Evaluation of antiplasmodial activity of medicinal plants from North Indian Buchpora and South Indian Eastern Ghats
Kaushik et al. Malaria Journal
Evaluation of antiplasmodial activity of medicinal plants from North Indian Buchpora and South Indian Eastern Ghats
Naveen K Kaushik 1 2
Asokan Bagavan 0
Abdul A Rahuman 0
Abdul A Zahir 0
Chinnaperumal Kamaraj 0
Gandhi Elango 0
Chidambaram Jayaseelan 0
Arivarasan V Kirthi 0
Thirunavukkarasu Santhoshkumar 0
Sampath Marimuthu 0
Govindasamy Rajakumar 0
Santosh K Tiwari 2 3
Dinkar Sahal 1
0 Unit of Nanotechnology and Bioactive Natural Products, Department of Zoology, C. Abdul Hakeem College , Melvisharam 632509, Vellore District, Tamil Nadu , India
1 Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg , New Delhi 110067 , India
2 Department of Bioscience & Biotechnology, Banasthali University , P.O. Banasthali Vidyapith, Rajasthan 304 022 , India
3 Present address: Department of Genetics, Maharshi Dayanand University , Rohtak, Haryana 124001 , India
Background: Development of resistance against the frontline anti-malarial drugs has created an alarming situation, which requires intensive drug discovery to develop new, more effective, affordable and accessible anti-malarial agents. Methods: Inspired by their ethnobotanical reputation for being effective against febrile diseases, antiplasmodial potential of ethyl acetate extracts (EAE) and methanol extracts (ME) of 17 medicinal plants collected from the Eastern Ghats of South India and Buchpora, North India were explored against Plasmodium falciparum in vitro using the SYBR Green assay. The results were validated both by confirmation that the fall in fluorescence signal was not due to quenching effects mediated by phytochemical extracts and by Giemsa-stained microscopy. Results: Using EAE or ME, promising antiplasmodial activity (IC50 Pf3D7 20 g/ml), was seen in Aerva lanata (Whole aerial parts-EAE), Anisomeles malabarica (Leaf-EAE), Anogeissus latifolia (bark-EAE), Cassia alata (leaves-EAE), Glycyrrhiza glabra (root-EAE), Juglans regia (seed-ME), Psidium guajava (leaf-ME and EAE) and Solanum xanthocarpum (Whole aerial parts-EAE). EAEs from leaves of Couroupita guianensis, Euphorbia hirta, Pergularia daemia, Tinospora cordifolia and Tridax procumbens as also ME from Ricinus communis (leaf and seed) showed good antiplasmodial activity (Pf 3D7 IC50 21 - 40 g/ml). Moderate activity (Pf 3D7 IC50: 40-60 g/mL) was shown by the leaf EAEs of Cardiospermum halicacabum, Indigofera tinctoria and Ricinus communis while the remaining extracts showed marginal (Pf 3D7 IC50 60 to >100 g/ml) activities. The promising extracts showed good resistance indices (0.41 - 1.4) against the chloroquine resistant INDO strain of P. falciparum and good selectivity indices (3 to > 22.2) when tested against the HeLa cell line. Conclusion: These results provide validity to the traditional medicinal usage of some of these plants and further make a case for activity-guided purification of new pharmacophores against malaria.
In the absence of a credible vaccine and with emergence
of resistance to almost all anti-malarial drugs, the dream
of eradication of malaria appears to be a huge challenge.
Caused by a protozoan parasite, malaria remains one of
the dreaded diseases of the developing world, killing
367,000755,000 people and causing disease in 124283
million people annually . The most severe
manifestations of malaria are caused by Plasmodium falciparum.
Even as malaria has been affecting both the economic
and emotional aspects of mankind for a long time, the
relief against malaria has been coming in the form of
herbal treatments, such as cinchona bark and Qing Hao
leaves, which gave quinine and artemisinin respectively.
