J. Agric. Food Chem.

2003, 51, 975980

975

Determination of Tea Polyphenols and Caffeine in Tea Flowers

(Camellia sinensis) and Their Hydroxyl Radical Scavenging and
Nitric Oxide Suppressing Effects
YUNG-SHENG LIN, SANG-SHUNG WU,

AND JEN-KUN

LIN*,

Institute of Biochemistry, College of Medicine, National Taiwan University,

No. 1, Section 1, Jen-ai Road, Taipei, Taiwan, and Taitung Substation,
Taiwan Tea Experiment Station, Taitung, Taiwan

The native occurrence of tea polyphenols, namely, (-)-epicatechin, (+)-catechin, (-)-epigallocatechin

3-gallate, (-)-epicatechin, and (-)-epicatechin 3-gallate, and caffeine in tea flowers was assessed
by an isocratic HPLC procedure. The levels of total catechins and caffeine were determined in tea
flowers collected from 10 different species of Camellia sinensis. The results showed the levels of
total catechin ranged from 10 to 38 mg/g, whereas the level of caffeine ranged from 3 to 8 mg/g.
Levels of catechins and caffeine in tea leaves and various teas were also determined and ranged
from 2 to 126 mg/g and from 23 to 49 mg/g, respectively. Both tea flower and tea leaf extracts exert
their strong hydroxyl radical scavenging effects in the Fenton reaction system and nitric oxide
suppressing effects in LPS-induced RAW 264.7 cells. Most tea flowers contain less caffeine, but
comparable amounts of total catechins, compared to tea leaves and teas. The present study
demonstrates that both tea flowers and tea leaves contain appreciable amounts of catechins and
caffeine. It is likely that tea flowers might be useful for making alternative tea beverages.
KEYWORDS: Tea flowers; tea leaves; catechins; tea polyphenols; caffeine; hydroxyl radical scavenging;
nitric oxide suppression

INTRODUCTION

Tea is one of the most widely consumed beverages in the

world. During the past decade numerous in vitro and in vivo
studies have suggested the possible protective effects of tea and
tea polyphenols in cancer and neurodegenerative and cardiovascular disease development (1-3). The molecular mechanisms
of cancer chemoprevention by tea and tea polyphenols in
animals and man have been intensively investigated (2, 4-11).
It has been demonstrated that the extracellular signals for cell
proliferation have been suppressed by tea polyphenols through
down-regulation of EGF-receptor signaling (2, 4, 5). The
prooxidant enzymes nitric oxide synthase and xanthine oxidase
have been shown to be strongly inhibited by tea polyphenols
(6-8). Suppression of lipopolysaccharide-induced NFB activity
by tea polyphenols through down-regulation of IKK activity in
macrophages has been demonstrated (9). Furthermore, induction
of apoptosis by oolong tea polyphenol theasinensin A through
cytochrome c release and activation of caspases-9 and -3 in
human U-937 cells has been observed (10). It is proposed that
cancer chemoprevention by tea polyphenols may occur through
modulation of signal transduction pathways (2, 3, 11).
* Corresponding author [telephone (886)-2-2356-2213; fax (886)-2-23918944; e-mail jklin@ha.mc.ntu.edu.tw].
National Taiwan University.
Taiwan Tea Experiment Station.

Although dried tea has been exported from China for at least
five centuries, it was not until the early 19th century that its
cultivation spread to other parts of Asia. An apparently wild
tea with larger leaves was discovered in Assam, and eventually
all Indian plantations were planted with this Assam tea
(Camellia sinensis var. assamica). It is now thought that the
species originated somewhere in southern China. It is also
possible that Assam tea is of hybrid origin, with Camellia
irrawadiensis one possible parent.
There are several kinds of flower teas in the commercial
markets, namely, jasmine, cinnamon, rose, lotus, and daisy
(chrysanthemum) flower teas. Jasmine flower tea (a green tea)
is a very popular tea and widely consumed in China, especially
in northern China. The aroma and fragrance of jasmine flower
are mild and lasting. The flowered teas are made from tea leaves
(Camellia sinensis) processed with different species of flowers.
However, a commercial drinking beverage from tea leaves with
tea flowers has never been made. It is important to determine
whether tea flowers are suitable for making a consumable
beverage. To answer this question, we have collected tea flowers
from tea plants and prepared their extracts with hot water. The
flavor of the extracts is similar to that of daisy flower tea, and
a pleasant bitter taste is persistent in the mouth after drinking.
We have performed a series of experiments to analyze the
chemical composition of tea flowers. We now report the highperformance liquid chromatographic (HPLC) determination of

