(-)-Kaur-16-en-19-oic acid 6730-83-2 C11874 Kaur-16-en-18-oic acid Kaurenic acid Kaurenoic acid ent-Kaur-16(17)-en-19-oic acid ent-Kaur-16-en-19-oate ent-Kaur-16-en-19-oic acid ent-Kaurenoic acid