Chemical study on T. ramosum led to the isolation of nine compounds including four alkaloids, one lignans, two megastigmane glucosides, one flavone C-glycoside and a benzylated disaccharide. And their structures were characterized as follows.
Compound 1 yellow crystals: C20H18NO4+, ESI-MS m/z336 [M]+,1H-NMR (DMSO-d6, 400 MHz) δ:9.87 (1H, s, H-8), 8.91 (1H, s, H-13), 8.19 (1H, d, J = 9.1 Hz, H-11), 7.98 (1H, d, J = 9.1 Hz, H-12), 7.77 (1H, s, H-1), 7.08 (1H, s, H-4), 6.17 (2H, s, OCH2O), 4.93 (2H, t, J = 6.2 Hz, H-6), 4.10 (3H, s, 9-OCH3), 4.07 (3H, s, 10-OCH3), 3.21 (2H, t, J = 6.2 Hz, H-5). 13C NMR (DMSO, 100 MHz) δ: 150. 4 (C-10), 149.8 (C-3), 147.7 (C-2), 145.4 (C-9), 143.7 (C-8), 137.5 (C-14), 133.0 (C-12a), 130.6 (C-4a), 126.8 (C-11), 123.5 (C-12), 121.4 (C-8a), 120.4 (C-14a), 120.1 (C-13), 108.4 (C-4), 105.4 (C-1), 102.5 (OCH2O), 61.9 (9-OCH3), 57.0 (10-OCH3), 55.2 (C-6), 26.3 (C-5). These data were consistent those of berberine in the literature [8]. Thus, compound 1 was elucidated as berberine.
Compound 2 yellow powder: 1H NMR (CD3OD, 400 MHz) δ: 9.74 (1H, s, H-8), 8.63 (1H, s, H-13), 8.09 (1H, d, J = 9.1 Hz, H-11), 7.99 (1H, d, J = 9.1 Hz, H-12), 7.55 (1H, s, H-1), 7.01 (1H, s, H-4), 5.95 (2H, m, H-6), 4.20 (3H, s, 9-OCH3), 4.10 (3H, s,10-OCH3) 3.96 (3H, s, 2-OCH3), 3.23 (2H, m, H-5). 13C NMR (CD3OD, 100 MHz) δ: 152.5 (C-9), 151.9 (C-2), 148.3 (C-3), 146.3 (C-8), 145.7 (C-10), 140.0 (C-13a), 135.3 (C-12a), 128.5 (C-4a), 128.1 (C-12), 124.4 (C-11), 123.3 (C-14), 121.1 (C-13), 120.7 (C-8a), 113.2 (C-4), 112.0 (C-1), 62.5 (9-OCH3), 57.7 (10-OCH3), 57.5 (3-OCH3), 56.7 (C-6), 27.8 (C-5). These data were consistent those of columbamine in the literature [9]. Compound 2 was elucidated as columbamine.
Compound 3 yellow powder: 1H NMR (DMSO-d6, 300 MHz) δ: 9.89 (1H, br s, H-8), 8.97 (1H, s, H-13), 7.90 (1H, br s, H-11), 7.90 (1H, br s, H-12), 7.85 (1H, s, H-1), 7.16 (1H, s, H-4), 6.20 (2H, s, OCH2O), 5.11 (1H, d, J = 13.0 Hz, H-5), 5.01 (1H, br s, H-6a), 4.84 (1H, d, J = 13.0 Hz, H-6b), 4.08 (3H, s, 9-OCH3). 13C NMR (DMSO-d6, 75 MHz) δ: 149.7 (C-3), 149.6(C-10), 148.6 (C-2), 145.0 (C-8), 141.3(C-9), 136.4 (C-14), 132.6 (C-12a), 132.2 (C-11), 131.3 (C-4a), 123.7 (C-12), 122.4 (C-8a), 120.5 (C-14a), 119.8 (C-13), 108.1 (C-4), 105.4 (C-1), 102.3 (OCH2O), 61.4 (C-6), 62.9 (9-O CH3), 60.8 (C-5). These data were consistent those of thalidastine in the literature [10]. So, compound 3 was elucidated as thalidastine.
