Pregnane-type

Buxus alkaloids have a imique steroid-triterpenoid pregnane type skeleton with C-4 methyls, 9fl, lOp cycloartenol system with a degraded C-20 side chain [21-33]. These alkaloids exhibit varions biological activities including anti-HIV, anti-TB,... 

Khalid A, Zaheer-ul-Haq Anjum S, Khan MR, et al. Kinetics and structure-activity relationship studies on pregnane-type steroidal alkaloids that inhibit cholinesterases, BioorgMed Chem 12 1995—2003, 2004. 

A histochemical investigation also established the presence of alkaloids in Pachysandra, Sarcococca, and Simmondsia (190). The alkaloids found in Sarcococca and Pachysandra are simple pregnane derivatives lacking the alkyl substitution at C-4 and C-14. The alkaloids isolated from Sarcococca pruniformis Lindley show close similarity in structure to alkaloids typical of pregnane-type alkaloids of Apocynaceae some of them were found in both families. 

Neuroactive steroids affect neurotransmission through their action at the membrane ion-gated and other neurotransmitter receptors.Recent studies have demonstrated that pregnane-type neuroactive steroids, such as pregnenolone (PREG) and its downstream conversion products, play an important role in the homeostatic mechanisms that counteract the inhibitory effect of stress on the 7-aminobutyric acid type A receptor function and... 

Pregnane Type Sapogenins/Saponins. 5a-Pregn-16-en-3P-ol-20-one was isolated from Solanum pimpinellifolium Jussl. sub nom. Lycopersicon pimpinellifo-lium (Jussl.) Mill, by Schreiber and Aurich (1966) and also by Bennett et al. (1967). The authors speculated that this aglycone could be a metabolite of the steroidal glycoalkaloid tomatine. Heftmann and Schwimmer (1972) added that... 

Other constituents present include the coumarin scopoletin (also called gelsemic acid and P-methylesculetin), an iridoid compound, volatile oil (0.5%), pregnane-type steroids (12-P-hydroxypregna-4,16-diene-3,20-dione and 12-(3-hydroxy-5-a-pregn-16-ene-3,20-dione), fatty acids (palmitic, stearic, oleic, and linoleic acids), n-pentatria-contane, and tannins (karrer list and hOrhammer). 

Huang, X., Deng, Z., Zhu, X., van Ofwegen, L., Proksch, P., and Lin, W. (2006) Krempenes A-D a series of unprecedented pregnane-type steroids from the marine soft coral Cladiella krempfi. Helv, Chim, Acta, 89, 2020-2026. 

Rifampicin and pregnenolone-16a-carbonitrile (PCN) induce members of the CYP3A family and represent a third type of inducer, in that the substrate specificity of the microsomes from treated animals differs from that of the microsomes from either phenobarbital-treated or TCDD-treated animals. Inducing substrates of this class include endogenous and synthetic glucocorticoids (e.g., dexamethasone), pregnane... 

Table 2 Nuclear receptors (NR) for enzyme inducers. Enzyme inducers are now known to act as ligands to nuclear receptors, leading to gene activation and increased synthesis of the enzyme. Affinity of inducers to die receptors is now known to be responsible for the differential induction potential and can explain die observed species-differences in induction. The receptors tabulated are aryl hydrocarbon receptors (AhR), constituitively androstane receptor (CAR), pregnane X receptor (PXR), and glucocorticoid receptor (GR). The isoforms in bold type are the major isoform regulated by the corresponding receptors.

Alkylnitrenes are very poor in functionalizing C—H bonds, even if the insertion is intramolecular. Earlier claims that pyrrolidines (6) could be formed by insertion of alkylnitrenes derived from simple alkyl azides have subsequently been disproved,and the only apparently genuine example of a reaction of this type involves the azidosteroid 6P-azido-5a-pregnane (7), which leads to functionalization of the... 

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