Steranes

Steranes are a class of triterpenoid hydrocarbons that are derived from the cyclization of squalene, a polyisoprenoid compound. They are characterized by their rigid, three-dimensional structure, which is composed of four fused rings. Steranes are commonly found in various biological systems, including plants, animals, and microorganisms. In geological contexts, steranes are significant components of sedimentary organic matter and are used as biomarkers for the presence of specific organisms or environmental conditions.

The structure of steranes is based on a tetracyclic framework, with a central ring system that includes a six-membered ring fused to three five-membered rings. This structure gives steranes their characteristic stability and resistance to degradation. Steranes can be further classified based on the number and position of methyl groups attached to the ring system. Common sterane types include cholestane, ergostane, and stigmastane, each named after the specific plant or animal source from which they were first isolated.

In biogeochemistry, steranes are used as indicators of the presence of specific organisms. For example, cholestane is a common sterane found in the tissues of animals, while ergostane is more prevalent in fungi and certain plants. The distribution and abundance of steranes in sedimentary rocks can provide insights into past environmental conditions, such as temperature, salinity, and the presence of specific organisms. This makes steranes valuable tools in the fields of paleontology, geochemistry, and environmental science.