IJMAP_2_2_2_Syzygiumpolyanthum

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Int. J. Med. Arom. Plants, ISSN 22494340

RESEARCH ARTICLEVol. 2, No. 2, pp. 219-228, June 2012

*Corresponding author: (E-mail) intan science.upm.edu.my http://www.openaccessscience.com

2012 Open Access Science Research Publisher [email protected]

Antioxidant activity, total phenolics and total flavonoids of Syzygium

polyanthum (Wight) Walp leaves

Lee Wei HAR, Intan Safinar ISMAIL*

Laboratory of Natural Products, Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor,

Malaysia

*Corresponding author, Tel.: (603) 89471490, Fax: (603) 89435380

Article History: Received 25th April 2012, Revised 30th May 2012, Accepted 31st May 2012.

Abstract: Methanolic extract ofSyzygium polyanthum leaves showed mild antioxidant activity with IC50 values of 90.85

g/ml compared to the standard quercetin (24.09 g/ml) on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengingassay. Nevertheless, the total phenolics was analysed via Folin-Ciocalteau method in which 11125 mg gallic equivalent(GAE) and 312.52 mg caffeic acid equivalent (CAE)/100 g dry leaves were obtained. Analyses by HPLC and LC-MS

confirmed the presence of gallic acid and caffeic acid as the major phenolic acids in the methanolic Syzygium polyanthumleaves extract. The total flavonoids analysis based on Down Method and HPLC suggested only a minute percentage of

flavonoids in the methanolic extract.

Keywords: Syzygium polyanthum; antioxidant; total phenolics; total flavonoids.

Introduction

Syzygium polyanthum (Wight) Walp which

is commonly known as Daun Salam or Indo-nesian Bay Leaf is usually found abundantly

distributed in Indonesia. The leaves of the plant

are widely used as spice due to its flavor

(Noorma 1995). Besides being used as spice, the

leaf and bark ofS. polyanthum have been used

as traditional remedies to treat diarrhea, rheuma-

tism and anti-hyperuricemia (Burkill 1966;

Haque 2004).

The previous studies on plants of Myrtaceae

family found that phenolics and flavonoids such

as gallic acid, eugenol, kaempferol andquercetin, which contributed to antioxidant ac-

tivity are present in Eugenia caryophyllata

Thumb, commonly known as clove (Bin et al.

2005). Eugenia carrissoides and Kunzea

pomifera F. Muell showed high phenolic con-

tents determined via Folin-Ciocalteau assay.

Cyanidin 3-glucoside and cyanidin-3-rutinoside

were detected in both plants through identifica-

tion and quantification using HPLC/ESI-MS-

MS and HPLC-DAD (Michael et al. 2006).Psidium guajava, another plant from the

Myrtaceae family was known to be a rich source

of phenolic acids and flavonoids with the detec-

tion of ferulic acid, chlorogenic acid, ellagic ac-

id, guavin B, quercetin, kaempferol, avicularin,

myricetin, luteolin, leucocyanidin and 3--L-arabinofuranoside (Rosa et al. 2008). The anti-

oxidant capacity and total phenolics content

studies on selected Malaysian underutilized

fruits showed that Syzygium jambos exhibited

high potential to be a source of antioxidants

with antioxidant capacity of 90.09 3.12 % and

phenolics content of 555.57 28.33 mg

GAE/100g edible portion (Emmy et al. 2009).

These previous studies on the Myrtaceae family

showed its plants are great potential source of

antioxidants due to many detected phenolics and

flavonoids. These findings suggested the possi-

bility of Syzygium polyanthum also possesses

high antioxidant property.

The methanolic extract of Syzygium

polyanthum leaves was subjected to DPPH-Thin

Layer Chromatography (TLC) autographic as-

say and showed a mild antioxidant activity.

Hence, total phenolics and total flavonoids

analyses were done on S. polyanthum leaves to

investigate the compounds responsible for theantioxidant property of this plant.
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Int. J. Med. Arom. Plants Antioxidant activity, total phenolics and flavonoids of Syzygium polyanthum

Har and Ismailhttp://www.openaccessscience.com

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Materials and method

Plant material

The leaves ofSyzygium polyanthum (Wight)

Walp were collected at Guar Chempedak, Ked-

ah in 2006 and identified by a botanist in Insti-

tute of Bioscience (IBS), Universiti Putra Ma-laysia (UPM). The voucher specimen

(ACP0159) is deposited in the herbarium at IBS,

UPM.

