5792
Vol. 74
NOTES TABLE I ACID HYDROLYSIS OF STEROIDAL SAPONISS Hydrochloric
acid
Saponin a n d derived sapogenin
normality
Sarsasaponin spirostan-3 $-01
1 2
1/6
80
'4
Dioscin A6-isospirosten-3 p-01
1 2
98
93
1
12 47 91 89
2 89 52 89
7
Y
4 100
3f Krider I+,
'-.
18
65 100
98
53
6
60
93
03 17 74 100 -41 98 61 30 80 100 94 100
8
7%
67 93 100
Rothmdn dnri C R
Time for SOc& hydrolysis, hours
>6 3-4 1-7 >5
28 78 100
>5 3 57
99
>s 1-2 5 >5
100 63 35 84 100
112-1
-
7
1
77
longer than the comparable -1: N period, and as shown in Table I, the times varied from '3 hours to more than 8 hours. all the experinlents, use of I hydrochloric acid was ineffective, as was also hydrolysis wit11 1 and 2 N sulfuric acid (not shown in table). Destruetion of sapogenins with excess heating tilne apparently occurrec~only wherl C, ,J hydrochloric acid was used. The limited data indicate that the structure of the steroidal aglucone portion of the molecule does not influence the rate of hydrolysis (;.e., isonlerislTl a t C6 or CP2 or nulnber of hydroxyl groups). This is best shown by the data obtained with 2 -V acid hydrolysis. Sarsasaponin, yielding spirostan-3 fi-01and gitonin, the precursor of isoallospirostan-2~,3 $diol, are the most rapidly hydrolyzed SaPoniIls. Dioxin, yielding aj-isospirosten-3i3-01, and digitonin forming isoallospirostari-2,,3d, 13(?)-triol,were more resistant to hydrolysis. Chloronin, forming isoallospirostan-3 P,G-diol, was the most difticultly hydrolyzable saponin tested. The results discussed above Suggest that the routine use of 2 jjr hydrochloric acid for the hydrolysis of u n k n o w n suponins in crude plant extracts can result in low sapogenin yields. Crude plant extracts such as those used by Marker, et ~ l . contain proteins and sugars. I t is not surprising therefore, that lvhell we attempted to hydrolyze such extracts with iv acid, large quantities of tar were produced, from which little Sapogenin Could be isolated. Subsequently, a procedure was developed at this Laboratorye in which saponins could be routinely separated from proteins and carbohydrates by extraction from the aqueous phase with butanol. After this treatment, the saponin preparations could be hydrolyzed by refluxing with 4 &Y acid for 3-1 hours with little tar formation. The sapogenins thus formed are readily isolated. A nuni6er of experiments comparing the direct 2 -V hydrolysis5 with the butanol purified 4 N hyc{rolysisA have irlvariably shown that the latter of sapoIlroceclure gives ~ 5 - l ~ o c / ' ,higher Kenin. .\I
70 91
>
6
(6) Paper I. A I 12 \\ail
47 87 93
I
4
Gitonin isoallospirostan2 4 p-diol
27 73 93 17 35 83
47 87 13 9
4
6 Digitonin isoallospirostati2,
[email protected](?)-triol
1
7-1
4 Chloronin isoallospirostan3p,&-diol
1/2
Percentage of total sapogenin (based on 4 X) Time (hours) 3 3 4 5
