzner and Moffatt.13 decided to try dimethyl sulfoxide (DMSO) as solvent. Instead of obtaining the expected couplings, they observed oxidation of alcohols to aldehydes and ketones. These oxidations were very remarkable, because at that time, on the nucleosides tested, no oxidants were known to be able to deliver efficiently the observed aldehydes and ketones. Furthermore, contrary to many other oxidants, no over-... 

Repeated Dose Dermal Tests. Twenty-one to 28-day dermal tests are particularly important when the expected route of human exposure is by contact with the skin, as is the case with many industrial chemicals or pesticides. Compounds to be tested are usually applied daily to clipped areas on the back of the animal, either undiluted or in a suitable vehicle. In the latter case, if a vehicle is used, it is also applied to the controls. Selection of a suitable solvent is difficult because many affect the skin, causing either drying or irritation, whereas others may markedly affect the rate of penetration of the test chemical. Com oil, methanol, or carboxymethyl cellulose are preferred to dimethyl sulfoxide (DMSO) or acetone. It should also be considered that some of the test chemical may be ingested as a result of grooming by the animal, although this can be controlled to some extent by use of restraining collars and/or wrapping. 

Dimethyl sulfoxide meeting USP testing specifications (Sigma, St. Louis, MO). 

Proline was among the first compounds to be tested in asymmetric conjugated reactions, both as a chiral ligand [8] and also as an organic catalyst [3]. The earliest asymmetric intermolecular Michael-type addition, in which proline catalyzed the reaction (arguably via enamine formation) was reported by Barbas and colleagues [9, 10] and by List and co-workers [11]. The reaction, which proceeded in high chemical yield (85-97%) and diastereoselectivity, albeit afforded near-racemic products in dimethyl sulfoxide (DMSO) [11] (Scheme 2.37). The enantio-selectivity of the addition was later ameliorated by Enders, who demonstrated that a small amount of methanol rather than DMSO was beneficial to the enantiose-lectivity of the addition reaction [12]. 

A number of companies supply reagent or spectroquality solvents that have been purified to remove UV-absorbing impurities. Some of them, particularly dimethyl sulfoxide, may be suitable for general electrochemical use as purchased. However, small quantities of electroactive impurities (particularly water) often are present in spectroquality solvents. Therefore, a particular batch of solvent always should be tested by measurement of the residual current with an appropriate supporting electrolyte and a platinum, gold, or carbon electrode (to test the anodic limits) and a platinum electrode (to test the cathodic limits). The voltage window or domain of electroactivity is a sensitive measure of the adequacy of the purification procedures. 

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