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Acetylenes in the genus dahlia, asteraceae in honour of professor G. H. neil towers 75TH birthday
\
Phytochemistry\ Vol[ 38\ No[ 1\ pp[ 402Ð408\ 0887 Þ 0887 Published by Elsevier Science Ltd[ All rights reserved Printed in Great Britain 9920Ð8311:87:,Ðsee front matter
Pergamon
PII] S9920Ð8311"87#99154Ð8
ACETYLENES IN THE GENUS DAHLIA\ ASTERACEAE IN HONOUR OF PROFESSOR G[ H[ NEIL TOWERS 64TH BIRTHDAY JO šRGEN LAM rhus V\ Denmark Klokkerbakken 3\ DK!7109 A "Received 8 April 0886^ received in revised form 19 June 0886#
Key Word Index*Dahlia species\ acetylenes\ Coreopsedinae\ Heliantheae\ Asteraceae[
Abstract*Dahlia species grow wild in several places of Mexico[ A series of Dahlia species have been propagated in Denmark and some of these plants have been studied at the Chemical Institute\ University of Aarhus in Denmark[ More than 39 compounds have been characterized after isolation from roots and tubers or from aerial plant material[ The major compounds were acetylenes that occur in these Dahlia species and other genera of Heliantheae\ a tribe within Asteraceae[ Dahlia merckii Lehm is unique both chemically and in terms of its chromosome number\ whereas Dahlia tubulata is also unique in the chemical sense that it contains many thiophene compounds some of which are acetylenes\ a new discovery among the Dahlia species[ Þ 0887 Published by Elsevier Science Ltd[ All rights reserved
INTRODUCTION
Various D[ coccinea strains and other species of the genus Dahlia have been obtained from the Botanical Garden of Copenhagen\ where the plants have been propagated from seeds collected from plants in Mexico by the Danish botanist J[ P[ Hjerting and his two colleagues R[ Lester and J[ G[ Hawkes in 0847[ Although the genus Dahlia originally grew wild in Mexico\ a few Dahlia species are however growing wild in Guatemala[ The D[ coccinea strains from Mexico were of di}er! ent colour and ploidy[ All Dahlia plants treated were subjected to investigation of] 0# roots and tubers^ 1# stems and leaves and 2# ~owerheads\ respectively[ The acetylenes were isolated during the years 0853 to 0881 ð0Ð09Ł[ A large number of Dahlia plants belonging to the subgroup Coreopsedinae\ Heli! antheae\ Asteraceae were investigated at the Chemical Institute\ University of Aarhus\ Denmark[ The solvent used for the tuber extractions was diethyl ether or a mixture of diethyl ether and light petroleum "b[p[ below 49>#[ For the aerial parts "leaves and stems\ and ~owerheads# light petroleum was used in order to get an extract almost free from chlorophyll[ Determination of chromosome numbers was car! ried out for a series of Dahlia species by Dr[ Peter Jacobsen\ Copenhagen[ Two of the D[ coccinea strains were diploid "1n 21# and two others were tetraploid "1n 53#[ D[ merckii Lehm "formerly anticipated to be D[ scapi`era "A[ Dietr[# Linked et Otto var[ scapi`era forma merckii "Lehm# is an aneuploid Dahlia with the
chromosome number n 07 and its chemical deviation from other Dahlia species makes it unique[ Inter! estingly Dahlia tubulata has a chromosome number of n 05 ð00Ł[ Dahlia tubulata P[ D[ Sorensen ð09Ł is also unique because of its sulfur compounds\ which have not been observed in any other Dahlia species[ Sulfur compounds isolated from this species are not usual for the genus Dahlia\ whereas comparable sulfur compounds are known to be present in the genera Coreopsis and Bidens which are closely related to the genus Dahlia in the subgroup Coreopsedinae[ To date more than twenty!_ve Dahlia species from various localities in Mexico have been investigated as described by Lam and Hansen ð01Ł[ Additionally several isolated compounds were pro! vided to Professor G[ H[ N[ Towers at the University of British Columbia for determination of their bio! logical activities about 0865[
