The skullcap herb, not to be confused with the deadly autumn skullcap mushroom,1 comes in two varieties: the American skullcap (Scutellaria lateriflora) and Chinese skullcap (Scutellaria baicalensis).2 Although they come from the same family and have medical uses, they are not interchangeable.
The American skullcap is found in North America but is also grown in Europe in other areas of the world. Many of the studies done on skullcap have used Chinese skullcap, native to China and parts of Russia. It has been used in traditional Chinese medicine (TCM) for the treatment of infections, headaches, inflammation and allergies.3
The American skullcap gets its name from the cap-like appearance of the purple or blue flowers gracing the heavily branched plant.4 The plant grows to 4 feet in height and may be found growing wild in the woods. The Chinese skullcap flowers on a single stem growing 1 foot high.5 Both herbs are available as a powdered extract, and the American skullcap may be found in liquid form.
One flavonoid compound — scutellarin — is found in the plant genus Scutellaria and Erigeron.6 An extract from the herb Erigeron breviscapus — breviscapine — has been used in TCM and in the treatment of a variety of diseases. Breviscapine contains high amounts of scutellarin, and scutellarin is also found in the American and Chinese skullcap herbs.
Flavonoid in Skullcap Has Neuroprotective Effect After Brain Injury
Breviscapine is an extract of flavonoids from the herb Erigeron breviscapus, which contains 85% of scutellarin also found in Scutellaria, or skullcap.7 A recent study published in the Journal of Cellular Biochemistry8 investigated the neuroprotective effects of breviscapine after traumatic brain injury (TBI).
Researchers induced a closed diffuse TBI in rats and then injected breviscapine into their abdomen 30 minutes later. The researchers performed neurological scores to measure behavioral outcomes as an indication of neurological damage. Histopathological tissue sections of the rat’s brains were subsequently used to evaluate cellular damage.
The researchers found nuclear factor erythroid 2–related factor 2 (Nrf2) and downstream proteins in the brain tissue. They concluded breviscapine could alleviate or reduce cell death following a TBI and improve neurobehavioral functions through upregulation of Nrf2.9
Nrf2 has been described as the “master regulator of oxidative responses.”10 It is recognized as one of the major mediators in the resolution of inflammation and has been found to induce the expression of antioxidants that are crucial in the initiation of healing.
The Journal of Cellular Biochemistry study11 concluded that the downstream proteins12 (including HO-1 and NQO-1) detected in the histological tissue sections indicated upregulation of Nrf2. Expression of Nrf2 and the interaction with signaling pathways may facilitate development of therapeutic approaches to help reduce chronic inflammatory diseases.
Nrf2 is also a regulator of cellular resistance to oxidants,13 as part of a complex antioxidant defense system. It may also control the expression of genes involved in detoxification and elimination of reactive oxidants.14
Protective Effect of Scutellarin Found in Heart, Liver and Kidney Studies
The protective effect breviscapine initiates in the NRF2 pathway against cellular apoptosis and oxidative stress following injury may also play a role in the positive effects it plays in the heart, liver and kidneys. Memorial Sloan-Kettering Cancer Center15 reports scutellarin has purported uses in atherosclerosis, inflammation, epilepsy and hepatitis.
In a study published in the Journal of Cardiovascular Pharmacology,16 researchers used Sprague-Dawley rats to induce focal cerebral ischemia and heart ischemia followed by treatment with breviscapine or scutellarin. Their results found the protective effects of scutellarin in both the heart and brain were better than the mixture in breviscapine.
An article in the Frontiers in Pharmacology17 reported several clinical studies found breviscapine may be used in conjunction with medication for a variety of cardiovascular diseases, including myocardial infarction, atrial fibrillation, chronic heart failure and pulmonary heart disease.
The active antioxidant effect also reduces liver ischemia-reperfusion injury. In a study18 of 40 rats, histopathologic analysis was performed 24 hours after reperfusion. Researchers found breviscapine reduced injury by inhibiting liver oxidative stress. During an ischemic event, cellular death begins. When blood supply is restored, additional damage may occur from free radical activity.19
Several other studies have described a renal protective effect of breviscapine in animal20 and human studies. In one meta-analysis,21 researchers found breviscapine injections had a therapeutic effect in those with diabetic nephropathy, including a renal protective effect.