Extraction

Extraction of Syzygium polyanthum dried

leaves (1.5 kg) was carried out by soaking for

24 hours in methanol (5 L), filtered through lay-

ers of gauze and the leaves were re-soaked with

fresh methanol. These steps were repeated threetimes, and the combined filtrates were concen-

trated in vacuo at 40C.

Extraction and purification of phenolic acids

Fractionation of phenolic acids present in

the methanolic crude extract of Syzygium

polyanthum into free phenolic acids, phenolic

acids liberated from ester bond and phenolic

acids liberated from glycosidic bonds was per-

formed according to the procedure reported by

Ryszard et al. (2008). Dried crude extract (0.5

g) was suspended in 50 ml of distilled water

which was acidified to pH 2 with 6M HCl. The

suspended crude was extracted five times with

diethyl ether, in the ratio of 1:1 v/v for each

time, by liquid-liquid partition at room tempera-

ture. The ether extracts were combined and

evaporated to dryness under vacuum at tempera-

ture 40 C. The combined diethyl ether frac-

tions were the known as free phenolic acids (A).

The obtained water phase was adjusted to pH 7with 2M of NaOH and evaporated to almost

dryness and the residue was treated with 20 ml

of 4M of NaOH under nitrogen for 4 hours at

room temperature. The reaction mixture was

then acidified to pH 2 with 6M of HCl and again

extracted by liquid-liquid partition with diethyl

ether as described above. This second combined

diethyl ether fractions were the phenolic acids

liberated from ester bond (B). The water phase

separated from B was adjusted to pH 7 with 2M

of NaOH and evaporated to almost dryness. Theresidue was heated in 50 ml of 2M of HCl for

30 minutes at 90 C and it was let cooled to

room temperature before extracted with another

volume of diethyl ether. The combined diethyl

ether fractions from this step are referred as

phenolic acid liberated from glycosidic bond

(C). Each of the phenolic acid fractions (A, B or

C) yielded from the three extractions was dis-solved in 50 ml of 5% NaHCO3 (pH 8). The

fractions were then extracted five times with

ethyl ether to remove lipid residual material.

The water phase obtained then acidified to pH 2

with 6M of HCl while the combined ether frac-

tions were evaporated to dryness.

TLC-DPPH autographic assay

The TLC-DPPH autobiographic modified

assay was adapted from Marina et al. (2005), inwhich ten concentrations of the crude extract in

descending order starting from 1000 to 1.95

ppm were prepared via two-fold dilutions. The

samples were spotted on normal phase silica gel

60 TLC plate (0.2 mm thickness; Merck, Darm-

stadt, Germany) and sprayed with 0.2% DPPH

solution in methanol and placed in the dark con-

dition for 30 minutes. The plate was observed

for active antioxidant compounds which ap-

peared as yellow to whitish spots against purple

background (Figure 1).

2,2-diphenyl-1-picrylhydrazyl (DPPH) radical

scavenging assay

The DPPH radicals scavenging assay was

adapted and modified from the method used by

Archana et al. (2005). The 5.0 mg methanolic

extract was dissolved in 1.0 ml methanol as

stock sample solution. 200 l of the stock solu-

tion of concentration 5000 g/ml was added 800

l methanol to prepare substock solution of1000 g/ml. Two-fold dilution was performed

on the substock to yield test solutions at the

concentrations of 500, 250, 125, 62.5, 31.25,

15.62, and 7.81 g/ml in a 96-wells plate.

DPPH solution (5 l of 2500 g/ml) in metha-

nol was added to each of the wells that were

filled with different concentrations of the test

solutions. The absorbance was recorded at 517

nm after 30 minutes of incubation in the dark

condition. The assay was done in triplicates.

