CC BY
10
https://doi.org/10.29013/AJT-22-7.8-42-47
Naubeev Temirbek Khasetullaevich, PhD {Chemistry}, docent, Head of Department"Oil & Gas Technology", Karakalpak State University Uteniyazov Karimbay Kuanishbaevich, PhD {Chemistry}, docent, Department "Organic and inorganic chemistry", Karakalpak State University Ramazonov Nurmurod Sheralievich, S. Yu. Yunusov Institute of the Chemistry of Plant Substances Doctor of Sciences, (in chemistry), Professor, Head of the laboratory Chemistry of glycosides Academy of Sciences of Uzbekistan
TRITERPENE GLYCOSIDES ASTRAGALUS AND THEIR GENINS XCV. CYCLOASCIDOSIDE В FROM ASTRAGALUS MUCIDUS
Abstract. Structure of the novel cycloartane glycoside, cycloascidoside B isolated from the aerial parts of Astragalus mucidus Bunge (Leguminosae) is determined as 3-0-^-D-(2-0Ac)-xylopyranoside, 6,25-di-0-^-D-glycopyranosides-24R-cycloartan-3p,6a,16p,24,25-pentanol. Structure of this glycoside had been proven based on chemical transformations and spectral data of NMR1H, 13 C.
Keywords: Astragalus mucidus Bunge, Leguminosae, cycloartan triterpenoids, cycloascidoside A, B and E, cycloasgenin C, spectra NMR1 H, 13 C, DEPT.
Continuing of our investigation of isoprenoid at 21.18 and 170.07. These data confirm that cycloas-
compounds from Astragalus (Leguminosae) plants cidoside B contains one acetyl group (table 2).
and their chemical transformation [1], from the Acidic hydrolysis of glycoside 1 gives genine (2)
aerial part of Astragalus mucidus Bunge we have iso- identified with cycloasgenin C [1-8]. Sugar fraction
lated a novel cycloarrtane glycoside named by us as of the yield of acidic hydrolysis contains D- glucose
cycloascidoside B (1). In the article we give proof and D- xylose (lyxosazone) which are determined by
of the chemical structure of the isolated glycoside. paper chromatography method (PC) in the presence
NMR1 H spectrum of the novel glycoside 1 in of samples of different carbohydrates.
high field at S 0.07 and 0.45 have two single-proton Alkaline hydrolysis of cycloascidoside B (1)
doublets is discernible with specific germinal spin- gives glycoside 3 identified with cycloascidoside
spin coupling constant (SSCC) 2 J = 4 hz and signal E (3). Consequently, cycloascidoside B (1) is mono-
of seven methyl groups at S 0.83 - 1.86. These data acetate of cycloascidoside E (figure 1) [8].
indicate that the isolated compound is cycloartane Partial hydrolysis of glycoside 3 gives cycloas-
type triterpene glycoside [2-5]. genin 2 and progenins 4 and 5.
NMR1H and 13 C spectrum have singlet signal of On basis of physical and chemical constants,
three proton units at 1.91 and signals of carbon atoms spectral data and results of TLC analysis monoside
5 was identified as 3-O-^-D- xylopyranoside of cy-cloasgenin C [3], and bioside 4 was identified as cy-cloascidoside A (figure 1) [1].
NMR1 H and 13 C spectra ofcycloascidoside B (1) have signals of three protons at 4.67; 4.81; 5.08 and signals of three anomeric carbon atoms of monosaccharide residue at 104.96; 104.62 and 98.57.
Thereby, the above mentioned datum confirm that the cycloascidoside B (1) is trioside.
Position of acetyl group in the molecule of isolated glycoside were found on basis of comparative analysis of 1 H and 13 C NMR spectra of compounds 1 and 3. Comparative analysis of chemical shifts of anomeric carbon atoms in 13 C NMR spectra confirms position of acetyl group in the molecule of cycloascidoside B (1) at C-21 atom of xylose (table 2). In 13 C NMR spectrum of cycloascidoside B (1)
Comparative analysis of13 C NMR spectrum data of cycloasgenin C (2) and cycloascidoside B (1) gives evidence that carbon atom C-3, C-6 and C-25 of cycloascidoside B (1) are endured glycosilation and resonate at 88.90; 79.14 and 80.86. These data shows that sugar residues are connected to genin through hydroxyl groups at C-3, C-6 and C-25 carbon atoms.
