Luteolin and its C-monoglycosides fromLupinus polyphyllus
The leaves of Lupinus polyphyllus Lindley, a wild-growing biennial plant, in the flowering phase were fixed with steam and dried in a thermostat at 55-60°C. The dry comminuted material (2 kg) was repeatedly extracted with 70% ethanol at room temperature by the steeping method, and the extract was distilled in vacuum. The concentrated residue was treated with 600 ml of hot water and filtered and the resulting filtrate was extracted successively with diethyl ether, yielding fraction i, and ethyl acetate, yielding fraction 2.
The Ultraviolet Spectra of Flavones and Flavonols
The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 – 400 nm1. These two peaks are commonly referred to as Band I (usually 300 – 380 nm, Table V-1 records the λmaxvalues for Band I for all flavones and flavonols examined in the present investigation), and Band II (usually 240 – 280 nm). Band I is considered to be associated with absorption due to the B-ring cinnamoyl system, and Band II with absorption involving the A-ring benzoyl system (see III) [1].
A procedure for the ultraviolet spectral detection of ortho-dihydroxyl groups in flavonoids
Abstract A spectroscopic procedure using anhydrous AlCl 3 and AlCl 3 /HCl is described for the detection of ortho -dihydroxyl groups in flavonoids. This method complements the sodium acetate-boric acid method which is commonly used for this purpose.