Compound 4 yellow amorphous powder: C20H24NO4+, ESI-MS m/z 342 [M+H]+, 1H NMR (CD3OD, 300 MHz) δ : 6.63 (1H, d, J = 7.2 Hz, H-9), 6.40 (1H, d, J = 7.2 Hz, H-8), 6.40 (1H, br s, H-3), 3.81 (3H, s, 10-OCH3), 3.72 (3H, s, 2-OCH3), 3.68 (1H, m, H-6a), 3.38 (1H, m, H-5β), 3.18 (3H, br s, N-OCH3β), 3.06 (1H, m, H-4α), 2.90 (1H, m, H-5α), 2.85 (1H, m, H-7β), 2.72 (3H, br s, N-OCH3α), 2.48 (1H, m, H-4β), 2.30 (1H, m, H-7α). 13C NMR (CD3OD, 75 MHz) δ : 153.0 (C-2a), 151.7 (C-10), 150.7 (C-1), 149.7 (C-11), 126.0 (C-7a), 123.5 (C-11a), 123.4 (C-11b), 121.0 (C-6b), 117.0 (C-8), 115.8 (C-3a), 110.5 (C-9), 109.3 (C-3), 70.9 (C-6a), 62.2 (C-5), 56.3 (2-OCH3), 55.9 (10-OCH3), 53.8 (N-CH3α), 43.5 (N-CH3β), 31.6 (C-7), 24.6 (C-4). The above spectral data were identical to those of magnoflorine reported in the reference [8]. Thus compound 4 was determined to be magnoflorine.
Compound 5 amorphous light-yellowish powder: C20H26O9, ESI-MS m/z 433[M+Na]+, 1HNMR (CD3OD, 500 MHz) δ : 7.04 (1H, d, J = 1.8 Hz, H-2), 7.02 (1H, d, J = 1.7 Hz, H-2′), 6.90 (1H, d, J = 8.2 Hz, H-5′), 6.85 (1H, dd, J = 8.2, 1.6 Hz, H-6′), 6.84 (1H, dd, J = 8.2, 1.6 Hz, H-6), 6.74 (1H, d, J = 8.1 Hz, H-5), 4.84 (1H, d, J = 5.8 Hz, H-7), 4.56 (1H, d, J = 6.0 Hz, H-7′), 4.36 (1H, dt, J = 5.7, 3.8 Hz,H-8), 3.87 (1H, dd, J = 12.0, 3.7 Hz, H-9a), 3.83 (3H, s, 3-OMe), 3.83 (3H, s, 3′-OMe), 3.80 (1H, dd, J = 12.0, 3.7 Hz,H-9b), 3.67 (1H, dt, J = 5.9, 4.1 Hz,H-8′), 3.50 (1H, dd, J = 11.2, 4.0 Hz, H-9′a), 3.38 (1H, dd, J = 11.2, 4.1 Hz,H-9′b); 13C NMR (CD3OD, 500 MHz) δ: 151.7 (C-3′), 148.7 (C-3), 148.6 (C-4′), 147.0 (C-4), 137.7 (C-1′), 134.2 (C-1), 121.0 (C-6), 120.5 (C-6′), 118.7 (C-5′), 115.6 (C-5), 112.3 (C-2′), 111.8 (C-2), 86.2 (C-8), 77.4 (C-8′), 75.1 (C-7′), 74.1 (C-7), 64.2 (C-9′), 62.2 (C-9), 56.5 (3′-OCH3), 56.3 (3-OCH3). These data were consistent those in the literature [11]. Therefore, compound 5 was elucidated as 1-(4-hydroxy-3-methoxy)-phenyl-2-[4-(1,2,3-trihydroxy-propyl)-2-methoxy]-phenoxy-1,3-propandiol.
