Topic
Steroid biosynthesis
About: Steroid biosynthesis is a research topic. Over the lifetime, 1721 publications have been published within this topic receiving 58977 citations.
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TL;DR: Biocompatible GOQDs demonstrate their high potential for human health by reducing oxidative stress and inhibiting neurotoxicity by efficiently reducing reactive oxygen species and H2O2 in 1‐methyl‐4‐phenyl‐pyridinium ion (MPP+)‐induced PC12 cells.
Abstract: Both oxidative stress and neurotoxicity are huge challenges to human health, and effective methods and agents for resisting these adverse effects are limited, especially in vivo. It is shown here that, compared to large graphene oxide (GO) nanosheets, GO quantum dots (GOQDs), as nanozymes, efficiently reduce reactive oxygen species (ROS) and H2O2 in 1-methyl-4-phenyl-pyridinium ion (MPP+)-induced PC12 cells. In addition, GOQDs exert neuroprotective effects in a neuronal cell model by decreasing apoptosis and α-synuclein. GOQDs also efficiently diminish ROS, apoptosis, and mitochondrial damage in zebrafish treated with MPP+. Furthermore, GOQDs-pretreated zebrafish shows increased locomotive activity and Nissl bodies in the brain, confirming that GOQDs ameliorate MPP+-induced neurotoxicity, in contrast to GO nanosheets. GOQDs contribute to neurotoxic amelioration by increasing amino acid metabolism, decreasing tricarboxylic acid cycle activity, and reducing steroid biosynthesis, fatty acid biosynthesis, and galactose metabolic pathway activity, which are related to antioxidation and neurotransmission. Meanwhile, H2O2 decomposition and Fenton reactions suggest the catalase-like activity of GOQDs. GOQDs can translocate into zebrafish brains and exert catalase-mimicking activity to resist oxidation in the intracellular environment. Unlike general nanomaterials, biocompatible GOQDs demonstrate their high potential for human health by reducing oxidative stress and inhibiting neurotoxicity.
109 citations
TL;DR: Changes in reproductive performance represents a common response in fish exposed to pulp mill effluent and other organic contaminants, but the biochemical basis for steroid hormone depression in fish associated with organic contaminant exposure is not consistent enough to allow generalizations at this time.
108 citations
TL;DR: Both naturally occurring disorders in humans and genetic manipulation in mice have demonstrated that the StAR protein is an absolute requirement in the rate-limiting step in steroidogenesis, the transfer of cholesterol into the mitochondria.
108 citations
TL;DR: The chemical consequences of involving either an FeV==O or an FeIII--OOH species for five different C--C bond cleavage reactions, including the formation of 17 alpha-hydroxyandrogen from pregnenolone, presents an interesting contrast.
Abstract: It is now well-known that conventional cytochrome P-450s catalyze hydroxylation reactions using an iron mono-oxygen species, the structure of which, as inferred from chemical model studies, may be drrepresented by the following canonical forms: FeV==O (.+)FeIV==O FeIV--O(.). Certain multifunctional P-450s, notably those involved in steroid biosynthesis, catalyze, in addition to hydroxylation reactions, an acyl-carbon cleavage process in which the participation of an iron peroxide intermediate, FeIII--OOH, has been suggested. However the possibility still exists that the C--C bond cleavage may also occur using the FeV==O species. We have scrutinized the chemical consequences of involving either an FeV==O or an FeIII--OOH species for five different C--C bond cleavage reactions. With respect to the status as well as the origin of hydrogen and oxygen atoms, in four of the examples the mechanism involving the FeV==O species makes the same prediction as that using the iron peroxide intermediate, that is, the incorporation of an atom of oxygen from O2 into acyl part of the cleaved fragment. The fifth example, however, involving the formation, with pig testes microsomes, of 17 alpha-hydroxyandrogen (androst-5-ene-3 beta,17 alpha-diol) from pregnenolone, presents an interesting contrast--in this case different outcomes are predicted by the two mechanisms. These possibilities have been experimentally evaluated using substrates stereo- and regiospecifically labeled with heavy isotopes and incubated with pig testes microsomes under either 16O2 or 18O2.(ABSTRACT TRUNCATED AT 250 WORDS)
108 citations
TL;DR: Cytochrome P-450 was detected and measured in human term placenta and its role in steroid hormone biosynthesis by this endocrine tissue was examined and side-chain cleavage of cholesterol, catalyzed by mitochondrial preparations, was inhibited by CO in the dark.
107 citations