Chemical constituents of Pedicularis longiflora var. tubiformis (Orobanchaceae), a common hemiparasitic medicinal herb from the Qinghai Lake Basin, China

Abstract Background: Pedicularis longiflora var. tubiformis (Orobanchaceae) is an abundant parasitic herb mainly found in the Xiaopohu wetland of the Qinghai Lake Basin in Northwestern China. The species has an important local medicinal value, and in this study, we evaluated the chemical profile of its stems, leaves and seeds using mass spectrometry. Methods: Dried samples of stems, leaves and seeds were grinded, weighted, and used for a series of extractions with an ultrasonic device at room temperature. The chemical profiles for each tissue were determined using Gas Chromatography-Mass Spectrometry (GC-MS) and Liquid Chromatography-Mass Spectrometry (LC-MS). Results: Twenty-seven amino acids and organic acids were identified and quantified from stems, leaves and seeds. The content of amino acids detected in leaves and seeds was higher than the amount found in stems. Eight flavonoids were also detected, including isoorientin, orientin, luteolin-7-O-glucoside, verbascoside, scopoletin, luteolin, apigenin and tricin. The concentrations of verbascoside, luteolin and tricin were the highest and more concentrated in leaves, while that of orientin and scopoletin were the lowest and mainly found in stems. Soluble monosaccharides and oligosaccharides below tetramer were also examined, and our analyses detected the presence of arabitol, fructose, galacturonic acid, glucose, glucuronic acid, inositol, sucrose, and trehalose. Conclusions: This is the first study to identify and quantify the main components of amino acids, organic acids, flavonoids and soluble sugars from stems, leaves and seeds of P. longiflora var. tubiformis . Eight of the amino acids detected are essential for humans, highlighting the medicinal importance of this species. Results shown here can be used as a reference case to develop future studies on the chemical constituents of Pedicularis herbs and other medicinal plants from the Tibetan region.