402
RESULTS AND DISCUSSION
The most common polyacetylenes occurring in a Dahlia species are listed below[ Some were biologically active when tested against mosquito larvae\ nema! todes and black~y larvae\ and they have also been shown to be phototoxic to certain freshwater algae ð02Ð04Ł[ {{Survial|| of acetylenes Very often the question has been put] How can highly unsaturated compounds persist in plants\
403
Short Report
The most prominent acetylenes of Dahlia coccinea Cav[ "0311# "scarlet#
cf[ Biochemical Systematics Vol[ 0\ pp[ 72Ð75\ 0862[
The most prominent acetylenes of yellow Dahlia coccinea "1n 53#
cf[ Phytochemistry Vol[ 6\ pp[ 158Ð164\ 0857[
The most prominent acetylenes of Dahlia pinnata
cf[ Phytochemistry Vol[ 7\ pp[ 0910Ð0913\ 0858[
Short Report The most characteristic acetylenes of Dahlia australis are]
cf[ Phytochemistry Vol[ 29\ pp[ 404Ð407\ 0850[
The most prominent acetylenes of Dahlia tenuicaulis
cf[ Phytochemistry Vol[ 09\ pp[ 1116Ð1117\ 0860[
The most prominent acetylenes of Dahlia rudis
cf[ Biochemical Systematics\ Vol[ 0\ pp[ 72Ð75\ 0862[
404
405
Short Report
The most prominent acetylenes of Dahlia sherf_i "0124#
cf[ Biochemical Systematics\ Vol[ 0\ pp[ 72Ð75\ 0862[
The most prominent acetylenes of Dahlia merckii
cf[ Phytochemistry Vol[ 20\ pp[ 1632Ð1634\ 0881 and Phytochemistry Vol[ 20\ 3242Ð3243\ 0881[
which are known to be decomposed very rapidly\ when exposed to ultraviolet light< Previously we have noticed that polyaromatic hydrocarbons like pyrene\ anthracene and other polyaromatic hydrocarbons were decomposed "discoloured# on tlc!plates covered with silica\ when exposed to ultraviolet light within a few hours\ whereas the same aromatic hydrocarbons\ when applied to tlc!plates covered with silica admixed 4 to 09 per cent of ca}eine were stabilized and did not decompose even after a long time "unpublished results#[ Suggesting that ca}eine has a stabilizing e}ect[ The p!electrons may interact with p!electrons in other compounds\ an e}ect that has also been noticed to be valid for polyacetylenes and other p! electron!rich compounds like thiophenes ð05Ł[ Indeed\ many experiments were carried out in order to prove that the p!electrons have the ability to interact with p!electrons in other compounds[ A selected series of
compounds either related to ca}eine "7!chlo! roca}eine\ uric acid and 0\2\6\8!tetramethyluric acid# or compounds often found in nature have been added to silica one by one and tlc!plates were produced[ A selected series of highly unsaturated compounds isolated from Dahlia species and from other plants of Asteraceae were applied to the above mentioned tlc! plates and after a certain time of irradiation in daylight "ultraviolet light# the percent of recovery could be determined and hence providing a measure of the e}ect of stabilization against irradiation[ It is not meant to be an exact determination\ but with a great number of attempts pointing to the same direction and with ca}eine as a controlling agent it seems to be a fairly good explanation for the relative stabilization of polyacetylenes and other unsaturated compounds as long as they are in the plants\ where several aro! matic compounds\ purines and chlorophylls\ are pre!
