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Biosynthesis of ticloidine in Physalis peruviana
BIOSYNTHESIS
OF TIGLOIDINE PERUVIANA
IN PHYSALIS
PAMELAJ. BERESFORD and JACKG. WOOLLEY School of Pharmacy, City of Leicester Polytechnic, Leicester LEl 9BH (Received 22 February 1974) Key Word Index-Physalis
peruviana;
Solanaceae; 3ccAgloyloxytropane; tigloidine (3j-tigloyloxytropane);
L-iso-
leucine; precursor of tiglic acid. Abstract-The aerial parts and roots of Physalis peruviana (Cape Gooseberry) have been shown to contain tigloidine (3/3-tigloyloxytropane) and 3a-tigloyloxytropane. The tiglic acid moiety of these alkaloids is derived from L-isoleucine.
THE MEDICINALLY useful alkaloid tigloidine (3fl-tigloyloxytropane), l unlike the 3a-tigloyl derivative, is of limited distribution in the Solanaceae and occurs in Duboisia2 Datura3~4 and Anthocersis.’ Recently it has also been isolated from Physalis alkekmgi and it appears to be present in all members of the genus so far examined,6 including Physalis peruviana (Cape Gooseberry). The alkaloidal spectrum of both plants is qualitatively very similar. In Datura, tiglic acid is known to be formed from L-isoleucine via 2-methylbutanoic acid7-9 and in the present series of experiments L-isoleucine-[U-14C] when infiltrated into the roots of P. peruviana gave radioactive tigloidine and 3u-tigloyloxytropane labelled solely in the tigloyl moiety after 3 days. /Me N 1 -
5
3 H
OCO
x
Me
Me
(1) The biosynthesis of the tropane ring has received considerable attention in recent years” and the first-formed bicyclic system, tropinone, is normally stereospecifically reduced to the 3~01 (tropine). The 3fi-01 (+-tropine) is not usually produced in such large quantities as it is in Physalis. To date, the C(6) and (7) hydroxy analogues of $-tropine
1 TODD, R. G. (1967) Mmtindale: The Extra Pharmacopoeia p. 1552, Pharmaceutical, London. ’ BARGER,G., MARTIN, W. F. and MITCHELL,W. (1937) J. Chem. Sot. 1821. ’ EVANS, W. C. and WELLENDORF,M. (1959) J. Chem. Sot. 1406. 4 EVANS, W. C. and TREAGUST,P. G. (1973) Phytochemistry 12,2077. ’ EVANS, W. C. and TREAGUST,P. G. (1973) Phytochemistry 12, 2505. 6 BASEY, K. and WOOLLEY,J. G. (1973) Phytochemistry 12,2557. ’ BASEY, K. and WOOLLEY, J. G. (1973) Phytochernistry 12,2197. * BASEY, K. and WOOLLEY, J. G. (1973) Phytochemistry 12,2883. 9 LEETE,E. (1973) Phytochemistry lo LEETE,E. (1972) Phytochemistry
12, 2202. 11, 1713.
’ ‘143
P. J. BEUSFOKD
2144
and J. G. WOOLLI.Y
esters (i.e. corresponding to the well known scrics based on tropine) have not been isolated from the Solanaceae, and presumably 3x substitution is a prerequisite for further [j hydroxylations in the tropane ring. TABLE 1. DISRIBL;SNIN OF RAINIACTIVITY FKOM L-ISOLECCINE-[U-"C]
01
FEEDING EXI’ERI.~NT IN Phy.sulis
sp. act. diluted piLrate (dpm:mM) x lo-“
wt picrate isolated (mg)
Wt base (mg)
Sp. act. (dpm/mM) x 10m5
sp. &.* x I03
Aerial parts I
0.43
1.13
0.6
0.664
6.9
2
0.35
7.0
4
403
6.1
Roots 1 2
0.34 0.17
8.78 26.6
4.6 14
4.07 x.94
7.3 3
1 Tigloidine. * Calculated
2 3a-Tigloyloxytropane. as sp. act. product x lOO/sp. act. precursor
sp. act. tiglic acid (dpm,‘mM) x 10 4 with 0o recovery
0,660 (99.3) 3.9x 19X.9)
dpm:mM.
