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Journal of the Science of Food and Agriculture J Sci Food Agric 85:186–190 (2005)
DOI: 10.1002/jsfa.1918
Analysis of carotenoids in ripe jackfruit
(Artocarpus heterophyllus) kernel
and study of their bioconversion in rats
UG Chandrika,1ER Jansz1∗and ND Warnasuriya2
1Department of Biochemistry, Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka
2Department of Paediatrics, Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka
Abstract: Vitamin A deficiency is of public health importance in Sri Lanka. Carotenoids are a significant
source of provitamin A. The objective of this study was to analyse the carotenoid composition of jackfruit
(Artocarpus heterophyllus sinhala: Waraka) kernel using MPLC and visible spectrophotometry and to
determine the bioavailability and bioconversion of carotenoids present in jackfruit kernel by monitoring
(i) the growth and (ii) levels of retinol and carotenoids in the liver and serum of Wistar rats provided with
jackfruit incorporated into a standard daily diet. Carotenoid pigments were extracted using petroleum
ether/methanol and saponified using 10% methanolic potassium hydroxide. Six carotenoids were detected
in jackfruit kernel. The carotenes β-carotene, α-carotene, β-zeacarotene, α-zeacarotene and β-carotene-
5,6-epoxide and a dicarboxylic carotenoid, crocetin, were identified, corresponding theoretically to 141.6
retinol equivalents (RE) per 100 g. Our study indicated that jackfruit is a good source of provitamin
A carotenoids, though not as good as papaya. Serum retinol concentrations in rats supplemented with
jackfruit carotenoids were significantly higher (p=0.008)compared with the control group. The same
was true for liver retinol (p=0.006). Quantification was carried out by RP-HPLC. These results show
that the biological conversion of provitamin A in jackfruit kernel appears satisfactory. Thus increased
consumption of ripe jackfruit could be advocated as part of a strategy to prevent and control vitamin A
deficiency in Sri Lanka.
2004 Society of Chemical Industry
Keywords: jackfruit; carotenoids; bioavailability; bioconversion
INTRODUCTION
Vitamin A deficiency is a nutritional deficiency
disorder of public health importance in Sri Lanka.
A recent national survey1revealed that 36% of
preschool children in Sri Lanka suffer from vitamin
A deficiency (serum retinol <20 µgdl
−1). In view of
its well-established association with child morbidity2
and mortality,3this is a cause for concern. The
main strategy for prevention of vitamin A deficiency
in Sri Lanka has been the promotion of general
consumption of vitamin A, especially as carotenoids
from plant sources. Yellow fruits and dark-green leafy
vegetables have been especially advocated. Owing to
the current controversy surrounding the bioavailability
of provitamin A carotenoids from dark-green leafy
vegetables,4it would be useful to identify as many
yellow and orange fruits and vegetables as possible
for their potential contribution as a dietary source of
provitamin A carotenoids. Among these carotenoids,
all-trans-β-carotene, with two unsubstituted β-ionone
rings and an attached polyene side chain, is expected to
give the highest vitamin A activity. Many carotenoids
not meeting these structural requirements lead to less
or no vitamin A activity. In addition to this traditional
role, carotenoids with or without vitamin A activity are
known to be involved in immunoenhancement5and
the treatment and prevention of cancer and to possess
antioxidant capacity.6
Even if provitamin A carotenoids are present,
the utilisation of provitamin A may not be entirely
satisfactory, as there are factors that interfere with
its availability. The bioavailability and bioconversion
of carotenoids present in the diet depend mainly on
the efficiency of their absorption into mucosal cells as
well as their conversion to retinol. Fruits of the jack
tree (Artocarpus heterophyllus) are readily available in
rural Sri Lanka. The jackfruit is the largest tree-borne
fruit in the world, reaching approximately 35 kg in
weight, 90 cm in length and 50 cm in diameter. The
exterior of the compound fruit is yellow when ripe.
