STRUCTURE OF A NEW TRITERPENE GLYCOSIDE FROM <i>CENTROSEMA BRACTEOSUM*</i>

SIMÃO, SHEILA MARINO; CARVALHO, MÁRIO GERALDO DE; BRAZ-FILHO, RAIMUNDO; MAGALHÃES, HÉLIO GUIGLIANELY

Artigo Original • Floresta Ambient. 4 • 1997 •

STRUCTURE OF A NEW TRITERPENE GLYCOSIDE FROM CENTROSEMA BRACTEOSUM*

Authorship SCIMAGO INSTITUTIONS RANKINGS

A new triterpene 3-O-[α-L-Rhamnopyranosyl (1 ->2)-(β-D-xy-lopyranosyl 16β,23 (R): 16α,30α-diepoxy-20(S)-hydraxydammar-24-ene (1) was isolated from roots of Centrosema bracteosum. The structure of this triterpenoid glycoside was elucidated by spectroscopic analysis of the natural product (1) and its peracetyl derivative (1a), including 2D NMR experiments.

Keywords:
Centrosema bracteosum; Leguminosae-Faboideae; triterpene glycoside; spectral data.

1		13^c
C	CDCI₃ δ_H^b	C₆D₆	δ_C CDCI₃	δ_C C₆D₅N	δ_H^b C₆D₅N	δ_C C₆D₅N	δ_H C₆D₅N
1'	4.46(d,J=5.9)	4.70(d,J=5.7)	103.47	106.62	4.86(d,J=6.7)
2'	3.80(dd, J=5.9,8.4)	4.2-3.9	74.51	80.93	4.2
3'	5.2-5.0	5.43(t,J=8)	69.14	79.29	4.2
4'	5.0-4.8	5.2-5.0	72.76	72.72	4.6
5'	3.37(t,J=8.6)	3.18(dd,J=8.6,11.6)	62.01	66.91	4.3
1"	4.2-3.9	4.2-3.9	-	-
2"	4.63(d,J=6.6)	4.79(d,J=6.2)	100.94	103.19	5.72(d,J=6.6)	102.60
	5.70(d,J=7.6)
3"	3.57(dd,J=6.6,8.6)	3.82(dd,J=6.2,8.3)	75.85	80.93	4.3	79.50
4"	5.2-4.9	5.41(t,J=8.3)	69.36	78.52	4.7	78.24
5"	5.0-4.8	5.2-5.0	72.76	71.68	4.1	70.90
1"'	3.31 (t,J=8.6)	3.31(dd,J=7.2,11.3)	61.48	66.91	4.3	66.90
2"'	4.2-3.9	4.2-3.9	-	-
3"'	4.89(br s)	5.24(br s)	97.94	102.31	6.35(s)	102.40	6.37(br
s)
4"'	5.07(br s)	5.50(d,J=2.9)	69.78	72.52	4.7	72.40
5"'	5.2-4.9	5.67(dd.J=2.9.9.6)	67.87	72.72	4.6	72.40
6"'	5.2-4.9	5.49(t, J=9.6)	70.65	74.43	4.3	74.36
OAc	4.1-3.9	4.47(dq,J=9.6,6.1)	66.84	69.72	4.9	69.51
	1.15(d,J=5.8)	1.53(d, J=6.1)	17.09	19.09	1.79(d, J=5.9)	18.91
	2.08(s)	2.01(s)	170.24	-	-
	2.06(s)	1.97(s)	170.11	-	-
	2.05(s)	1.79(s)	169.88	-	-
	2.01 (s)	1.77(s)	169.60	-	-
	1.99(s)	1.77(s)	20.72	-	-
	1.97(s)	1.72(s)	20.67	-	-
	1.94(s)	1.72(s)	20.60	-	-

1a(CDCI₃)	1(C₅D₅N)	9^b	CDCI₃	C₅D₅N
C	δ^C δ^H	δ^C δ^H	δ^C	10 11^c 12^c
1	38.49		39.90		39.00	39.0	39.5
	33.7
2	25.85		27.03		26.70	27.4	26.8
	25.5
3	89.69	3.1-2.9	89.54	3.25(m)	88.10	78.9	89.5
	75.9
4	39.37	-	40.11	-	39.70	39.0	39.8
	37.6
5	55.89	0.7	56.48	0.7	56.30	55.9	56.7
	49.5
6	17.88		18.64		18.30	18.3	18.6
7	35.52		37.33		36.00	35.3	35.3
8	37.13	-	37.49		37.30	40.4	40.3
9	52.51	0.8	53.29	0.8	53.00	50.7	50.4
10	36.98	-	37.49	-	37.30	37.1	37.2
11	21.30		22.03		21.80	21.6
12	27.91		28.77		28.60	25.4
13	36.85		38.96	2.80(m)	35.70	42.3
14	53.29	-	53.96		53.70	50.3
15	35.39	1.6-1.4	37.77	2.48(d, J=11.7)	37.10	31.2
16	109.48	-	110.87	-	110.60	27.6
17	52.62	1.1	54.15	1.4	53.90	49.9
18	18.51	1.06(s)	19.15	1.04(s)	18.30	16.2*	16.2*
19	15.88	0.77(s)	16.58	0.77(s)	16.40	15.5*	16.2*
20	69.23	-	68.72	-	68.50	75.4
21	29.84	1.14(s)	30.27	1.29(s)	30.00	24.9
22	44.36	1.6-1.4	45.60	1.7	45.30	40.5
23	68.60	4.60	68.93	5.27(dd, J=8.9,6.0)	68.50	22.6
24	125.04	5.15	127.21	5.51(d,J=6.0)	127.00	124.8
25	135.28	-	134.56	-	134.2	131.5
26	18.26	1.63(br s)	19.09	1.66(s)	25.50	17.7
27	25.51	1.67(br s)	25.91	1.64(s)	18.90	25.7
28	27.60	0.94(s)	28.77	1.22(s)	28.00	28.0	28.2
	28.5
29	16.02	0.80(s)	16.71	1.04(s)	16.80	15.4*	16.6*
	22.1
30	65.72		66.12		65.8	16.5

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[1] a Chemical shifts in d (ppm), coupling constants (J) in Hz and TMS as internal standard. Assignments were made with the aid of the DEPT and 2D-shift-correlated [1H x 13C-COSY, optimized for one-bond couplings (1JCH)] spectra. 1H Chemical shifts described with only one decimal correspond to approximate values of 1a and 1 and may correspond to only one proton in the case of the methylene groups.

[2] b The assignments of carbon atoms C-7, C-8, C-10, C-13, and C-15 need to be re-examined.

[3] c We described only useful values for comparison.

[TFN2] ^*
From the authors of the paper: "values in any vertical column may be reversed although those given here are preference".