OH OH IXoh
anomeric carbon atom C-11 resonates at 104.96. Comparing of these data in cycloascidoside E (3) shows that atom C-11 of xylose in cycloascidoside B (1) have endured diamagnetic displacement (shift) to 1.41. This data shows that acetyl residue is located in molecule of xylose. Value of upfield shift of carbon atom C-11 indicates that acetyl group attached to carbon atom C-21. This conclusion is also proved out by
OH
RjO
or2 3
3. Rj=Xylp, R2=R3=Glcp
4. Rj=Xylp, Rj=Glcp, R3=H
5. Rj=Xylp, Rj=R3=H
Figure 1. Acidic and alkaline hydrolysis of cyclolastioside B (1)
upfield shift ofsignal C-31 to 2,93. Abovementioned Analysis of1H and 13C NMR spectra (table 2) of data let us to make conclusion that acetyl group in glycoside 1 shows, that it has three monosaccharide cycloascidoside B (1) is attached at C-21 of xylose. residue and is trioside.
Table 1.- 13 C NMR data of aglycone part of cycloascidoside B (1), cycloasgenin C (2), cycloascidoside E (3), cycloascidoside A (4) and 3-O-P-D- xylopyranoside of cycloasgenin C (5) (C5D5N, 8, J/Hz)
Atom C DEPT 1 2 [3] 3 4 5 [3]
1 CH2 32.01 32.83 32.20 32.20 32.97
2 CH2 29.83 31.45 30.22 30.18 30.85
3 CH 88.90 78.41 88.55 88.55 89.20
4 C 42.18 42.45 42.65 42.64 43.20
5 CH 52.37 54.05 52.48 52.49 54.61
6 CH 79.14 68.35 79.16 79.16 68.40
7 CH2 34.35 38.62 34.23 34.24 38.93
8 CH 45.64 47.27 45.62 45.59 47.50
9 C 21.40 21.34 21.38 21.41 21.84
10 C 28.63 29.67 28.71 28.73 29.71
11 CH2 26.17 26.43 26.26 26.29 26.79
12 CH2 33.08 33.28 33.14 33.14 33.64
13 C 45.74 45.78 45.66 45.75 46.19
14 C 46.80 47.00 46.89 46.99 47.41
15 CH2 48.00 48.83 48.05 48.19 49.20
16 CH 71.70 71.83 71.75 71.69 72.20
17 CH 57.17 57.31 57.15 57.02 57.70
18 CH3 18.51 18.80 18.47 18.50 19.27
19 CH2 30.02 30.40 30.33 28.16 30.46
20 CH 31.46 31.66 31.55 31.63 32.11
21 CH3 18.72 19.10 18.80 18.82 19.46
22 CH2 34.86 34.86 34.96 34.82 35.31
23 CH2 29.18 29.43 29.25 29.32 29.86
24 CH 78.88 80.58 78.94 80.58 81.07
25 C 80.86 72.71 80.56 72.67 73.16
26 CH3 21.58 25.86 21.50 25.95 26.41
27 CH3 24.13 26.22 24.22 26.10 26.64
28 CH3 19.80 20.31 19.83 19.86 20.70
29 CH3 28.44 29.34 28.52 28.53 29.36
30 CH3 16.49 16.12 16.63 16.64 17.18
Anomeric protons ofmonosaccharide residue are resonated in 1H NMR spectra of glycoside 1 at S 4.67 (H-1 of residue of (3-D-xylopyranoses, d, 3J = 8 Hz), S 4.81 (H-1 ofresidue of^-D- glucopyranose, d, 3J =7.5 Hz) and S 5.08 (H-1 of residue of (3-D-glucopyranose, d, 3J=7.6 Hz) (table 2). It means that monosaccharide residues in the glycoside have pyranose form, 4C1- con-
formation and ^-configuration of chemical structure. This conclusion is also confirmed by chemical shift value of carbon atoms of monosaccharide residues in 13C NMR spectra of cycloascidoside B. Mentioned values of 13C NMR also point at terminal character of both monosaccharide residues. Accordingly, cycloascidoside B is trisdesmoside glycoside.