10.1021/jf020870v CCC: $25.00 2003 American Chemical Society

Published on Web 01/10/2003

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Lin et al.

Figure 1. Chemical structures of tea catechins.

tea polyphenols and caffeine in tea flowers as well as the

hydroxyl radical scavenging and nitric oxide suppressing effects
of the tea flower extracts.
Numerous HPLC methods for the determination of tea
polyphenols and methylxanthines have been published (1214). In most studies the tea polyphenols and tea methylxanthines
are determined separately by HPLC (14) or other nonchromatographic methods. Because both tea polyphenols (catechins) and
tea methylxanthines (caffeine, theophylline, and theobromine)
have been demonstrated to exert their significant healthy effects
in humans, we have developed a reliable and rapid HPLC
method for the simultaneous determination of the levels of these
two constituents in a given tea sample (12, 13). In this study,
we have adapted these procedures with slight modifications and
developed a simple and precise isocratic HPLC method for the
determination of tea polyphenols and caffeine in various tea
samples.
MATERIALS AND METHODS
Chemicals and Reagents. (-)-Epigallocatechin 3-gallate (EGCG),
(-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC),
(-)-epicatechin 3-gallate (ECG), (-)-gallocatechin 3-gallate (GCG)
(chemical structures of these tea catechins are depicted in Figure 1),
caffeine, lipopolysaccharide (LPS, Escherichia coli 0127:E8), sulfanilamide, dithiothreitol, and naphthylethylenediamine dihydrochloride
were purchased from Sigma Chemical Co. (St. Louis, MO). Agarose,
ethidium bromide, dimethyl sulfoxide (DMSO), hydrogen peroxide,
and ferrous sulfate were purchased from E. Merck Co. (Darmstadt,
Germany). The plasmid pcDNA 3, 1-E expression vector was purchased
from the Invitrogen Life Technologies, Carlsbad, CA.
Collection of Tea Flowers. Fresh tea flowers from 10 species were
plucked from the Taitung Tea Experiment Substation (Taitung, Taiwan).
The collected tea flowers were dried at 70 C overnight in an electric
oven with a rotating fan to keep the heat evenly distributed. The weight
of the tea flowers was checked from time to time until a constant weight
was reached.
In this study, 10 species of tea flowers were analyzed by HPLC for
their tea polyphenols and caffeine. Three species, namely, Wuu-Yi,
Huang-Gan, and Dayeh-Oolong, are local varieties, whereas another
seven species, TTES 1-6 and 12, are hybrid varieties established by
the Taiwan Tea Experiment Station (TTES) (15).
Preparation of Extracts from Tea Leaves and Tea Flowers. Each
of the dry tea leaves or tea flowers (1 g) was steeped in boiling distilled

