The genus Scorzonera L. (Asteraceae): A comprehensive review on traditional uses, phytochemistry, pharmacology, toxicology, chemotaxonomy, and other applications

The genus Scorzonera L. comprises of approximately 175 species, which are mainly distributed in temperate and arid regions of Central Europe, Central Asia, and Africa. Twenty-nine Scorzonera traditional ethnomedicines have been used for treating colds and fevers, pulmonary diseases, asthma, dyspepsia, malignant stomach neoplasia, liver disorder, jaundice, kidney diseases, mastitis, women's vaginitis, herpes zoster, poisonous ulcers, rheumatic pain, diabetic, atherosclerosis, headache, hypertension, dysentery, pregnant vomiting, snakebites, etc. This review aims to systematically evaluate the genus Scorzonera over its ethnomedicinal uses, phytochemistry, pharmacology, and toxicology, discuss the relationship between traditional uses, phytochemistry and pharmacological properties, and put forward some suggestions to promote further development and utilization of Scorzonera. This review is based on published scientific research works obtained from the following databases: Elsevier, Web of Science, PubMed, Springer, Wiley, Taylor & Francis, Google Scholar, CNKI, Baidu Scholar, ResearchGate, and others (the Flora of China, 1997 edition; Chinese herbal books, PhD dissertation and Master thesis in Chinese). The genus 81 Scorzonera plants have been studied for their traditional usage, phytochemistry, and pharmacology. Altogether 421 chemical constituents are isolated from the 54 species of Scorzonera, which include sesquiterpenoids, monoterpenes, diterpenes, triterpenoids, steroids, quinic acid derivatives, flavonoids, cumarinoids, lignanoids, phenylpropanoids, stilbene derivatives, benzylphthalides, kava lactones, phenolics, aliphatic acids, phthalic acids, alkanes, vitamins, sugars, alkaloids, and other constitutes. Besides those listed above, there are also volatile oils, polysaccharides, tannins, amino acids, enzymes, and inorganic elements. The extracts and compounds extracted from 55 Scorzonera species exhibit extensive pharmacological activities, such as anti-inflammatory, antinociceptive, wound healing, anti-cancer, hepatoprotective, anti-microbial, anti-ulcerogenic, antidiarrheal, antidiabetic, hypolipidemic, antioxidant, repairing cerebral ischemia, antidepressant, immunomodulatory activities, enzyme inhibitory effects, etc. Clinical applications strongly indicate that certain species are effective in treating herpes zoster and pregnancy resistance. Certain species are studied over applicationssuch as pharmacokinetic and histological distribution, and toxicity, the product extraction process, quick-freezing processing technology, synthesized metabolites, etc. Chemotaxonomy is also discussed on Scorzonera. This review provides information on traditional usage, phytochemistry, pharmacology, toxicology, chemotaxonomy, other applications aspects, and future prospects of the genus Scorzonera. However, only around one third of Scorzonera species have been studied so far. This review may be used as the basis for future endeavors, including further biological and chemical investigations, and efforts of seeking more applications.