The percentage of inhibition and IC50 values ofthe methanolic extract tested was determined.
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Standard caffeic acid c a f f e i c a c i d

0 . 0 2 . 0 4 . 0 6 . 0 8 . 0 1 0 . 0 1 2 . 0 1 4 . 0 1 6 . 0 1 8 . 0 2 0 . 0 2 2 . 0 2 4 . 0 2 6 . 0 2 8 . 0 3 0 . 0

R e t e n t io n T i m e [ m i n ]

0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

Int

e

n

s

ity

[

V

]

c a f f e

Standard caffeic acid free phenolic acids (A) c a f f e i c

b

c

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0

R e t e n t i o n T i m e [ m i n ]

0

5 0 0 0 0 0

1 0 0 0 0 0 0

I

n

t

e

n

s

it

y

[

V

]

f r e e p

Free phenolic acids liberated from ester bond (B) g a l ic a c i d

c a f f e i c a c i d

c

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0


0

2 0 0 0 0 0

4 0 0 0 0 0

In

te

n

s

ity

[

V

]

f r e e p

Free phenolic acids liberated from glycosidic bond (C)

g a l l ic a c i d


c d e f

g

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0R e t e n t i o n T i m e [ m i n ]

0

2 0 0 0 0 0

4 0 0 0 0 0

6 0 0 0 0 0

I

n

t

e

n

s

it

y

[

V

]

f r e e p

Figure 1: HPLC chromatograms of standard caffeic acid and free phenolic acid derivatives of S.

polyanthum leaves at 254nm.


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Folin-Ciocalteau method(Chun et al. 2003)

Methanolic crude extract (1 mg/ml) was

added to a 25 ml volumetric flask filled with 9

ml of deionized water. A blank sample using

deionized water instead of sample was prepared

in the same manner. Folin-Ciocalteaus phenolreagent (1 ml) was added to the mixture and

mixed well. After 5 minutes, 10 ml of 7%

Na2CO3 solution was added and mixed well with

the mixture. The mixture solution was diluted to

the volume (25 ml) with deionized water and

then allowed to stand for 90 minutes. The ab-

sorbance was measured at 750 nm versus the

prepared blank. Gallic acid in the concentrations

of 100 to 10 mg/l was tested and a straight-line

interpolation graph was plotted between the

concentrations and observed absorbances.

Down colorimetric method (Coulidiati et al.

2009)

The total flavonoids content in Syzygium

polyanthum was estimated according to the

Down method. The 2 ml of 1 mg/ml of

methanolic crude extract was mixed with 2 ml

of aluminum trichloride (AlCl3) in 2 % metha-

nol. The absorbance at 415 nm was recorded

after 10 minutes against a blank sample consist-

ing of 2 ml of methanol and 2 ml of crude ex-

tract without AlCl3. Quercetin at the concentra-

tion ranging from 0 to 50 mg/l was tested as

standard and a straight-line standard curve was

plotted against the absorbances obtained.

High performance liquid chromatography

(HPLC)

Total phenolics and total flavonoids anal-yses on methanolic extract of Syzygium

polyanthum leaves were carried out using Jasco

HPLC (Tokyo, Japan) consisting of a pump

(PU-2089 Plus) and UV detector model UV-

2077 Plus with ChromNAV on a XBridge ana-

lytical column (RP-C18; 5m, 4.6 X 150 mm)

(Waters Inc., USA) with gradient solvent system

and parameter condition as shown in Table 1.

The chromatograms were observed at wave-

lengths of 254, 270, 280 and 329 nm. All the

analyses were carried out at sample concentra-tion of 1 mg/ml and injection volume of 20l.

Liquid chromatography-mass spectrometer

Phenolic acids fractions from methanolic ex-

tract ofSyzygium polyanthum were analyzed via

LC-MS on an XBridge analytical column (RP-

C18; 5m, 4.6 X 150 mm) (Waters Inc., USA),

attached to Mass Spectrometry(ThermoFinnigan LCQDECA) and the mass were

recorded on a Polaris Q system. The LC param-

eter used is similar to that described for HPLC.

Table 1: Gradient solvent composition in HPLC

and LC-MS used in total phenolics and total fla-

vonoids analyses.