The quinoline-based quinine first and chloroquine later
proved to be effective therapies against malaria till
resistance against quinolines began to surface and spread to
large parts of the world . Against this scenario,
artemisinin proved to be a smart, fast acting, potent drug
against chloroquine-resistant malaria. However,
artemisinin resistance in the form of delayed clearance of the
parasite is now on the horizon conjuring images of a
world where mankind may be left with no effective drug
against malaria. This calls for a rigorous search for novel
One optimistic source for new affordable treatments
against malaria lies in the use of traditional herbal
remedies. Despite the recent successes in rational drug design
and synthetic chemistry techniques by pharmaceutical
companies, natural products and particularly medicinal
plants have remained an important source of new drugs
[4,5]. A definite virtue with medicinal plants is the rich
ethnopharmacological history of traditional knowledge
and usage associated with them. It is quite possible that
their use as nutrients or spices may already be providing a
significant degree of protection to people at large against
malaria. However if the gist of traditional knowledge can
be validated by scientific experiments, affordable and
dependable cures can be found against the drug resistant
dreaded forms of malaria. Further such exploratory
endeavours can pave the path for identifying novel
pharmacophores against malaria, which can be
chemically synthesized and fine tuned as drugs of the
future. With this perspective in mind, here is described
the antiplasmodial potential of the extracts of 17
medicinal plants having the reputation of their usage
against febrile diseases.
Methodology of collection of ethnomedical information
Recommendation of traditional healers and available
literature were referred for selection and collection of
medicinal plants. Information regarding the pharmacological
usage of these plants is given in Additional file 1.
Identification and collection of plant materials
The seeds of Juglans regia (Juglandaceae) were collected
from the Buchpora, Srinagar district, (34814N 75216
E, altitude 2743 m) of Jammu and Kashmir, North India
between October and November 2010 (Figure 1). The
leaves of Anisomeles malabarica (Lamiaceae), Psidium
guajava (Myrtaceae), Tridax procumbens (Asteraceae),
leaves and seeds of Ricinus communis (Euphorbiaceae),
Figure 1 Sites of collection of medicinal plants from North Indian Buchpora and South Indian Eastern Ghats.
and the flowers of Gloriosa superba (Liliaceae), Pergularia
daemia, Tinospora cordifolia, bark of Anogeissus latifolia,
root of Glycyrrhiza glabra, and whole aerial parts of
Solanum xanthocarpum were collected from the
tropical region of Javadhu Hills, Jamunamarathur,
Tiruvannamalai district (123610N, 0785307E, altitude
705 m), Tamil Nadu, South India (Figure 1). The leaves of
Cardiospermum halicacabum, Cassia alata, Couroupita
guianensis, Euphorbia hirta, Indigofera tinctoria and
whole aerial parts of Aerva lanata were collected from
the Eastern Ghats, Kombaikkadu, Yercaud, Salem
district (114620N, 78125E, altitude 1,515 m), Tamil
Nadu, South India. The taxonomic identifications of
collected samples were made by Dr. C. Hema, Department
of Botany, Arignar Anna Govt. Arts College for Women,
Walajapet, Vellore, India, following which the voucher
specimens were numbered and kept in laboratory for
further reference. During raw material collection, sustainable
harvesting was practiced in order to protect the habitat.
For each medicinal plant, information about its vernacular
name, the part used, preparation, administration and
posology was obtained (Additional file 1).
Preparation of crude plant extracts
The collected plants samples were air-dried for 730
days in the shade at the environmental temperatures
(27C37C) and the leaves (250 g), flowers (550 g),
seeds (350 g) were powdered mechanically using a
commercial electrical stainless steel blender and
extracted with a) ethyl acetate (Qualigens) and b)
methanol (Qualigens) in a Soxhlet apparatus (boiling point
range 6080C) for 8 h. Extracts were concentrated on
a rotary evaporator under a reduced pressure of 22
26 mm Hg at 45C and the residues obtained were
weighed and stored at 4C.
In vitro cultivation of Plasmodium falciparum
Chloroquine (CQ)-sensitive strain 3D7 and CQ-resistant
strain INDO of Plasmodium falciparum were used for
in vitro blood stage culture to test the antiplasmodial
efficacy of different plant extracts. The culture was
maintained at the Malaria Research Laboratory, International
Centre for Genetic Engineering and Biotechnology, New
Delhi, India. Plasmodium falciparum culture was
maintained according to the method described by Trager and
Jensen  with minor modifications, in fresh O + ve
human erythrocytes suspended at 4% haematocrit in RPMI
1640 (Sigma) containing 0.2% sodium bicarbonate, 0.5%
albumax I, 45 g/L hypoxanthine, and 50 g/L
gentamicin and incubated at 37C under a gas mixture of 5% O2,
5% CO2, and 90% N2. Every day, infected erythrocytes
were transferred into fresh complete medium to
propagate the culture.
