China
Africa
Explore chapters and articles related to this topic
Role of Process Standardisation in Development of Natural Products
Published in Dilip Ghosh, Pulok K. Mukherjee, Natural Medicines, 2019
Arunporn Etherat, Romanee Sanguandeekul, Panadda Nontahnum, Pimpinan Somsong, George Srzednicki
Anthocyanins in plants occur as glycosides of six common anthocyanidins including cyanidin, delphinidin, petunidin, peonidin, pelargonidin and malvidin, which give a different colour spectrum of anthocyanins ranging from red to purple (Figure 6.1). The structure of anthocyanins is polar, so they can be extracted using various organic polar solvents. The common solvents used for anthocyanin extraction are methanol, ethanol, acetone, water or a mixture of these solvents. Methanol is efficient in terms of anthocyanin extraction, but its toxicity limits its use, especially when the anthocyanins are meant to be used in foods. Acetone is less toxic than many other solvents and allows an efficient and more reproducible extraction. Using acetone to extract plant anthocyanins can avoid the interference from pectin that is generally dissolved in alcohol or water. Acetone requires lower temperature for evaporation after extraction. Acid is added into the extraction solvent to keep anthocyanin in its stable flavylium cation form at an acidic pH that is generally lower than pH 2. Still, highly acidic solution may cause partial hydrolysis of acyl moieties in acylated anthocyanins. Hydrochloric acid was widely used in the past, but more recently weaker acids such as formic acid, tartaric acid or citric acid have become more commonly used. After solvent extraction, solid phase purification is used to purify anthocyanin from other compounds such as organic acids that are co-present in the crude extract.
Technical Considerations of an Electroconvulsive Therapy Apparatus
Published in Barry M. Maletzky, C. Conrad Carter, James L. Fling, Multiple-Monitored Electroconvulsive Therapy, 2019
Any time an electrode is placed on tissue the electrode interface impedance has to be considered. This is particularly true when the electrode is to be used to conduct current to the tissue. The surface or dead layer of the epidermis is a very poor conductor and it must either be removed or penetrated to obtain a good conductive electrode site. Usually when an electrode is used to monitor a physiological signal, such as ECG, a conductive paste or jelly is sufficient to penetrate the poor conductive layer. In the case of ECT electrodes, it is recommended that the dead layer of skin and the fatty oils in the electrode site be removed with a good fat solvent such as alcohol. Acetone also is an excellent solvent for this purpose but is extremely flammable.
Chemical Leukoderma (Depigmentation)
Published in Francis N. Marzulli, Howard I. Maibach, Dermatotoxicology Methods: The Laboratory Worker’s Vade Mecum, 2019
Howard I. Maibach, Jorge R. Toro, Gerald A. Gellin, Leslie P. McCarty
Almost all substances were tested in acetone, propylene glycol, hydrophilic ointment, and 100% DMSO. DMSO was tested in 10% increments from 30 to 90% in mice only. Acetone is easy to apply, readily absorbed into the skin, and dissolves most lipophilic chemicals. The disadvantages are that it evaporates readily if the container is not tightly closed, which raises the molarity of the solute, and that it has given false negative results with known depigmenters such as MBEH. MBEH was the first alkyl phenol shown to depigment human skin (Oliver et al., 1939). Propylene glycol dissolves some test substances. It has the disadvantages that it is difficult to apply to animal skin due to its viscosity. It is not quickly absorbed so that it tends to spread beyond application sites, and it is more irritating than acetone or hydrophilic ointment. DMSO is readily absorbed through animal skin. Test materials are easily incorporated into it. Its disadvantages include its offensive odor; slower absorption on animal skin compared to acetone, resulting in some of the solution rolling away from sites of application; and irritant action, at concentrations of 70% or more (Kligman, 1965). Hydrophilic ointment is mildly irritating. It is difficult to deliver exact amounts in replicate studies. It tends to spread away from sites of application with animal movements such as rubbing against the cage and scratching, and it promotes retention of scales because of its occlusive nature.
PLGA sustained-release microspheres loaded with an insoluble small-molecule drug: microfluidic-based preparation, optimization, characterization, and evaluation in vitro and in vivo
Published in Drug Delivery, 2022
Yue Su, Jia Liu, Songwen Tan, Wenfang Liu, Rongrong Wang, Chuanpin Chen
The effects of dichloromethane to acetone (D/A) volume ratio on EE% and DL% were investigated when BCL concentration was 7.5 mg/mL and PLGA concentration was 1 wt%. As shown in Figure 3(A), with the decrease of the D/A volume ratio, the EE% and DL% of microspheres first increased and then decreased. When the D/A volume ratio was 3:1, DL% and EE% of microspheres were the highest. BCL was slightly dissolved in DCM, and DL% and EE% of the microspheres prepared were low when only DCM was used as the solvent. When acetone was added, DL% and EE% increased as the ratio of the D/A volume ratio decreased, because acetone was beneficial to the dissolution of BCL. However, acetone is a miscible solvent with water. When the volume of acetone increased to a certain level, part of the drug could diffuse into the water phase with acetone, resulting in the reduction of the drug content in the microspheres.
Occupational exposure assessment with solid substances: choosing a vehicle for in vitro percutaneous absorption experiments
Published in Critical Reviews in Toxicology, 2022
Catherine Champmartin, Lisa Chedik, Fabrice Marquet, Frédéric Cosnier
Except when seeking to mimic exposure to aqueous solutions of toxicants, water should be used with caution as it is a well-known enhancer, interacting with both lipids and corneocytes in the SC. Considering the various effects of ethanol, it is not recommended for use neat, and it should particularly be avoided when studying skin metabolism. There is little advantage to using it in combination with water. The use of a volatile solvent may be an alternative means to directly deposit solid substances. In this case, a small deposit volume should be used to allow rapid evaporation and limit the effect on the skin barrier. Acetone is preferable to ethanol. Although more realistic, the use of artificial sebum requires first to decide on its composition, and then to develop a technique to evenly apply a small volume to the skin, to accurately mimic its secretion in vivo. After all these preliminary steps, it will be necessary to assess the effects of the artificial sebum on the skin. For artificial sweat, it is currently difficult to conclude, given the paucity of data and the lack of consensus composition. However, we recommend that the solution be isotonic, including artificial sweat or NaCl 0.9% in water, rather than ultrapure water in its composition.
EEG Electrode-induced Skin Injury among Adult Patients Undergoing Ambulatory EEG Monitoring
Published in The Neurodiagnostic Journal, 2019
Sumika Ouchida, Armin Nikpour, Greg Fairbrother, Maricar Senturias
It is possible that the use of acetone solution during electrode removal may have contributed to skin irritation. A further comparative study to establish which commercially available water-soluble products used for the removal of electrodes minimize skin irritation/inflammation. Making small changes to the position of the placement of the electrodes at the time of reassessment may also help. When placing T3/T4 electrodes, for example, we can attach these electrodes 5 mm above the eyeglass frames to prevent skin irritation at the temporal regions. As well, bandaging practices may need to change because bandaging by individuals produces unequal and inconsistence pressure on the scalp of patients. The use of tubular elastic bandage or tubular elastic net bandage, which provides equal and consistent pressure may yield improved results in terms of preventing electrode dislodgment and reducing skin irritation/inflammation.