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https://doi.org/10.29013/AJT-21-7.8-48-51
Naubeev Temirbek Khasetullaevich, PhD (Chemistry), docent, Head of Department"Oil & Gas Technology", Karakalpak State University E-mail: [email protected] Ramazanov Nurmurod Sheralievich, S. Yu. Yunusov Institute of natural compounds Doctor of Sciences, (in chemistry), Professor, Head of the laboratory Chemistry of glycosides Academy of Sciences of Uzbekistan
CYCLOASCIDOSIDE F FROM AERIAL PARTS OF ASTRAGALUS MUCIDUS (LEGUMINOSAE)
Abstract. New oxylisine glycoside from cycloartanic array named as Cycloascidoside F had been isolated from aerial part of Astragalus mucidus Bunge (Leguminosae). Structure of this glycoside was proved by chemical transformations and spectral data. Cycloascidoside F is trisdesmoside of cycloasgenin C and it consist of 3-O-a-L-arabinopyranosil, 6,25-di-0-^-D-glucopyranoside-24R-cycloartan - 3^,6a,16p,24,25-pentaol.
Keywords: Astragalus mucidus, Leguminosae, triterpene glycosides, Cycloascidoside F, cycloasgenin C, NMR spectrum 1H; 13C; DEPT, HMBC, HSQC.
Keeping research of cycloartan triterpenoids and Acid hydrolysis of 1 and further analysis of hy-
their glycosides, we had isolated new triterpene gly- drolysate by paper chromatography (PC) method
coside named by us as Cycloascidoside F (1) from based on biogenetic considerations allows us to
aerial part of Astragalus mucidus Bunge (Leguminose) identify L- arabinose and D-glucose. [1-3]. This research article describes proof for struc- A genin, identified as cycloasgenin C (2) was iso-
ture of this glycoside. lated from the byproducts of acidic hydrolysis.
NMR spectrum of being investigated substance 1 Anomeric protons of monosaccharide residues,
in strong field at S 0.60 and 0.21 ppm we can see two resonates in 1H NMR spectrum of new glycoside 1 at
single-proton doublet with relevant geminal spin-spin S 4.85 ppm (H-1 residue of a-L- arabinopyranosil),
compound constant (SSCC) 2J=4 Hz and clearly ap- S 4.93 ppm (H-1' residue of (3-D- glucopyranose) and
pears resonance line peaks of seven methyl groups at S 5.22 ppm. (H-1'' residue of (3-D- glucopyranose) as
0.98; 1.08; 1.24; 1.32; 1.39; 1.53 and 2.05 ppm. doublets with SSCC3J=7.5, 3J=7.5 h 3J=7.5 Hz accord-
13 C NMR spectrum show carbonic atoms of ingly. Consequently, monosaccharide residues consist-
cyclopropane ring C-9, C-10 and C-19 resonates ing ofbeing investigated glycoside have pyranose form,
accordingly at 21.89, 29.22 and 28.69 ppm (table 4 C1- conformation, (3- configuration D- glucoses and
1). This data bears evidence of belonging of being a- configuration L- arabinoses. It's justified by chemical
investigated matter to triterpenoids of cycloartanic shift rate ofcarbonic atoms ofmonosaccharide residues
series [2-8]. in 13C NMR spectrum of Cycloascidoside F.
OH
OH
OH
HO
OH
OH 2
OH
Illustration 1. Acid hydrolysis of Cycloascidoside F (1)
Mentioned values of 13C NMR spectrum also in- residues. Accordingly, Cycloascidoside F is trisdes-dicates the terminal nature of both monosaccharide moside glycoside.
