Introduction

Green tea contains catechins and caffeine as its ingredients. Four kinds of catechins including epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate are mainly contained in green tea, and it has been reported that body fat reducing effect can be seen by ingesting high concentration tea catechin group for a long period. Catechin, catechingallate, etc. are also a kind of catechins.

Catechin has antioxidant effect, and the effect of preventing oxidation of LDL cholesterol has been confirmed. Among these catechins, gallate type catechins act to suppress absorption by inhibiting the function of enzymes that digest fat and cholesterol.

In this article, catechins and caffeine in green tea were measured.

LC-4500 Compact HPLC system

Experimental

Column: Unifinepak C18 (4.6 mm I.D. x 150 mmL, 5 µm)
Eluent A: 0.2 % Phosphoric acid in water / acetonitrile (90/10)
Eluent B: 0.2 % Phosphoric acid in water / acetonitrile (50/50)
Gradient condition: (A/B), 0 min (100/0) → 5 min (100/0) → 30 min (70/30) → 30.1 min (0/100) → 35 min (0/100) → 35.1 min (100/0) (1 cycle: 50 min)
Flow rate: 1.0 mL/min
Column temp.: 30 ˚C
Wavelength: 280 nm
Injection volume: 10 µL
Standard Sample: Catechins and caffeine mixture (EGC, Cg: 20 µg/mL each,  Caf, C, EC, EGCg, ECg: 10 µg/mL each)

Structure

Keywords

Catechins, caffeine, green tea, Unifinepak C18, UV detector

Results

The chromatogram of catechins and caffeine is shown in Figure 1. Good separation of 6 kinds of catechins and caffeine has been obtained.

Figure 1. Chromatogram of standard catechins and caffeine standard sample (1: EGC, 2: Caf, 3: C, 4: EC, 5: EGCg, 6: ECg, 7: Cg)

Figure 2 shows the chromatogram of green tea.

Figure 2. Chromatogram of green tea (1: EGC, 2: Caf, 3: C,    4: EC, 5: EGCg, 6: ECg, 7: Cg)

Sample preparation: Dilute commercially available green tea in a plastic bottle by 10 times, then filtrate by 0.45 μm membrane filter