Short Report
406
The most prominent acetylenes of Dahlia tubulata
cf[ Phytochemistry Vol[ 18\ pp[ 2042Ð2043\ 0889[
sent to stabilize the highly unsaturated compounds like polyacetylenes and other compounds by p!elec! tron interactions ð06Ł[ In the pure state or in solution many of the poly! acetylenes and related compounds are known to exert a high grade of phototoxicity[ If it is possible to sta! bilize to some extent the often very active poly! acetylenes with naturally occurring substances or with degradable synthetic products\ that will exert a loose interaction\ there should be basis for a commercial production of biologically active and stabilized but still bio!degradable pesticides[ Localities in Mexico where Dahlia species have been collected in 0847 by J[ G[ Hawkes\ J[ P[ Hjertling and R[ Lester[ Numbers Collection 0124 D[ sherf_i Sorensen "formerly D[ pinnata "det[ D[ Philcox## Mexico\ Chihuahua State "Pilares de# Majalca\ 39 miles north! west of Chihuahua\ August 03\ 0847[ Alt[] 1099 m[ Flowers magenta!pink\ discs yel! low[ 0284 D[ merckii Lehm\ Mexico State\ new high! way 46 from Mexico City to San Juan del
0311
0424
0459
0611
Rio at 056 km\ near Calpulalpan\ San Martin\ September 3\ 0847[ Alt[] 2099 m[ Flowers pink[ D[ coccinea Cav Mexico\ Queretaro State\ road from San Juan del Rio!Queretaro Highway north to Bernal\ Cerro Galeras\ east of road\ September 4\ 0847[ Alt[] 1949 m[ Flowers ~ame!coloured[ D[ coccinea Cav Mexico\ Michoacan State\ near Chilchota\ road from Morelia to Gua! dalajara between Carapan and Tan! guancicuraro\ September 10\ 0847[ Alt[] 0599 m[ Flowers scarlet[ D[ coccinea Cav Mexico\ Michoacan State\ near Morelia\ Cerro Punguato\ September 15\ 0847[ Alt[] 1199 m[ Flowers yellow[ D[ tenuicaulis Ss³rensen Mexico\ Oaxaca State\ Sierra de Juarez\ road from Oaxaca to Ixtlan de Juarez\ 02[4 miles from Oax! aca!Tehuantepec highway\ October 10\ 0847[ Alt[] 1699 m Damp oak forests[ Stem woody[ Flowers magenta[
Collections have been carried out later by J[ P[ Hjer! ting in 0872\ 0873 and 0877[
407
Short Report
Short Report
Dahlia seeds obtained from professor Dr[ Paul Sor! ensen in Illinois "0869# have been propagated in the botanical garden of Copenhagen by J[ P[ Hjerting[
5[
5389
6[
D[ pinnata[ Seeds collected 0[4 miles north of Villa Guerrero\ Mexico State\ Sep! tember 0855[
7[ 8[
Acknowled`ements*For the collection and propa! gation of the Dahlia plants Dr[ J[ P[ Hjerting is cordi! ally acknowledged[ The great botanical assistance car! ried out by J[ P[ Hjerting and H[ V[ Hansen at the botanical garden of Copenhagen is highly appreciated and the close collaboration between Dr[ Hjerting and Dr[ Paul Sorensen has been of great value for the veri_cation of the plant material[ Mrs[ Annette T[ Larsen\ Chemical Institute\ University of Aarhus\ is thanked for the printing of this publication[
09[ 00[ 01[
02[
03[ REFERENCES
0[ Lam\ J[\ Kaufmann\ F[ and Bendixen\ O[\ Phyto! chemistry\ 0857\ 6\ 158[ 1[ Bendixen\ O[\ Lam\ J[ and Kaufmann\ F[\ Phyto! chemistry\ 0858\ 7\ 0910[ 2[ Kaufmann\ F[ and Lam\ J[\ Acta Chemica Scan! dinavica\ 0854\ 08\ 0156[ 3[ Lam\ J[\ Phytochemistry\ 0860\ 09\ 1116[ 4[ Sorensen\ P[ D[\ Thesis about systematics of the