Dilutions of drugs and test samples
Stock solutions of plant extracts and artemisinin were
prepared in dimethyl sulfoxide (DMSO) while CQ stock
solution was in water (Milli-Q grade). All stocks were
then diluted with culture medium to achieve the
required concentrations (in all cases except CQ, the final
solution contained 0.4% DMSO, which was found to be
non-toxic to the parasite). Drugs and plant extracts were
then placed in 96-well flat bottom tissue culture grade
In vitro antiplasmodial assays on Plasmodium falciparum
in human red blood cell culture
The extracts of experimental plants were evaluated for
their antiplasmodial activity against 3D7 and INDO strains
of P. falciparum. For drug screening, SYBR green I-based
fluorescence assay was set up as described . Sorbitol
synchronized parasites  (100 l) were incubated under
normal culture conditions at 2% haematocrit and 1%
parasitaemia in the absence or presence of increasing
concentrations of plant extracts. CQ and artemisinin
were used as positive controls, while 0.4% (v/v) DMSO
was used as the negative control. After 48 h of
incubation, 100 l of SYBR Green I lysis buffer was added to
each well and mixed twice gently with multi-channel
pipette and incubated in dark at 37C for 1 h.
Fluorescence was measured with a Victor fluorescence
multiwell plate reader (PerkinElmer, Waltham, MA) with
excitation and emission wavelength bands centered at
485 and 530 nm, respectively. The fluorescence counts
were plotted against the drug concentration and the
50% inhibitory concentration (IC50) was determined by
analysis of dose response curves. Results were validated
microscopically by examination of Giemsa stained smears
of extract treated parasite cultures. In view of the
fluorescence basis of the SYBR Green assay, it was important to
assess artefacts due to quenching effects caused by
phytochemicals present in each of the plant extracts tested. To
accomplish this, parasite cultures (2% haematocrit and
10% parasitaemia) were incubated with or without test
extracts (100 g/ml) for 1 hr at 37C following which 100 l
of SYBR green lysis buffer was added and further
incubated in dark at 37C for 1 h. Fluorescence was measured
with a Victor fluorescence multi-well plate reader with
excitation and emission wavelength bands centered at 485
and 530 nm, respectively. Fluorescence of treated and
untreated cultures was compared to detect quenching
Cytotoxic activity on HeLa cells using MTT assay
The cytotoxic effects of extracts on host cells were
assessed by functional assay as described in ref  using
HeLa cells cultured in RPMI containing 10% foetal
bovine serum, 0.21% sodium bicarbonate (Sigma) and
50 g/mL gentamicin (complete medium). Briefly, cells
(104 cells/200 l/well) were seeded into 96 - well
flatbottom tissue culture plates in complete medium. Drug
solutions were added after 24 h of seeding and incubated
for 48 h in a humidified atmosphere at 37C and 5%
CO2. DMSO (as positive inhibitor) was added at 10% v/v.
Twenty micro liters of a stock solution of MTT (5 mg/mL
in 1X phosphate buffered saline) was added to each well,
gently mixed and incubated for another 4 h. After
spinning the plate at 1,500 RPM, 30C for 5 min, supernatant
was removed and 100 l of DMSO (stop agent) was
added. Formation of formazan was read on a microtiter
plate reader (VersaMax Microplate Reader, Molecular
Devices, USA) at 570 nm. The 50% cytotoxic
concentration (TC50) of test samples was determined by
analysis of doseresponse curves. Therapeutic index was
calculated as a ratio of TC50 HeLa /IC50 3D7.
Results and discussion
Indigenous healthcare systems have always played a vital
role in the management of community health and
discovery of novel chemotherapeutic agents. Medicinal plants
which offer a wide diversity of medicinal properties have
proved to be a boon for malaria therapy as two of the
most important anti-malarial drugs, namely quinine and
artemisinin, have their origins in the medicinal plants
Cinchona officinalis and Artemisia annua, respectively.
Ethnomedicinal plants could be attractive start
materials as they are wide spread and also a large
population relies on them for their curative effects. In the present
study, 17 medicinal plants known for their traditional
medicinal usage (Additional file 1) and pharmacological
activities (Additional file 2) were evaluated for (a) their
antiplasmodial activity against CQ-sensitive P.
falciparum 3D7 and CQ-resistant P. falciparum INDO strains
and (b) their toxicity against HeLa cell line (Table 1).