Compound 6 amorphous powder: C19H30O8, ESI-MS m/z 409 [M+Na]+,1H NMR (Pyridine-d5, 500 MHz) δ : 6.04 (1H, s, H-8), 5.14 (1H, d, J = 7.7 Hz, H-1′), 5.10 (1H, m, H-3), 4.48 (1H, dd, J = 11.5, 2.2 Hz, H-6′a), 4.31 (1H, dd, J = 11.5, 5.3 Hz, H-6′b), 3.99 (1H, t, J = 8.1 Hz, H-2′), 3.62 (1H, s), 3.04 (1H, dd, J = 13.6, 2.0 Hz, H-4a), 2.30 (1H, dd, J = 12.5, 2.4 Hz, H-2a), 2.23 (3H, s, H-10), 1.79 - 1.72 (2H, m, H-2b,4b), 1.70 (3H, s, H-13), 1.69 (3H, s, H-12) and 1.21 (3H, s, H-11). 13C NMR (Pyridine-d5, 125 MHz) δ : 212.0 (C-7), 198.1 (C-9), 119.3 (C-6), 101.4 (C-1′), 99.0 (C-8), 79.7 (C-5), 78.7 (C-3′), 78.7 (C-5′), 75.7 (C-2′), 72.2 (C-4′), 63.3 (C-3), 63.0 (C-6′), 50.8 (C-2), 47.9 (C-4), 36.9 (C-1), 32.8 (C-12), 30.3 (C-11), 27.6 (C-10) and 27.0 (C-13). These data were consistent those in the literature [12]. Compound 6 was elucidated as citroside B.
Compound 7 pale yellow amorphous powder: 1H NMR (DMSO-d6, 600 MHz) δ : 6.03 (1H, dd, J = 15.6 Hz, H-7), 5.75 (1H, s, H-4), 5.71 (1H, dd, J = 15.5, 6.1 Hz, H-8), 4.98 (2H, s, H-13), 4.32 (1H, m, H-9), 4.13 (1H, d, J = 7.8 Hz, H-1′), 2.55 (1H, d, J = 16.6 Hz, H-2a), 2.05 (1H, d, J = 16.4 Hz, H-2b), 1.82 (3H, d, J = 1.3 Hz, H-10), 0.94 (3H, s, H-11), 0.92 (3H, s, H-12). 13C NMR (DMSO-d6, 150 MHz) δ : 200.8 (C-3), 166.9 (C-5), 132.6 (C-7), 131.3 (C-8), 127.0 (C-4), 104.5 (C-1′), 80.0 (C-6), 77.9 (C-5′), 77.8 (C-3′), 75.1 (C-2′), 74.8 (C-13), 72.0 (C-9), 71.5 (C-4′), 62.7 (C-6′), 50.7 (C-2), 42.4 (C-1), 23.5 (C-11), 24.6 (C-12) and 19.7 (C-10). These data were consistent those in the literature [13]. Compound 7 was elucidated as glochidionionoside A.
Compound 8 yellow powder: 1H NMR (DMSO-d6, 500 MHz) δ : 13.76 (1H, s, 5-OH), 7.95 (2H, d, J = 8.8 Hz, H-2′, 6′), 6.93 (2H, d, J = 8.8 Hz, H-3′,5′), 6.81 (1H, s, H-3), 4.87 (1H, d, J = 6.8 Hz, H-1), 4.63 (1H, d, J = 9.7 Hz, H-1?). 13C NMR (DMSO-d6, 125MHz) δ : 163.6 (C-2), 102.6 (C-3), 182.1 (C-4), 161.2 (C-7), 121.5 (C-1′), 128.6 (C-2′, 6′), 115.9 (C-3′, 5′), 159.5 (C-4′), 75.2 (C-1″), 71.4 (C-2″), 78.7 (C-3″), 69.7 (C-4″), 70.5 (C-5″), 74.6 (C-1?), 70.9 (C-2?), 78.8 (C-3?), 69.9 (C-4?) and 70.3 (C-5?). These data were consistent those in the literature [14]. Compound 8 was elucidated as apigenin 6,8-di-C-β-D-xylopyranoside.
Compound 9 pale yellow amorphous powder: C19H28O10, m/ z 439 [M+Na]+, 1H NMR (CD3OD, 300 MHz) δ : 7.38 (2H, d, J = 6.7 Hz, H-2, 6), 7.30 (2H, m, H-3, 5), 7.23 (1H, m, H-4), 4.75 (1H, d, J = 11.8 Hz, H-7a), 4.82 (1H, s, H-1''), 4.60 (1H, d, J = 11.8 Hz, H-7b), 4.29 (1H, d, J = 7.6 Hz, H-1'), 3.96 (1H, dd, J = 11.2 Hz, H-6'b), 3.84 (1H, m, H-6'a), 1.23 (3H, d, J = 6.2 Hz, H-6''). 13C NMR (CD3OD, 75 MHz) δ : 138.8 (C-1), 129.3 (C-2, 3, 5, 6), 128.8 (C-4), 103.1 (C-1'), 102.3 (C-1''), 78.0 (C-3'), 76.9 (C-5'), 75.1 (C-2'), 74.0 (C-4''),72.3 (C-3''), 72.2 (C-2''),71.8 (C-7), 71.7 (C-4'), 69.8 (C-5''), 68.1 (C-6') and 18.1 (C-6''). These data were consistent those in the literature [15]. So, compound 9 was elucidated as hydrangeifolin I (Figure 1).
