Pak. J. Bot., 35(2): 127-140, 2003.
CHEMOTAXONOMIC STUDY OF INULA L. (S.STR.) AND ITS
ALLIED GENERA (INULEAE - COMPOSITAE) FROM
PAKISTAN AND KASHMIR
RUBINA ABID AND M. QAISER
Department of Botany,
University of Karachi, Karachi-75270, Pakistan.
Abstract
Leaves of 21 taxa belonging to Inula L. (s.str.) and its allied genera viz., Pentanema Cass.,
Duhaldea DC., Dittrichia Greuter and Iphiona Cass., have been analyzed from Pakistan and Kashmir
for their phenolic compounds. Analysis was carried out by two dimensional chromatography. Spectral
analysis was performed on Shimadzu UV-spectrophotometer. The chemical data of this intricate group
also support the generic delimitation of Dittrichia by having O-coumaric acid and Sakuranetin, while
tricin 5-glucoside is exclusive for Iphiona and Duhaldea is distinctive by the presence of Vitexin and
Isovitexin. However, Inula and Pentanema shared a mix pattern of compounds which points out the
close relationship of both genera as compared to other genera of this group.
Introduction
There are several reports on the chemotaxonomy of the family Compositae. Most of the
workers gave the attention to the flavonoids, sesquiterpene lactones and some other
compounds (Crawford, 1970; Geissman & Irwin, 1973; Bohlmann et al., 1981; ValantVetschera & Wollenweber, 1981; Ates et al., 1982; Shukla & Gupta, 1985; Ling, 1992;
Iwashina et al., 1995; Tzakao et al., 1995 and Akkal et al., 1997). Although some of the
individual species of Inula and its allied genera were also chemically investigated but the
chemical data was not utilized in the taxonomy of the genus. Dombrowicz & Greiner (1968)
isolated quercetin and isoquercitrin from the aerial parts of Inula britannica L., Baruah et al.,
(1979) reported three new flavonoids from the aerial parts of Inula cappa (=Duhaldea
cappa), Oksuz & Topcu (1987) reported a new Kaempferol derivative from the aerial parts of
Inula britannica, Ahmed & Ismail (1991) isolated the sterols and a new flavonol from the
aerial parts of Inula grantioides (=Iphiona grantioides). Oksuz & Topcu (1992) analyzed the
extract of aerial parts of Inula graveolens (=Dittrichia graveolens) and isolated sesquiterpene
lactones, flavonoids, dihydroflavonols and flavones. It is therefore evident from the preceding
literature that some chemical informations are available on few taxa of Inula L., and its allied
genera but no attempt has ever been made to utilize this data for taxonomical purposes. The
present study was carried out to utilize the chemical data as a taxonomic evidence.
Materials and Methods
Leaves of 21 taxa belonging to Inula L. (s.str.) and its allied genera were analyzed for
their phenolic compounds. For extraction, approximately 1 gm of dried leaves from
herbarium specimens were extracted with 70% ethanol at room temperature. Extracts were
concentrated and chromatographed two dimensionally on Whatman no.1 paper
RUBINA ABID & M. QAISER
128
using two solvent combinations, i.e., BAW (n-butanol: acetic acid: water, 4:1:5) versus 15%
acetic acid and BAW versus distilled water, following standard procedure of Harborne
(1973). A list of voucher specimens is given in appendix-I.
Phenolic compounds were identified by comparing with authentic markers along with the
Rf values and colour in ultra-violet light before and after fuming with ammonia vapours.
Compounds were repeatedly purified by paper chromatography, till the absorption
properties became constant. Hence an elute of a paper blank in 95% ethanol (usually about
150cm2) was taken and applied (spotted) to the paper, and run in BAW and 15% HOAc
separately. After the purification of compounds, the spots of chromatogram were cut and
shaken in 95% ethanol for 30 minutes. The solution was filtered and allowed to concentrate,
and directly used for spectral analyses on Shimadzu UV-240 spectrophotometer.
Results and Discussion
Paper chromatography of the aqueous ethanolic extracts from the leaves of 21 taxa of
Inula L., and its allied genera led to the isolation of 42 (including 11 unknown compounds)
different phenolic compounds (phenolic acids, flavonols, flavones, glycosylflavones,
flavanones and chalcones) (Table 1.1-1.5, Fig. 1.1-1.7).