Table 2.- 13C NMR data of carbohydrate part of cycloascidoside B (1), cycloascidoside E (3), cycloascidoside A (4) and 3-O-P-D- xylopyranoside of cycloasgenin C (5) (C5D5N, ô, J/Hz)
Atom C 3-O-3-D-Xylp
1 104.96 106.37 107.63 108.12
2 76.13 75.57 75.59 76.13
3 75.52 78.45 78.51 79.02
4 71.23 71.22 71.23 71.74
5 66.98 66.99 67.03 67.55
Ac 21.18
170.07
6-O-3-D-Glcp
1 104.62 105.54 105.18
2 75.52 75.57 75.59
3 79.00 79.13 79.16
4 71.70 71.77 71.83
5 77.95 78.14 78.09
6 63.02 63.07 63.12
25-O-3-D-Glcp
1 98.57 98.45
2 75.23 75.40
3 78.57 78.54
4 71.79 71.77
5 78.05 78.24
6 62.69 62.66
According to comparative analysis of 13 C NMR spectra of compounds 1 and 2 location of residue of D-xylopyranose found be at C-3, and location of D-glucopyranose residues at C-6 and C-25. From table 1, signal of carbon atom C-3 have downfield shift to 10.49, and signals of C-6 and C-25 carbon atoms have downfield shift to 10.79 and 8.15 comparatively with cycloasgenin C.
Anomeric carbon atoms of monosaccharide residues resonate at §104.96 (C-1 of^-D-xylopyranoses), 104.62 (C-1 ofp-D-glucopyranose) and 98.57 (C-1 of ^-D-glucopyranose) in 13 C NMR spectra of cycloascidoside E. Chemical shift values of anomeric carbon atoms show that residue of D-xylose is attached to C-3, and residues of D-glucose are attached to C-6 and C-25 of genin.
Thereby, on basis of above described experimental data the chemical structure of isolated novel cy-cloartane line triterpene glycoside, cycloascidoside
B is 3-0-p-D-(2-0Ac)- xylopyranoside, 6,25- di-O-P-D-glycopyranosides-24R-cycloartan-3^, 6a,16^, 24, 25-pentaol.
Experimental part. General Experimental Procedures [1]. Following solvent systems were used: chloroform - methanol - water, 70:12:1 (l), chloroform - methanol, 9 : 1 (2), chloroform - methanol - water, 70 : 23 : 3 (3). NMR spectrum of the compounds were recorded on Unityplus 400 (Varian) referenced with respect to the residual solvent signal of C5D5N. 13C NMR spectrum were recorded at complete suppression of C-H interaction and under DEPT conditions. Chemical shifts of protons of compositions 1, 3 were described in reference to HMDS.
Extraction and isolation. Isolation method of isoprenoids from aerial part Astragalus mucidus Bunge were given in [1]. 150 mg (0.01%) of cycloascidoside B was isolated by elution of silica gel column with the system 3.
Cycloascidoside B (1), CHg2O21, melting point. 280-282°C (from methanol). Spectra NMR1H (400 MHz, C5D5N, S, ppm., J/hz): 0.07, 0.45 (each 1H, d, J=4, H-19), 0.83 (3H, c, Me-28), 0.95 (3H, d, J=6.4, Me-21), 1.24, 1.25, 1.37, 1.38, 1.86 (each 3H, c, Me-30, 18, 27, 26, 29), 1.91 (3H, s, OAc), 3.41 (1H, dd, J=11.6, 4.9, H-3), 3.57 (1H, dd, J=11.3, 10, H-5a, Xylp), 3.68 (1H, td, J=9, 3.8, H-6), 3.78 (1H, ddd, J=9.2, 5.1, 2.7, H-5 Glcp), 3.84 (1H, m, H'-5, Glcp,), 3.86 (1H, dd, J=8.4, 7.8, H'--2, Glcp), 3.93 (1H, dd, J=8.9, 7.8, H-2, Glcp), 4.00 (1H, t, J=8.5, H-3, Xylp), 4.04 (1H, t, J=8.8, H-3', Glcp), 4.06 (1H, t, J=8.9, H-4, Glcp), 4.08 (1H, t, J=8.9, H-4, Xylp), 4.09 (1H, t, J=8.7, H'-4, Glcp), 4.11 (1H, t, J=8.9, H-3, Glcp), 4.20 (1H, dd, J=11.7, 5.5, H-6, Glcp), 4.20 (1H, dd, J=11, 5.1, H-5e, Xylp), 4.38 (1H, dd, J=11.7, 3.1, H-6, Glcp), 4.40 (1H, dd, J=11.6, 2.6, H-6', Glcp), 4.52 (1H, td, J=7.6, 5.2, H-16), 3.76 (1H, dd, J=10.5, 2, H-24), 4.67 (1H, d, J=8, H-1, Xylp), 4.81 (1H, d, J=7.5, H-1, Glcp), 5.08 (1H, d, J=7.5, Glcp, H-1), 5.40 (1H, dd, J=8.8, 8, Xylp, H-2). For Spectra 13C refer to table 1, 2.