water (100 mL) for 30 min or in 75% ethanol (100 mL) at 60 C for
30 min. The infusion was filtered with a 0.45 m PVDF filter disk
(Millipore, Bedford, MA). The filtrate was analyzed with the HPLC
system as described below.
The filtrate was dried under reduced pressure by rotavapor to give
a powdered crude extract and kept in a refrigerator at -20 C until
use. In most experiments, the crude extract was dissolved in DMSO
(50 mg/mL) and diluted to desired concentrations.
Reverse-Phase HPLC Analysis of Tea Polyphenols and Caffeine.
The compositions of tea polyphenols (catechins) and caffeine in
different samples (from tea flowers or tea leaves) were determined by
HPLC analysis using a Waters 600E system controller. The HPLC
method used a 250 4.6 mm i.d., 5 m Cosmosil 5C18-MS packed
column (Nacalei Tesque, Inc., Kyoto, Japan). The tea or tea flower
extract was filtered through a 0.45 m filter disk and then was injected
onto the column. The concentrations of caffeine and tea polyphenol
working solutions were 100 g/mL. Five hundred nanograms of each
authentic standard compound [caffeine, (-)-epigallocatechin 3-gallate,
(-)-epigallocatechin, catechin, (-)-epicatechin, (-)-epicatechin 3-gallate, and (-)-gallocatechin 3-gallate] was injected. The mobile phase
was methanol/doubly distilled water/formic acid (19.5:82.5:0.3, v/v/v)
degassed by sonication (Branson 5200), with isocratic elution at a flow
rate of 1.0 mL/min. A Waters 484 tunable absorbance detector was
used to detect tea constituents at 280 nm, and all peaks were plotted
and integrated by a Waters 745 data module. Identification of caffeine
or individual tea polyphenols was based on the comparison of the
retention times of unknown peaks to those of authentic reference
standards. The amount of each constituent in the tea leaf or tea flower
extract was estimated by the integrated datum provided by the Waters
data module.
Protection of Supercoiled DNA from Strand Breakage by Fenton
Reaction. pcDNA-3 superhelix form plasmid DNA (200 ng) was
incubated with 0.35% H2O2 and 50 M ferrous sulfate in the presence
or absence various concentrations of crude extract of tea or tea flower
at 37 C for 30 min. DNA relaxation to an open circular form was
induced by the hydroxyl radicals generated by the Fenton reaction (H2O2
and Fe2+). DNA was separated on 1% agarose gel and stained with
ethidium bromide (16). The percentage of supercoiled forms of DNA
among total DNA was calculated using a densitometer (IS-100 Digital
Imaging System) and expressed as the ratio of supercoiled forms
plasmid DNA to total plasmid DNA.
Cell Culture. RAW 264.7 cells, which were derived from murine
macrophages, were obtained from the American Type Culture Collection (ATCC) (Rockville, MD). RAW 264.7 cells were cultured in
DMED (without phenol red) supplemented with 10% endotoxin-free,

Tea Polyphenols and Caffeine in Tea Flowers

J. Agric. Food Chem., Vol. 51, No. 4, 2003

977

Table 1. Polyphenol Composition of Various Fresh Tea Flowers in Water or 75% Ethanol Extracta
mg/g of flower
caffeine

TTES 1
TTES 2
TTES 3
TTES 4
TTES 5
TTES 6
TTES 12
Wuu-Yi
Huang-Gan
Da-Yeh
oolong

EGCG

EGC

water

ethanol

water

ethanol

water

ethanol

water

3.48 0.14
5.71 0.57
4.33 0.35
5.20 0.23
6.16 0.20
6.35 0.28
5.56 0.35
5.85 0.45
5.12 0.16
5.50 0.13

7.04 0.24
8.32 0.27
6.73 0.35
6.31 0.12
7.35 0.12
6.75 0.20
7.11 0.15
6.83 0.24
6.95 0.36
6.82 0.39

3.89 0.43
6.73 0.23
5.51 0.43
5.93 0.18
6.45 0.14
6.83 0.76
4.77 0.43
7.08 0.46
5.20 0.34
7.42 0.18

10.08 0.58
9.41 1.20
7.29 0.96
6.50 0.85
5.61 0.47
5.23 0.61
6.95 1.45
7.01 1.02
7.40 1.56
7.73 0.24

2.54 0.44
9.82 3.16
12.98 3.95
8.40 2.24
12.41 0.80
16.53 4.86
8.34 3.35
9.78 6.21
12.48 2.01
16.22 3.61

11.93 1.28
19.57 3.01
16.60 12.9
10.50 1.71
7.61 1.42
9.11 3.34
12.47 0.87
17.01 2.64
13.70 4.96
12.65 6.21

0.47 0.08
1.15 0.29
0.12 0.01
0.63 0.18
3.13 0.45
1.08 0.20
0.55 0.19
1.12 0.17
1.66 0.46
1.38 0.43

