Geranylated flavanones from the secretion on the surface of the immature fruits of Paulownia tomentosa

The viscous secretion on the surface of the immature fruits of Paulownia tomentosa yielded nine flavanones substituted with either a geranyl group, its oxidized forms, or a prenyl group at the C-6 position, along with six known flavanones. Some of these compounds showed more potent anti-oxidant activity than tocopherol towards DPPH radicals.