Nocellara del Belice, a cultivated variety (cultivar) of olive tree (Olea europæa L.), was examined with respect to the medium-polar compounds present in the wastewaters of olive oil extraction at the end of 2007. Charcoal-polyamide chromatography of obtained wastewaters showed the presence of the chemotaxonomical markers of Olea europaea. In addition a new compound was isolated which resulted to be a lactone related to oleuropein aglycone. We propose the name of nocellaralactone (NOC). This compound is also present in the leaves and it appears to be structurally, probably biogenetically, related to jasminanhydride, a monoterpenoid previously isolated from Jasminum grandiflorum. NOC showed a significant in vitro anti-inflammatory activity.