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Flavonoids of Cassia italica
Phytochemistry,Vol. 31, No. 6, p. 2187,1992 Printed in Great Britain.
0031 9422/92$S.oO+O.m 0 1992Pergamon Press Lrd
FLAVONOIDS
OF CASSIA ITALICA
NABIL H. EL-SAYED,* A. M. ABU DooH,t
E. A. M. EL-KHRISY and TOM J. MABRY~
National Research Centre, Dokki, Cairo, Egypt; TDepartment of Chemistry, Faculty of Science, Aswan, Egypt $The University of Texas at Austin, Austin, TX 78713-7640, U.S.A. (Received in revisedform 25 October 1991)
Key Word Index-Cassiu
italica; Leguminosae;
Caesalpinioideae;
flavonoids;
tamarixetin
3-rutinoside-7-
rhamnoside.
Abstract-Ten rhamnoside.
flavonoids were isolated from Cassia italica, including the first report of tamarixetin
INTRODUCTION
Cassia
italica
Miller F. W. Andr., (Leguminosae, Caesalpinioideae) is one of 600 species that comprise the genus Cassia [l]. We report here from C. italica the previously unreported tamarixetin 3-rutinoside-7rhamnoside as well as the known 7-glucosides of apigenin, kaempferol and quercetin, the 3-rutinoside of kaempferol and quercetin, the 3-rutinoside-7-rhamnoside of isorhamnetin and the aglycones apigenin, kaempferol and quercetin. RESULTS AND DISCUSSION
Known compounds were identified by standard procedures. Since the new compound 1 appeared purple on paper under UV light and this colour did not change with either ammonia or NA (Naturstoffreagenz A) reagent, the compound could be assigned a free 5-hydroxyl group and a substituted 4’-hydroxyl function. The low intensity of Band I in sodium methoxide relative to the same band in methanol confirmed that the 4’-hydroxyl was substituted, while the absence of Band III in sodium methoxide and a lack of a bathochromic shift for Band II in sodium acetate relative to the same band in methanol suggested that the 7-hydroxyl group was also substituted. The magnitude of the AK&-HCl bathochromic shift (48 nm) of Band I relative to Band I in methanol suggested a 5-hydroxy-3-substituted flavonol[2]. Acid hydrolysis of 1 yielded beside tamarixetin as the aglycone, the sugar moieties being glucose and rhamnose in a 1: 2 ratio (co-PC, ‘H NMR). The triglycosidic nature of I and the position of glycosylation was confirmed through ‘HNMR spectra [2-41, which showed three anomeric sugar protons at 65.48 (d, J=7.5 Hz) for H-l of the glucosyl moiety at the 3-position; 5.33 (d, J = 2.5 Hz) for the H-l of the rhamnosyl group at the 7-position and at 4.31 (d, J = 2.5 Hz) for H-l of the rhamnosyl unit attached to the glucosyl moiety at the 3-position. All other data were in accord with the assigned structure. Therefore, 1 is identified as tamarixetin 3-0-rutinoside 7-0-rhamnoside. EXPERIMENTAL Plant material. Cash italica Miller F. W. Andr. was collected by A. M. Abu-Dooh from Wadi Kubbania, northwest of Aswan
3-rutinoside-7-
(Egypt-Sudan border). A voucher specimen has been deposited in the Herbarium of the National Research Centre, Dokki, Cairo, Egypt. Extraction, isolation and identification of Javonoids. Dried aerial parts of C. italica (500 g) were defatted with petroleum ether (m-80”) and then exhaustively extracted with 70% ethanol. The ethanolic extract was subjected to cellulose CC using H,O then MeOH-H,O with increasing proportions of MeOH, yielding four main fractions. Further separations were performed using PPC with BAW as eluant. Each pure compound was further purified by Sephadex LH-20 using aq. MeOH as eluant prior to spectral analysis. UV data were recorded according to standard procedures [2] while ‘HNMR spectra were recorded in DMSO at 200 MHz. Tamarixetin 3-0-rutinoside-7-0-rhamnoside (1) was separated by PPC using BAW as eluant; R, values obtained were 0.2 (BAW) and 0.7 (15% HOAc); R, of rutin as standard in the same conditions were 0.52 and 0.45 in BAW and 15% HOAc, respectively; UV I.