Radical scavenging activity and apoptotic effects in HT-29 human colon cancer cells of black sesame seed extract

Functionality of black sesame seed methanol extracts (BSME) including radical scavenging activity and apoptotic effects on human colon cancer cell lines were measured. Radical scavenging activities of BSME was determined by 2,2′-diphenyl-1-pycryl-hydrazil (DPPH) and 2,2′-azino-bis [3-ethylbenzthiazoline-6-sulphonic acid (ABTS)]methods. Total phenolic contents (TPC) were also measured. Cell toxicity effects of BSME on human colon cancer cell HT-29 were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and apoptotic effects were tested by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL) assay and reverse transcription-polymerase chain reaction (RT-PCR) expressions of BCL-2 and BAX. TPC of BSME was 4.80 ± 0.21 μm tannic acid equivalent mg^-1 BSME. DPPH and ABTS radical scavenging abilities by BSME in EC₅₀ were 27.10 and 6.12 mg mL^-1 BSME, respectively. Concentration from 6.7 to 10.0 mg mL^-1 BSME exhibited proper cell toxicity based on the results of MTT assay and was enough to increase the apoptosis of colon cancer cells with typical apoptotic characteristics from TUNEL assay. In RT-PCR, 6.7-10.0 mg mL^-1 BSME reduced the expression of BCL-2 and increased the expression of BAX, compared with untreated controls. BSME possessing phenolic compounds with radical scavenging ability may be related with inducing colon cancer cell death.