04[ 05[ 06[
408
genus Dahlia "Coreopsedinae\ Heliantheae#[ The University of Iowa 0856[ Lam\ J[\ Biochemical systematics "now Bio! chemical Systematics Ecolo`y#\ 0862\ 0\ 72[ Lam\ J[ and Kaufmann\ F[\ Phytochemistry\ 0860\ 09\ 0766[ Neushield\ K[\ Christensen\ L[ P[ and Lam\ J[\ Phytochemistry\ 0881\ 20\ 1632 and 3242[ Lam\ J[\ Christensen\ L[ P[ and Thomasen\ T[\ Phytochemistry\ 0880\ 29\ 404[ Christensen\ L[ P[\ Lam\ J[ and Thomasen\ T[\ Phytochemistry\ 0889\ 18\ 2042[ Hansen\ H[ V[ and Hjerting\ J[ P[\ Nordic Journal of Botany0885\ 05"3#\ 334[ Lam\ J[ and Hansen\ L[\ in Methods in Plant Bio! chemistry\ Vol 3\ chapter 5\ ed[ J[ L[ Harwood and J[ R[ Bowyer\ Academic Press\ 0889\ p[ 048[ Wat\ C[!K[\ Prasad\ S[ K[\ Graham\ E[ A[\ Part! ington\ S[\ Arnason\ T[\ Towers\ G[ H[ N[ and Lam\ J[\ Biochemical Systematics Ecolo`y\ 0870\ 8\ 48[ Arnason\ T[\ Stein\ J[ R[\ Graham\ E[\ Wat\ C[! K[\ Towers\ G[ H[ N[ and Lam\ J[\ Canadian Journal of Botany\ 0870\ 48\ 43[ McLachlan\ D[ and Arnason\ T[\ Lam\ J[\ Bio! chemical Systematics Ecolo`y\ 0875\ 03\ 06[ Lam\ J[\ Planta Medica\ 0862\ 13\ 096[ Lam\ J[ and Thomasen\ T[ in Chemistry and Biolo`y of Naturally Occurrin` Acetylenes and Realted Compounds "NOARC#\ ed[ J[ Lam\ H[ Breteler\ T[ Arnason L[ and Hansen[ The Series of Bioactive Molecules\ Vol 6[ Elsevier\ 0877[
Phytochemistry\ Vol[ 38\ No[ 1\ pp[ 402Ð408\ 0887 Þ 0887 Published by Elsevier Science Ltd[ All rights reserved Printed in Great Britain 9920Ð8311:87:,Ðsee front matter
Pergamon
PII] S9920Ð8311"87#99154Ð8
ACETYLENES IN THE GENUS DAHLIA\ ASTERACEAE IN HONOUR OF PROFESSOR G[ H[ NEIL TOWERS 64TH BIRTHDAY JO šRGEN LAM rhus V\ Denmark Klokkerbakken 3\ DK!7109 A "Received 8 April 0886^ received in revised form 19 June 0886#
Key Word Index*Dahlia species\ acetylenes\ Coreopsedinae\ Heliantheae\ Asteraceae[
Abstract*Dahlia species grow wild in several places of Mexico[ A series of Dahlia species have been propagated in Denmark and some of these plants have been studied at the Chemical Institute\ University of Aarhus in Denmark[ More than 39 compounds have been characterized after isolation from roots and tubers or from aerial plant material[ The major compounds were acetylenes that occur in these Dahlia species and other genera of Heliantheae\ a tribe within Asteraceae[ Dahlia merckii Lehm is unique both chemically and in terms of its chromosome number\ whereas Dahlia tubulata is also unique in the chemical sense that it contains many thiophene compounds some of which are acetylenes\ a new discovery among the Dahlia species[ Þ 0887 Published by Elsevier Science Ltd[ All rights reserved
INTRODUCTION
Various D[ coccinea strains and other species of the genus Dahlia have been obtained from the Botanical Garden of Copenhagen\ where the plants have been propagated from seeds collected from plants in Mexico by the Danish botanist J[ P[ Hjerting and his two colleagues R[ Lester and J[ G[ Hawkes in 0847[ Although the genus Dahlia originally grew wild in Mexico\ a few Dahlia species are however growing wild in Guatemala[ The D[ coccinea strains from Mexico were of di}er! ent colour and ploidy[ All Dahlia plants treated were subjected to investigation