epoxycarotenoid 9-cis-epoxycarotenoid 419.295 419.61880 C29H39O2R CHEBI:51973 C\C([*])=C/C=C/C(C)=C/C=C/C=C(C)/C=C/C=C(C)\C=C\[C@@]12O[C@]1(C)C[C@@H](O)CC2(C)C a 9-cis-epoxycarotenoid chebi_ontology