Cytotoxic and Antioxidant Activities of Antidesma thwaitesianum Mull Arg (Euphorbiaceae) Fruit and Fruit Waste Extracts

Purpose: To investigate the cytotoxic and antioxidant activities of the fruit and fruit waste (residue and marc) extracts of Antidesma thwaitesianum Mull. Arg., known as mamao in Thai, using chemical and cell-based assays. Methods: The cytotoxicity of mamao fruit and fruit waste extracts obtained by expression, maceration and decoction against a panel of six human cancer cell lines (COR-L23, A549, LS174T, PC-3, MCF7 and HeLa) was determined by sulforhodamine B (SRB) assay. In addition, their antioxidant activities were measured by chemical methods: 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay and ferric ion reducing antioxidant power (FRAP) assay and cell-based methods: nitroblue tetrazolium (NBT) dye reduction assay and nitric oxide ( NO) scavenging assay. The phenolic and flavonoid contents were assessed colorimetrically at 765 nm and 415 nm respectively. Results: Among the test extracts, the ethanol extracts of fresh fruits (FME) and marc left after squeezing fresh fruits (MME) exhibited moderate cytotoxicity against human breast MCF7 cells while the extract obtained by decocting the residue left after maceration of dried fruits (RDW) was moderately cytotoxic to lung large cell carcinoma COR-L23 cells. In the chemical assays, the extract obtained by decocting the residue left after maceration of dried marc (RMW) displayed the strongest ABTS radical-scavenging and ferric-reducing activities among the extracts. In the cell-based assays, however, FME and DME exerted potent nitric oxide scavenging activity whereas the extract obtained by decocting the residue left after maceration of fresh fruits (RFW) showed moderate superoxide radical-scavenging activity relative to the test extracts. The ABTS radical-scavenging and ferric-reducing activities of these extracts strongly correlate with their phenolic and flavonoid contents, indicating their specific contributions to such activities. Conclusion: The ethanol extracts of fresh and dried mamao fruits exhibit both cytotoxic and cellular antioxidant activities, and thus possess great potentials for application in the development of effective dietary supplements to prevent oxidative stress-induced diseases.