Generic key based on chemical characters
1. +
-
Vitexin and iso-vitexin both present ......................…………………… Duhaldea
No such compounds present ...........................................……………………….. 2
2. +
-
Tricin 5-glucoside present ...................................……………………….. Iphiona
Tricin 5-glucoside absent ...............................................……………………….. 3
3. +
-
Sakuranetin present ....................................................………………… Dittrichia
Sakuranetin absent ........................………………….………... Inula, Pentanema
The results suggested that the chemical data of flavonoids is not always correlated with
the classification. This contention was also supported by Heywood (1973), as he pointed out
that the flavonoids themselves could not be taken as independent evidence relative to
supporting a particular classification. However, it may be useful in taxonomic delimitation at
generic or specific level. Iphiona and Dittrichia are chemically related to Inula (s.str.) as all
of these genera share a number of flavonoids, although the presence of O-coumaric acid
along with sakuranetin in Dittrichia, and tricin 5-glucoside in Iphiona, keep them distinct
from the other genera. Duhaldea is chemically separated from the other genera due to the
occurrence of vitexin, iso-vitexin and quercetin 4-glucoside.
The flavonoid patterns of the genera Inula (s.str.) and Pentanema are similar to the other
genera as they share number of flavonoids and do not possess any specific compounds of
their own. Although the presence of certain specific compounds in other genera, make them
separate. However, the rarer occurrence of ferulic acid, aesculetin, aesculin, some glycosides
of quercetin, kaempferol, luteolin and hesperitin in Inula (s.str.) further make it distinct from
all the other genera.
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
129
130
RUBINA ABID & M. QAISER
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
131
132
RUBINA ABID & M. QAISER
Table 1.4. Total number of flavonol, flavone glycoside and c-glycosyl
flavones in Inula L. (s.str.) and its related genera.
Total no. of compounds
Name of genera
Flavonol
Flavone
C-glycosyl
glycosides
glycosides
flavones
32
12
5
Inula
9
2
Pentanema
4
2
7
Duhaldea
3
1
Dittrichia
3
2
Iphiona
Table 1.5. Unidentified compounds of Inula L. (s.str.) and its related
genera.
Rf values
Colour in UV
Name of taxa
BAW
15%
With
Without
HOAc
ammonia ammonia
54.96
74.40
l. yell.
yell. br.
Inula koelzii
60.02
99.33
yell.gr.
yell. gr.
55.38
74.84
l. yell.
Yell. br.
I. royleana
62.92
100.02
yell.gr.
yell. gr.
0.0
92.0
b.bl.
l. bl.
I. racemosa
19.38
97.74
b. purp.
purp. bl.
61.88
99.81
yell. gr.
yell. gr.
22.22
100.0
b. purp.
purp. bl.
I. stewartii
0.0
97.50
d. br.
d. br.
92.91
86.90
Yell.
Yell.
I. orientalis
28.05
17.20
b. yell.
b. yell.
I. clarkei
94.28
86.88
yell.
yell.
I. obtusifolia
95.66
87.05
yell.
yell.
I. britannica
20.50
45.25
bl.
bl.
I. acuminata
I. falconeri
70.75
26.30
b. purp.
purp. bl.
I. rhizocephala
19.28
39.99
bl.
bl.
0.0
91.66
b. bl.
l. bl.
Pentanema
glanduligerum
24.80
99.87
b. purp.
purp. bl.
19.99
98.20
b. purp.
purp. bl.
P. indicum
P. divaricatum
P. vestitum
59.25
93.06
b. bl.
l. bl.
Duhaldea cappa
D. eupatorioides
D. cuspidata
69.21
92.42
yell.
d. yell.
Dittrichia graveolens
Iphiona aucheri
82.05
99.12
yell.
yell. gr.
I. grantioides
Key: yell. = yellow; gr. = green; br. = brown; purp. = purple; bl. = blue; b. =
bright; d. = dull; l. = light.
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
133
Fig. 1.1. Absorption spectra of Caffeic acid (curve A) and Chlorogenic acid (curve B) in 95% EtOH.
Fig. 1.2. Absorption spectra of Ferulic acid (curve A, marker; curve B, isolated compound) in 95% EtOH.
Fig. 1.3. Absorption spectra of Aesculetin (curve A) and Aesculin (curve B) in 95% EtOH.
134
RUBINA ABID & M. QAISER
Fig. 1.4. Absorption spectra of Rutin (curve A, marker; curve B isolated compound) and Quercetagetin
(curve C) in 95% EtOH.
Fig. 1.5. Absorption spectra of Luteolin 7-glucoside (curve A) and Kaempferol 3-sophorotrioside 7rhamnoside (curve B) in 95% EtOH.
