Purpose: To investigate the cytotoxic and antioxidant activities of the fruit and fruit waste (residue and
marc) extracts of
Antidesma thwaitesianum
Müll. 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 radicalscavenging
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.
