Novel steroidal saponins from Dioscorea esculenta (Togedokoro)

Figures & data

Table 1. ¹H (600 MHz) and ¹³C NMR (151 MHz) data of aglycone moiety of 9, 11, 14, and 15 in C₅D₅N.

	9		11		14		15
	^1H	^13C	^1H	^13C	^1H	^13C	^1H	^13C
1	3.72 (1H, ddd, 11.6, 6.1, 4.8)	77.96	0.97 (1H, m) 1.72 (1H, m)	37.50	0.94 (1H, m) 1.71 (1H, m)	37.48	1.00 (1H, m) 1.76 (1H, m)	37.53
2	2.34 (1H, m) 2.60 (1H, m)	40.87	1.85 (1H, m) 2.07 (1H, m)	30.18	1.89 (1H, m) 2.10 (1H, m)	30.10	1.87 (1H, m) 2.08 (1H, m)	0.20
3	4.04 (1H, m)	75.00	3.88 (1H, m)	78.07	3.97 (1H, m)	77.68	3.89 (1H, m)	78.09
4	2.84 (2H, m)	39.44	2.74 (1H, m) 2.82 (1H, m)	38.99	2.76 (1H, m) 2.82 (1H, m)	38.72	2.75 (1H, m) 2.82 (1H, m)	39.00
5	–	139.08	–	140.83	–	140.79	–	140.79
6	5.55 (1H, m)	125.22	5.33 (1H, m)	121.84	5.35 (1H, m)	121.89	5.31 (1H, m)	121.88
7	1.53 (1H, m) 1.88 (1H, m)	32.29	1.49 (1H, m) 1.89 (1H, m)	32.34	1.52 (1H, m) 1.91 (1H, m)	32.36	1.48 (1H, m) 1.88 (1H, m)	32.36
8	1.60 (1H, m)	32.93	1.59 (1H, m)	31.91	1.59 (1H, m)	31.93	1.58 (1H, m)	31.70
9	1.37 (1H, m)	51.21	0.91 (1H, m)	50.35	0.91 (1H, m)	50.32	0.91 (1H, m)	50.36
10	–	43.83	–	37.15	–	37.17	–	37.16
11	1.76 (1H, m) 2.89 (1H, m)	24.16	1.42 (1H, m) 1.46 (1H, m)	21.07	1.41 (1H, m) 1.45 (1H, m)	21.07	1.45 (1H, m) 1.47 (1H, m)	21.13
12	1.23 (1H, m) 1.76 (1H, m)	40.51	1.17 (1H, m) 1.97 (1H, m)	39.66	1.18 (1H, m) 1.97 (1H, m)	39.67	1.12 (1H, m) 1.75 (1H, m)	39.94
13	–	40.23	–	40.73	–	40.74	–	40.80
14	1.15 (1H, m)	56.83	1.12 (1H, m)	56.88	1.13 (1H, m)	56.90	1.08 (1H, m)	56.61
15	1.50 (1H, m) 2.08 (1H, m)	32.49	1.52 (1H, m) 2.10 (1H, m)	32.46	1.52 (1H, m) 2.11 (1H, m)	32.47	1.48 (1H, m) 2.04 (1H, m)	32.51
16	4.54 (1H, m)	81.11	4.65 (1H, m)	81.82	4.66 (1H, m)	81.83	4.95 (1H, m)	81.14
17	1.81 (1H, dd, 8.4, 6.6)	63.17	2.15 (1H, dd, 8.4, 6.0)	59.67	2.15 (1H, dd, 8.1, 5.7)	59.67	1.94 (1H, m)	63.83
18	0.91 (3H, s)	16.61	0.93 (3H, s)	16.41	0.93 (3H, s)	16.41	0.90 (3H, s)	16.50
19	1.39 (3H, s)	13.75	1.05 (3H, s)	19.42	1.06 (3H, s)	19.42	1.07 (3H, s)	19.43
20	1.96 (1H, m)	42.01	2.40 (1H, m)	50.67	2.40 (1H, m)	50.68	2.24 (1H, m)	40.72
21	1.11 (3H, d, 6.6)	15.07	4.03 (1H, m) 4.21 (1H, m)	62.51	4.04 (1H, m) 4.21 (1H, m)	62.52	1.33 (3H, d, 6.6)	16.50
22	–	109.28	–	109.29	–	109.29	–	110.68
23	1.67 (1H, m) 1.71 (1H, m)	31.86	1.83 (1H, m) 2.11 (1H, m)	33.28	1.83 (1H, m) 2.10 (1H, m)	33.29	1.98 (1H, m) 2.09 (1H, m)	37.19
24	1.58 (2H, m)	29.30	1.59 (2H, m)	29.28	1.59 (2H, m)	29.28	1.70 (1H, m) 2.07 (1H, m)	28.34
25	1.59 (1H, m)	30.63	1.62 (1H, m)	30.56	1.62 (1H, m)	30.57	1.95 (1H, m)	34.46
26	3.52 (1H, m) 3.60 (1H, m)	66.87	3.56 (2H, m)	66.90	3.55 (2H, m)	66.90	3.49 (1H, dd, 9.6, 7.2)	75.42
							4.10 (1H, dd, 9.6, 6.0)
27	0.70 (3H, d, 6.0)	17.36	0.69 (3H, d, 5.4)	17.34	0.69 (3H, d, 6.0)	17.34	1.04 (3H, d, 6.6)	17.46
C1–OH	6.27 (1H, d, 6.2)		–		–		–
C21–OH	–		5.62 (1H, dd, 5.2, 5.2)		5.62 (1H, dd, 5.3, 5.3)		–
C22–OH	–		–		–		6.69 (1H, br. s)

Table 2. ¹H (600 MHz) and ¹³CNMR (151 MHz) data of sugar moiety of 9, 11, 14, and 15 in C₅D₅N.