of] 0# roots and tubers^ 1# stems and leaves and 2# ~owerheads\ respectively[ The acetylenes were isolated during the years 0853 to 0881 ð0Ð09Ł[ A large number of Dahlia plants belonging to the subgroup Coreopsedinae\ Heli! antheae\ Asteraceae were investigated at the Chemical Institute\ University of Aarhus\ Denmark[ The solvent used for the tuber extractions was diethyl ether or a mixture of diethyl ether and light petroleum "b[p[ below 49>#[ For the aerial parts "leaves and stems\ and ~owerheads# light petroleum was used in order to get an extract almost free from chlorophyll[ Determination of chromosome numbers was car! ried out for a series of Dahlia species by Dr[ Peter Jacobsen\ Copenhagen[ Two of the D[ coccinea strains were diploid "1n 21# and two others were tetraploid "1n 53#[ D[ merckii Lehm "formerly anticipated to be D[ scapi`era "A[ Dietr[# Linked et Otto var[ scapi`era forma merckii "Lehm# is an aneuploid Dahlia with the
chromosome number n 07 and its chemical deviation from other Dahlia species makes it unique[ Inter! estingly Dahlia tubulata has a chromosome number of n 05 ð00Ł[ Dahlia tubulata P[ D[ Sorensen ð09Ł is also unique because of its sulfur compounds\ which have not been observed in any other Dahlia species[ Sulfur compounds isolated from this species are not usual for the genus Dahlia\ whereas comparable sulfur compounds are known to be present in the genera Coreopsis and Bidens which are closely related to the genus Dahlia in the subgroup Coreopsedinae[ To date more than twenty!_ve Dahlia species from various localities in Mexico have been investigated as described by Lam and Hansen ð01Ł[ Additionally several isolated compounds were pro! vided to Professor G[ H[ N[ Towers at the University of British Columbia for determination of their bio! logical activities about 0865[
402
RESULTS AND DISCUSSION
The most common polyacetylenes occurring in a Dahlia species are listed below[ Some were biologically active when tested against mosquito larvae\ nema! todes and black~y larvae\ and they have also been shown to be phototoxic to certain freshwater algae ð02Ð04Ł[ {{Survial|| of acetylenes Very often the question has been put] How can highly unsaturated compounds persist in plants\
403
Short Report
The most prominent acetylenes of Dahlia coccinea Cav[ "0311# "scarlet#
cf[ Biochemical Systematics Vol[ 0\ pp[ 72Ð75\ 0862[
The most prominent acetylenes of yellow Dahlia coccinea "1n 53#
cf[ Phytochemistry Vol[ 6\ pp[ 158Ð164\ 0857[
The most prominent acetylenes of Dahlia pinnata
cf[ Phytochemistry Vol[ 7\ pp[ 0910Ð0913\ 0858[
Short Report The most characteristic acetylenes of Dahlia australis are]
cf[ Phytochemistry Vol[ 29\ pp[ 404Ð407\ 0850[
The most prominent acetylenes of Dahlia tenuicaulis
cf[ Phytochemistry Vol[ 09\ pp[ 1116Ð1117\ 0860[
The most prominent acetylenes of Dahlia rudis
cf[ Biochemical Systematics\ Vol[ 0\ pp[ 72Ð75\ 0862[
404
405
Short Report
The most prominent acetylenes of Dahlia sherf_i "0124#
cf[ Biochemical Systematics\ Vol[ 0\ pp[ 72Ð75\ 0862[
The most prominent acetylenes of Dahlia merckii
cf[ Phytochemistry Vol[ 20\ pp[ 1632Ð1634\ 0881 and Phytochemistry Vol[ 20\ 3242Ð3243\ 0881[