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
135
Fig. 1.6. Absorption spectra of Apigenin 7-glucoside (curve A, marker; curve B isolated compound) in
95% EtOH.
Fig. 1.7. Absorption spectra of Isoliquiriteginin 4-glucoside (curve A) and Butein 4-glucoside (curve
B) in 95% EtOH.
RUBINA ABID & M. QAISER
136
Key to the species of Inula (s.str.) based on chemical characters
1. +
-
Kaempferol 3-sophoroside 7-rhamnoside and kaempferol 3-sophorotrioside 7rhamnoside both present ........................……………………………….. I. koelzii
No such compounds present ...........................................……………………….. 2
2. +
-
Iso-orientin present ..........................................………………………… I. clarkei
Iso-orientin absent .........................................……………………… I. obtusifolia
3. +
-
Kaempferol 3-lathyroside 7-rhamnoside and luteolin 7-glucoside both present.
………………………………………................................................................... 4
Both the compounds absent ……………………............................................…. 5
4. +
-
Kaempferol 3-sophoroside 7-rhamnoside present ……………...…... I. orientalis
No such compound present ............................……………………... I. britannica
5. +
-
Butein 4-glucoside present ................ I. acuminata, I. falconeri, I. rhizocephala
Butein 4-glucoside absent ..............................................……………………….. 6
6. +
-
Quercetagetin present …............................................………………... I. stewartii
Quercetagetin absent ........................................................……………………… 7
7. +
Apigenin 7-glucoside and apigenin 8-rhamnosyl glucosyl both present ……...
………………………………………………………………………... I. royleana
Both the compounds absent ...............................……………………. I. racemosa
-
In the genus Inula L. (s.str.), I. koelzii Dawar & Qaiser, I. royleana DC., I. racemosa
Hook.f., and I. stewartii R. Abid & Qaiser are generally related in their morphology as they
have upper sessile and semiamplexicaul, while lower winged petiolate leaves and 3-4 mm
long and usually glabrous cypselas, similarly, the chemical data of these species also
strengthen the above morphological correlation due to the presence of iso-orientin,
kaempferol 3-sophorotrioside 7-rhamnoside and caffeic acid. Some other glycosides of
kaempferol, quercetin, apigenin, luteolin and tricin are absent from all the four species.
However, the four species can still be differentiated on the basis of flavonoid pattern, I.
koelzii and I. stewartii have aesculetin but lacks in I. racemosa and I. royleana, while I.
koelzii and I. stewartii differ from each other by the presence of ferulic acid and rutin
respectively. On the other hand, I. royleana and I. racemosa differ due to occurrence of
apigenin glucoside in I. royleana and hesperidin in I. racemosa respectively.
Inula britannica L., I. acuminata Royle ex DC., and Inula falconeri Hook.f., are more or
less morphologically related species which share several compounds viz., rutin, quercetagetin
and apigenin 6-OH but I. britannica can be delimited from both the species by the presence
of kaempferol 3-lathyroside 7-rhamnoside, luteolin 7-glucoside and isoliquiritigenin 4glucoside. I. acuminata and I. falconeri could not be distinguished chemically from each
other and share all the compounds with the exception of an unidentified compound with Rf
values 20.5 (BAW), 45.25 (15% HOAc) and with unchanged blue colour, that is exclusive
for I. acuminata. On the other hand, the specific compounds of I. britannica are also shared
with I. orientalis Lamk., although both are morphologically dissimilar furthermore, both the
species are also delimited due to the occurrence of kaempferol 3-sophoroside 7-rhamnoside
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
137
in I. orientalis and apigenin 6-OH in I. britannica. Likewise, Inula obtusifolia Kern., and
Inula clarkei (Hook.f.) Stewart are also closely related species as they share ferulic acid,
caffeic acid, quercetin 3-sophoroside 7-glucoside, quercetagetin, kaempferol 3-rutinoside 7glucuronide and apigenin 8-rhamnosyl glucosyl. However, these 2 species can be
differentiated from each other as the quercetin aglycon and iso-orientin are present in I.
obtusifolia and I. clarkei respectively. However, Inula rhizocephala Schrenk is
morphologically distinct from rest of the species due to stemless habit, similarly the presence
of aesculin in I. rhizocephala also makes it chemically distinct from rest of the species of
Inula L.