%:” nm: 264,355; + NaOMe: 266,395 with decrease in intensity: +NaOAc: 265, 365; +NaOAc-H,BO,: 261, 301, 355; +AICI,: 272, 305, 401; +A&-HCI: 270, 303, 400. ‘HNMR (DMSO): 86.83 (d, J=7.5 Hz, H-S), 7.6 (dd, J=7.5; 2.5 Hz, H-6’), 7.48 (d, J=2.5 Hz, H-2’), 6.38 (d, J=2.5 Hz, H-8), 6.18 (d, J=25 Hz, H-6), 5.48 (d, J=7.5 Hz, H-l glucosyl at 3-position), 5.33 (d, J=2.5 Hz, H-l rhamnosyl at ‘I-position), 4.32 (d, J = 2.5 Hz, H-l rhanmosyl at 3-position), 3.8 (OMe at C4’), 3.1-3.84 (m, sugar protons), 1.1,0.95 (d, J=6 Hz, two signals for two rhamnosyl methyl groups). Acknowledgement-This
work was supported at The University of Texas at Austin by the National Institutes of Health (GM-35710) and the Robert A. Welch Foundation (Grant F-l 30). REFERENCES
1. Harborne, J. B., Boulter, D. and Turner, B. L. (eds) (1971) Chemotaxonomy of the Leguminosae, p. 11. Academic Press, London, New York. 2. Mabry, T. J., Markham, K. R. and Thomas, M. B. (1970) The Systematic Identification of Flavonoids, pp. 54 and 269. Springer, New York. 3. Harbome, J. B., Mabry, T. J., and Mabry, H. (eds) (1975) The Flavonoids, pp. 6&70. Chapman 8t Hall, London. 4. R&ler, H., Mabry, T. J., Crammer, M. F. and Kagan, J. (1965) J. Org. Chem. 30,4346.
*Author to whom correspondence should be addressed. 2187
0031 9422/92$S.oO+O.m 0 1992Pergamon Press Lrd
FLAVONOIDS
OF CASSIA ITALICA
NABIL H. EL-SAYED,* A. M. ABU DooH,t
E. A. M. EL-KHRISY and TOM J. MABRY~
National Research Centre, Dokki, Cairo, Egypt; TDepartment of Chemistry, Faculty of Science, Aswan, Egypt $The University of Texas at Austin, Austin, TX 78713-7640, U.S.A. (Received in revisedform 25 October 1991)
Key Word Index-Cassiu
italica; Leguminosae;
Caesalpinioideae;
flavonoids;
tamarixetin
3-rutinoside-7-
rhamnoside.
Abstract-Ten rhamnoside.
flavonoids were isolated from Cassia italica, including the first report of tamarixetin
INTRODUCTION
Cassia
italica
Miller F. W. Andr., (Leguminosae, Caesalpinioideae) is one of 600 species that comprise the genus Cassia [l]. We report here from C. italica the previously unreported tamarixetin 3-rutinoside-7rhamnoside as well as the known 7-glucosides of apigenin, kaempferol and quercetin, the 3-rutinoside of kaempferol and quercetin, the 3-rutinoside-7-rhamnoside of isorhamnetin and the aglycones apigenin, kaempferol and quercetin. RESULTS AND DISCUSSION
Known compounds were identified by standard procedures. Since the new compound 1 appeared purple on paper under UV light and this colour did not change with either ammonia or NA (Naturstoffreagenz A) reagent, the compound could be assigned a free 5-hydroxyl group and a substituted 4’-hydroxyl function. The low intensity of Band I in sodium methoxide relative to the same band in methanol confirmed that the 4’-hydroxyl was substituted, while the absence of Band III in sodium methoxide and a lack of a bathochromic shift for Band II in