title: Anti-allergic triterpenes isolated from olive milled waste.
abstract: The degranulation of basophils stimulated by antigen is one of the allergic mechanisms of immediate hypersensitivity reactions. In a previous study, the β-hexosaminidase release of rat basophilic leukemia (RBL-2H3) cells stimulated by IgE cross-linking was specifically inhibited by ethanol extract of olive milled waste (OMW). OMW is a potential source of triterpenes, which show several biological activities. However, little is known about the effect of triterpenes in OMW on β-hexosaminidase release. Here we investigated anti-allergic triterpenes from the ethanol extract of OMW, and we discuss the structure-activity relationship. We subjected ethanol extract of OMW to activity-guided fractionation; this led to the isolation of five known triterpenes, i.e., maslinic acid (1), oleanolic acid (2), punicanolic acid (3), 2-O-acetylmaslinic acid (4), and epimaslinic acid (5) as well as one new triterpene, 11-oxo-maslinic acid (6). An anti-allergic assay revealed that 2-O-acetylmaslinic acid (4) and 11-oxo-maslinic acid (6) showed anti-allergic activity. Considering the structure-activity relationship of these triterpenes, it appears that the existence of a ketone group at C-11 or an acetyl group at C-2 would influence the anti-allergic activity.
authors.affiliation: Division of Systematic Forest and Forest Products Sciences, Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Kishikawa
authors.affiliation: Division of Systematic Forest and Forest Products Sciences, Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.|Department of Pharmacognosy, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.
authors.forename: Yhiya
authors.initials: Y
authors.lastname: Amen
authors.affiliation: Division of Systematic Forest and Forest Products Sciences, Department of Agro-Environmental Sciences, Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. shimizu@agr.kyushu-u.ac.jp.
authors.forename: Kuniyoshi
authors.initials: K
authors.lastname: Shimizu
keywords: 11-oxo-maslinic acid; 2-O-acetylmaslinic acid; Olive milled waste; RBL-2H3; Triterpene; β-Hexosaminidase release