Key to the species of Pentanema based on chemical characters
1. +
-
Rutin present ............................................................…………………………… 2
Rutin absent ..........................................………………………. P. glanduligerum
2. +
-
Quercetagetin present …………………………................................................... 3
Quercetagetin absent .......................................………………………. P. indicum
3. +
Apigenin 7-glucoside and kaempferol 3-sophorotrioside 7-rhamnoside both
present .......................................…………………………………. P. divaricatum
No such compounds present ……...............................………………. P. vestitum
-
Species of Pentanema Cass., could be delimited on the basis of flavonoid pattern. On the
other hand morphologically unrelated species share the similar compounds for instance,
kaempferol 3-sophorotrioside 7-rhamnoside is present in 2 morphologically different species
viz., Pentanema glanduligerum (Krasch.) Gorschk., and Pentanema divaricatum Cass.
Similarly apigenin 7-glucoside is found in Pentanema indicum (L.) Ling and P. divaricatum
both of them are morphologically dissimilar to some extent. However P. glanduligerum is
distinguished from all of the other species of Pentanema by having the quercetin aglycone
while other 3 species have rutin. P. vestitum (Wall. ex DC.) Ling and P. divaricatum are
separated from P. indicum by the presence of caffeic acid and quercetagetin but absent from
P. indicum. P. divaricatum is splitted from P. vestitum due to the presence of apigenin 7glucoside and kaempferol 3-sophorotrioside 7-rhamnoside which are exclusive for P.
divaricatum.
Key to the species of Duhaldea based on chemical characters
1. +
-
Apigenin 7-glucoside and iso-vitexin both present ...............…………………... 2
No such compounds present ........................…………………... D. eupatorioides
2. +
-
Quercetagetin present ...................................………………………. D. cuspidata
Quercetagetin absent ..........................................………………………. D. cappa
Chemical variation is not so pronounced within all the species of Duhaldea DC., as
Duhaldea eupatorioides (Wall.ex DC.) A.Anderb., shares all its compounds with D.
cuspidata (Wall.ex DC.) A.Anderb., and no specific compound is found in D. eupatorioides.
However, the D. cuspidata can be separated from D. cappa (Ham.ex D.Don) A.Anderb., due
to the occurrence of chlorogenic acid and quercetagetin which are exclusive for D. cuspidata.
138
RUBINA ABID & M. QAISER
Key to the species of Iphiona based on chemical characters
1. +
-
Quercetagetin present ..................................………………………. I. grantioides
Quercetagetin absent ..........................................……………………… I. aucheri
Both the species of Iphiona Cass., are chemically distinguished from each other due to
the presence of quercetagetin in I. grantioides (Boiss.) A. Anderb., but absent from I. aucheri
(Boiss.) A. Anderb.
Apart from the known compounds several unidentified compounds are also found within
the genus Inula L. (s.str.) and its allied genera (Table 1.5). Those spots which have more or
less same Rf-values and colours are tentatively grouped in 11 different compounds.
Morphologically dissimilar taxa share same unknown compounds. For instance a compound
with Rf-values 0.0 and 91.66-94.93 (blue coloured) respectively in BAW and 15% HOAc is
common in Inula racemosa and Pentanema glanduligerum. Another compound which is
purplish blue in colour having the Rf-values from 19.38-24.8 (BAW) and 97.74-100 (15%
HOAc) is found in Inula stewartii, I. racemosa, Pentanema glanduligerum and Pentanema
indicum. Inula rhizocephala and Inula acuminata also share a compound, which has blue
colour with Rf-values from 19.28-20.5 (BAW) and 39.99-45.25 (15% HOAc). On the other
hand Dittrichia graveolens (L.) Greuter has an exclusive unknown compound with the Rfvalues 69.21 (BAW) and 92.42 (15% HOAc) (colour change from yellow to dull yellow after
ammonia fumigation). Similarly, Inula rhizocephala has an exclusive unknown compound
with purplish shade and 70.75 (BAW) and 26.30 (15% HOAc) Rf-values. However, Inula
clarkei and I. obtusifolia are closely related but an unknown compound with the Rf-values
28.05 (BAW) and 17.20 (15% HOAc) with bright yellow colour is found only in I. clarkei.
Likewise, Iphiona grantioides has an unknown compound which is yellow / yellowish green
in colour with the Rf-values 82.05 and 99.12 in BAW and 15% HOAc respectively is not
shared by closely related taxon Iphiona aucheri.
