Bioactivities of Eriobotrya japonica (Thunb.) Lindl. Leaf and Its Triterpenes

The dried leaves of Eriobotrya japonica have traditionally been widely used to treat various diseases, such as chronic bronchitis, cough, inflammation, skin disease, and diabetes. Our previous studies have reported several functions and their molecular mechanisms of E. japonica leaf extract and triterpenes contained in the extract. In this review article, we focus on the effects of E. japonica leaf extract and triterpenes on inflammatory mediators, proliferation of cancer cells, and ghrelin production. 1) The leaf extract of E. japonica suppressed inflammatory mediators including nitric oxide (NO) and prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-stimulated RAW264 murine macrophage cells. The anti-inflammatory properties of E. japonica leaf extract resulted from inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions through downregulation of nuclear factor-κB (NF-κB) activation and mitogen-activated protein kinases (MAPK) phosphorylation. 2) E. japonica leaves contain triterpenes such as corosolic acid, ursolic acid, maslinic acid, and oleanolic acid. Corosolic acid exterted the strongest anti-proliferative activity in human leukemia cell lines. Moreover, corosolic acid induced apoptosis mediated by mitochondrial dysfunction and caspase activation. 3) Ghrelin is an appetite-stimulating peptide hormone with an octanoyl modification at serine 3 that is essential for its orexigenic effect. Our investigation of triterpenes from E. japonica, corosolic acid, oleanolic acid, and ursolic acid suppressed octanoylated ghrelin levels in AGS-GHRL8 cell line, which produces octanoylated ghrelin in the presence of octanoic acid, without decreasing transcript expression of ghrelin O-acyltransferase (GOAT) or furin.