Acidic hydrolysis of cycloascidoside B. Glycoside 1 (30 mg) was dissolved in 10 ml of methanol that contains 0.5% of sulfuric acid, and boiled it in boiling-water bath for 1 hour. Then the reaction mixture was diluted with water up to 30 ml and MeOH was evaporated. Formed sediment was filtered, washed with water and dried. Filtrate was neutralized with BaCO3. After removing of precipitate the solvent was concentrated and analyzed by TLC method using solvent system 3 and in comparison with samples D-glucose and D- xylose were found.
Residue was rechromatographed silica gel column by eluating with system 2. Genin 2 (15 mg) identified with cycloasgenin C in comparison with samples by TLC analysis and on basis of 1H NMR spectrum.
Cycloasgenin C. 1H NMR spectra (400 MHz, C5D5N, S, ppm, J/hz): 0.21, 0.49 (each 1H, d, J=4, H-19), 0.92 (3H, s, Me-28), 1.00 (3H, d, J=6.4, Me-21), 1.25, 1.30, 1.36, 1.39, 1.77 (3H, c, Me-30,
Me-18, Me-27, Me-26, Me-29), 3.55 (1H, dd, J=11.4, 4.7, H-3), 3.67 (1H, dd, J=10.4, 2.3, H-24), 3.69 (1H, td, J=9.4, 3.7, H-6), 4.60 (1H, td, J=7.8, 5.0, H-16).
Alkaline hydrolysis of cycloascidoside B. Cycloascidoside B (1) 50 mg was saponified in 20 ml of 0,5% methanol solution of potassium hydroxide. Reaction mixture was set at room temperature during 24 hour, then diluted with 25 ml of water. Then the mixture was neutralized with acetic acid. MeOH was evaporated and extracted with BuOH. The obtained residue was rechromatographed with silica gel. 30 mg of cycloascidoside E (3) was isolated by eluating with system 3, C47H80O19, mp 276-278 °C (from MeOH). 1H NMR spectra of cycloascidoside E (400 MHz, C5D5N, S, ppm, J/Hz): 0.06, 0.45 (each 1H, d, J=4, H-19), 0.84 (3H, s, Me-28), 0.96 (3H, d, J=6.4, Me-21,), 1.23, 1.25, 1.38, 1.39, 1.91 (3H, s, Me-30, Me-18, Me-27, Me-26, Me-29), 3.40 (1H, dd, J=11.6, 4.3, H-3,), 3.56 (1H, dd, J=11.3, 10, H--5a Xylp), 3.67 (1H, td,J=8.4, 4.3, H-6,), 3.77 (1H, dd, J=10.5, 2, H-24,), 3.78 (1H, ddd, J=9.2, 5.1, 2.7, Glcp H-5), 3.85 (1H, m, Glcp H'-5), 3.87 (1H, dd, J1=8.4, 7.9, Glcp H'-2), 3.92 (1H, dd, J=8.6, 7.5, Glcp H--2), 3.93 (1H, dd, J=8.6, 7.5, Xylp H-2), 4.03 (1H, t, J=8.6, Xylp H-3), 4.05 (1H, t, J=8.9, Glcp H-4), 4.06 (1H, t, J=8.8, Glcp H'-3), 4.09 (1H, t, J=8.9, Xylp H-4), 4.10 (1H, t, J=8.7, Glcp H'-4), 4.11 (1H, t, J=8.9, Glcp H-3), 4.20 (1H, dd, J=11.7, 5.5, Glcp H--6), 4.21 (1H, dd, J=11.5, 5.1, Xylp H-5e), 4.35 (1H, dd, J=11.6, 3, Glcp H-6), 4.38 (1H, dd, J=11.6, 2.6, Glcp H'-6), 4.54 (1H, td, J=7.7, 5.3, H-16), 4.76 (1H, d, J=7.8, Glcp H-1). 4.79 (1H, d, J=7.5, Xylp H-1), 5.06 (1H, d, J=7.8, Glcp H'-1). 13C NMR spectrum of cycloascidoside E is given in tables 1, 2.
Partial hydrolysis of cycloascidoside E. Glycoside 3 (30 mg) was dissolved in 100 ml of methanol that contains 0.5% of sulfuric acid, and boiled it in boiling-water bath for 1 hour. The reaction mixture was diluted with water up to 30 ml and MeOH was removed by evaporation. Formed precipitation was filtered, washed with water and dried. Filtrate was
neutralized with BaCO3. Filtrate was analyzed by TLC method using system 3 in comparison with samples and found D-glucose and D-xylose.