sodium acetate relative to the same band in methanol suggested that the 7-hydroxyl group was also substituted. The magnitude of the AK&-HCl bathochromic shift (48 nm) of Band I relative to Band I in methanol suggested a 5-hydroxy-3-substituted flavonol[2]. Acid hydrolysis of 1 yielded beside tamarixetin as the aglycone, the sugar moieties being glucose and rhamnose in a 1: 2 ratio (co-PC, ‘H NMR). The triglycosidic nature of I and the position of glycosylation was confirmed through ‘HNMR spectra [2-41, which showed three anomeric sugar protons at 65.48 (d, J=7.5 Hz) for H-l of the glucosyl moiety at the 3-position; 5.33 (d, J = 2.5 Hz) for the H-l of the rhamnosyl group at the 7-position and at 4.31 (d, J = 2.5 Hz) for H-l of the rhamnosyl unit attached to the glucosyl moiety at the 3-position. All other data were in accord with the assigned structure. Therefore, 1 is identified as tamarixetin 3-0-rutinoside 7-0-rhamnoside. EXPERIMENTAL Plant material. Cash italica Miller F. W. Andr. was collected by A. M. Abu-Dooh from Wadi Kubbania, northwest of Aswan
3-rutinoside-7-
(Egypt-Sudan border). A voucher specimen has been deposited in the Herbarium of the National Research Centre, Dokki, Cairo, Egypt. Extraction, isolation and identification of Javonoids. Dried aerial parts of C. italica (500 g) were defatted with petroleum ether (m-80”) and then exhaustively extracted with 70% ethanol. The ethanolic extract was subjected to cellulose CC using H,O then MeOH-H,O with increasing proportions of MeOH, yielding four main fractions. Further separations were performed using PPC with BAW as eluant. Each pure compound was further purified by Sephadex LH-20 using aq. MeOH as eluant prior to spectral analysis. UV data were recorded according to standard procedures [2] while ‘HNMR spectra were recorded in DMSO at 200 MHz. Tamarixetin 3-0-rutinoside-7-0-rhamnoside (1) was separated by PPC using BAW as eluant; R, values obtained were 0.2 (BAW) and 0.7 (15% HOAc); R, of rutin as standard in the same conditions were 0.52 and 0.45 in BAW and 15% HOAc, respectively; UV I.%:” nm: 264,355; + NaOMe: 266,395 with decrease in intensity: +NaOAc: 265, 365; +NaOAc-H,BO,: 261, 301, 355; +AICI,: 272, 305, 401; +A&-HCI: 270, 303, 400. ‘HNMR (DMSO): 86.83 (d, J=7.5 Hz, H-S), 7.6 (dd, J=7.5; 2.5 Hz, H-6’), 7.48 (d, J=2.5 Hz, H-2’), 6.38 (d, J=2.5 Hz, H-8), 6.18 (d, J=25 Hz, H-6), 5.48 (d, J=7.5 Hz, H-l glucosyl at 3-position), 5.33 (d, J=2.5 Hz, H-l rhamnosyl at ‘I-position), 4.32 (d, J = 2.5 Hz, H-l rhanmosyl at 3-position), 3.8 (OMe at C4’), 3.1-3.84 (m, sugar protons), 1.1,0.95 (d, J=6 Hz, two signals for two rhamnosyl methyl groups). Acknowledgement-This
work was supported at The University of Texas at Austin by the National Institutes of Health (GM-35710) and the Robert A. Welch Foundation (Grant F-l 30). REFERENCES
1. Harborne, J. B., Boulter, D. and Turner, B. L. (eds) (1971) Chemotaxonomy of the Leguminosae, p. 11. Academic Press, London, New York. 2. Mabry, T. J., Markham, K. R. and Thomas, M. B. (1970) The Systematic Identification of Flavonoids, pp. 54 and 269. Springer, New York. 3. Harbome, J. B., Mabry, T. J., and Mabry, H. (eds) (1975) The Flavonoids, pp. 6&70. Chapman 8t Hall, London. 4. R&ler, H., Mabry, T. J., Crammer, M. F. and Kagan, J. (1965) J. Org. Chem. 30,4346.
*Author to whom correspondence should be addressed. 2187