References
The two hydrolysable tannin-related isolates, ellagic acid
(8) [18] and gallic acid (10) [19]were identified by comparison with literature data. The eight hydrolysable tannin isolates comprised three ellagitannins and five gallotannins. The three ellagitannins were identified as casuarinin (3) [20], corilagin (7) [21] and chebulagic acid (9) [21,22] by comparison with published data. In the same vein, three of the five gallotannin isolates were identified by comparison with literature as chebulic acid (4) [23], 5-O-galloylshikimic acid (5) [24] and pentagalloyl glucose (6) [25,26]. The remaining two gallotannins, whose comparative 1H (500 MHz) and 13C (125 MHz) NMR data are as shown in Table 1, and herein named chebumeinin A (1) and chebumeinin B (2), are new isomeric ester analogues of chebulic acid (4). The structures of 1 and 2 were determined as [(1-galloyl)glucopyranosyl-6′-yl]-12-chebulate and [(1-galloyl)glucopyranosyl-4′-yl]-12-chebulate respectively by a concurrent analysis of their spectradata as shown below.
ReferencesThe two hydrolysable tannin-related isolates, ellagic acid(8) [18] and gallic acid (10) [19]were identified by comparison with literature data. The eight hydrolysable tannin isolates comprised three ellagitannins and five gallotannins. The three ellagitannins were identified as casuarinin (3) [20], corilagin (7) [21] and chebulagic acid (9) [21,22] by comparison with published data. In the same vein, three of the five gallotannin isolates were identified by comparison with literature as chebulic acid (4) [23], 5-O-galloylshikimic acid (5) [24] and pentagalloyl glucose (6) [25,26]. The remaining two gallotannins, whose comparative 1H (500 MHz) and 13C (125 MHz) NMR data are as shown in Table 1, and herein named chebumeinin A (1) and chebumeinin B (2), are new isomeric ester analogues of chebulic acid (4). The structures of 1 and 2 were determined as [(1-galloyl)glucopyranosyl-6′-yl]-12-chebulate and [(1-galloyl)glucopyranosyl-4′-yl]-12-chebulate respectively by a concurrent analysis of their spectradata as shown below.
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