EC
ethanol

NDb

0.95 0.06
ND
ND
0.30 0.03
0.28 0.09
2.03 0.36
0.64 0.21
1.30 0.63
0.60 0.41

ECG

total catechins

water

ethanol

water

ethanol

1.00 0.06
2.98 0.09
0.70 0.01
1.46 0.13
4.06 0.07
3.22 0.16
1.22 0.04
2.21 0.21
2.41 0.07
3.28 0.16

1.22 0.15
2.00 0.42
0.38 0.02
0.68 0.05
2.42 0.18
1.83 0.52
0.99 0.38
1.58 0.10
2.00 0.33
2.09 0.21

2.96 0.30
5.08 0.54
3.30 0.39
3.64 0.19
5.38 0.26
5.27 0.20
3.86 0.32
7.11 0.78
4.55 0.15
5.67 0.21

5.68 0.67
6.26 0.66
4.00 0.40
3.94 0.08
4.50 0.08
4.24 0.34
4.06 0.33
6.61 0.41
4.65 0.18
5.04 0.49

water ethanol
10.87
25.76
22.62
20.06
31.43
32.93
18.74
27.29
26.30
33.98

28.91
38.19
28.27
21.62
20.45
20.69
26.49
32.86
29.04
28.12

a Each of the tea leaves (1 g) was extracted by 100 mL of boiling water or 75% ethanol at 60 C for 30 min. Each value represents the mean SE of five individual
determinations. b ND, not detectable.

heat-inactivated fetal calf serum (GIBCO, Grand Island, NY). When

the cells reached a density of (2-3) 106 cells/mL, they were activated
by incubation in medium containing E. coli 0127:E8 LPS (50 ngmL).
Various test crude extracts dissolved in DMSO were added together
with lipopolysaccharide at a final concentration of 50 g/mL or
indicated concentration.
HL-60 (human promyelocytic leukemia) cells obtained from ATCC
were grown in 90% RPMI 1640 and 10% fetal bovine serum (Gibco,
BRL) supplemented with 2 mM glutamine. The medium was normally
changed to phenol red-free RPMI 1640 before tea or tea flower crude
extract treatment.
Nitrite Determination. The nitrite concentration in the cultured
RAW264.7 cells medium was measured as an indicator of NO
production, according to the Griess reaction (17). One hundred
microliters of each supernatant was mixed with the same volume of
Griess reagent (1% sulfanilamide in 5% phosphoric acid and 0.1%
naphthylethylenediamine dihydrochloride in water). Absorbance of the
mixture at 550 nm was determined with a Dynatech MR-7000 enzymelinked immunosorbant assay plate reader (Dynatech Labs, Chantilly,
VA).
RESULTS

HPLC Analysis of Authentic Standard Tea Polyphenols

and Caffeine. A mixture of authentic standard tea catechins
including (-)-epigallocatechin, catechin, (-)-epigallocatechin
3-gallate, (-)-epicatechin, (-)-gallocatechin 3-gallate, and (-)epicatechin 3-gallate as well as caffeine was analyzed by
isocratic HPLC. The structures of six catechins are shown in
Figure 1. The amount of each tea constituent was 0.5 g except
that of (-)-epigallocatechin (2 g). A representative HPLC
chromatogram is illustrated in Figure 2A. Complete baseline
separation of these catechins and caffeine was achieved by this
HPLC procedure in 80 min. It has been demonstrated that (-)gallocatechin 3-gallate is an artifact produced during the
chemical handling of the catechin mixture. Therefore, (-)gallocatechin 3-gallate is absent from most freshly and naturally
extracted tea samples.
HPLC Analysis of Tea Polyphenols and Caffeine in Tea
Flowers. The levels of tea polyphenols and caffeine in tea
flowers were analyzed from 10 different tea varieties, and the
data are summarized in Table 1.The chemical compositions of
tea polyphenols and caffeine in tea flowers were analyzed by
the HPLC procedure described. The tea flowers (1 g) were
extracted by boiling water (100 mL) or 75% ethanol (100 mL)
at 60 C for 30 min. The HPLC chromatograms for these two
extracts are very similar, as illustrated in parts B and C,
respectively, of Figure 2. Furthermore, the HPLC chromatogram