Figure 1: Structures of compounds 1-9.
Even though Thalictrum showed different morphological features from Coptidis Rhizoma, many Thalictrum plants have a very close name to Coptidis Rhizoma (horsetail-Coptidis-Rhizoma) and were used as the succedaneum of Coptidis Rhizoma for the treatment of inflammation and infectious diseases for thousands years in China. As is known, bioactivities and functions of herbal medicine are closely related with its chemical composition. The phytochemical investigation in current study and reported literatures showed that the plants of those two genera (Thalictrum and Copdis) contain some same constituents such as berberine-type alkaloid [16-18]. Berberine-type alkaloids showed potent anti-inflammatory and antibacterial activities [19-23]. Compounds berberine (1), columbamine (2) and magnoflorine (3) has also been reported from Coptidis Rhizoma before [10]. Those compounds occurrence in both genera led them to have some same functions and explained why those Thalictrumplants were used as the substitute of Coptidis Rhizoma for the treatment of inflammatory and infectious diseases. Furthermore, together with Thalictrum genus, Coptis genus, the source of Coptidis Rhizoma, also belongs to the subfamily Thalictroideae. Researches on the chemical composition and pharmacological activities should be beneficial for the further development and application of T. ramosum and other plants of Thalictrum genus.
The n-BuOH solution was concentrated and gives a residue (344 g), which was separated by a silica gel column using CHCl3-MeOH (1:0 → 1:1) as eluent, affording 14 fractions (Fr. 1-14). Compound 1 was obtained by recrystallization of Fr. 7. Fr. 8 (8.6 g) was purified by a silica gel column using EtOAc-MeOH (10:1→5:1) as eluent to afford Fr. 8.1 - Fr. 8.7 (0.7 g). The same elution method was applied to Fr. 8.7 to afford Fr. 8.7.1 which was further purified by Sephadex LH-20 chromatography with MeOH to afford compound 2 (2.6 mg). Fr. 12 was purified by an ODS chromatographic method elueted with MeOH-Water (10%→90%) to afford Fr. 12.1 - Fr. 12.4. Fr. 12.3 was further purified by Sephadex LH-20 chromatography using MeOH-Water (90:10) as eluent to afford Fr. 12.1 - Fr. 12.3. Compound 4 (22.5 mg) and 9 (24.1 mg) was isolated from Fr. 12.3.3 by Prep-HPLC using CH3CN-H2O (15:85) as eluent.
Fr. 9 (25 g) was purified by a silica gel column using CDCl3-MeOH (10:1→1:1) as eluent to afford Fr. 9.1 - Fr. 9.7. Fr. 9.6 was purified by an ODS chromatographic method using MeOH-Water (10% → 90%) as eluent to afford Fr. 9.6.1 - Fr. 9.6.3. Prep-HPLC was applied to Fr. 9.6.2 using CH3CN-H2O (25:75) as eluent to afford compound 3 (50 mg). Fr. 9.5 was purified by an ODS chromatographic method using MeOH-Water (10% → 90%) and then further purified by Sephadex LH-20 chromatography using MeOH-H2O (90:10) as eluent to afford Fr. 9.5.1.1 and Fr. 9.5.1.2. Prep-HPLC was applied to Fr. 9.5.1.1 using CH3CN-H2O (18:82) as eluent to afford compound 6 (12.1 mg) and 7 (2.0 mg). Compound 5 (10.1 mg) was isolated from Fr. 9.5.1.2 by Prep-HPLC using CH3CN-H2O (13:87) as eluent. Fr-14 was chromatographedon a macropourous resin column using EtOH-Water (0% → 95%) as eluent to afford Fr. 14. 1 - Fr. 14.6. Fr. 14.4 was purified by an ODS chromatographic method using MeOH-Water (10% → 90%) as eluent to afford Fr. 14.4.1 - Fr. 14.4.6. Prep-HPLC was applied to Fr. 14.4.5 using CH3CN-H2O (12:88) as eluent to afford compound 8.