A New Polyoxygenated Triterpene and Two New Aeginetic Acid Quinovosides from the Roots of Rehmannia glutinosa

Abstract

Rehmanniae Radix is the fresh or dry root of Rehmannia glutinosa LIBOSCH. (Scrophulariaceae). As officially listed in the Korean Pharmacopoeia, this herbal drug is to be used in dried form or after processing.1) The dry roots of R. glutinosa have been used in traditional Chinese medicine as an antipyretic and hemostatic.2,3) A number of chemical constituents with diverse structures, including iridoids, [4][5][6][7][8][9][10][11][12][13] ionone glucosides, 14,15) sesquiterpenes, 16,17) phenylethanoid glycosides, 18,19) norcarotenoids, 20,21) cerebrosides, 12) carbohydrates, and others, [22][23][24][25][26] have been isolated from this plant. During our ongoing studies of bioactive constituents used in traditional Chinese medicines, we characterized the 70% EtOH extracts of the roots of Paeonia lactiflora [27][28][29][30][31] and Astragalus membranaceus, [32][33][34][35] and the aerial parts of Lonicera japonica, [36][37][38][39][40][41] and several constituents have been isolated and characterized from these extracts. In the continuing search for new chemical and biomarkers from the medicinal plant R. glutinosa for quality control studies of related herbal medicines, a new polyoxygenated triterpene and two aeginetic acid quinovosides, together with other known components, were isolated. In the present investigation, we report the isolation and structure elucidation of a minor polyoxygenated triterpene named glutinolic acid (1) and two new aeginetic acid quinovosides (2, 3) from the roots of R. glutinosa cultivated in Korea. Results and DiscussionThe dried roots of R. glutinosa were crushed and extracted with 70% EtOH. The concentrated extract was suspended in H 2 O and successively extracted with EtOAc and BuOH. The EtOAc extract was added to 90% aqueous MeOH and extracted with hexane to give hexane and 90% MeOH extracts. The 90% MeOH extract was subjected to sequential column chromatography over silica gel, MCI gel and RP-18 gel to yield a new minor polyoxygenated triterpene named glutinolic acid (1) and two new aeginetic acid quinovosides (2, 3).Glutinolic acid (1) C-NMR data for 1 revealed the presence of one oxymethine carbon at d 71.3, two oxymethylene carbons at d 68.7 and 66.3, two oxygenated quaternary carbons at d 74.9 and 76.6, a carboxylic acid carbon at d 183.0, and an olefinic double bond (d 129.5, 139.5) supporting a pentahydroxy-urs-12-en-oic acid skeleton bearing an a-hydroxyl at C-19. Regarding the two hydroxyl groups and a carboxylic acid group on the D/E rings, two methyl groups on the D/E rings were transformed into the COOH and one CH 2 OH group, respectively. The latter group and the remaining hydroxyl group on the D/E rings were assigned at C-20 due to its quaternary nature. A comparison of the 13 C-NMR spectra of 1 and 3b,19a,23,30-tetrahydroxyurs-12-en-28-oic acid (30-hydroxyrotundic acid) 28-O-glucoside 44) showed the expected downfield shifts for absorption due to C-20 (ϩ28.4 ppm) and C-30 (ϩ3.8 ppm), and upfield shifts for C-18 (Ϫ4.8 ppm), C-22 (Ϫ5.0 ppm), and C-29 (Ϫ4.7 ppm) due to t...

A new megastigmane from fresh roots of Rehmannia glutinosa

“…Fig. 1) with 1 allowed sequential assignments of the homonuclear coupling correlations for -CH 2 -CH 2 -CH(OH)-and -CHQCH-C(CH 3 )QCH-CH 2 OH, the latter of which were in a good agreement with those of the side chain, (2E,4E)-3-methylpenta dienoic ol [18][19][20][21] . The NMR spectra (Table 1) were very similar to the known compound of aeginetic acid 18,19 which was reported from R. glutinosa, except for the presence of an oxygenated methine (δ C 74.5/δ H 3.73) and an oxygenated methylene (δ C 59.4/δ H 4.23).…”

Ionone glycosides from the roots of Rehmannia glutinosa

“…The known ionone glycosides and analogues were identified as aeginetic acid (6) [2], dihydroxy-b-ionone (7) [2], rehmapicrogenin (8) [2], trihydroxy-bionone (9) [2], sec-hydroxyaeginetic acid (10) [2], rehmaionoside C (11) [9], aeginetic acid 5-O-b-D-quinovoside (12) [11], neo-rehmannioside (13) [12], oxyrehmaionoside B (14) [13], and dihydrophaseic acid 4 0 -O-b-D-glucopyranoside (15) [14], by NMR analysis and comparison with literature data.…”

Natural Support for Autoimmune and Inflammatory Disease

“…60,61 Modern pharmacological research has isolated various components in Rehmannia, which may be responsible for its adrenal tonifying, immune-modulatory, and anti-inflammatory effects. 62,63 Rehmannia also reduces allergic reactions by decreasing histamine release caused by TNF-alpha activity on mast cells. 64 Rehmannia, like most TCM herbs, is almost always used in a time-honored formulation with other items from the TCM pharmacopoeia.…”