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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.
Norethisterone exposure alters the transcriptome of Marine Medaka (Oryzias melastigma) larvae
Published in Chemistry and Ecology, 2021
Xueyou Li, Xiaona Lin, Yuebi Chen, Zhongduo Wang, Yusong Guo, Gyamfua Afriyie, Ning Zhang, Zhongdian Dong
Progestins are important steroid chemicals [1,2] that can be classified into several categories; the first generation includes estrane, such as norethisterone or norethindrone (NET), the second generation includes levonorgestrel (LNG) and norgestimate, and the third generation, gonanes, includes desogestrel, gestodene, and drospirenone (DRSP) [3]. In addition to the progestogenic activity of progestins and their metabolites, they can also exhibit estrogenic, antiandrogenic, and androgenic activity [4,5]. In aquatic environments, the major sources of synthetic progestins are anthropogenic, from wastewater and agricultural runoff [6]. Synthetic progestins have high biological activity: a low concentration (sub ng/L to ng/L) can have a negative effect on organisms, and some progestins are not eliminated by sewage treatment plants [6–8]. These chemicals can cause changes in gene expression patterns, which may adversely affect the health of biota, especially aquatic organisms [7,9]. Therefore, there is widespread concern about the exposure of aquatic organisms to progestins [6,10,11].