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Microbial Transformation of Steroids and Sterols
Published in Nduka Okafor, Benedict C. Okeke, Modern Industrial Microbiology and Biotechnology, 2017
Nduka Okafor, Benedict C. Okeke
Steroids and sterols differ from each other in two ways: (a) the number, type, and position of the substituents and (b) the number and position of the double bonds in the ring. Steroid molecules are usually flat. However, the substituents at each of the junctions of Rings A and B, Rings B and C, and Rings C and D may be either above or below the plane of the ring. When the substituent group lies above the plane of the molecule (denoted by a solid line), the substituent is denoted by β; when it is below (denoted by a broken line), it is denoted by α. When, as is the case in many steroid hormones, a double bond exists between C4 and C5, the situation is denoted Δ4. The individual compounds are named systematically as derivatives of steroidal hydrocarbons like gonane, estrane, androstane, pregnane, cholane, and cholestane to name the most important ones. Thus, cortisone, a derivative of pregnane, is ∆4-pregnene-17a, 24-diol-3 11, 20-trione.
Pesticides and Chronic Diseases
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
These pesticide and herbicide exposures may account for the rising amount of feminization in men in this world. Competitive inhibition of thyroid hormone receptors by OPs and inhibition of progesterone action by pyrethroids are other findings regarding endocrine disruption by pesticides.1146 However, the results of various transactivation assays using mammalian and yeast cells indicated agonistic or antagonistic activity of pesticides toward aryl hydrocarbon receptors and some members of the nuclear receptor superfamily including RA receptors, pregnane X receptors, and peroxisome proliferator-activated receptors1147,1148 (for more information, see the section “Endocrine Disruption”). We find many males made impotent with the estrogen effect and the antitestosterum-type response, while the females get disruption of their menstrual cycle.
Estrogen and Androgen Blockade for Advanced Prostate Cancer in the Era of Precision Medicine
Published in Shaker A. Mousa, Raj Bawa, Gerald F. Audette, The Road from Nanomedicine to Precision Medicine, 2020
Tetsuya Fujimura, Kenichi Takayama, Satoru Takahashi, Satoshi Inoue
The steroid and xenobiotic receptor (SXR), also known as the human pregnane X receptor, constitutes members of the nuclear receptor superfamily of ligand-activated transcription factors [44, 45]. The elimination of dihydrotestosterone (DHT), which is the active androgen in the prostate, is critical for successful endocrine therapy for PC. Testosterone is inactivated in the liver and prostate by Cytochrome P450 (CYP) enzymes [46–48]. SXR regulates CYP3A4 and CYP2B6, which are responsible for the hydroxylation of testosterone in the liver and prostate [48–50]. SXR and its target genes CYP3A4 and CYP2B6 participate in the regulation of PC via intra-prostatic testosterone metabolism [49–52].
Sedimentary environment and facies of the Huagang Formation in the northern central Xihu Depression, East China Sea Basin, China
Published in Australian Journal of Earth Sciences, 2020
Z. X. Zhao, C. M. Dong, C. Y. Lin, X. G. Zhang, X. Huang, B. J. Li, W. Guo, Z. Q. Zhu
Under normal circumstances, steranes with different carbon numbers do not interact with each other because of the relatively stable molecular structure of sterane (Liu, Meng, Liu & Dong, 2009). Therefore, sterane is commonly used as important parameter for studying the type of organic matrix and the degree of thermal evolution. C27, C28 and C29 sterols differ in their bioorganic matter content. Specifically, C27 sterols predominate in aquatic plankton, while C29 sterols predominate in terrestrial organisms. During the evolution of organic matter, C27, C28 and C29 sterols in bioorganic matter are hydrogenated and dehydroxylated into sterane with the same carbon number, while the C–C skeleton remains unchanged. Therefore, the source of organic matter can be determined from the relative content of C27, C28 and C29 regular steranes in mudstone extracts. In samples from the study area, the lines between C27, C28 and C29 regular decanes are basically in a ‘V’ shape (Figure 5). The values of ∑C29/∑(C27+C28+C29) range from 0.29 to 0.4 (mean 0.35), indicating that the most samples are derived mainly from aquatic organic matter, with a lower content of terrestrial higher organisms. Figure 5 shows data points mainly distributed in the IV, VI and VII regions indicating that organic matter is derived from mixed sources. In addition to regular sterane, pregnane (C21 and C22) and 4-methyl steranes (C30) are two compounds with unique geochemical significance in the steroid biomarkers. Pregnane is mainly derived from the biological hormones associated with pregnancy, progesterone and the side-chain breakage of regular steranes during thermal evolution. When organic matter is in an immature stage, the pregnane is mainly derived from the deposition of the original organic matter. When it enters the low-maturity stage, the organic matter undergoes thermal degradation and generates a large amount of pregnane with the greatest number of pregnanes produced during the maturation stage (Balzer, 1990). The 20S/(20S+20R) ratio of ααα-C29 steranes ranges from 0.26 to 0.49 (mean of 0.42; Table 3), indicating that it was in the low maturation-maturity phase, which is consistent with the results obtained in previous studies. Therefore, there is no comparative significance in the origin of pregnane in the study area. The occurrence of 4-methyl sterane, which comes from dinophytol, may also suggest a lacustrine sedimentary environment in the study area (Figure 6).