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Chemical compound
Chamaecydin is a chemical compound with the molecular formula C30H40O3. It is made up of three six-membered rings and two five-membered rings and has one polar hydroxyl functional group. It is well preserved in the rock record and is only found in a specific family of conifers, the swamp cypress subfamily. The presence and abundance of chamaecydin in the rock record can reveal environmental changes in ancient biomes.
Background.
Notable properties.
Chamaecydin is a hexacarboxylic triterpene with a highly conjugated core. Its melting point is 197–198 °C. Its crystal structure is orthorhombic. Chamaecydin shows significant antifeedant activity against the larvae of "Spodoptera litura" and has an antifeedant index (AFI) of +0.44
Preservation.
Chamaecydin is a biomarker for certain species of Conifer trees. Once living organism die, the organic molecules they biosynthesized often undergo various chemical transformations in the soil and thus usually retain only basic structures of the molecules that were synthesized. These modified molecules are biomarkers but can often only be used as chemical tracers for a wide group of organisms. Chamaecydin is rare because it is a polar molecule that is found perfectly preserved millions of years later, and can therefore be used to trace specific species. Despite being a polar compound, chamaecydin is likely preserved because it is found trapped in resinous plant material, where it is prevented from bonding to kerogen. In the paleorecord, it is found in clayey sediments, which prevents further oxidation. Chamaecydin is found in concentrations ranging 3–8.7 mg/g of organic carbon.
Biological sources.
It was first isolated from the seed of "Chamaecyparis obtusa" (Cupressaceae) and then from the leaves of "Cryptomeria japonica" D. Don. Chamaecydin has since been found to be unique to the swamp cypress subfamily (Taxodioideae), specifically, it has been most studied in these species: "Cryptomeria japonica", "Glyptostrobus pensilis", "Taxodium distichum", and "Taxodium mucronatum". The molecule is found in the leaflets, seed cones, and wood of the cypress trees and can be traced back to the Cretaceous period (c.  million years ago). The other key biomarkers for this sub-family are ferruginol and 7α-"p"-cymenylferruginol. The synthesis methods of chamaecydin have not yet been studied.
Occurrence.
Conifers, deduced by the presence of chamaecydin in the paleorecord, managed to flourish across a wide range of latitudes over Earth's history. Below are some well studied occurrences of conifers.