The interior consists of large edible bulbs of yellow,
banana-flavoured flesh (kernel) that encloses smooth,
∗Correspondence to: ER Jansz, Department of Biochemistry, Faculty of Medical Sciences, University of Sri Jayewardenepura, Gangodawila,
Nugegoda, Sri Lanka
E-mail: erjansz@sjp.ac.lk
Contract/grant sponsor: IPICS; contract/grant number: SRI:07
(Received 9 June 2003; revised version received 19 April 2004; accepted 2 June 2004)
Published online 12 October 2004
2004 Society of Chemical Industry. J Sci Food Agric 0022 – 5142/2004/$30.00 186
Carotenoids in jackfruit kernel
oval, light-brown seeds. There may be 100 or up to
500 seeds in a single fruit. Each kernel weighs about
5 g. The ripe kernel is yellow in colour owing to its
content of carotenoids. To our knowledge, there has
not been any study on the carotenoid composition of
jackfruit kernel. Therefore the objective of this study
was to analyse the carotenoid composition of jackfruit
kernel using MPLC and visible spectrophotometry and
to determine the bioavailability and bioconversion of
carotenoids present in jackfruit kernel by monitoring
(i) the growth and (ii) levels of retinol and carotenoids
in the liver and serum of Wistar rats provided with
jackfruit incorporated into a standard daily diet. This
would serve to determine if jackfruit kernel could
contribute to the alleviation of vitamin A deficiency in
Sri Lanka.
METHODOLOGY
Sampling
Five ripe (judged by their strong fruity odour)
jackfruits were collected in and around the suburbs
of Colombo, Sri Lanka and cut open. The bulbs
of kernels and seeds were removed and the seeds
were separated and discarded. A total of 500 –750 g
of kernel is available in a single jackfruit. The kernels
were cut into small pieces and homogenised in a
mechanical blender.
Sample preparation
A homogeneous, representative sample of fruit pulp
(50 g) was ground with cold acetone and celite
using a mortar and pestle and filtered through
a sintered glass crucible. Grinding and filtration
were repeated until the residue was colourless (four
times). The carotenoids were transferred to petroleum
ether at room temperature (25 ◦C) by adding small
portions of the combined acetone extract to 100 ml
of petroleum ether (specified boiling range 60 –80 ◦C)
in a separatory funnel. After each addition, water
was poured in gently, the two layers were allowed to
separate and the lower aqueous layer was discarded.
When the entire extract had been added, the petroleum
ether layer was washed five times with water to
remove residual acetone, and the combined extract
was collected in an Erlenmeyer flask. The petroleum
ether layer was saponified for 16 h (in the dark at
room temperature) with an equal volume of 10%
potassium hydroxide in methanol containing butylated
hydroxytoluene (1% in petroleum ether). The alkaline
solution was washed with water in a separatory funnel
until neutral. The carotenoid solution was then dried
with anhydrous sodium sulphate, concentrated in
a rotary evaporator (35 ◦C) and used for medium-
pressure liquid chromatography (MPLC).
Medium-pressure liquid chromatography
The carotenoid sample in petroleum ether (1 ml) was
injected onto an MPLC column (10 cm ×1.5 cm)
of MgO (Merck, Darmstadt, Germany)/celite (1:1,
activated for 2 h at 110 ◦C) at 15 ml min−1flow rate,
equilibrated with 100% petroleum ether. The fractions
were eluted successively with 2, 5, 8, 10, 15 and
20% acetone in petroleum ether; separation of the
carotenoids was monitored visually and each separated
fraction was collected as it left the column. The
visible spectra of carotenoid bands in 1 cm quartz
cuvettes were recorded from 350 to 600 nm on a
Shimadzu (Kyoto, Japan) UV-1601 visible recording
spectrophotometer.
Identification of carotenoids
The carotenoids were identified through a combina-
tion of several parameters such as visible absorption
spectra, position on the column, TLC on silica gel
G60 (6% methanol in toluene solvent system) as
well as chemical reactions such as iodine-catalysed
isomerisation7and epoxide tests.7The identification
procedures and interpretation of the results were car-
ried out according to Rodriguez-Amaya.7
Quantification of carotenoids
The concentrations of the various carotenoids were
determined spectrophometrically using molar extinc-
tion coefficients as described by Rodriguez-Amaya.7
Five different ripe jackfruit kernel samples of similar
colour (visually) were analysed in duplicate.
Biological assay
Healthy 4-week-old male Wistar rats (weight 200 ±
8.6 g) purchased from the Medical Research Institute,
Colombo, Sri Lanka, were used. They were housed
in stainless steel cages under standard conditions
and randomly divided into two groups of eight rats
each. All rats were weighed weekly using a single-pan
spring balance. Before commencement of the feeding
schedule, all rats were given a standard control diet
without added vitamin A for 2 weeks and blood was
collected from the tail vein for the determination of
serum retinol levels. For the test diet, jackfruit kernel
was incorporated (20% dry weight) into the standard
World Health Organisation rat and mouse breeding
feed8in the morning. Each day for 4 weeks, one group
received the test diet and the other (control) group was
given only the standard diet. At weekly intervals, body
weights were recorded for the determination of growth
rates. At the end of 4 weeks, all rats were anaesthetised
with diethyl ether and their blood was collected by
heart puncture using a 5 ml disposable syringe. The
blood was allowed to clot and the serum was separated
by centrifugation. The livers of the animals were also
removed. Serum and liver samples were stored at
−20 ◦C prior to analysis.