Time

(min)

Composition (%)

Solvent A

(ACN)

Solvent B (H2O,

pH 2.5)Initial 2.0 98.0

5.00 2.0 98.0

15.00 5.0 95.0

17.00 100.0 0.035.00 100.0 0.0

Flow rate [ml/min] 0.7

Method time 35 min

Results and discussion

The DPPH-TLC autographic assay on the

methanolic crude extract of Syzygiumpolyanthum leaves in various concentrations

exhibited antioxidant activity until 62.5 ppm

suggesting that this plant leaves possess a mild

antioxidant property. Hence, the plant

methanolic extract was subjected to spectropho-

tometric 96-well microplate DPPH assay for

specific measurement of the antioxidant activity.

In the DPPH radical-scavenging assay, the

ability of a substance to donate hydrogen atoms

or electrons in transformation of the stable, pur-ple-coloured radical DPPH into its reduced,

non-radical yellow-coloured DPPH-H form was

determined (Archana et al. 2005). The graphs on

percentage inhibition of standard quercetin and

the methanolic extract were plotted and com-

pared in Figure 2. The concentration of antioxi-

dant required for 50% scavenging of DPPH rad-

icals in the period of 30 minutes of the assay

was defined as the IC50 value of the antioxidant.

The IC50 values of the standard quercetin and

Syzygium polyanthum leaves extract was deter-mined to be 24.09 and 90.85 g/ml respectively


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which implied that the plant sample has a mild

antioxidant activity compared to the standard

quercetin.

Figure 2: Comparison of percentage of inhibi-

tion of standard quercetin (X) and methanolic

extract ofSyzygium polyanthum leaves (Y)

The antioxidant assays showed thatSyzygium polyanthum leaves has mild antioxi-

dant activity. Phenolic acid and flavonoids were

known to be contributing to the antioxidant ac-

tivity (Michael et al., 2006). Hence, total

phenolics and flavonoids analyses were carriedout to investigate the phenolics and flavonoids

present in the plant.

Folin Ciocalteau analysis

Total phenolic content of methanolic extract

ofSyzygium polyanthum leaves was determined

by Folin-Ciocalteau (F-C) colourimetry based

on a chemical reduction of the reagent which is

a mixture of tungsten and molybdenum oxides.

This fast and simple assay is commonly used toestimate the total phenolics content in botanical

samples such as wine and tea (Wiseman et al.,

2001). Folin-Ciocalteau colourimetry assay by

using gallic and caffeic acid as phenolic stand-

ards were carried out on methanolic extract of

Syzygium polyanthum. Figure 3 shows a linear

calibration curve, of gallic acid as a phenolic

standard in the range of 0.01 to 0.1 mg/ml, with

coefficient of determinant (r2) value of 0.997.

The total phenolics estimated in methanolic ex-

tract of Syzygium polyanthum leaves based onthe linear standard curve (Figure 3) was found

to be 11125 mg gallic equivalent (GAE)/100 g

dry leaves. Caffeic acid was also found to be

present in the extract via the HPLC analysis on

methanolic extract of Syzygium polyanthum

leaves in comparison with a few phenolic stand-

ards including caffeic acid and 3-

hydroxybenzoic acid. Hence, F-C colorimetryassay was repeated by using caffeic acid as the

phenolic standard to estimate the total phenolic

content referring to caffeic acid. The linear cali-

bration curve of caffeic acid (Figure 4) plotted

in the range of 0.01 to 0.1 mg/ml has coefficient

of determinant (r2) value of 0.983. The total

phenolic content in methanolic extract of S.

polyanthum leaves as a reference to caffeic acid

was found to be 312.52 mg caffeic acid equiva-

lent (CAE)/100 g dry leaves.

Figure 3: Calibration curve of gallic acid.

Figure 4: Calibration curve of caffeic acid.


