ANTI-OXIDANT ACTIVITY AND NON-GENOTOXIC PROPERTY OF EXTRACTS OF 'LONGKONG' LANSIUM DOMESTICUM FRUITS

Lansium domesticum (Meliaceae) is an economic plant grown in the Southern, Eastern and Northern parts of Thailand. Fruit of L. domesticum (LD) is very popular in Thailand and commonly called ‘Longkong’. The aim of this study was to investigate anti-oxidant activity and genotoxicity property of L. domesticum fruits, particularly the skins and seeds. The air-dried samples of skin (SK) and seed (SD) were extracted with 50 and 95% ethanol. The ethanolic extracts were partitioned between dichloromethane (DCM) and 50% aqueous ethanol. The aqueous phase was further extracted with ethyl acetate (EA) to yield a total of 12 fractions. Their anti-oxidant capacity was determined on superoxide anion (O₂^-∙) scavenging by photochemiluminescence (PCL) assay, of both lipid (ACL) and water (ACW) soluble substance systems. The deoxyribose assay was also performed to assess their hydroxyl radicals (OH-∙) scavenging activity. Our results suggested that skin of L. domesticum fruits possessed higher antioxidant potential than seeds, particularly when extracted with 50% ethanol and partitioned with ethyl acetate, which had high potential both hydrophilic and lipophilic antioxidant substances. The genotoxicity effect of ethanolic extract of L. domesticum was investigated in TK6 human lymphoblasts using cytokinesis-blocked micronucleus (CBMN) assay. Mitomycin C (MMC) served as a positive control and results were analyzed on micronucleus (MN) frequencies in binucleated cells (BNC). We found that there was no significant increase in MN frequencies in L. domesticum-treated cells whereas MMC-treated cells clearly exhibited a marked increase in MN frequency (40-72 MN/1000 BNC). It indicated that the ethanolic extracts of L. domesticum seeds were non- genotoxic to TK6 cells.