Abstract
Dimocarpus longan var. obtusus, commonly called Lumyai Thao (LT) is a scandent shrub
belonging to Sapindaceae family. LT is the local longan cultivar planted in Chonburi province
and found only in Thailand. LT seeds have been used as traditional medicines among local
Thai people to relieve swelling. However, there is still little information of their biological
activities including anti-inflammation and antioxidant activities. The objective of this study
was to investigate in vitro anti-inflammatory, antioxidant and cancer preventive effects of
crude extract of LT seeds. Dried LT seeds were sequentially extracted with ethyl acetate,
ethanol, and water. The extracts were then evaluated for their anti-inflammation using
nitric oxide (NO) inhibitory effect in lipopolysaccharide (LPS)-activated RAW 264.7 cells.
The results showed the IC50 of ethyl acetate, ethanol, and water extracts of LT seeds were
957.8±49.9, 638.2±15.7 and 465.9±15.7 µg/ml, respectively in a dose dependent manner
and no cell toxicity was detected. The crude extracts of LT seeds were analyzed for their
antioxidant activities using DPPH and FRAP assays. LT water extract showed the highest
potency of antioxidant activity. Furthermore, LT water extract exhibited the induction of
quinone reductase (QR) in cultured Hepa1c1c-7 (mouse hepatoma) cells with CD value of
389.8±64.5 µg/ml. HPLC analysis tentatively identified gallic acid as a major constituent of LT
extract. This finding may provide the basis for the purported anti-inflammatory, antioxidant
and anti-cancer effects of LT seed.
