A review of the ethnopharmacology, phytochemistry, pharmacology, and quality control of Scutellaria barbata D. Don

Scutellaria barbata D. Don (S. barbata) is a well-known perennial herb that is used in traditional Chinese and Korean medicine. In China, it is known as Ban Zhi Lian, while in Korea, it is known as Banjiryun. In the Traditional Chinese Medicine (TCM) system, S. barbata has heat-clearing and detoxifying properties (Qingre Jiedu in Chinese). To provide a systematic review on current multifaceted understanding of S. barbata, with particular emphasis on the correlation between its traditional applications and pharmacological activities. All available S. barbata-related information from internet databases, including PubMed, Science Direct, Elsevier, China National Knowledge Internet, and Google Scholar (up to October 2018) were searched. Additional information was gathered from classical books on Chinese Herbals, Chinese Pharmacopoeia, and so on. In the TCM system, S. barbata is mainly prescribed for its heat-clearing and detoxifying effects. More than 203 compounds have been isolated and identified from this herb, with neo-clerodane diterpenoids and flavonoids as the main compounds. Most neo-clerodanes have been demonstrated to have cytotoxic effects against different cancer cell types in vitro. The S. barbata extracts exhibited anti-inflammatory, anti-microbial, antitumor, and other pharmacological activities. To add, flavonoids, including wogonin, baicalein, apigenin, naringenin, and scutellarin, were identified as the key to quality control. The heat-clearing effects of S. barbata could be attributed to its anti-inflammatory and hepatoprotective activities, whereas its detoxifying effects might be due to the anti-microbial functions of neo-clerodane diterpenoids and flavones. S. barbata may display anti-tumor effects and through active ingredient analysis, neo-clerodane diterpenoids are suggested to be its representative compounds. Overall, many pre-clinical studies have been conducted but very little concrete evidences are available on its specific effects, which are of therapeutic relevance.