which are known to be decomposed very rapidly\ when exposed to ultraviolet light< Previously we have noticed that polyaromatic hydrocarbons like pyrene\ anthracene and other polyaromatic hydrocarbons were decomposed "discoloured# on tlc!plates covered with silica\ when exposed to ultraviolet light within a few hours\ whereas the same aromatic hydrocarbons\ when applied to tlc!plates covered with silica admixed 4 to 09 per cent of ca}eine were stabilized and did not decompose even after a long time "unpublished results#[ Suggesting that ca}eine has a stabilizing e}ect[ The p!electrons may interact with p!electrons in other compounds\ an e}ect that has also been noticed to be valid for polyacetylenes and other p! electron!rich compounds like thiophenes ð05Ł[ Indeed\ many experiments were carried out in order to prove that the p!electrons have the ability to interact with p!electrons in other compounds[ A selected series of
compounds either related to ca}eine "7!chlo! roca}eine\ uric acid and 0\2\6\8!tetramethyluric acid# or compounds often found in nature have been added to silica one by one and tlc!plates were produced[ A selected series of highly unsaturated compounds isolated from Dahlia species and from other plants of Asteraceae were applied to the above mentioned tlc! plates and after a certain time of irradiation in daylight "ultraviolet light# the percent of recovery could be determined and hence providing a measure of the e}ect of stabilization against irradiation[ It is not meant to be an exact determination\ but with a great number of attempts pointing to the same direction and with ca}eine as a controlling agent it seems to be a fairly good explanation for the relative stabilization of polyacetylenes and other unsaturated compounds as long as they are in the plants\ where several aro! matic compounds\ purines and chlorophylls\ are pre!
Short Report
406
The most prominent acetylenes of Dahlia tubulata
cf[ Phytochemistry Vol[ 18\ pp[ 2042Ð2043\ 0889[
sent to stabilize the highly unsaturated compounds like polyacetylenes and other compounds by p!elec! tron interactions ð06Ł[ In the pure state or in solution many of the poly! acetylenes and related compounds are known to exert a high grade of phototoxicity[ If it is possible to sta! bilize to some extent the often very active poly! acetylenes with naturally occurring substances or with degradable synthetic products\ that will exert a loose interaction\ there should be basis for a commercial production of biologically active and stabilized but still bio!degradable pesticides[ Localities in Mexico where Dahlia species have been collected in 0847 by J[ G[ Hawkes\ J[ P[ Hjertling and R[ Lester[ Numbers Collection 0124 D[ sherf_i Sorensen "formerly D[ pinnata "det[ D[ Philcox## Mexico\ Chihuahua State "Pilares de# Majalca\ 39 miles north! west of Chihuahua\ August 03\ 0847[ Alt[] 1099 m[ Flowers magenta!pink\ discs yel! low[ 0284 D[ merckii Lehm\ Mexico State\ new high! way 46 from Mexico City to San Juan del
0311
0424
0459
0611
