ABSTRACT
OBJECTIVE：To st udy the chemical constituents of diterpenoids from Buyi medicine Isodon coetsa ，and to provide reference for the development and utilization of the medicinal resources. METHODS ：The 95％ methanol extract of Buyi medicine I. coetsa were isolated and purified with silica gel column ，Sehadex LH- 20 gel column and MCI column. The structures of the compounds were obtained by spectral analysis （mass spectrum ，hydrogen spectrum and carbon spectrum ），and then compared with active components of Miao medicine “Isodon flavidus ”. RESULTS & CONCLUSIONS ：Ten diterpenoids were obtained from I. coetsa，including rabdocoetsin B （Ⅰ），megathgrin B （Ⅱ），rabdocoetsin A （Ⅲ），enanderianin N （Ⅳ），rabdocoetsin D （Ⅴ）， megathyrin A （Ⅵ），lophanic acid （Ⅶ），rubesanolide D （Ⅷ），excisanin D （Ⅸ），excisanin K （Ⅹ）. The compounds Ⅶ，Ⅸ and Ⅹ were isolated from this specie for the first time. Compound Ⅶ（lophanic acid ）is a common active component in the Buyi medicine I. coetsa and Miao medicine “I. flavidus ”.
ABSTRACT
Objective: To investigate chemical constituents from Isodon coetsa distributed in Guizhou. Methods: Chemical constituents were isolated and purified by chromatography with silica gel, Sephadex LH-20, and semi-preparative HPLC, and their structures were identified by analysis of spectroscopic evidences and physicochemical properties as well as relevant references. Results: A total of 19 compounds were isolated from plant material extracted with 95% aqueous methanol, which were elucidated as β-sitosterol (1), stigmasterol (2), β-daucosterol (3), methyl linolenat (4), 9,12-octadecadienoic acid-2-hydroxy-1,3-propanedinyl ester (5), ursolic acid (6), oleanoic acid (7), 3β-hydroxy-urs-20-en-28-oic acid (8), betulinic acid (9), kurarinone (10), maslinic acid (11), 2α-hydroxy ursolic acid (12), 2α,3α-dihydroxy-urs-12-en-28-oic acid (13), 2α,3α,24-trihydrxyolean-12-en-28-oic acid (14), 2α,3β,24- trihydroxyolean-12-en-28-oic acid (15), formononetin (16), emodin (17), uracil (18), and sucrose (19). Conclusion: Compounds 2, 4, 5, 9, 11, 13-19 are isolated from this plant for first time, and compounds 11, 17, 19 are isolated from the genus of Isodon for the first time.
ABSTRACT
Objective To study the fragmentation pathways of five 7,20-cyclo-ent-kaurane diterpenoid compounds (rabdocoetsin B, megathyrin B, rabdocoetsin A, enanderianin N, and megathyrin A) in Isodon coetsa. Methods The samples were analyzed by ultra-high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS2). According to the fragment in MS2 of five compounds, the possible fragmentation pathways of these diterpenoid compounds were inducted. Results In negative mode, the typical fragmentation pathways of these compounds in high-quality areas were mainly loss of substituents on C-1, C-7, and the oxygen bridge on C-20. The fragmentation pathways were different as a result of the difference of the substituents on C-1. The fragment, which in medium and low quality areas, suggested that fracture order of these compounds were A ring to B and then to C ring. Conclusion The study on fragmentation pathways contributed to the structural identification of 7,20-cyclo-ent-kaurane diterpenoid compounds.