Comparison on the Antioxidant Activities of Extracts from Six Tropical Fruit Tree Leaves

Phenolic acids concentrations, total phenolic and flavonoid contents and antioxidant activities in extracts from Naseberry, Jackfruit, Longan, Litchi, Carambola and Loquat leaves were determined. The total phenolic contents varied from 4.43% in Litchi to 11.97% in Naseberrys. The Four major phenolics, rutin, ellagic acid, chlorogenic acid and salicylic acid were by HPLC (high performance liquid chromatography) analysis. Rutin was the most abundant phenolic in Jackfruit (up to 445.45 ug/g DW) and Litchi (up to 304.44 ug/g DW), whereas ellagic acid was the dominant phenolic in Naseberry (about 363 ug/g DW). The methanol extracts of these fruit leaves had strong free radical scavenging capability, metal chealting capacity and reducing power. In general, the six leaves are good sources of natural antioxidants and could be used as natural antioxidant ingredients.