Phenolic compound and antioxidant activity of Indonesian ginger leaves (Zingiber officinale Roscoe var Roscoe)

Ageing causes an increase imbalance oxidant and antioxidant that induce degenerative diseases. Fruit, vegetable and
other plant are known have chemical compound as antioxidant such as phenolic. That’s why study of phenolic
compound and antioxidant activity in plant is very important. Information of phenolic compound and antioxidant
activity of ginger (Zingiber officinale Roscoe var Roscoe) in rhizomes numerous but less information in leaves. The aim
of these research to determine antioxidant activity and phenolic content of leaves and rhizome Indonesian Zingiber
officinale Roscoe var Roscoe. This research was conducted with descriptive quantitative research using dried ginger in
decoction and infusion extraction method. Phenolic compound was determination with Folin-Ciocalteu method and
DPPH method was used for antioxidant activity by using UV-VIS Spectrophotometer. Based on Mann Whitney U test
showed that phenolic compound in infusion leaves lower (4.47±0.47 mg GAE/g) than rhizomes (12.3±0.26 mg GAE/g)
at α 0.05 and antioxidant activity in infusion of rhizomes (50.21 ± 0.56 %) higher than in leaves (33.97±2.79 %). Based
on independent t-test total phenolic compound in decoction of rhizomes were higher (23.89±0.66 mg GAE/g) than in
leaves (18.23±0.57 mg GAE/g) and antioxidant activity in rhizomes (65.93±0.92 %) higher than in leaves (56.22±5.56
%). The conclusion of these research is total phenolic compound and antioxidant activity on leaves lower than in
rhizomes, but still more than 50% in infusion and decoction extraction method.