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Standard gallic acid g a l li c a c i d

0 . 0 2 . 0 4 . 0 6 . 0 8 . 0 1 0 . 0 1 2 . 0 1 4 . 0 1 6 . 0 1 8 . 0 2 0 . 0 2 2 . 0 2 4 . 0


0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

Int

e

n

s

it

y

[

V

]

g a l ic

Free phenolic acids (A)

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0R e t e n t i o n T i m e [ m in ]

0

5 0 0 0 0 0

1 0 0 0 0 0 0

I

n

t

e

n

s

ity

[

V

]

f r e e

Free phenolic acids liberated from ester bond (B)

g a l li c a c i d

c a f f e i c a c id

c d e f

g

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0


0

2 0 0 0 0 0

4 0 0 0 0 0

6 0 0 0 0 0

In

te

n

s

ity

[

V

]

f r e e p

Free phenolic acids liberated from glycosidic bond (C) g a l i c a c i d


c

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0

R e t e n t i o n T i m e [ m in ]

0

2 0 0 0 0 0

4 0 0 0 0 0

I

n

t

e

n

s

it

y

[

V

]

f r e e p

Figure 5: HPLC chromatograms of standard gallic acid and free phenolic acid derivatives ofS.

polyanthum leaves at 254nm.


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HPLC and LC analyses

HPLC and LC-MS analyses were carried out

on the methanolic extract of Syzygium

polyanthum leaves to determine the phenolic

acid content in the plant extract. The phenolic

acids present in the methanolic extract werefractionated into free and bound forms namely

free phenolic acids (A), free phenolic acid liber-

ated from ester bond (B) and free phenolic acids

liberated from glycosidic bond (C). Each of the

phenolic acid fractions obtained was purified by

removing the residual lipid and prior to the

HPLC and LC-MS analyses, the phenolics were

extracted by using 80% aqueous methanol. The

HPLC and LC-MS profiles of the free phenolic

acid fractions were compared with the phenolic

standards which were gallic acid, caffeic acid,3-hydroxybenzoic acid and chlorogenic acid.

All the standards and samples were analyzed at

the same concentration of 1 mg/ml. Based on

the comparison of the HPLC chromatograms,

caffeic acid was found to be present in all of the

phenolic acid fractions (A, B and C) as shown in

Figure 1, while gallic acid was only detected in

fractions B and C (Figure 5). The percentages of

gallic acid and caffeic acid detected were calcu-

lated based on areas of sample and standard

peaks obtained in the HPLC chromatograms

(Figure 6). The percentages amount of gallicacid detected in free phenolic acids liberated

from ester bond (B) and free phenolic acids lib-

erated from glycosidic bond (C) were deter-

mined to be 60.68 and 38.14 % respectively.

The percentage values showed that the amount

of gallic acid present in phenolic acids linked to

sugars by ester bonds is higher compared to gal-

lic acid liberated from glycosidic bond. The free

phenolic acids fraction (A) gave the highest per-

centage of caffeic acid (76.35 %) among all the

free phenolic acids fractions (A, B and C) test-

ed. The percentages of caffeic acid in B and C

are 35.40 and 51.59 %, respectively which are

relatively low compared to the free phenolic ac-

ids (A) (Figure 7).

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0

R e t e n t i o n T im e [ m i n ]

0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

In

te

n

s

ity

f r e ef r e ef r e eg a l ic

Figure 6: Overlay of HPLC chromatograms of standard gallic acid and free phenolic acid derivatives

at 254nm

0 . 0 5 . 0 1 0 . 0 1 5 . 0 2 0 . 0 2 5 . 0 3 0 . 0 3 5 . 0


0

1 0 0 0 0 0 0

2 0 0 0 0 0 0

I

n

t

e

n

s

it

y

c a f f ef r e e pf r e e pf r e e p

Figure 7: Overlay of HPLC chromatograms of standard caffeic acid and free phenolic acid deriva-tives at 254nm.


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Table 2: Percentage amount of gallic acid and

caffeic acid detected in the free phenolic acids

fractions based on percentage of peak areas.

Standard *Percentage amount of

gallic / caffeic acid

detected (%)

Gallic acid 100Caffeic acid 100

Sample

Free phenolic acids (A)

Gallic acid Not detected

Caffeic acid 76.35Free phenolic acids liberated

from ester bond (B)

Gallic acid 60.68

Caffeic acid 35.40

Free phenolic acids liberatedfrom glycosidic bond (C)

Gallic acid 38.14Caffeic acid 51.59

All of the standards and samples were analyzed

at 1 mg/ml.

