Radix Astragali (Astragalus): Latest Advancements and Trends in Chemistry, Analysis, Pharmacology and Pharmacokinetics

Radix Astragali (Astragalus) has been used in Traditional Chinese Medicine for over 2000 years, and still widely used in Asian countries to enhance the immune system and to protect the body against various stresses. In Europe and the United States, Astragalus is commonly used as nutritional dietary supplements and additives to foods and beverages. During the last several years, we have witnessed a steady expansion in the number of publications made associated with this herb. This review focuses on latest advancements and trends in chemistry, analysis, pharmacology and pharmacokinetics of Radix Astragali. Several types of constituents including triterpene saponins, flavonoids and astragalus polysaccharides have been summarized, and astragalus polysaccharides are still a challenging issue. With the rapid development of analytical techniques, a great number of methods have been developed for the identification and quantification of the plant material, extracts, and products of Radix Astragali. Separation was achieved using thin layer chromatography (TLC), high performance liquid chromatography (HPLC), callipary electrophoresis (CE), and high-speed counter-current chromatography (HSCCC). Among these techniques HPLC and hyphenated methods like HPLC with ultraviolet (UV), evaporative light scattering detection (ELSD), or mass spectrometry (MS) are by far the most employed. Radix Astragali has attracted ever-increasing attention in a variety of biological activity studies; its immunomodulatory effects, cardioprotective effects, antihyperglycemic effects, hepatoprotective effects and anticancer effects were strengthened in this review. Pharmacokinetic studies showed that the flavonoids could be absorbed and metabolized in vivo, and their major metabolic pathways are glucuronidation and sulfation, while the bioavailability of saponins is extremely low.