Qualitative and quantitative phytochemical characterization of Myrothamnus flabellifolia Welw

Abstract

The upper aerial parts and leaf tips of Myrothamnus flabellifolia Welw. (Myrothamnaceae), a resurrection plant indigenous to southern Africa, are used in African traditional medicine for infections of the respiratory and urinary system as well as for inflammation of mucosa and skin. Within a phytochemical investigation of the herbal material from M. flabellifolia the flavonoid fraction was shown to contain quercetin 10 as well as the respective 3-O-β-d-galactosides, glucosides, -glucuronides and 3-O-α-l-rhamnosides of quercetin (6, 7, 8, 26) and kaempferol (1, 2, 3, 9). Additionally mono-galloylated 12, 13, di-galloylated 15 and tri-galloylated 16 flavonol glycosides were identified. 3,4,5-Tri-O-galloyl- 14 and 1,3,4,5-tetra-O-galloyl quinic acid 28 were isolated and characterized, beside arbutin 27 and 2″,3″-di-O-galloyl-arbutin 11. Furthermore, the depside 2-O-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxyphenylacetic acid 5, 1,2,3,4,6-penta-O-galloyl-β-d-glucose 22 and seven ellagitannins were found: 1,2-di-O-galloyl-(4,6-(S)-hexahydroxydiphenoyl)-β-d-glucose 20, 1,3-di-O-galloyl-(4,6-(S)-hexahydroxydiphenoyl)-β-d-glucose 21, 2,3-di-O-galloyl-(4,6-(S)-hexahydroxydiphenoyl)-β-d-glucose (tellimagrandin-I) 19, 1,2,3-tri-O-galloyl-(4,6-O-hexahydroxydiphenoyl)-β-d-glucose (tellimagrandin-II) 23, and two so far not described dimers of tellimagrandin-I and -II (myrodigamin-I and -II, 24, 25). The presence of trehalose (3.3%), raffinose (0.2%) and stachiose (0.2%) beside a fructan (2.1%) was determined. Two ICH2-validated UHPLC methods have been developed and used within batch analysis for unambiguous identification of the herbal material and quantification of the major compounds myrodigamin-I (0.9 to 1.7%), tellimagrandin-II (0.3 to, 0.9%) and 3,4,5-tri-O-galloyl quinic acid (0.1 to 0.7%), besides kaempferol (0.1 to 0.3%) and quercetin content (0.2 to 0.3%) after hydrolysis of the respective glycosides.

Keywords: Arbutin; Ellagitannins; Flavonoids; Myrothamnaceae; Myrothamnus flabellifolia Welw.; Quinic acid; Tannins; Tellimagrandin-II.