Scutellaria lateriflora, known commonly as blue skullcap, mad dog skullcap, and side-flowering skullcap, is a hardyperennial herb of the mint family, Lamiaceae, native to North America. It has an upright habit, growing 60 to 80 centimeters in maximum height. It is a wetland-loving species and grows near marshes, meadows, and other wet habitat. The blue flowers are just under a centimeter long. Most of the flowers do not appear at the top of the main stem, but are produced along the length of side branches that grow from the leaf axils.
Traditional uses and research
Scutellaria lateriflora contains flavonoids. Other skullcaps used for similar purposes include common skullcap, western skullcap, and southern skullcap. Its extracts are used in herbal medicine intended as a mild sedative and sleep promoter. Cherokee women have used it as an emmenagogue. Skullcap products have been analyzed, with some adulterated by Teucrium canadense or T. chamaedrys, also known as germander, which contains potentially hepatotoxic diterpenes. β-Elemene in the herb is under preliminary research in vitro, but studies in humans have not confirmed any efficacy. Diterpenes isolated from S. barbata had cytotoxic activity against three human cancer cell linesin vitro.
Pharmacology
The principal phenolics in the leaves, stems, and roots of some Scutellaria species are baicalin, baicalein, wogonin, and oroxylin A. Baicalin has anti-inflammatory and analgesic effects in a rat model of thermal hyperalgesia. Another study identifies 5,6,7-trihydroxy-2'- methoxyflavone and its 7-O-glucuronide. A number of the flavones found in S. lateriflora have been reported to selectively bind with high affinity to central benzodiazepine receptor sites, leading to the view that the flavones exert anxiolytic and other benzodiazepine effects in rats. The flavonoids are found throughout the plant but are more concentrated in the leaves, and the concentrations are found to decrease slightly as the plant matures. The dried leaf is reported to contain about 50 milligrams of flavonoid per gram. The flavonoids are readily extracted using hot water. Scutellarin is transformed by hydrolysis into scutellarein.