Figure 2. Isocratic HPLC separation of tea catechins and caffeine: (A)

mixture of authentic standard compounds, 2 g of EGC, and 0.5 g each

of other compounds; (B) water extract of tea flower (Wuu-Yi species);
(C) 75% ethanol extract of tea flower (Wuu-Yi species). Abbreviations of
tea catechins are given under Materials and Methods.

of tea flower extract is very similar to that of tea leaf extracts

(data not shown). Qualitatively, the compositions of tea
polyphenols and caffeine in tea flowers are similar to that of
tea leaves, but quantitatively, tea flowers contain far less caffeine
and (-)-epigallocatechin 3-gallate and more (-)-epicatechin
3-gallate in some cases (Tables 1 and 2).
Levels of Tea Polyphenols and Caffeine in Tea Flowers.
For comparison purposes, the levels of tea polyphenols and
caffeine in nine kinds of tea leaves were also analyzed and are
summarized in Table 2. Among the tea flower extracts, the
water extracts gave lower levels of caffeine and (-)-epigallocatechin 3-gallate as compared with 75% ethanol extracts (Table
1). Levels of (-)-epigallocatechin, catechin, (-)-epicatechin,

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Table 2. Polyphenol Composition in 75% Ethanol Extract of Various Tea Leaves

mg/g of tea

caffeine

EGCG

EGC

EC

ECG

total catecins

fresh tea leaves

TTES 8
TTES 12
wild type
av

26.81 2.04
23.40 1.21
41.36 0.56
30.52

21.19 2.42
4.33 0.48
14.20 3.41
13.24

36.21 10.4
17.58 4.17
NDb
17.93

0.72 0.18
1.77 0.41
ND
0.83

1.11 0.22
0.29 0.09
0.27 0.09
0.56

5.36 0.61
1.51 0.17
5.54 0.43
4.14

64.59
25.48
20.01
36.72

green tea

TTES 12
wild type
av

26.74 1.70
47.50 1.45
37.12

30.12 5.36
59.03 5.00
44.58

83.19 15.1
44.13 10.8
63.66

1.51 0.27
0.87 0.28
1.19

4.21 0.84
4.72 0.77
4.47

4.46 0.62
20.00 2.61
12.23

123.49
128.75
126.13

oolong tea

TTES 12
wild type
av

35.26 0.86
49.14 1.20
42.2

27.75 2.35
65.15 4.45
46.45

39.87 6.89
31.20 7.70
35.54

0.68 0.10
0.55 0.14
0.62

3.64 0.25
4.23 0.45
3.94

5.94 0.62
19.30 1.53
12.62

77.88
120.43
99.16

black tea

TTES 8
wild type
av

42.74 0.55
49.79 4.11
46.27

5.01 0.67
1.31 1.24
3.16

0.41 0.00
ND
0.21

0.64 0.04
0.16 0.08
0.40

3.02 0.21
1.51 0.37
2.27

9.08
2.98
6.03

ND
ND
ND

a Each of the tea leaves (1 g) was extracted by 100 mL of 75% ethanol at 60 C for 30 min. Each value represents the mean SE of five individual determinations.
ND, not detectable.