EXPERIMENTAL PIzysalis prrwiann L. plants (seed obtained from Zentralinstitut fur Genetik und Kulturpflanzenforschung Gatersleben. D. D. R.) were grown on open land in Leicester. L-isoleucinr-[U-14C] was purchased from the Radiochemical Centre, Amersham. Administration of frucv~‘s. Four h-month-old Phy~cdis prr~rcirrntr plants were carefully uprooted. washed and allowed to stand in blackened beakers containing an aqueous solution of I.-isoleucine-[U-‘4C] (40 /tCi) sp. act. 8.7 mCi/mM for 5 days when the roots and aerial parts were separately dried at 60 for IX hr. Zsolutio~ of alkaloids. The roots (35 g) and the aerial parts (145 g) were extracted with Ca(OH)z-- H,O-Et,0 as described previouslyh and separately submitted to partition column chromatography on kleselguhr (10 g) containmg 5 ml 0.5 M phosphate buffer pH 68. ” Flution _ with light petrol. (100ml) gate two bases. dctectcd by TLC Aluminium oxide G (Merck) Et,O-~EtOH 9: I and Et?0 corresponding to tigloidme (K, 0.8 and 0.5) and 3;c-tigloyloxytropane (R, 0.4 and 0.1). Two methods were adopled for the ~rccolution of these bases. From the roots, the hascs were chromatoglaphcd on alumina (grade 1). 7.5 x I cm column. u\mg f t,O folio\\cd b! l-tl<>- LtOH 4: 1 and in order gave tigloidinc (0.34 mg) and then 3x-tigloylox)tropanc (0.2 mg). Partition chromatography at pH 6.6 was used to separate tigloidine (0.43 mg), eluted with light petrol. and ix-tlgloyloxytropane (0.35 mg), eluted with Et,O, from the aerial parts. The latter method was prcfcrred. All the bases wc~-c diluted \vith carrier and isolated as the picrates for counting. and hydrolysed hq, boiling with 5”#, Ba(OH), Ackr?owledgernents-One of us (P. J. B.) wishes to thank the Lelcester Education Authority for a Research Assistantship. We also wish to thank Dr. K. Basey who carried out the initial screening of P. /~~~ruL~iczncr. and Miss V. J. Charles. Mrs. A. Abbott and Mr. D. Penny for technical assistance. ” EVANS. W. C. and PARTKtI)GE. M. W. (1952) J. Phm
P/tar~~~uco/4, 769.
OF TIGLOIDINE PERUVIANA
IN PHYSALIS
PAMELAJ. BERESFORD and JACKG. WOOLLEY School of Pharmacy, City of Leicester Polytechnic, Leicester LEl 9BH (Received 22 February 1974) Key Word Index-Physalis
peruviana;
Solanaceae; 3ccAgloyloxytropane; tigloidine (3j-tigloyloxytropane);
L-iso-
leucine; precursor of tiglic acid. Abstract-The aerial parts and roots of Physalis peruviana (Cape Gooseberry) have been shown to contain tigloidine (3/3-tigloyloxytropane) and 3a-tigloyloxytropane. The tiglic acid moiety of these alkaloids is derived from L-isoleucine.
THE MEDICINALLY useful alkaloid tigloidine (3fl-tigloyloxytropane), l unlike the 3a-tigloyl derivative, is of limited distribution in the Solanaceae and occurs in Duboisia2 Datura3~4 and Anthocersis.’ Recently it has also been isolated from Physalis alkekmgi and it appears to be present in all members of the genus so far examined,6 including Physalis peruviana (Cape Gooseberry). The alkaloidal spectrum of both plants is qualitatively very similar. In Datura, tiglic acid is known to be formed from L-isoleucine via 2-methylbutanoic acid7-9 and in the present series of experiments L-isoleucine-[U-14C] when infiltrated into the roots of P. peruviana gave radioactive tigloidine and 3u-tigloyloxytropane labelled solely in the tigloyl moiety after 3 days. /Me N 1 -
5
3 H
OCO
x
Me
Me
(1) The biosynthesis of the tropane ring has received considerable attention in recent years” and the first-formed bicyclic system, tropinone, is normally stereospecifically reduced to the 3~01 (tropine). The 3fi-01 (+-tropine) is not usually produced in such large quantities as it is in Physalis. To date, the C(6) and (7) hydroxy analogues of $-tropine
1 TODD, R. G. (1967) Mmtindale: The Extra Pharmacopoeia p. 1552, Pharmaceutical, London. ’ BARGER,G., MARTIN, W. F. and MITCHELL,W. (1937) J. Chem. Sot. 1821. ’ EVANS, W. C. and WELLENDORF,M. (1959) J. Chem. Sot. 1406. 4 EVANS, W. C. and TREAGUST,P. G. (1973) Phytochemistry 12,2077. ’ EVANS, W. C. and TREAGUST,P. G. (1973) Phytochemistry 12, 2505. 6 BASEY, K. and WOOLLEY,J. G. (1973) Phytochemistry 12,2557. ’ BASEY, K. and WOOLLEY, J. G. (1973) Phytochernistry 12,2197. * BASEY, K. and WOOLLEY, J. G. (1973) Phytochemistry 12,2883. 9 LEETE,E. (1973) Phytochemistry lo LEETE,E. (1972) Phytochemistry
12, 2202. 11, 1713.
