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Food Types, Dietary Supplements, and Roles
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Most antioxidants and vitamins in animal and plant organisms are chiral compounds, and exist under single stereoisomer form only. The same chiral artificial products obtained by chemical synthesis are often under racemic form – a mixture of two stereoisomers such as d-isomer and l-isomer, S- and R-enantiomers, or cis- and trans-isomers. Our body is a great factory of chiral selectors, and can well distinguish the stereoform of a biological compound (87). That means our organism is smart enough to differentiate the ‘good’ and the ‘bad’ isomer present in our body, although both isomers have the same apparent chemical structure. For example, alpha-lipoic acid, a chiral endogenous antioxidant, exists only under R-isomer in humans, animals, and plants, while its dietary supplement is a racemic (R,S) form. When alpha-lipoic acid supplement is introduced in our body, only the ‘good’ R-isomer is selected for use, while the ‘bad’ S-form is eliminated. We must ask if this is the reason why artificial products are less effective than natural ones. More research is needed to perform the synthesis of bio-compounds so that synthetic antioxidants, vitamins, or drugs may become more effective and safe for use in therapy with one isomer form only as natural chiral compounds.
Central Nervous System Effects of Essential Oil Compounds
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Elaine Elisabetsky, Domingos S. Nunes
A couple of compounds that also wait for comparative structure-activity-mechanism of action studies is formed by linalool 9 (C10, monoterpene) and nerolidol 10 (C15, sesquiterpene). These are tertiary alcohols with α,β-unsaturation to the carbon that bears the hydroxyl group. The extremities of the open chains of these two alcohols are identical: a tertiary hydroxyl on one side and an isoprenic C5 unity on the other. Both present an asymmetric center in the tertiary carbon and may be present in EOs with only one optic isomer (R or S) or as a mixture of the two. Another factor to consider is that nerolidol 10 has cis-trans isomerism in the double bond C6–C7, which increases the number of possible isomers and conformers.
Alternate Methods for Visualizing and Constructing
Published in Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk, Survival Guide to General Chemistry, 2019
Patrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk
Constitutional isomers are different bonding patterns for the same molecular formula. Another isomer could be formed by simply exchanging a hydrogen on a carbon with a fluorine on an oxygen. A more interesting variation would be the use of one triple bond instead of the two double bonds as shown in constitutional isomer #2; note that this is not the only possible structure with a triple bond.
An overview of ProTide technology and its implications to drug discovery
Published in Expert Opinion on Drug Discovery, 2021
Michaela Serpi, Fabrizio Pertusati
In most of the preclinical studies, in which different class of phosphate prodrugs have been applied to antiviral and anticancer NAs, the ProTide was found to be superior to other prodrug approaches. The synthetic methodologies used for their preparation are robust and afford, in most cases, the prodrugs with excellent yields. However, although the synthetic methodologies available for the preparation of diastereomerically pure Sp and Rp diastereoisomers have made excellent progresses, they are far from being ideal. Some methodologies are high-priced, time consuming and hard to scale up and/or limited by low yields [31–33]. Unfortunately, the most advanced stereoselective methodology can afford exclusively the Rp isomer, which in only one case is reported to have superior biological activity [34]. In addition, while for the preparation of single isomer phosphoramidate there are different methods, phosphonamidates (P-C bond) still lack of such diastereoselective synthesis. Therefore, we still believe that further synthetic efforts should be made to fill the gap in this area. Investigations should be directed to elaborate a broadly applicable synthetic methodology, less dependent from the nature of the phosphoramidating agent, which is often the critical component rather that the parent molecule.
Polycystic ovarian syndrome and infertility: overview and insights of the putative treatments
Published in Gynecological Endocrinology, 2021
Julie Collée, Marie Mawet, Linda Tebache, Michelle Nisolle, Géraldine Brichant
Inositol is one of the therapeutic alternatives which has recently been investigated [23]. It acts as the first line of treatment. There are nine different stereoisomers of inositol. Myoinositol is widely found in nature in plants and animal tissues. D-chiro-inositol is the second common isomer. Inositol can be produced in human cells from glucose and is directly involved in insulin cellular signaling [32]. It acts as an intracellular second messenger to regulate hormones like TSH, FSH and insulin. Inositol plays different roles with these stereoisomers, one enhancing cell glucose transportation through the stimulation of the glucose-transporter 4 (GLUT4) translocation to the cell membrane, a second one downregulating the release of free fatty acids from adipose tissue. D-chiro-inositol upregulates the pyruvate dehydrogenase enzyme leading to the production of adenosine triphosphate (ATP), glycogen synthesis and in the ovaries, regulating the insulin-induced androgen synthesis. Myoinositol and D-chiro-inositol promote the enzyme-inducing the conversion from glucose to glycogen.
Comparison of the Bone Regenerative Capacity of Three-Dimensional Uncalcined and Unsintered Hydroxyapatite/Poly-d /l -Lactide and Beta-Tricalcium Phosphate Used as Bone Graft Substitutes
Published in Journal of Investigative Surgery, 2021
Yunpeng Bai, Jingjing Sha, Takahiro Kanno, Kenichi Miyamoto, Katsumi Hideshima, Yumi Matsuzaki
The composite 3D-HA/PDLLA is polymerized from u-HA, the two stereoisomers of polylactic acid (PLA), high-molecular-weight bioresorbable polymer poly-d-lactic acid (PDLA), and PLLA [13]. The properties of the resulting polymer depend on the dextrorotatory (D) and levorotatory (L) configurations [14]. The l-isomer is characterized by higher crystallinity and less rapid resorption, whereas the d-isomer is characterized by more rapid resorption and a less crystalline structure [15]. Hence, PDLLA combines the advantages of PDLA and PLLA, which is why these composites exhibit sufficient plasticity to modify various scaffold shapes and prevent their rapid destruction following implantation [16]. Based on our previous research, 3D-HA/PDLLA performs well in vitro; showing an excellent capability to promote preosteoblast MC3T3-E1 cell proliferation and differentiation [17]. After cell culture for 48 h, the Alamar Blue reduction rate increased over four times from time zero. During the follow-up period, the genes Runt-related transcription factor 2 (Runx2) and Osterix (Sp7) were upregulated dramatically in 3D-HA/PDLLA compared with dense-HA/PDLLA, which contains a homogeneous mixture of HA/PDLLA but lacks internal pores. However, the in vivo study showed identical bone reformation in 3D-HA/PDLLA and beta-tricalcium phosphate (β-TCP). Furthermore, the expression of bone transcriptional factors such as Runx2 and osteocalcin (OCN) in the 3D-HA/PDLLA and β-TCP groups was not compared in our previous study [17].