Bilirubin Conjugates: Isolation, Structure Analysis and Synthesis
Karel P. M. Heirwegh, Stanley B. Brown in Bilirubin, 1982
Determining the site of attachment of the acyl group in rearranged azodipyrrole glucuronides represented a difficult analytical problem. The basic approach, exemplified for the 2-O-acylglucuronide in Figure 5, consisted of replacement of the labile acyl group with a stable methyl group and further chemical modification to derivatives suitable for mass spectral analysis.20 Free hydroxyl groups were protected as the acetals with ethyl vinyl ether. Treatment with LiAlH4 or LiAl2H4 removed the acyl group and reduced the C-6 carboxymethyl group. Methylation of the newly formed hydroxyl groups with dimsyl anion and MeI was followed by deprotection in acid medium, reduction with NaBH4 or NaB2H4 to the alditols and acetylation.
Dendrimers as Drug and Gene Delivery Systems
Mansoor M. Amiji in Nanotechnology for Cancer Therapy, 2006
Frechet and coworkers synthesized novel dendritic unimolecular micelles with a hydrophobic polyether dendrimer core surrounded by hydrophilic PEGs.21 For the G-3 micelle, the loading of indomethacin was found to be of 11%, a value corresponding to approximately nine to ten drug molecules per micelle, and preliminary in vitro release tests showed that sustained release characteristics were achieved. Recently, linear dendritic block copolymers comprising PEG and either a polylysine or polyester dendrons were designed, and highly acid-sensitive cyclic acetals were attached to the dendrimer periphery for pH-responsive micelle systems.22 At pH 7.4, the fluorescence of micelle-encapsulated Nile Red was constant, indicating it was retained in the micelle, whereas at pH 5, the fluorescence decreased, consistent with its release into aqueous solution. The rate of release was strongly correlated with the rate of acetal hydrolysis. These results suggest that the loading and controlled-release of drugs are dependent on the chemical structure of the dendrimer.
Influence of Light on Essential Oil Constituents
K. Hüsnü Can Başer, Gerhard Buchbauer in Handbook of Essential Oils, 2020
The formation of 6 requires a formyl 1,3-migration and is a newly identified photoreaction product. Diethyl acetals 11 and 12 were not obtained in the dark under these conditions, but might be formed by the hydrogen abstraction reaction of excited citral. Limonene, terpinolene, and nonanal decreased in amount, whereas p-cymene increased. Other constituents, such as citronellal, linalool, sesquiterpene hydrocarbons, and terpineols, were only insignificantly changed. The fresh, sweet, and characteristically lemon-like odor decreased and a dusty odor became predominant, which is mostly ascribable to compound 6 (Iwanami et al., 1997).
Potential factors affecting free base nicotine yield in electronic cigarette aerosols
Published in Expert Opinion on Drug Delivery, 2021
Vinit V. Gholap, Adam C. Pearcy, Matthew S. Halquist
Earlier studies have shown that at high power settings, an increase in VG content increases carbonyl products in e-cigarette aerosol [22]. Such products include but not limited to formaldehyde, acetaldehyde, acrolein, and acetals. Aldehydes can be easily oxidized to acids in the presence of moisture, oxygen, and a heated coil surface. Acetic acid and formic acid are also well-known thermal decomposition products of both propylene glycol and vegetable glycerin in e-liquids [23]. These decomposition products are well known for their inflammatory and carcinogenic as well as immunomodulatory properties [24–26]. Additionally, these products can have potential to affect the nicotine absorption as the acidic nature of these degradants can result in a decrease in the free base nicotine yield in the high VG e-liquid aerosols at high power settings.
Fluorinated scaffolds for antimalarial drug discovery
Published in Expert Opinion on Drug Discovery, 2020
Charu Upadhyay, Monika Chaudhary, Ronaldo N. De Oliveira, Aniko Borbas, Prakasha Kempaiah, Poonam S, Brijesh Rathi
In view of these intriguing observations, O’Neill et al. [77] also prepared a library of C-10 acetal derivatives 53a-53f (Figure 10). These derivatives were synthesized by the C-10 phenoxylation of DHA 50a with trimethylsilyl trifluoromethanesulfonate (TMSOTf), silver perchlorate (AgClO4), and substituted phenols to give C-10 acetal derivatives 53a-53f with optimum yields and magnificent stereoselectivity. In vitro results showed that analogue 53a (IC50 = 3.66 nM) and 53b (IC50 = 3.92 nM) were the most active against the PfK1 CQ-resistant strain. Derivatives 53d and 53e showed equal potency against PfK1 strain. Based on these promising results and high stereoselectivity of C-10, acetal derivatives 53a and 53c with an IC50 values of 3.66 and 5.29 nM, respectively, were subjected to animal testing. Notably, analogue 53c was found to be extremely effective against CQ-sensitive P. berghei-infected mice (ED50 = 2.1 mg/kg) [77].
Estradiol alters body temperature regulation in the female mouse
Published in Temperature, 2018
Sally J. Krajewski-Hall, Elise M. Blackmore, Jessi R. McMinn, Naomi E. Rance
TSKIN was monitored using a Star-Oddi DST (data storage tag) Nano-T temperature probe (EMKA Technologies, Falls Church, VA). The temperature probes were confirmed to be accurate against a National Institute of Standards and Technology certified thermocouple recorder. After testing various materials, sizes and attachment methods, the final housing was manufactured from 0.5 inch diameter Delrin acetal rods (WB Enterprises, Tucson Arizona). The clear window at the end of the Star-Oddi DST probe allowed the temperature sensor to be oriented adjacent to the ventral surface of the tail with the window oriented towards the mouse. Different groove widths (5.0, 5.5 and 6.0 mm) were made to accommodate various tail sizes so the temperature sensor could be placed a consistent distance from the base of the tail. A 4 cm line was marked from the base of the tail to mark the distal attachment of the housing. Loctite 454 prism instant adhesive gel glue (Fisher Scientific, Pittsburgh, VA) was applied on the lateral grooves of the housing and then the housing was attached to the tail with the mouse under brief isoflurane anesthesia (Fig. 1). Fig. 1E shows a representative TSKIN recording over a 3 day period.
Related Knowledge Centers
- Chemical Stability
- Functional Group
- Ketone
- Organic Chemistry
- Aldehyde
- Carbon
- Hydrogen
- Oxidation State
- Carbonyl Group
- Saturated & Unsaturated Compounds