’ ‘143
P. J. BEUSFOKD
2144
and J. G. WOOLLI.Y
esters (i.e. corresponding to the well known scrics based on tropine) have not been isolated from the Solanaceae, and presumably 3x substitution is a prerequisite for further [j hydroxylations in the tropane ring. TABLE 1. DISRIBL;SNIN OF RAINIACTIVITY FKOM L-ISOLECCINE-[U-"C]
01
FEEDING EXI’ERI.~NT IN Phy.sulis
sp. act. diluted piLrate (dpm:mM) x lo-“
wt picrate isolated (mg)
Wt base (mg)
Sp. act. (dpm/mM) x 10m5
sp. &.* x I03
Aerial parts I
0.43
1.13
0.6
0.664
6.9
2
0.35
7.0
4
403
6.1
Roots 1 2
0.34 0.17
8.78 26.6
4.6 14
4.07 x.94
7.3 3
1 Tigloidine. * Calculated
2 3a-Tigloyloxytropane. as sp. act. product x lOO/sp. act. precursor
sp. act. tiglic acid (dpm,‘mM) x 10 4 with 0o recovery
0,660 (99.3) 3.9x 19X.9)
dpm:mM.
EXPERIMENTAL PIzysalis prrwiann L. plants (seed obtained from Zentralinstitut fur Genetik und Kulturpflanzenforschung Gatersleben. D. D. R.) were grown on open land in Leicester. L-isoleucinr-[U-14C] was purchased from the Radiochemical Centre, Amersham. Administration of frucv~‘s. Four h-month-old Phy~cdis prr~rcirrntr plants were carefully uprooted. washed and allowed to stand in blackened beakers containing an aqueous solution of I.-isoleucine-[U-‘4C] (40 /tCi) sp. act. 8.7 mCi/mM for 5 days when the roots and aerial parts were separately dried at 60 for IX hr. Zsolutio~ of alkaloids. The roots (35 g) and the aerial parts (145 g) were extracted with Ca(OH)z-- H,O-Et,0 as described previouslyh and separately submitted to partition column chromatography on kleselguhr (10 g) containmg 5 ml 0.5 M phosphate buffer pH 68. ” Flution _ with light petrol. (100ml) gate two bases. dctectcd by TLC Aluminium oxide G (Merck) Et,O-~EtOH 9: I and Et?0 corresponding to tigloidme (K, 0.8 and 0.5) and 3;c-tigloyloxytropane (R, 0.4 and 0.1). Two methods were adopled for the ~rccolution of these bases. From the roots, the hascs were chromatoglaphcd on alumina (grade 1). 7.5 x I cm column. u\mg f t,O folio\\cd b! l-tl<>- LtOH 4: 1 and in order gave tigloidinc (0.34 mg) and then 3x-tigloylox)tropanc (0.2 mg). Partition chromatography at pH 6.6 was used to separate tigloidine (0.43 mg), eluted with light petrol. and ix-tlgloyloxytropane (0.35 mg), eluted with Et,O, from the aerial parts. The latter method was prcfcrred. All the bases wc~-c diluted \vith carrier and isolated as the picrates for counting. and hydrolysed hq, boiling with 5”#, Ba(OH), Ackr?owledgernents-One of us (P. J. B.) wishes to thank the Lelcester Education Authority for a Research Assistantship. We also wish to thank Dr. K. Basey who carried out the initial screening of P. /~~~ruL~iczncr. and Miss V. J. Charles. Mrs. A. Abbott and Mr. D. Penny for technical assistance. ” EVANS. W. C. and PARTKtI)GE. M. W. (1952) J. Phm
P/tar~~~uco/4, 769.