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Terpenoids in Treatment of Neurodegenerative Disease
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Terpenoids have been strongly linked to the origin of life. Living systems consist of a cell or a number of cells, each surrounded by a physical boundary or membrane to separate it from the external atmosphere. The prevailing theories of the origin of life have originated around the formation of the first nucleic acids, proteins or sugars for a living cell to function and replicate, but another theory less discussed is the importance of the surrounding membrane, without which a living cell cannot perform. It is suggested that primitive membranes originated from terpenoids, which are lipid in nature, in the form of vesicles and later on evolved into more complex structures consisting of hopanoids in bacterial membranes or cholesterol and phospholipids in higher organisms (Ourisson and Nakatani, 1994). Recently, it has been suggested that polyprenyl phosphates, the root of all membrane terpenoids, could be the precursors of prokaryotic membrane lipids and a likely candidate for the most primitive membrane constituents (Nakatani et al., 2012).
Diversities in biomarker compositions of Carboniferous–Permian humic coals in the Ordos Basin, China
Published in Australian Journal of Earth Sciences, 2018
The distribution of the extended (C31–C35) 17α(H)-hopanes is similar throughout the coal samples at all levels of maturation, being predominantly C31 compounds, but the concentrations of αβ homohopanes in Group A coals are higher than those in groups B and C. These compounds probably originate from specific bacterio-hopanetetrol and other polyfunctional C35 hopanoids, which are common in the lipid membranes of many prokaryotes (Ourisson, Albrecht, & Rohmer, 1979, 1984; Rohmer, 1987). The reduction in homohopane concentrations at enhanced maturity levels may be due to dilution by catagenetic generation of hopanes. Furthermore, the C3222S/(S+R) ratio (0.56–0.68; Table 2), which has been considered as a maturation index, has reached the equilibrium values of 0.57 to 0.62, corresponding to the vitrinite reflectance in the study area (Peters et al., 2005).