Wikipedia
Oxovitisin
Oxovitisins are a type of pyranoanthocyanin with a pyranone ( 2-pyrone) component found in aged Port wines. They do not contain an oxonium ion component ( flavylium cation), as anthocyanins do. Therefore they do not have an absorption maximum at 520 nm. Oxovitisins are stable yellowish pigments with similar unique spectral features, displaying only a pronounced broad band around 370 nm in the UV−vis spectrum.