Among the seventeen plants studied, seven (Aerva lanata,
Anisomeles malabarica, Anogeissus latifolia, Couroupita
guianensis, Indigofera tinctoria, Juglans regia and Solanum
xanthocarpum) have been tested for their antiplasmodial
activity against both the 3D7 and INDO strains for the
first time. As shown in Figure 2 and Table 1, five of these
seven plants showed promising (Pf3D7 IC50 6 g/ml to
20 g/ml) antiplasmodial activity. Interestingly four of
these plant extracts showed greater potency against the
CQ-resistant INDO strain than against the CQ-sensitive
3D7 strain. Further the selectivity indices (HeLa cells
versus P. falciparum) for the promising extracts ranged
from 3 to >22 (Table 1).
For the remaining ten plants, which have been studied
for antiplasmodial activity by previous investigators,
experiments were performed to find which part of plant
and solvent of extraction could contribute
phytochemicals with superior antiplasmodial activity. In this context,
leaf methanol and ethyl acetate extracts of Psidium
guajava were found to show promising antiplasmodial
activity (IC50 Pf3D7: 15 & 12.5 g/ml respectively)
(Table 1, Figure 2). Earlier Nundkumar and Ojewole 
have reported promising activity of aqueous stem-bark
extract of Psidium guajava against CQ-sensitive P. falciparum
D10 strain (IC50: 20 g/ml). This suggests that Psidium
guajava leaves could be a better source for antiplasmodial
molecules than stem-bark since leaves are renewable while
girding for stem bark can cause severe injury to the tree.
Methanol extracts of seed and leaf of Ricinus communis
(IC50 Pf3D7: 30 & 34 g/ml respectively) showed good
antiplasmodial activity. However the corresponding ethyl
acetate extracts (IC50 Pf3D7 > 71g/ml) showed moderate
to poor antiplasmodial activity (Table 1, Figure 2). Clarkson
et al.  also reported similar moderate activity (IC50
P. falciparum D10: 27.5 g/ml) in R. communis leaves
DCM-methanol extract whereas they reported promising
activity in its stem dichloromethane/methanol extract
(IC50 P. falciparum D10: 8 g/ml).
Leaf ethyl acetate extract of Tridax procumbens showed
good activity (IC50 3D7: 32 g/ml) whereas the
corresponding methanol extract showed moderate
antiplasmodial activity (IC50 3D7: 62 g/ml) (Table 1, Figure 2).
However Appiah-Opong et al.  reported poor
antiplasmodial activity in whole plant extracts (water, ethanol,
chloroform and ethyl acetate) (IC50: 140430 g/ml). This
suggests that leaves should be preferred over the whole
plant and extraction should be made in ethyl acetate for
enriching antiplasmodial molecules.
Ethyl acetate flower extract of Gloriosa superba
showed moderate (IC50 3D7: 62 g/ml) antiplasmodial
activity whereas corresponding methanol extract was
found to be inactive up to 100 g/ml (Table 1 and Figure 2).
Bagavan et al.  have reported that ethyl acetate and
methanol extracts of the leaves of Gloriosa superba have
good antiplasmodial effect against CQ resistant strain of
P. falciparum INDO (IC50: 3040 g/ml) which
suggests that leaves of Gloriosa superba may be preferred
over its flowers as a source of antiplasmodial molecules.
Cardiospermum halicacabum also known as the balloon
plant is a climbing plant widely distributed in tropical and
subtropical Africa and Asia. As shown in Figure 2 and
Table 1, the leaves ethyl acetate extract of this plant was
found to have moderate antiplasmodial activity (IC50
Pf3D7: 42 g/mL). Clarkson et al.  reported that the
dichloromethane / methanol (1:1) whole balloon plant
extract showed good in vitro antiplasmodial activity
(P. falciparum D10 IC50: 20 g/mL) whereas Waako
et al.  extracted its shoots with different solvents
and reported moderate to poor activity in ethyl acetate
(P. falciparum D10 IC50: 28 g/mL) and methanol extracts
(P. falciparum D10 IC50: 62 g/mL). This comparative
study suggests that the stem of Cardiospermum
Table 1 Antiplasmodial activity, Cytotoxicity and selectivity of methanol (M) and ethyl acetate (EA) extracts of selected
Cytotoxicity (TC50 g/mL)
against HeLa cell line
Name of the plants
Whole aerial EA
halicacabum may have more potent antiplasmodial
molecules which makes shoots ethyl acetate extract
more potent than leaves ethyl acetate extract.
