Effects of decoction and infusion on the antioxidant properties of herbal tea from dried pink guava leaves / Naimah Daraman Sah

Traditional herbal medicines form an important part of the healthcare system of Malaysia. Psidium guajava L, supposed to be the oldest medical system in the world, provides potential leads to find active and therapeutically useful compounds from plants. This study was conducted to investigate the effects of dried ground leaves of Psidium guajava L.(guava) extracted with water using different stepping methods (decoction and infusion) and different time intervals (10 minutes, 15 minutes and 20 minutes). Toxicity test using BSLA (Brine Shrimp Lethality Assay) method exhibited LC50 more than 500 ppm, which means that the leaves were safe for consumption. The total phenolic content in the extracts was determined spectrophotometrically according to Follin-Ciocalteu’s phenol method. The results indicated that the 10 minutes infusion possessed the highest total phenolic content 239.70 mg GAE/100 g of dried weight material. The antioxidant properties of freeze dried pink guava leaves extracts were determined by means of 2,2-diphenyl-1-picrylhydryzyl (DPPH) colorimetry and reducing ferric ion antioxidant potential (FRAP) assays. The activity was evaluated by the decrease in absorbance as the result of DPPH colour change from purple to yellow with detection wavelength at 517 nm. The higher the sample concentration used, the stronger was the free radical-scavenging effect. On the other hand, the ability of the extracts to reduce Fe (III) to Fe (II) and to bind to Fe (II) ion was determined by spectrophotometer with detection wavelength at 700 nm. The results obtained showed that the decoction method was higher in the antioxidant activities compared to infusion method. This study revealed that the decoction method of guava leaf tea comprise effective potential source of natural antioxidant and this very important for the human health.