and (-)-epicatechin 3-gallate in tea flowers were quite comparable in both extracts.
The total tea polyphenols (catechins) in tea flowers varied
greatly from species to species. The total catechins in tea flower
water extracts were found to range from 33 mg/g in TTES 6 to
11 mg/g in TTES 1. Meanwhile, the total catechins in tea flower
75% ethanol extracts were found to range from 39 mg/g in TTES
2 to 21 mg/g in TTES 5 (Table 1). The total catechins in fresh
tea leaves and different manufactured teas (green, oolong, and
black teas) as estimated from their 75% ethanol extracts are
shown in Table 2. Three tea varieties, namely, TTES 8 (large
leaves), TTES 12 (small leaves), and a wild local species (large
leaves), were used as fresh starting tea leaves for making green,
oolong, and black teas. It appeared that green tea provided more
total catechins in TTES 12 (123 mg/g) or wild species (129
mg/g). Oolong tea also provided high levels of total catechins
in TTES 12 or wild species (120 mg/g), whereas black tea
contained very low levels of total catechins in TTES 8 (9
mg/g) or wild species (2 mg/g). It is interesting to note that
the freshly plucked tea leaves contained a moderate amount of
total catechins in TTES 12 (25 mg/g) or wild species (20 mg/
g). The levels of total catechins in freshly plucked tea flowers
(11-39 mg/g; as indicated in Table 1) are comparable with
that in freshly plucked tea leaves (20-25 mg/g) as indicated in
Table 2.
Hydroxyl Radical Scavenging Effects of Tea Flowers. The
antioxidant effects of tea flower extracts were evaluated by the
Fenton reaction system. The hydroxyl radical-induced DNA
damage was significantly inhibited by the presence of tea flower
extracts as shown in Figure 3A,B. Treatment of pcDNA-3
plasmid with Fenton reagent (hydrogen peroxide and ferrous
sulfate) relaxed the supercoiled form DNA concentration- and
time-dependently (data not shown). However, on cotreatment
of plasmid DNA and tea flower extracts, the latter provided a
protective effect on the damage of plasmid DNA in a concentration-dependent manner (Figure 3A). The arbitrary values
coming from the densitometric analysis represent the ratio of
supercoiled forms of plasmid DNA to relaxed forms plasmid
DNA, and the relative level was calculated as the ratio of
supercoiled/relaxed observed relative to the control group
(Figure 3B). The potency of the hydroxyl radical scavenging
effect of tea flower extract is stronger than that of vitamin E
and 75% ethanol extract of fresh tea leaf extract. It appeared

that the potency of tea flower extracts is lower than that of water
extracts of fresh tea leaves (Figure 3B).
Suppressing Effects of Tea Flowers on the LPS-Induced
NO Production in Macrophages. Treatment of RAW 264.7
cells with LPS for 16 h produced nitric oxide (NO) in the culture
medium (Table 3). The production of NO in this cell culture
was strongly inhibited by the presence of green, oolong, black,
pu-erh, and fresh tea leaf extracts. It seemed that more inhibitory
substances were found to be present in the 75% ethanol extracts
(Table 3). It has been demonstrated that (-)-epigallocatechin
3-gallate in green tea and theaflavins in black tea suppress the
NO production in the LPS-activated macrophages (8-10). An
appreciable amount of this NO inhibitory substance was
alsofound in the tea flower extracts. The chemical properties
of this inhibitory substance in tea flowers are worthy of further
investigation.
Induction of Apoptosis by Tea Extracts but Not by Tea
Flower Extracts. In a preliminary experiment, the induction
of apoptosis in HL-60 cells by tea and tea flower extracts was
performed. The results indicated that both oolong and green
tea extracts induced strong apoptosis in HL-60 cells, whereas
black tea extracts induced moderate apoptosis at the same
concentration. Pu-erh tea extract was inactive in this experiment.
Old fresh tea leaf extracts showed strong apoptotic induction
in HL-60 cells, whereas no apoptotic effect was observed in
young tea leaf extracts. It is also noteworthy that the tea flower
extracts (either from water extraction or from 75% ethanol
extraction) showed no apoptotic effects in HL-60 cells under
the same experimental conditions.
DISCUSSION

The isocratic HPLC system successfully separated the five

tea catechins in the tea flower extracts (Figure 2). Some
flavonoids, such as quercetin, quercetin glycosides, rutin,
apigenin, genistein, genistin, hesperetin, hesperidin, myricetin,
kaempferol, and others, could not be resolved by this system.
Another gradient elution HPLC system has been developed for
these flavonoids. Further studies on the flavonoid composition
of tea flowers are now in progress in our laboratory.
Both green and oolong teas were manufactured from freshly
plucked tea leaves. The total catechin contents of green and
oolong teas were higher than that of fresh tea leaves as indicated
in Table 2. It appears that the catechin biosynthesis has

