Flavonoids ofGoebelia pachycarpa
The following substances were isolated and were identified on the basis of chemical and spectral characteristics: kaempferol, quercetin, and genistein. A fourth compound C26H2sO14 (I), mp 125-128°C, [a]~ 2 --34.4 ± 2 ° (c 1.05 MeOH) was an isoflavone derivative according to its UV spectrum (%maxethanol, nm: 263, 328 sh; log g 4.56, 3.73) [i]. Its IR spectrum contained absorption bands at (cm -I) 3527-3295 (OH groups), 1660 (C=O of a a-pyrone), 1622, 1589 (aromatic ~ bonds), and 1098-1040 (C O vibrations of glycosides).
The Ultraviolet Spectra of Isoflavones, Flavanones and Dihydroflavonols
Isoflavones, flavanones and dihydroflavonols all give similar UV spectra as a result of their having little or no conjugation between the A- and B-rings. They are all readily distinguished from flavones and flavonols by their UV spectra, which typically exhibit an intense Band II absorption with only a shoulder or low intensity peak representing Band I.
Isolation of isoflavones inhibiting DOPA decarboxylase from fungi and streptomyces.
By screening of culture filtrates of fungi and streptomyces for activity in inhibit dopa decarboxylase the following isoflavone compounds were obtained: psi-tectorigenen (I), genistein (II), orobol (IV), 8-hydroxygenistein (V) and a new compound (III). III was elucidated to be 3', 4', 5, 7-tetrahydroxy-8methoxy isoflavone. Among these isoflavones, IV and III showed the strongest activity in inhibiting dopa decarboxylase. All these isoflavones also inhibited histidine decarboxylase and catechol-O-methyltrasnferase. Activities of these compounds to inhibit tyrosine hydroxylase and dopamine beta-hydroxylase were examined. Orobol which showed no or only slight inhibition of tyrosine hydroxylase and dopamine beta-hydroxylase exhibited a significant hypotensive effect on spontaneously hypertensive rats.