	9		11		14		15
	^1H	^13C	^1H	^13C	^1H	^13C	^1H	^13C
	3-O-Glc		3-O-Glc		3-O-Glc		3-O-Glc
1′	5.00 (1H, d, 6.6)	100.47	4.97 (1H, d, 7.8)	100.36	4.97 (1H, d, 7.2)	99.98	4.97 (1H, d, 6.6)	100.38
2′	4.23 (1H, m)	77.81	4.24 (1H, m)	77.96	4.25 (1H, m)	77.03	4.25 (1H, m)	77.93
3′	4.24 (1H, m)	77.76	4.25 (1H, m)	77.76	4.22 (1H, m)	89.62	4.25 (1H, m)	77.76
4′	4.44 (1H, m)	77.50	4.44 (1H, m)	77.64	4.10 (1H, m)	69.58	4.44 (1H, m)	77.64
5′	3.60 (1H, m)	77.07	3.62 (1H, m)	77.05	3.85 (1H, m)	77.95	3.62 (1H, m)	77.05
6′	4.04 (1H, m)	61.09	4.06 (1H, m)	61.21	4.28 (1H, m)	62.45	4.06 (1H, m)	61.21
	4.14 (1H, br.d, 11.4)		4.21 (1H, m)		4.46 (1H, m)		4.21 (1H, br.d, 10.8)
	Ext-Rha (a)		Ext-Rha (a)		Ext-Rha (a)		Ext-Rha (a)
1″	6.44 (1H, d, 1.8)	102.18	6.44 (1H, d, 1.2)	102.22	6.42 (1H, d, 1.8)	102.28	6.44 (1H, br.s)	102.21
2″	4.89 (1H, br. s)	72.57	4.88 (1H, br. s)	72.56	4.92 (1H, br.s)	72.54	4.88 (1H, br.s)	72.56
3″	4.69 (1H, m)	72.89	4.66 (1H, m)	72.88	4.61 (1H, m)	72.82	4.67 (1H, dd, 9.3, 2.7)	72.88
4″	4.39 (1H, m)	74.17	4.39 (1H, m)	74.17	4.35 (1H, m)	74.17	4.39 (1H, m)	74.17
5″	4.99 (1H, m)	69.59	4.99 (1H, m)	69.60	4.97 (1H, m)	69.65	4.98 (1H, m)	69.59
6″	1.74 (3H, d, 6.0)	18.65	1.79 (3H, d, 6.0)	18.68	1.78 (3H, d, 6.0)	18.74	1.79 (3H, d, 6.0)	18.69
	Int-Rha		Int-Rha		Ext-Glc		Int-Rha
1″′	5.87 (1H, s)	102.21	5.87 (1H, s)	102.23	5.14 (1H, d, 7.8)	104.60	5.87 (1H, br.s)	102.23
2″′	4.57 (1H, m)	72.96	4.58 (1H, m)	72.95	4.05 (1H, m)	75.01	4.57 (1H, m)	72.95
3″′	4.58 (1H, m)	73.34	4.59 (1H, m)	73.34	4.21 (1H, m)	78.56	4.58 (1H, m)	73.34
4″′	4.47 (1H, m)	80.46	4.48 (1H, m)	80.45	4.15 (1H, m)	71.52	4.47 (1H, m)	80.44
5″′	4.97 (1H, m)	68.32	4.98 (1H, m)	68.34	4.06 (1H, m)	78.77	4.96 (1H, m)	68.33
6″′	1.61 (3H, d, 6.6)	18.92	1.61 (3H, d, 6.0)	18.92	4.30 (1H, m)	62.45	1.61 (3H, d, 6.0)	18.92
					4.59 (1H, m)
	Ext-Rha (b)		Ext-Rha (b)				Ext-Rha (b)
1″″	6.32 (1H, d, 1.8)	103.38	6.32 (1H, d, 1.2)	103.37			6.32 (1H, br.s)	103.37
2″″	4.93 (1H, br. s)	72.70	4.94 (1H, br. s)	72.69			4.93 (1H, br.s)	72.69
3″″	4.54 (1H, m)	72.90	4.54 (1H, m)	72.89			4.53 (1H, dd, 9.3, 2.7)	72.90
4″″	4.33 (1H, m)	74.05	4.33 (1H, m)	74.05			4.33 (1H, m)	74.05
5″″	4.40 (1H, m)	70.46	4.40 (1H, m)	70.46			4.39 (1H, m)	70.46
6″″	1.62 (3H, d, 6.0)	18.47	1.62 (3H, d, 6.6)	18.47			1.62 (3H, d, 6.0)	18.47
							26–O–Glc
1″″′							4.84 (1H, d, 7.8)	105.19
2″″′							4.04 (1H, m)	75.26
3″″′							4.26 (1H, m)	78.65
4″″′							4.26 (1H, m)	71.70
5″″′							3.96 (1H, m)	78.55
6″″′							4.41 (1H, m)	62.82
							4.57 (1H, m)

Fig. 1. Structure of the identified steroidal saponins.

Fig. 2. The important HMBC (arrow) and ¹H–¹H COSY (bold line) correlations.