It is generally agreed that flavonol glycosides (kaempferol, quercetin, particularly
myricetin) are present in the supposedly more primitive dicotyledons and flavone oglycosides (apigenin and luteolin) occur in more highly advanced dicotyledons, c-glycosyl
flavones (vitexin, iso-vitexin, orientin and iso-orientin) are considered as an intermediate
state between flavonols and flavone o-glycosides (William & Harborne, 1971; Harborne,
1977; Crawford, 1978; Omer et al., 1996). The present studies are also in accordance with
this contention. All the genera have shared a mix pattern of flavonol, flavone o-glycoside and
c-glycosyl flavone. Although the flavonols predominated over flavone. Likewise, Inula L.
(s.str.) shared some morphologically primitive and advance characters so it is paraphyletic in
origin and this paraphyletic condition of the genus was earlier reported by Anderberg (1991).
However, primitive characters are quite dominant in this genus with always radiate capitula
and pappus bristles in large number, while on the other hand it is also characterized by the
presence of herbaceous nature of plants and conspicuously ribbed cypselas. So this
morphological evolution in Inula (s.str.) also support the above mentioned generalizations as
in this genus flavonol glycosides predominated over flavone glycosides by the presence of 32
flavonol glycosides and 10 flavone glycosides and the number of flavonol gradually reduced
to 9, 4, 3, and 3 in the remaining genera viz., Pentanema, Duhaldea, Dittrichia and Iphiona
respectively (Table 1.4). This clearly indicated gradual co-evolution of flavonoids and
morphological characters. This predominant pattern of flavonols over flavones was also
observed by Seelingmann (1996) in certain tribes of Compositae. The mix pattern of flavonol,
flavone o-glycoside and c-glycosyl flavone in all the genera is also in agreement with a
number of instances given by Crawford (1978) and Averett et al., (1986) in which all three
types (flavonols, flavone o-glycoside and c-glycosyl flavones) have been observed.
CHEMOTAXONOMIC STUDY OF INULA AND ITS ALLIED GENERA
No.
1.
2.
Taxon
Inula koelzii
I. royleana
3.
I. racemosa
4.
5.
I. stewartii
I. orientalis
6.
I. clarkei
7.
I. obtusifolia
8.
9.
10.
I. britannica
I. acuminata
I. falconeri
11.
I. rhizocephala
12.
Pentanema glanduligerum
13.
P. indicum
14.
P. divaricatum
15.
P. vestitum
16.
Duhaldea cappa
17.
18.
D. eupatorioides
D. cuspidata
19.
20.
Dittrichia graveolens
Iphiona aucheri
21.
I. grantioides
139
Appendix-I
Collector, number and herbarium
W. Koelz 2900a (KUH); W. Koelz 2827a (NY)
Y. Nasir & Rubina Akhtar 12996 (RAW); M.
Qaiser & Rizwan Y. Hashmi 7868 (KUH)
R.R. Stewart 14052 (KUH); R.R. Stewart 19550
(RAW)
R.R. Stewart s.n. (RAW)
S. Abedin & M. Qaiser 8887 (KUH); Tahir Ali, M.
Qaiser & M. Ajmal 503 (KUH).
Hans Hartmann s.n. (RAW); E. Nasir & G.L.
Webster 5804 (RAW)
M. Qaiser, S. Omer & S.Z. Hussain 8414 (KUH);
R.R. Stewart 18803 (RAW)
R.R. Stewart 54 (RAW)
Stainton 3077 (RAW); R.R. Stewart 26356 (RAW)
R.R. Stewart 20484 (KUH); M.A. Siddiqui, Y.
Naisr & Zaffar 4182 (K)
R.R. Stewart 18859 (RAW); S. Omer & M. Qaiser
2360 (KUH)
G.R. Sarwar & S. Omer 256 (KUH); Stainton 2944
(RAW)
A. Rashid 26985 (RAW); Farrukh Hussain s.n.
(RAW)
S. Abedin & Abrar Hussain 6232 (KUH); S.M.H.
Jafri 2854 (KUH)
Y. Nasir & Rubina Akhter 11863 (RAW); S.
Abedin 2659 (KUH)
A. Ghafoor & Tahir Ali 4005 (KUH); S.A.
Farooqui & M. Qaiser 3172 (KUH)
R.R. Stewart & I.D. Stewart 4145 (RAW)
Tahir Ali, M. Qaiser & M. Ajmal 367 (KUH); Y.
Nasir & Nazir 10519 (RAW)
J.L. Stewart 245 (K)
Tahir Ali & G.R. Sarwar 2868 (KUH); Tahir Ali
1478 (KUH)
S. Omer & Rizwan Y. Hashmi 2003 (KUH); A.
Ghafoor & S. Omer 1825 (KUH)
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(Received for publication 30 December 2002)