*Based on the comparison between the area of

peaks of standards and samples

The determined percentages amount of gal-

lic and caffeic acid showed that the main phe-

nolic acids that was present in methanolic ex-

tract of Syzygium polyanthum leaves is caffeic

acid. Gallic acid was only present in the phenol-ic acids liberated from ester bonds (B) (Table

2). The presence of gallic acid and caffeic acid

were also confirmed via LC-MS analysis by

comparison of the free phenolic acid derivatives

with gallic and caffeic acid standards. The LC-

MS data obtained (Table 3) supported the find-

ings in HPLC analyses wherein the trace of

caffeic acid was detected in all the phenolic ac-

ids fractions (A, B and C) while gallic acid was

only present in bound phenolic acids (B). This

suggested that gallic acid and caffeic acid are

the major phenolic acids that were found inSyzygium polyanthum leaves. Previous studies

by Bin et al., (2005) on 26 common spices ex-

tracts from 12 botanical families on antioxidant

capacity analyses showed that the presence of

phenolic acids such as caffeic and gallic acid is

the main contributing factors to high antioxidant

capacity. Hence, gallic acid and caffeic acid

may also be the main phenolic acids that con-

tribute to the antioxidant property of themethanolic Syzygium polyanthum leaves extract.

Table 3: Phenolic acids identified via LC-MS

analysis based on their mass data

Standard Observedm/z,

[M-H]-

Calculated

m/z

Gallic acid 170.13

Caffeic acid 180.08

SampleFree phenolic acids (A)

Gallic acid Not detected -

Caffeic acid 179.15 180.08

Free phenolic acidsliberated from ester

bond (B)

Gallic acid 169.29 170.13Caffeic acid 179.34 180.08

Free phenolic acids

liberated fromglycosidic bond (C)

Gallic acid 169.27 170.13

Caffeic acid 179.14 180.08

The HPLC method with diode-array detec-

tion (DAD) of wavelength from 200 to 650 nm

was used to identify the flavonoids presence in

the methanolic extract of S. polyanthum. The

analysis was done by using similar HPLC con-

ditions as for total phenolics determination.

Quercetin, 3-O-glucoside-kaempferol, luteolin

and scutellarein were used as standard flavo-

noids. However, none of the compounds compa-

rable to the used standards was detected in themethanolic extract of Syzygium polyanthum

leaves.

Down colorimetric method

The flavonoids which are in class of phenol-

ic compounds which may be present in the

methanolic extract of Syzygium polyanthum

leaves could also contribute to the antioxidant

property. Hence, total flavonoid analysis by us-

ing Down colorimetric method was carried out

to determine the flavonoids content in the stud-

ied plant. This fast and simple assay is common-

ly used to estimate the total flavonoids content

in botanical samples such as fruits and plant ex-

tract (Chang et al. 2002). Quercetin was used as

the flavonoid standard which its linear calibra-

tion curve was plotted in the range of 10-60

mg/L with coefficient of determinant (r2) value

of 0.9539 as shown in Figure 8. The total flavo-

noids calculated in methanolic extract ofSyzygium polyanthum leaves is 14.87 mg


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quercetin equivalent (QE)/100 g dry leaves. The

small QE value obtained suggesting that the

percentage of flavonoids presence is minor.

However, there might be other flavonoids pre-

sent which were not used as standards as com-

parison to the methanolic extract of S.

polyanthum.

Figure 8: Calibration curve of quercetin.

Conclusion

Antioxidant analysis on the methanoliccrude extracts of Syzygium polyanthum leaves

showed a mild antioxidant activity with IC50value of 90.85 g/ml compared to the standard

quercetin. The antioxidant activity of the plant

led to the analyses of total phenolics and total

flavonoids which confirmed the presence of gal-

lic acid and caffeic acid in the methanolic ex-

tract of this plant leaves via HPLC and LC-MS

methods. The mild antioxidant property of

Syzygium polyanthum leaves could be due to

both of the detected phenolic acids, gallic andcaffeic acid.

Acknowledgement: The work was supported

by the Ministry of Science, Technology and In-

novation (MOSTI), Malaysia under the

ScienceFund (02-01-04-SF0900).

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