Panax quinquefolium (American Ginseng) and Physostigma venenosum (Calabar Bean)
Azamal Husen in Herbs, Shrubs, and Trees of Potential Medicinal Benefits, 2022
The bioactive compounds that are present in AG and exert various beneficial effects on human health are known to be ginsenosides or panaxosides. They are basically glycosides in nature consisting of sugar chain along with non-sugar (aglycone) moiety. The chemical structure of ginsenosides contains three types of aglycone – dammarane-type tetracyclic triterpene, pentacyclic oleanolic acid, and tetracyclic ocotillol type. The sugar part of ginsenosides comprises hexoses (glucose, galactose), 6-deoxyhexoses (furanose, rhamnose), pentoses (arabinose, xylose), and uronic acids (glucuronic acid). They are cyclic in nature and connected with aglycone part by hemiacetal bonds (Kochan et al., 2017; Nag et al., 2012). The nomenclature of ginsenosides is designed as “Rx”, where “R” indicates root and “x” indicates the polarity of the molecule in alphabetical order from “a” to “h” index.
Characterization of Phyto-Constituents
Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg in Promising Drug Molecules of Natural Origin, 2020
Glycosides are blends containing starch and a non-sugar development in a comparable molecule. Glycosides are characterized as the buildup results of sugars (counting polysaccharides) with a large group of various assortments of natural hydroxy (once in a while thiol) compounds (constantly monohydrate in character), in such a way, that the hemiacetal moiety of the starch must participate in the buildup. The carbohydrate or glycone is appended by an acetal linkage at carbon particle 1 to a nonsugar buildup or aglycone. On the basis of its pharmacological activity, sugar component and chemical property of aglycon component, glycosides are classified. Examples include cardiac glycosides (like digitalis acts on the heart), anthracene glycosides (like aloe and rhubarb used as purgative, and for treatment of skin diseases), chalcone glycoside (anticancer), alcoholic glycosides (salicin used as analgesic), cyanogenic glycosides (like amygdalin, prunasin) are used as flavoring agents in many pharmaceutical preparations. Amygdalin as shown in Figure 3.3 has been also utilized as antimalignant agent (HCN which is evolved in gastro kills cancer cells), and also as a cough suppressant in various preparations (Abraham et al., 2016). Overdose of cyanogenic glycosides can be lethal.
Intracellular Peptide Turnover: Properties and Physiological Significance of the Major Peptide Hydrolases of Brain Cytosol
Gerard O’Cuinn in Metabolism of Brain Peptides, 2020
Although moderate inhibition of prolyl oligopeptidase can be obtained with chloromethyl ketone derivatives60, the first highly potent and specific inhibitor synthesized was a peptide aldehyde, Z-Pro-Prolinal5. Peptide aldehydes by forming a hemiacetal adduct with the active site serine act as transition state analog inhibitors67. Z-Pro-Prolinal is of interest because it crosses the blood brain barrier to inhibit the brain enzyme. Thus 60 min after an intraperitoneal dose of 0.5 mg/kg to mice, the brain enzyme was 50% inhibited68. Moreover at this time point, a dose as low as 5μg/kg, still produced 39% inhibition of the brain enzyme. Inhibition is long lasting, and significant inhibition of the brain enzyme is seen 6.5 h following a dose of 5 mg/kg. A series of prolinal derivatives were synthesized and their inhibitory potencies were compared. Within this series Z-Pro-Prolinal was the most potent, inhibiting the bovine brain enzyme with a Ki of 0.21 nM69. The most potent inhibitors thus far described are derivatives of thioproline. The Ki of Z-thiopro-thioprolinal is 10 pM70. It should be noted that prolinal derivatives must be used with caution in in vivo studies. Z-Pro-Prolinal also inhibits the serine-type carboxypeptidase lysosomal Pro-X carboxypeptidase (EC 3.4.16.2) (Ki = 2.6X10−7M)71.
Potential lipid-based strategies of amphotericin B designed for oral administration in clinical application
Published in Drug Delivery, 2023
Xiaoming Zhong, Jianqiong Yang, Hongyan Liu, Zhiwen Yang, Ping Luo
AmB has a molecular weight of 924 Da (Cuddihy et al., 2019; Liu et al., 2017). Molecular structure of AmB is comprised of a macrolactone ring and non-polar heptene group (Figure 1). The ring is β-glycosylated at C19 with a mycosamine group, exhibiting an almost flat chromophore with seven conjugated double bonds in the trans conformation. At C13 and C17, the macrolactone ring also contains a hemiketal ring. The presence of an amino group in the mycosamine head group and a carboxyl group at C16 determines the amphoteric nature of AmB (Cuddihy et al., 2019; Liu et al., 2017). Additionally, the specific three-dimensional structure of this molecule is determined to own hydrophobic and hydrophilic regions, further conferring its amphipathic properties (Cuddihy et al., 2019; Liu et al., 2017). Consequently, AmB is responsible for poorly soluble in highly polar and nonpolar solvents (Cuddihy et al., 2019; Liu et al., 2017; Ciesielski et al., 2016).
Green synthesis of metallic nanoparticles using pectin as a reducing agent: a systematic review of the biological activities
Published in Pharmaceutical Biology, 2021
Kogilavanee Devasvaran, Vuanghao Lim
The RG-I region makes up approximately 20–35% of pectin and is composed of arabinan and galactan side chains, which contain hydroxyl groups (Mohnen 2008; Hileuskaya et al. 2020). Due to the shift of the tautomeric equilibrium (cyclo-oxo-tautomerism), the free hemiacetal hydroxyl groups may be converted to free aldehyde groups in an alkaline medium. The reducing properties of pectin macromolecules are provided by these aldehyde groups (Hileuskaya et al. 2020). Thus, RG-1 reduces metal salts to metal nanoparticles (Figure 2), enabling pectin to reduce metallic nanoparticles (MNPs) and form pectin metallic nanoparticles (Pe-MNPs). The RG-II region, however, is the most complex and is made up of some of the rarest moieties, such as 3-deoxy-d-lyxo-2-heptulosaric acid (DHA), 3-deoxy-d-manno-2-octulosonic acid (Kdo), aceric acid, fucose, and apiose (Tan et al. 2018). This region has contributed to several studies, including mitogenic activity and immune complexes clearance enhancing activity (Shin et al. 1997; Sakurai et al. 1999).
Synthesis, antiasthmatic, and insecticidal/antifungal activities of allosamidins
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Gangliang Huang, Hualiang Huang
To synthesize α-trichloroacetimidate donor 8 (Scheme 3), the preparation of α-D-allosamine-hydrochloride 11 was carried out53. Compound 11 was treated with benzyloxycarbonyl (Cbz)-Cl and NaHCO3/H2O, N-benzyloxycarbonyl protected allosamine 12 in 85% yield was obtained. Compound 12 was acetylated in pyridine to obtain the α/β isomer (4:1) mixture of tetraacetate 13. The anomeric acetyl group was selectively removed in N,N-Dimethylformamide (DMF) with hydrazine acetate to obtain the hemiacetal 14. In the presence of 1,8-diaza[5.4.0]bicycloundec-7-ene (DBU), the compound 14 was reacted with the CCl3CN to obtain 82% yield of α-trichloroacetimidate donor 8.
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