Flavones

Apigenin

chamomile, parsley and celery; chamomile holds most of it as apigenin-7-glucoside

Luteolin

artichoke, thyme, celery and weld, the old yellow dye plant

Chrysin

passionflower, propolis and honey

Baicalein, baicalin, wogonin and oroxylin A

Chinese skullcap root

Scutellarein and scutellarin

American skullcap

Diosmin

citrus, and the venous drug made from hesperidin

Vitexin, isovitexin and orientin

the C-glycosides of hawthorn and passionflower

Amentoflavone

a double flavone (biflavone) in ginkgo and St John's wort

Nobiletin and tangeretin

the methoxylated flavones of citrus peel

Flavones share the general flavonoid profile of antioxidant and anti-inflammatory activity in laboratory work. Two clinical threads stand out, and they are unrelated to each other.

The first is the nervous system. Apigenin, chrysin, baicalein and wogonin bind the benzodiazepine site of the GABA-A receptor in laboratory and animal studies, and are thought to contribute to the calming reputation of chamomile, passionflower and skullcap. The human trials test the whole herbs, not the isolated flavones.

The second is the veins. A purified flavonoid fraction of 90% diosmin and 10% hesperidin is a prescription treatment for chronic venous disease and haemorrhoids in much of Europe, with trial evidence for reduced leg symptoms and swelling.

Chrysin is widely sold as a natural aromatase blocker to raise testosterone. In a human trial, 400 mg a day for three weeks did not change urinary testosterone; very little of it is absorbed.