Residue was set to column with silica gel and was eluated with system 2. Genin 2 (7 mg) was isolated and identified with cycloasgenin C by TLC method and according to information of 1H NMR spectrum.
Monoside 5 (8 mg) (3-O-^-D- xylopyranoside of cycloasgenin C), C35H60O9, mp 252-254°C (from MeOH) and bioside 4 were isolated by eluting the silica gel column with system 1 [1; 3]. 1H NMR spectra of progenin 5 (400 MHz, C5D5N, S, ppm, J/Hz): : 0.30, 0.58 (each 1H, d, J=4, H-19), 1.05 (3H, s, Me-28), 1.13 (3H, d, J=6.4, Me-21), 1.36, 1.42, 1.51, 1.53, 2.02 (3H, s, Me-30, Me-18, Me-27, Me-26, Me-29), 3.60 (1H, dd, J=11.2, 9.8, Xylp H-5a), 3.64 (1H, dd, J=11.7, 4.6, H-3), 3.67 (1H, td,J=9.7, 3.6 H--6), 3.75 (1H, dd, J=10.5, 2.4, H-24), 3.83 (1H, dd, J=8.8, 7.5,XylpH-2),4.06 (1H, t,J=8.6, XylpH-3), 4.15 (1H, m, Xylp H-4), 4.36 (1H, dd, J=11.3, 5, Xylp H-
-5e), 4.71 (1H, td, J=7.7, 4.9, H-16), 4.92 (1H, d, J=7.5, Xylp H-1). For spectra 13 C NMR spectra of progenin 5 is given in the (table 1).
Progenin 4. 1H NMR spectra (400 MHz, C5D5N, S, ppm, J/Hz): 0.06, 0.45 (each 1H, d, J=4.3, H-19), 0.85 (3H, s, Me-28), 0.97 (3H, s, J=6.4, Me-21,), 1.24, 1.26, 1.36, 1.39, 1.90 (3H, s, Me-30, Me-18, Me-27, Me-26, Me-29), 3.40 (1H, dd, J1=11.6, 4.3, H-3), 3.56 (1H, dd, J=11.3, 10, Xylp H-5a), 3.67 (1H, dd, J=10.5, 2.4, H-24), 3.68 (1H, td, J=8.4, 4.3, H-6), 4.57 (1H, td, J=7.5, 4.9, H-16), 3.77 (1H, ddd,J=9.2, 5.1, 2.7, Glcp H-5), 3.91 (1H, dd, J=8.9, 7.8, Glcp H-2), 3.92 (1H, dd, J=8.6, 7.5, Xylp H-2), 4.02 (1H, t, J=8.6, Xylp H-3), 4.09 (1H, m, Xylp H--4), 4.11 (1H, t, J=8.9, Glcp H-3), 4.19 (1H, dd, J=11.6, 5.4, Glcp H-6), 4.22 (1H, dd, J=11.5, 5.1, Xylp H-5e), 4.35 (1H, dd, J=11.6, 3, Glcp H-6'), 4.71 (1H, d, J=7.5, Xylp H-1), 4.79 (1H, d, J=7.8, Glcp H--1). 13C NMR spectra of the progenin 4 is given in the (table 1).
References:
1. Naubeev T. Kh., Uteniyazov K. K., Isaev M. I. Chem. Nat. Compd.,- 47. 2011.- 250 p.
2. Naubeev T. Kh., Zhanibekov A. A., Isaev M. I. Chem. Nat. Compd.,- 48. 2012.- 813 p.
3. Naubeev T. Kh., Zhanibekov A. A., Uteniyazov K. K., Bobakulov Kh.M., Abdullaev N. D. Chem. Nat. Compd.,- 49. 2014.- 1048 p.
4. Naubeev T. Kh., Uteniyazov K. K., Tlegenov R. R., Uteniyazov K.J. Uzbek Chemical Register, - 29. 2008.
5. Isaev M. I., Gorovits M. B., Abdullaev N. D., Abubakirov N. K. Chem. Nat. Compd.- 18, 1982.- 424 p.
6. Isaev M. I. Chem. Nat. Compd.,- 31. 1995.- 690 p.
7. Kucherbayev K. D., Uteniyazov K. K., Kachala V. V., Saatov Z., Shashkov A. S. Chem. Nat. Compd.- 38. 2002.- 447 p.
8. Naubeev T. X., Janibekov A. A., Kucherbayev K. Dzh. Uzb. Biol. J.,- 35. 2017.