Tablel.- Chemical shift of carbonic atoms and values of DEPT spectrum of aglycone part of Cycloascidoside F (1) and cycloasgenin C (2) (C5D5N, 5, ppm, J/Hz, 0-TMC)
Atom C DEPT Compound Atom C DEPT Compound
1 2 1 2
1 CH2 32.69 32.83 16 CH 71.73 71.83
2 CH2 30.68 31.45 17 CH 57.63 57.31
3 CH 89.05 78.41 18 CH3 18.97 18.80
4 C 43.14 42.45 19 CH2 28.69 30.40
5 CH 52.98 54.05 20 C 32.07 31.66
6 CH 79.67 68.35 21 CH3 19.31 19.10
7 CH2 34.74 38.62 22 CH2 35.40 34.86
8 CH 46.11 47.27 23 CH2 29.68 29.43
9 C 21.89 21.34 24 CH 79.23 80.58
10 C 29.22 29.67 25 C 81.39 72.71
11 CH2 26.76 26.43 26 CH3 22.02 25.86
12 CH2 33.61 33.28 27 CH3 24.74 26.22
13 C 46.19 45.78 28 CH3 20.32 20.31
14 C 47.41 47.00 29 CH, 29.03 29.34
15 CH2 48.59 48.83 30 CH3 17.12 16.12
In 13C NMR spectrum of Cycloascidoside F there are indication of three anomeric carbonic atoms at S 107.40, 105.64 and 99.20 (Table 2)
Chemical shift wave and interaction constant belonging to carbohydrate residues evidentiates the existence of arabinose and glucose. 1H NMR spec-
troscopy data traceable to genine part is peculiar to triterpenoids of cycloartan series and matches to cycloasgenin C. However resonance of carbons matches to C-3 (S 89.05), C-6 (S 79.67) u C-25 (S 81.39) is the subject of shift +9; +11 ppm in comparison with Cycloascidoside C.
Table 2.- H 1 and 13 C NMR spectrum data of carbohydrate part of Cycloascidoside F (1) (C5D5N, 5, ppm, J/Hz)
Compound 1
Atom C 8c 8H(J) Atom C 8c 8H(J) 8c 8h(J)
3-O-a-L-Arap 6-O-ß 5-D-Glcp 25-O-ß-D-Glcp
1 107.40 4.85 d, (8) 1 105.64 4.93 d, (7.5) 99.20 5.22 d, (7.5)
2 72.96 4.47 dd, (8.8, 8) 2 75.86 3.92, dd, (8.9, 7.8) 75.44 3.97, dd, (8.4, 7.8)
3 74.94 4.14 t, (8.5) 3 79.02 4.08 t, (8.9) 78.73 4.26 t, (8.8)
4 69.55 4.29 t, (8.9) 4 72.31 4.03 t, (8.9) 71.73 4.21 t, (8.7)
5 67.55 3.81dd, (11.3, 10) 4.32 dd, (11, 5.1) 5 78.61 3.78, ddd, (9.2, 5.1, 2.7) 78.73 3.83 m
6 63.58 4.18 dd, (11.7, 5.5) 4.35 dd, (11.7, 3.1) 63.24 4.16 dd, (11.7, 5.5) 4.37 dd, (11.6, 2.6)
In point of fact comparative analysis of13 C NMR spectrum of cycloasgenin C and Cycloascidoside F shows that in molecule of last one atoms of C-3, C-6 and C-25 of genine part undergo the glycosi-lation effect, that resonates at S 89.05, 79.67 and 81.39 accordingly. consequently, new glycoside 1 is tridesmodidal glycoside, carbohydrate composing of which are within C-3, C-6 and C-25 of cycloasgenin.
13C NMR spectrum of Cycloascidoside F shows anomeric carbonic atoms of monosaccharide residues are be discernible at S 107.40 ppm (C-1 residue of a-L- arabinopyranose), 105.64 ppm (C-1 residue of f-D- glucopyranose) and 99.20 ppm (C-1 residue of f-D- glucopyranose). Chemical shift rates of anomeric carbomic atoms bear evidence of fact that reside of L- arabinose is within C-3, and residue of D-glucose - within C-6 and C-25.
These assumptions proves HMBC correlation between H-1(S 4.85) arabinose and C-3 (S 89.05), H-1' (S 4.93) glucose and C-6 (S 79.67) and H-1" (S 5.22) glucose and C-25 (S 81.39) of aglycone.
