Dual Modulatory Effects of Phytochemicals from Iris ×germanica L. var. florentina Dykes Rhizome Extract on Melanogenesis.

Abnormal skin pigmentation can cause significant esthetic concerns and impact quality of life. As melanin determines pigmentation, melanogenesis is a key target to manage pigmentation disorders. This study investigated the effects of extracts from the rhizome of Iris ×germanica L. var. florentina Dykes (often called Iris florentina L.) on melanogenesis. Active phytochemicals were identified by combining LC-MS-MS metabolic profiling with subsequent bioassay-directed fractionation of chromatographic eluent collected into 96-well plates. Fractions 41-43 increased melanin and contained germanaism B, providing evidence that it is a melanogenesis stimulator. In contrast, fractions 90-93 reduced melanin and contained iriflorental and iripallidal, identified as prospective melanogenesis inhibitors. To explore extract-based applications, the plant was subjected to ethanolic, chloroform, and supercritical carbon dioxide (SC-CO2) extractions and tested in skin equivalent tissues. The ethanolic extract (rich in germanaism B) increased pigmentation, while the chloroform extract (higher in iriflorental and iripallidal) decreased it. The SC-CO2 extract, with minimal germanaism B and enriched iriflorental and iripallidal, showed stronger depigmenting effect. This study is the first to report that rhizome of I. florentina contains phytochemicals with opposing effects on melanogenesis. Through different extraction processes, targeted extracts from a single botanical can address both hyper- and hypopigmentation, offering a novel approach to pigmentation modulation.