Analysis of serum vitamin A
Serum (100 µl),ethanol(100 µl)and retinyl acetate
as an internal standard were mixed vigorously in
a vortex mixer. HPLC-grade hexane (600 µl)was
added and the contents were mixed again until the
J Sci Food Agric 85:186 – 190 (2005) 187
UG Chandrika, ER Jansz, ND Warnasuriya
bottom layer was thoroughly extracted. The contents
were centrifuged at 2000 rpm for 5 min, then the
upper hexane layer (400 µl)was transferred to a
small test tube and evaporated under nitrogen. The
remaining residue was dissolved in 50 µl of 95%
methanol and analysed using RP-HPLC. Both the
retinyl acetate internal standard and a linear standard
curve (r2=0.9926)were used for quantification.
Liver vitamin A extraction
The extraction method used was a slight modification
of a previously published procedure.9Liver tissues
(0.5 g) were first homogenised (Ultra-Turrax T-25-
Basic, IKA-WERKE, Colombo, Sri Lanka), then
anhydrous sodium sulphate and retinyl acetate internal
standard were added. After the addition of 2
volumes (v/w) of 2-propanol/dichloromethane (1:1)
the mixture was vortexed and allowed to stand for
2–3 min. The extract was decanted and the insoluble
residue was re-extracted three or four times more
with dichloromethane as previously described.9After
filtration, 200 µl portions of the pooled extract were
evaporated to dryness using nitrogen gas and dissolved
in 95% methanol for the analysis of vitamin A. An
aliquot (20 µl)was analysed by RP-HPLC.
RP-HPLC for vitamin A analysis
For reverse phase gradient HPLC, Waters Associates
(Milford, MA, USA) pumps (model 515), Shimpak
column CLC-ODS (M) C18, 25 cm ×4.6 mm, rheo-
dyne injection valve, SCL-6A system controller and
CR-6A recorder were used. Serum extract solution
(20 µl)was injected onto the RP-HPLC column, and
vitamin A levels were analysed using methanol/water
(95:5) as mobile phase and detection at 325 nm. Cal-
culation of the retinol concentration was done using
standard curves to verify linearity over the sample con-
centration and passage of graph through the origin. A
one-point calibration was carried out on each day of
analysis. Retinyl acetate was used as an internal stan-
dard for extraction correction factor. Linear standard
curve r2=0.9926. Small correction factors needed to
be applied to values calculated for liver and serum
samples respectively.
RP-HPLC for β-carotene analysis
β-Carotene was analysed in the same HPLC system
but using acetonitrile/methanol/trifluoroacetic acid
(58:35:7) as mobile phase and detection at 450 nm.
Plasma β-carotene concentrations were calculated
using standard curves to verify linearity over the
sample concentration and passage through the origin.
A one-point calibration was carried out on each day
of analysis.
RESULTS AND DISCUSSION
The characteristics that helped identify the major
provitamin A and non-provitamin A carotenoids in
jackfruit kernel were UV spectra, chemical tests
and TLC Rfvalues (Table 1). Six carotenoids were
detected in jackfruit kernel, namely β-carotene, α-
carotene, β-zeacarotene, α-zeacarotene, β-carotene-
5,6-epoxide and a dicarboxylic carotenoid, crocetin.
Fig 1 shows that the solvent system adopted gives a
good separation of carotenoids. Petroleum ether sep-
arated the hydrocarbon (non-oxygenated) carotenes,
namely α-carotene and β-carotene, while the oxy-
genated carotenoids and crocetin were progressively
eluted with increasing % acetone; the most oxygenated
required the highest % acetone.
α-carotene PE
PE
2% AC in PE
5% AC in PE
10% AC in PE
50% AC in PE
α-zeacarotene
β-carotene
β-zeacarotene
β-carotene 5.6 enoxide
crocetin
Figure 1. Separation pattern and eluting solvents of carotenoids from
saponified jackfruit extract on MgO/celite column (ascending
chromatography). PE, petroleum ether; AC, acetone.
