In this study, phenolic content, antioxidant activity and antibacterial
activity of various N. lappaceum peel and seed extracts
were determined. The extraction yields (g/100 g
lyophilized rambutan) from various extractants, i.e. ether,
methanol and water are presented in Table 1. The total phenolic
contents of the extracts were determined by FolineCiocalteu
method. The high amounts of phenolic compounds were
found in the peel extracts in the following order: methanolic
fraction (542.2 mg/g), aqueous fraction (393.2 mg/g) and ether
fraction (293.3 mg/g) (Table 1). Although low amounts of phenolic
compounds were observed in the seed extracts, the methanolic
fraction of seed extract contained the highest phenolic
content (58.5 mg/g).
The extracts obtained by various solvent extractions were
determined for their antioxidant activities. The extracts were
investigated for the reductive capabilities by using the potassium
ferricyanide reduction method. The reducing ability
may serve as a significant indicator of potential antioxidant activity
(Meir, Kanner, Akiri, & Hadas, 1995). The peel and seed
extracts increased in reducing powers with increasing concentration
(Fig. 1) and the peel extracts exhibited higher reducing
ability than the seed extracts. The methanolic extract showed
the highest activity, followed by the aqueous and ether
extracts. When compared to the BHT, the methanolic fraction
showed significantly (P < 0.05) higher activity at all concentrations.
Yen and Chen (1995) reported that the extract which