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Essential Oils and Volatiles in Bryophytes
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Agnieszka Ludwiczuk, Yoshinori Asakawa
When liverworts are crushed, an intense mushroom-like, sweet woody, or seaweed scent is emitted. The presence of 1-octen-3-ol (1) and its acetate is responsible for the mushroom-like scent of a number of liverworts. Generally, 1-octen-3-yl acetate is more abundant than the free alcohol. A Tahitian liverwort, Cyathodium foetidisimum emits an incredibly unpleasant odor, for which the presence of skatole (2) is responsible (Ludwiczuk et al., 2009; Sakurai et al., 2018). The stink bug smell of the New Zealand Chiloscyphus pallidus is attributable to (Z)-, and (E)-pent-2-enal (3), (Z)-dec-2-enal (4), and (E)-dec-2-enal (Toyota and Asakawa, 1994). Cheilolejeunea imbricata produces strong milky smelling (R)-dodec-2-en-1,5-olide (5) and (R)-tetradec-2-en-1,5-olide. A very tiny liverwort, Leptolejeunea elliptica emits sweet mold-like odor, which is mainly due to the presence of 1-ethyl-4-methoxybenzene (6) (Toyota et al., 1997).
The Role of Fecal Microflora in Colon Carcinogenesis
Published in Herman Autrup, Gary M. Williams, Experimental Colon Carcinogenesis, 2019
Both tryptophan and tyrosine, derived from protein degradation, may be degraded by intestinal bacteria. Tryptophan may be degraded by many organisms including bacteroides, eubacteria, fusobacteria, Clostridia, and E. coli. Depending upon the organism and the incubation conditions tryptophan is degraded to indole propionic acid, tryptamine, indole acetic acid, skatole, or indole31 (Figure 1). Skatole is also produced by incubations with mixed human fecal flora.32 Mammalian systems metabolize tryptophan to substrates such as 2-amino-3-hydroxyacetophenone, hydroxy-anthranilic acid, and hydroxy kynurenine with a known carcinogenic potential.33 There is no evidence that human fecal organisms can degrade tryptophan to these products, but trace amounts have been isolated from in vitro incubations with rat fecal flora. Human fecal flora can, however, degrade this amino acid to the essential intermediates such as tryptamine or skatole.
Introduction
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
The final stage of digestion occurs in the colon through the activity of bacteria that inhabit the lumen. Mucus is secreted by the glands of the large intestine, but no enzymes are secreted. Chyme is prepared for elimination by the action of bacteria, which ferment any remaining carbohydrates and release hydrogen, carbon dioxide, and methane gases. These gases contribute to flatus in the colon, termed flatulence when it is excessive. Bacteria also convert any remaining proteins to amino acids and break down the amino acids into simpler substances: indole, skatole, hydrogen sulfide, and fatty acids. Some of the indole and skatole is eliminated in the feces and contributes to their odor; the rest is absorbed and transported to the liver, where these compounds are converted to less toxic compounds and excreted in the urine. Bacteria also decompose bilirubin to simpler pigments, including stercobilin, which give feces their brown color. Several vitamins needed for normal metabolism, including some B vitamins and vitamin K, are bacterial products that are absorbed in the colon.
2-Oxidation, 3-methyl hydroxylation, and 6-hydroxylation of skatole, a contributor to the odour of boar-tainted pork meat, mediated by porcine liver microsomal cytochromes P450 1A2, 2A19, 2E1, and 3A22
Published in Xenobiotica, 2023
Yasuhiro Uno, Saho Morikuni, Norie Murayama, Hiroshi Yamazaki
Female minipig liver microsomes (Figure 2) and recombinant P450 2A19 (Figure 5(B)) mediated the biotransformation of skatole to 3-methyloxindole, indole-3-carbinol, and 6-hydroxyskatole at similar rates at low substrate concentrations (10 μM). Because male minipig livers barely metabolise the typical human P450 2A6 substrate coumarin (Ushirozako et al. 2023), significantly low activities of primary oxidation of skatole, especially to 6-hydroxyskatole by male pig liver microsomes (Figure 2(A)), may result from P450 2A19 in male pigs. In male livers, pig P450 1A2 (Figure 5(A)) and 3A22 (Figure 5(E)) were able to transform skatole to indole-3-carbinol and 3-methyloxindole, respectively, in a compensatory manner, with minor roles of pig P450 2C36 (Figure 5(C)) or 2E1 (Figure 5(D)). Positive cooperativity was observed in 3-methyloxindole formation from skatole mediated by male minipig liver microsomes (Figure 3) and by pig P450 3A22 (Figure 5(E)) with Hill coefficients of 1.2–1.5 (Table 2). Biotransformation of skatole to its primary oxidative metabolites mediated mainly by pig P450 1A2, 2A19, and 3A22 under the present conditions is summarised in Figure 6. Previous research (Diaz et al. 1999; Wiercinska et al. 2012; Rasmussen and Zamaratskaia 2014) has reported roles of pig liver microsomal P450 enzymes, such as P450 2 A or 2E, in skatole oxidation in vitro, however, the roles of pig P450 2E1 should be concluded to be minor in skatole oxidation.
The contribution of gut bacterial metabolites in the human immune signaling pathway of non-communicable diseases
Published in Gut Microbes, 2021
F. Hosseinkhani, A. Heinken, I. Thiele, P. W. Lindenburg, A. C. Harms, T. Hankemeier
Skatole (3-methylindole) is another indole-derived metabolite that occurs naturally in feces. The fecal skatole concentration can vary considerably between individuals and may indicate different health states.65 Fecal skatole levels in healthy individuals are usually ~5 μg/g feces, whereas fecal skatole levels may increase up to 80–100 μg/g feces in persons who suffer from disturbed intestinal microbiota, such as patients with colorectal and colon cancer.70 Despite little information is available on the role of skatole in immune signaling, an elevated level in inflammation may highlight the importance of further studies.
Toxicological evaluation of a nonlethal riot control combinational formulation upon dermal application using animal models
Published in Cutaneous and Ocular Toxicology, 2023
Sanghita Das, Achintya Saha, Amartya Banerjee, Danswrang Goyary, Sanjeev Karmakar, Sanjai Kumar Dwivedi, Pronobesh Chattopadhyay
Skatole (CAS: 83–34-1) was purchased from Sigma Aldrich (Sigma-Aldrich, St. Louis, MO, USA). A gift sample of OC (CAS: 8023–77-6) from capsicum annum with pungency of 50,29,438 (5 million) SHU and capsaicin purity of 30.67% w/v, was received from Ozone Naturals (Ozone Naturals, Haryana, India). A commercially available dye Kevi stain violet 4010 (CAS: 8004–87-3) was purchased from Khatau Valabhdas (Khatau Valabhdas & Co. Indian globe chambers, Mumbai, India). Biochemical reagents were purchased from Coral Clinical Systems, (Coral, Verna, Goa, India). Chemicals and solvents used were of analytical grade.