Table 1. Major provitamin A and non-provitamin A carotenoids in jackfruit kernel
Characterisation method
λmax in petroleum
ether (nm)
Response to
chemical tests7
Rfvalue in methanol/toluene
(95:5)
Provitamin A carotenoids
β-Carotene 422, 449, 476 Positive to trans form 1
β-Carotene-5,6-epoxide 424, 444.5, 468 Positive to trans form,
positive to 5,6-epoxide
test (one group)
0
α-Carotene 422, 445, 472 Positive to trans form 1
β-Zeacarotene 403, 426, 447 Positive to trans form 0.95
Non-provitamin A carotenoids
α-Zeacarotene 399, 421, 447.5 Positive to trans form 0.93
Crocetin 402, 423, 450 — 0.33
188 J Sci Food Agric 85:186–190 (2005)
Carotenoids in jackfruit kernel
The carotenoid profile of jackfruit kernel is shown in
Table 2. The calculated retinol equivalent was 141.6
RE per 100 g. The results show that, although jackfruit
kernel is a good source of provitamin A, it is not as
good as papaya, which has an RE range of 152–280.10
However, as jackfruit is cheap, found more commonly
island-wide, and the kernel, like papaya, is well
accepted organoleptically by the population, it is clear
that jackfruit kernel could be as significant a source of
vitamin A as papaya in Sri Lanka. This is important,
Table 2. Quantification of major provitamin A and non-provitamin A
carotenoids in jackfruit kernel
Concentration (µgg
−1)
Provitamin A carotenoids
β-Carotene 5.6±0.3
β-carotene-5,6-epoxide 3.1±0.3
α-Carotene 1.7±0.1
β-Zeacarotene 3.1±0.3
Non-provitamin A carotenoids
α-Zeacarotene 3.5±0.2
Crocetin 2.1±0.1
Calculations were done in duplicate for each jackfruit kernel; n=5
jackfruits. Retinol equivalent 141.6 RE per 100 g.
as papaya is the most advocated source of vitamin A
at present.
Fig 2 shows that rats fed the diet supplemented with
ripe jackfruit kernel had slightly higher rates of growth,
but the differences were not significant.
The carotenoids of jackfruit kernel are clearly
both bioavailable and bioconvertible (Table 3). Serum
retinol levels increase significantly (p=0.008)on
supplementation of feed with jackfruit kernel. Liver
retinol also shows a significant increase (p=0.006)
over control (unsupplemented) feed.
The β-carotene content in the liver of rats fed a
supplement of jackfruit kernel was 23.4±2.2µgg
−1.
Other provitamin A and non-provitamin A carotenoids
were seen to be present on the HPLC scan, though to
such a small extent that they were not quantified.
There was no detectable β-carotene in the liver
in the control group, which was not unexpected.
β-Carotene was also not detected in the serum
of rats in both groups studied. This is probably
due to transport of β-carotene in chylomicrons and
rapid uptake of serum β-carotene not only by the
liver but also perhaps by adipose and other tissues,
indicating that β-carotene has a short residence time
in the serum.
Duration of supplementation (weeks)
Weight of rats (g)
Figure 2. Growth of rats supplemented with ripe jackfruit kernel.
Table 3. Effects of jackfruit kernel supplementation on rat serum and liver retinol concentrations
Serum retinol (µgdl
−1)Liver retinol (µgg
−1)
Control Test Control Test
Before supplementation 43.4±11.539.9±12.1ND ND
After supplementation 33.1±4.750.0±8.9∗1.0±0.53.6±1.7∗∗
Values are mean ±SD of eight determinations. ND, not detected. ∗Significantly different from control at p=0.008. ∗∗ Significantly different from
control at p=0.006.
J Sci Food Agric 85:186 – 190 (2005) 189
UG Chandrika, ER Jansz, ND Warnasuriya
Biological conversion of provitamin A in jackfruit
kernel appeared satisfactory after 4 weeks of feeding
rats the diet supplemented with jackfruit kernel. This
showed good bioavailability and bioconversion of the
provitamin A carotenoids of jackfruit kernel. The fact
that β-carotene levels increase significantly in the
liver of rats on the kernel-supplemented diet shows
that the quantity of β-carotene in the supplement is
sufficient to saturate the bioconversion to retinal by the
dioxygenase system, and therefore some β-carotene is
absorbed without bioconversion.
It is concluded that increased consumption of ripe
jackfruit could be advocated as part of a strategy to
prevent and control vitamin A deficiency in Sri Lanka.
However, it would be useful to carry out follow-up
studies on bioavailability using a human model.
ACKNOWLEDGEMENT
Financial assistance through IPICS research grant
SRI:07 is gratefully acknowledged.
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