Another22 found breviscapine injections, in combination with antihypertensive drugs, improved clinical outcomes in those treated for hypertensive nephropathy and could serve as a renal protective strategy for patients.
Additional Health Benefits From Scutellarin
In a letter to the editor in the Journal of Cellular and Molecular Medicine,23 researchers describe the use of breviscapine in an animal study demonstrating its effect against pulmonary embolism. They concluded there was a reduction in inflammation in the lung tissues, which facilitated reduction in vasoconstriction.
Scutellarin has a traditional use as a potent antiplatelet agent. In one study,24 using mice with induced endometriosis, researchers concluded scutellarin was an efficient treatment by suppressing platelet aggregation and inhibiting proliferation, fibrogenesis and angiogenesis. These factors resulted in a reduction in lesion size and an improvement in pain in the mice.
American skullcap is also a traditional herbal medicine used in the treatment of stress and anxiety.25 In one placebo-controlled, double-blind, crossover study26 using 43 healthy participants, researchers found American skullcap “significantly enhanced global mood without a reduction in energy or cognition.”
The effects of scutellarin have also been considered a promising candidate for the development of therapeutic drugs against transmissible spongiform encephalopathies (TSEs) leading to the loss of neurons and synaptic functions.27 In humans, TSEs include neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease.
Additionally, Chinese skullcap has antihistamine properties, traditionally used to treat allergic rhinitis, asthma and eczema.28 Scutellarin has also demonstrated in vitro antibacterial and in vivo anti-inflammatory properties.29
Researchers found the anti-inflammatory effects of scutellarin to be helpful as an additional treatment with bleomycin, a broad-spectrum antitumor drug. The study30 was aimed at investigating a combined treatment protocol using in vivo and in vitro experiments in animals.
The results suggested scutellarin enhanced the anticancer effect of bleomycin, and at the same time reduced the drug’s side effect of pulmonary fibrosis.31 The herb also has been used in TCM for the treatment of:32,33,34
Potential Side Effects of Skullcap
While use of herbs is a traditional approach to strengthen the immune system and treat disease, some may trigger side effects and interact with supplements or medications. Penn State Milton S Hershey Medical Center35 warns that the American skullcap herb has been contaminated in the past and so should be obtained from a reliable source.
Those with diabetes should take Chinese skullcap only under a doctor’s supervision, as it may reduce blood sugar levels and raise the risk of hypoglycemia. Chinese skullcap may exacerbate stomach or spleen problems and should not be used during pregnancy or breastfeeding.36
American skullcap may induce mental confusion, irregular heartbeat and seizures when taken in high doses. Both also have a sedative effect and may increase the effect from anticonvulsants, barbiturates, benzodiazepines, tricyclic antidepressants, alcohol and drugs used to treat insomnia.37
The Flowers Are Beautiful and the Tea Promotes Relaxation and Other Health Benefits
While skullcap is available in powder and tincture form, you may also enjoy a hot cup of skullcap tea in the evening. Take care if you drink it during the day as it has a sedative effect. Driving or operating machinery after drinking it may be dangerous.
You may get two servings of tea from 1 tablespoon of high-quality skullcap herb and 2 cups of boiling water.38 Steep the tea in a teapot for 10 minutes and then, if you prefer, sweeten with raw honey, Luo han or stevia.
American skullcap typically blooms between May and August in zones 4 to 839 and prefers partial shade to full sun, while Chinese skullcap enjoys full sun and dry sandy soil. Skullcap may easily be grown from seed as they germinate at a naturally high rate, especially when stratified.40
In this process,41 you treat the seeds to simulate germination. Cold stratification is easily done in the refrigerator. Mix a quarter cup of sand in a mixing bowl and add water until it can form ball. Add your desired seed amount to the sand, mix it thoroughly and place it in a bag in the refrigerator for one week.
The seeds can be sown indoors before the first frost or outdoors once the threat of frost is gone. Ensure the soil is moist, but well-drained. You may also propagate by dividing roots or cuttings and allowing them to spread. Skullcap can be harvested once the flowers are in full bloom using a pair of scissors or shears to retrieve the flowers and leaves.