Cassia alata is an important medicinal as well as an
ornamental flowering plant of subfamily Caesalpinioideae.
The results described here indicate promising
antiplasmodial activity in the ethyl acetate extract of C. alata against
both CQ sensitive 3D7 (IC50: 18 g/mL) and CQ resistant
INDO (IC50: 20 g/mL) strains with low toxicity to
HeLa cells (TC50: 100 g/mL). However, Zirihi et al.
 found no antiplasmodial activity up to 50 g/mL
in leaf ethanol extract of Cassia alata whereas Kayembe
et al.  reported promising antiplasmodial activity
(IC50: 12.5 g/mL) in the seed ethanol extract of Cassia
alata. This suggests that ethyl acetate is a better solvent for
extraction of promising molecules from leaves compared
to ethanol whereas ethanol is equally good in their
extraction from seeds.
Euphorbia hirta is a pantropical weed, native to India.
It is a hairy herb that grows in open grasslands,
roadsides and pathways. It is widely used as a medicinal herb
in most places it grows (Additional file 1). In the present
study, good antiplasmodial activity (IC50 Pf3D7: 21 g/
mL) has been found in leaves ethyl acetate extract of
Euphorbia hirta. However, Tona et al.  who studied the
ethanol, petroleum ether and isoamyl alcohol extracts of
Euphorbia hirta whole plant have reported promising
antiplasmodial activity (IC50: 2.4, 1.2 and 2.6 g/mL respectively).
This indicates the importance of solvents and choice of
plant parts towards enriching promising metabolites.
Figure 2 Dose dependent growth inhibition curves of Plasmodium falciparum 3D7 by plant extracts. (a) ethyl acetate extracts and
(b) methanol extracts of Ricinus communis leaf (RcL), Ricinus communis seed (RcS), Gloriosa superba flower (GsF), Anisomeles malabarica leaf
(AmL), Psidium guajava leaf (PgL), Tridax procumbens leaf (TpL) and Juglans regia seed (JrS). c) ethyl acetate extracts of Anogeissus latifolia
Bark (AnlB), Glycyrrhiza glabra Roots (GgR), Aerva lanata whole aerial part (AelW), Solanum xanthocarpum whole aerial part (SxW), Cassia alata leaves (CaL) and
d) ethyl acetate extracts of Tinospora cordifolia leaves (TcL), Euphorbia hirta leaves (Eh), Indigofera tirictoria leaves (ItL), Pergularia daemia leaves (PdL),
Cardiospermum helicacabum leaves (ChL) and Couroupita guianensis leaves (CgL). Superscript numbers in label index refer to IC50 (g/mL).
Glycyrrhiza glabra (liquorice) is a herb belonging to the
pea and bean family, and is cultivated for its underground
stems that are used to flavour confectionery. In the
present study, the roots of this plant were found to have
promising anti-plasmodial activity against both 3D7 and
INDO strains (IC50: 6 & 4.5 g/mL). Prior reports
indicate that methanol extract  of its aerial parts
exhibits poor antiplasmodial activity against CQ sensitive
3D7 (IC50: >64 g/mL) and good activity against the
CQ resistant K1(IC50: 17.5 g/mL) strain of P. falciparum.
The results reported here suggest that roots may be better
source for antiplasmodial molecules than the aerial part of
Pergularia daemia is a hispid, perennial vine of
Apocynaceae family, with an extensive range in the Old
World tropics and subtropics. It has been used
traditionally to treat a number of ailments (Additional file 1).
Kantamreddi and Wright  studied the leaves
methanol extract of Pergularia daemia against 3D7 and K1
strains of P. falciparum and indicated it to be poorly
antiplasmodial (IC50: 203.8 and 244.1 g/mL,
respectively). However in the present study, extraction of leaves
with ethyl acetate resulted in about 10-fold potentiation
of antiplasmodial activity (Pf3D7IC50: 21 g/mL)
reiterating the crucial role of solvents in extraction of
metabolites that hold promise.