Rio at 056 km\ near Calpulalpan\ San Martin\ September 3\ 0847[ Alt[] 2099 m[ Flowers pink[ D[ coccinea Cav Mexico\ Queretaro State\ road from San Juan del Rio!Queretaro Highway north to Bernal\ Cerro Galeras\ east of road\ September 4\ 0847[ Alt[] 1949 m[ Flowers ~ame!coloured[ D[ coccinea Cav Mexico\ Michoacan State\ near Chilchota\ road from Morelia to Gua! dalajara between Carapan and Tan! guancicuraro\ September 10\ 0847[ Alt[] 0599 m[ Flowers scarlet[ D[ coccinea Cav Mexico\ Michoacan State\ near Morelia\ Cerro Punguato\ September 15\ 0847[ Alt[] 1199 m[ Flowers yellow[ D[ tenuicaulis Ss³rensen Mexico\ Oaxaca State\ Sierra de Juarez\ road from Oaxaca to Ixtlan de Juarez\ 02[4 miles from Oax! aca!Tehuantepec highway\ October 10\ 0847[ Alt[] 1699 m Damp oak forests[ Stem woody[ Flowers magenta[
Collections have been carried out later by J[ P[ Hjer! ting in 0872\ 0873 and 0877[
407
Short Report
Short Report
Dahlia seeds obtained from professor Dr[ Paul Sor! ensen in Illinois "0869# have been propagated in the botanical garden of Copenhagen by J[ P[ Hjerting[
5[
5389
6[
D[ pinnata[ Seeds collected 0[4 miles north of Villa Guerrero\ Mexico State\ Sep! tember 0855[
7[ 8[
Acknowled`ements*For the collection and propa! gation of the Dahlia plants Dr[ J[ P[ Hjerting is cordi! ally acknowledged[ The great botanical assistance car! ried out by J[ P[ Hjerting and H[ V[ Hansen at the botanical garden of Copenhagen is highly appreciated and the close collaboration between Dr[ Hjerting and Dr[ Paul Sorensen has been of great value for the veri_cation of the plant material[ Mrs[ Annette T[ Larsen\ Chemical Institute\ University of Aarhus\ is thanked for the printing of this publication[
09[ 00[ 01[
02[
03[ REFERENCES
0[ Lam\ J[\ Kaufmann\ F[ and Bendixen\ O[\ Phyto! chemistry\ 0857\ 6\ 158[ 1[ Bendixen\ O[\ Lam\ J[ and Kaufmann\ F[\ Phyto! chemistry\ 0858\ 7\ 0910[ 2[ Kaufmann\ F[ and Lam\ J[\ Acta Chemica Scan! dinavica\ 0854\ 08\ 0156[ 3[ Lam\ J[\ Phytochemistry\ 0860\ 09\ 1116[ 4[ Sorensen\ P[ D[\ Thesis about systematics of the
04[ 05[ 06[
408
genus Dahlia "Coreopsedinae\ Heliantheae#[ The University of Iowa 0856[ Lam\ J[\ Biochemical systematics "now Bio! chemical Systematics Ecolo`y#\ 0862\ 0\ 72[ Lam\ J[ and Kaufmann\ F[\ Phytochemistry\ 0860\ 09\ 0766[ Neushield\ K[\ Christensen\ L[ P[ and Lam\ J[\ Phytochemistry\ 0881\ 20\ 1632 and 3242[ Lam\ J[\ Christensen\ L[ P[ and Thomasen\ T[\ Phytochemistry\ 0880\ 29\ 404[ Christensen\ L[ P[\ Lam\ J[ and Thomasen\ T[\ Phytochemistry\ 0889\ 18\ 2042[ Hansen\ H[ V[ and Hjerting\ J[ P[\ Nordic Journal of Botany0885\ 05"3#\ 334[ Lam\ J[ and Hansen\ L[\ in Methods in Plant Bio! chemistry\ Vol 3\ chapter 5\ ed[ J[ L[ Harwood and J[ R[ Bowyer\ Academic Press\ 0889\ p[ 048[ Wat\ C[!K[\ Prasad\ S[ K[\ Graham\ E[ A[\ Part! ington\ S[\ Arnason\ T[\ Towers\ G[ H[ N[ and Lam\ J[\ Biochemical Systematics Ecolo`y\ 0870\ 8\ 48[ Arnason\ T[\ Stein\ J[ R[\ Graham\ E[\ Wat\ C[! K[\ Towers\ G[ H[ N[ and Lam\ J[\ Canadian Journal of Botany\ 0870\ 48\ 43[ McLachlan\ D[ and Arnason\ T[\ Lam\ J[\ Bio! chemical Systematics Ecolo`y\ 0875\ 03\ 06[ Lam\ J[\ Planta Medica\ 0862\ 13\ 096[ Lam\ J[ and Thomasen\ T[ in Chemistry and Biolo`y of Naturally Occurrin` Acetylenes and Realted Compounds "NOARC#\ ed[ J[ Lam\ H[ Breteler\ T[ Arnason L[ and Hansen[ The Series of Bioactive Molecules\ Vol 6[ Elsevier\ 0877[