The Animal Pigment Bilirubin Identified in Strelitzia reginae, the Bird of Paradise Flower

Abstract

Strelitzia reginae Aiton is an iconic plant known for its vibrant orange and blue inflorescences. Floral pigments include carotenoids and the anthocyanin delphinidin-3-rutinoside. S. reginae has black seeds with vivid orange arils, yet the basis for the orange color is unknown. We recently discovered bilirubin in the arils of S. nicolai. Previously, this pigment was known only to exist in animals as a breakdown product of heme. Using high-performance liquid chromatography (HPLC) and HPLC/electrospray ionization–tandem mass spectrometry, we now show that bilirubin is the primary aril pigment of S. reginae and is also present in low concentrations in its sepals (less than 44.0 ng·g−1).