Tinospora cordifolia is used in the Indian Ayurvedic
system of medicine for the treatment of jaundice,
diabetes, and rheumatoid arthritis, and is also used as an
immunostimulant. Simonsen et al.  reported that the
stem ethanol extract of Tinospora cordifolia is poorly
antiplasmodial (IC50 Pf3D7: 62 g/mL). However, Tran
et al.  have reported that the stem methanol and
methanol : water (1:1) extracts with IC50 6.1 and 3.2 g/
mL, respectively against FCR-3 strain of P. falciparum
possessed promising antiplasmodial activity. In the present
study it was found that ethyl acetate leaf extract of
Tinospora cordifolia is moderately antiplasmodial
(Pf3D7IC50: 31 g/mL) against 3D7 strain of P. falciparum.
Promising extracts (Pf3D7IC50: < 20 g/mL) of Aerva
lanata, Anisomeles malabarica, Anogeissus latifolia, Cassia
alata, Glycyrrhiza glabra, Juglans regia, Psidium guajava
and Solanum xanthocarpum on further analysis against
chloroquine resistant INDO strain also showed good
resistance indices (0.41 1.4) suggesting that they may be
equally effective against both chloroquine-sensitive and
Figure 3 Validation of SYBR Green results by Microscopy and estimation of quenching of fluorescence by plant extracts. (a) Micrographs of
synchronized ring stage parasite cultures treated with ethyl acetate extract of Anisomeles malabarica leaf and Psidium guajava leaf after 48 h. Note that
at 12.5 g/ml, the parasitemia is decreased and the parasite is arrested at trophozoite stage in case of Pg while the arrest in case of Am is at early
schizont stage. (b) Examination of fluorescence quenching effects in plant extracts: Untreated and extract treated (100 g/ml) parasite cultures
(10% parasitemia) were subjected to SYBR Green fluorescence intensity measurements. The nearly identical intensities across untreated
control and extract treated test samples indicate that the test extracts showed no significant quenching of SYBR green 1-DNA fluorescence.
resistant-strains of Plasmodium. Further the selectivity
indices of 3 to > 22.2 observed with some of the plant extracts
studied by us suggest that they exhibit considerable
selectivity against the malaria parasite over the mammalian HeLa
cell line (Table 1).
The results of SYBR Green assay described above were
further validated by microscopy and experimental
estimation of SYBR Green fluorescence in parasitized red
blood cells in presence vs absence of the plant extracts
studied here (Figure 3). Microscopic evaluation of ethyl
acetate extracts of Anisomeles malabarica and Psidium
guajava showed dose dependent inhibition of parasite
growth (Figure 3a). Further none of twenty five extracts
studied by us showed any significant quenching effects
at 100 g/ml (Figure 3b) providing validity to the SYBR
Green assay based results described above.
These results indicate a possible explanation of the
traditional use of some of these medicinal plants against
malaria or malaria like conditions. These results are
significant since they report for the first time broad spectrum
antiplasmodial activities in the extracts of Aerva. lanata,
Anisomeles malabarica, Anogeissus latifolia, Cassia alata,
Couroupita guianensis, Glycyrrhiza glabra, Indigofera
tinctoria Juglans regia, Psidium guajava and Solanum
xanthocarpum. Further both plant parts and preferred
solvents were identified that provide extracts of high
antiplasmodial potency. This paves the paths for (a)
standardized plant extracts based therapy against
malaria and (b) for antiplasmodial activity guided isolation
of new pharmacophores and their subsequent
development towards phytochemical based novel drugs against
Additional file 1: Medicinal properties of selected plant species.
Additional file 2: Ethnobotanical exploration and biological activity
of selected medicinal plants.
The authors declare that they have no competing interests.
AB Collected the plant material, AAZ, CK, GE, CJ, AVK, TS, SM, GR prepared
the plant extracts. NKK carried out the biological assays, AAR, DS, SKT
participated in the design of the study and performed the statistical analysis.
NKK, AB, SKT, AAR, DS participated in manuscript drafting. All authors read
and approved the final manuscript.
All traditional healers and herborists are highly acknowledged for sharing
their indigenous medicinal knowledge on plants and help rendered during
the field work. NKK thanks ICMR, New Delhi for Senior Research Fellowship.
NKK and DS thank MR4 who generously provided the Chloroquine resistant
INDO strain used in the study. Thanks to X. Su who deposited this strain with
MR4. AB, AAR, AAZ, CJ, CK, GE and AVK are grateful to Zoology Department,
C. Abdul Hakeem of the College for providing the facilities to carry out this
work. Asokan Bagavan gratefully thanks University Grants Commission,
(F.No.35-71/2008 SR) Government of India, New Delhi for Junior
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