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979

Figure 3. Hydroxyl radical scavenging effects of tea flowers and tea leaves: (A) protection of plasmid DNA damage by different tea and tea flower

extracts (50 and 100 g/mL, respectively); (B) relative level calculated as the ratio of supercoiled to relaxed forms coming from densitometric analysis.
The ratio of supercoiled/relaxed observed in the control group is set at 1.00. Abbreviations: C, blank control system; Fenton, Fenton reaction mixture
containing plasmid DNA as positive control; Vit E, vitamin E; FW, tea flower, water extract; FE, tea flower, 75% ethanol extract; OW, old tea leaves,
water extract; OE, old tea leaves, 75% ethanol extract; YW, young tea leaves, water extract; YE, young tea leaves, 75% ethanol extract.
Table 3. Effects of Tea and Tea Flower Extracts on Suppression of

Nitric Oxide Production in the Culture Medium of LPS-Stimulated

Macrophage RAW 264.7 Cells
treatment

nitric oxide (nM)

control
LPS
LPS + black tea (W)
LPS + black tea (E)
LPS + oolong tea (W)
LPS + oolong tea (E)
LPS + pu-erh tea (W)
LPS + pu-erh tea (E)
LPS + green tea (W)
LPS + green tea (E)
LPS + tea flower (W)
LPS + tea flower (E)
LPS + old fresh tea leaves
LPS + old fresh tea leaves (E)
LPS + young fresh tea leaves (W)
LPS + young fresh tea leaves (E)

0
43
2
0
30
4
1
0
17
0
27
8
3
0
27
0

a The content of nitric oxide was determined as described under Materials and
Methods. Abbreviations: W, water extract; E, 75% ethanol extract. Fresh tea leaves
are tea leaves plucked freshly from the tea plants and dried immediately.

continued during the manufacturing processes, increasing the

amounts of total catechins. Another explanation is that the
mechanical operation in the withering process may rupture the
outer membrane of the tea leaves, liberating the intracellular
catechins and rendering them available for extraction.
Two solvent systems, namely, boiling water and 75% ethanol
at 60 C, were used to extract the total catechins and caffeine
from the tea flowers. The results indicated that more catechins
and caffeine were extracted by the 75% ethanol system.
The occurrence of tea polyphenols [five catechins, namely,
(-)-epigallocatechin, catechin, (-)-epigallocatechin 3-gallate,
(-)-epicatechin, and (-)-epicatechin 3-gallate] and caffeine in

tea flowers (10 species of C. sinensis) has been demonstrated

by an HPLC procedure (Table 1). The levels of tea catechins
and caffeine in most tea flowers are lower or sometimes
comparable with that of tea leaves. To our knowledge, this may
be the first description of the occurrence and levels of tea
catechins and caffeine in tea flowers (Table 1).
In the process of tea cultivation, the growth and proliferation
of tea leaves are the most important, because the harvested tea
leaves are used for manufacturing different kinds of teas. It has
been demonstrated in some tea plants such as Chinsin Oolong
and TTES 12 that blossoming of tea flowers may hamper the
growth and proliferation of tea leaves; on the other hand, in
some tea plants such as TTES 8 and wild species, the
blossoming of tea flowers does not affect the growth and
proliferation of tea leaves (18). Some chemicals, such as
ethephon and NAA, have been employed to inhibit the blossoming of tea flower to promote the production of tea leaves
(18).
In the present study, tea flowers were found to contain tea
catechins and caffeine in quantities approaching those of tea
leaves. From an economic point of view, both tea flowers and
tea leaves should be treated equally. We propose that more
scientific and field work should be done on the promotion of
tea flowers as beneficial to health and well-accepted agricultural
products.
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Received for review August 8, 2002. Revised manuscript received
November 18, 2002. Accepted November 21, 2002. This study was
supported by the National Science Council (NSC 90-2320-B-002-163
and NSC 90-2320-B-002-164), by the National Health Research Institute
(NHRI-EX91-8913BL), and by the Ministry of Education (ME
89-B-FA01-1-4).

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