As can be seen from the above described spectral data allows us to made conclusion that Cycloascidoside F(l) has the structure 3-O-a-L- arabinopyrano-sil, 6,25-di-O-^-D- glucopyranoside-24R- cycloar-tan -3^,6a,16^,24,25-pentaol.
Experimental. Applied solvent system: 1) chloroform-methanol (9:1), 2) chloroform-methanol-
water (70:28:3), 3) chloroform-methanol-water (60 : 35 : 5).
NMR spectrum were registered on spectrometer UNITYplus 400 (Varian) in deuteropyridine. 13 C NMR spectrum were registered at complete suppression of C-H and under the condition of DEPT. Two-dimension spectrum of compound 1 was registered by standard program of Varian company. Chemical shift of protons of compounds 1, 2 are described relative to UVLC, and in 13C NMR spectrum of compounds 1, 2 chemical shift of carbonic atoms are described relative to indication of ^-carbonic atoms of deuteropyridine chemical shift rate of which is S 123.493 ppm relative to TMS.
Isolation of isoprenoids from aerial part of Astragalus mucidus Bunge. Air-dry aerial parts of plant (1.5 kg) prepared in June 2008 in Namangan Region of Uzbekistan (Kutirbulag crest) was exhaustively extracted by with methanol (8 l x 5). Methanol extract was evaporated to sirupy consistence, diluted with double water volume, water solution was treated with double water volume, first water solution was treated with chloroform then with n-butyl alcohol. Butanol extraction was boiled-off to dryness, solid residual was chroma-tographed on column with silica gel. During column elution process at significance level 70 : 23 : 3 (chloroform-methanol-water) 72 mg of mater was
extracted (0.0048%, hereinafter was calculated per air-dry matter).
Cycloascidoside F (1), C47H80O19, melt. temp. 303-305 °C (from methanol). 1 H NMRspectrum of Cycloascidoside F (400 MHz, C5D5N, S, ppm, J/Hz) : 0.21, 0.60 (each1H, d, J = 4, H-19), 0.98 (3H, s, Me-28), 1.08 (3H, d, J=6.4, Me-21), 1.24, 1.32, 1.39, 1.53, 2.05 (each 3H, s, Me-30, 18, 27, 26, 29), 3.53 (1H, dd, J=11.6, 4.9, H-3), 3.68 (1H, td, J=9, 3.8, H-6), 3.90 (1H, dd, J=10.5, 2, H-24), 4.56 (1H, t.d, J=7.6, 5.2, H-16).
For detail information on 13 C spectrum refer to (table 1).
Partial hydrolysis of Cycloascidoside F. Glycoside 1 (30 mg) was dissolved in 15 ml of methanol containing 0.5% of sulfuric acid and it was boiled in boiling-water bath within 1 hour. Then reaction mix was dissolved in water to 15 ml and boiled-off with methanol. Past precipitation was filtered, washed-off
and dried. Filter effluent was neutralized with barium carbonate. Upon neutralizing process we have detected L- arabinose and D- glucose in filter effluent by paper chromatography method in comparison with invariable samples.
Residue was chromatographed on column, eluat-ing at significance level 1. 12 mg of genine identified with cycloasgenin C was separated in comparison with invariabled sample on thin-layer chromatography (TLC).
1 H NMR chromatography of cycloasgenin C (400 MHz, C5D5N, S, ppm, J/Hz, 0-UVLC): 0.21 and 0.49 (2H-19, d, 2J=4), 0.92 (CH3, s), 1.00 (cH3--21, d, 3J=6.4), 1.25, 1.30, 1.36, 1.39, 1.77 (5xCH3, s), 3.55 (H-3, dd, 3J1=11.4, 3J2=4.6), 3.67 (H-24, dd, 3J=10.4, 3J2=2.3), 3.69 (H-6, td, 3J1=3J2=9.4,3J3=3.8), 4.60 (H-16, td, 3J1=3J2=7.9, 3J3=5.1). For detail information on 13C NMR chromatography of cycloasgenin C refer to (table 1).
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