In vitro anti-cancer activities of Job’s tears (Coix lachryma-jobi Linn.) extracts on human colon adenocarcinoma

The whole seed (W), endosperm (E) and hull (H) of five cultivars of Job’s tears (Coix lachryma-jobi Linn. var. ma-yuen Stapf) including Thai Black Phayao, Thai Black Loei, Laos Black Loei, Laos White Loei and Laos Black Luang Phra Bang were processed before solvent extraction by non-cooking, roasting, boiling and steaming Each part of the Job’s tears was extracted by the cold and hot process by refluxing with methanol and hexane. The total of 330 extracts included 150 methanol extracts and 180 hexane extracts were investigated for anti-proliferative activity on human colon adenocarcinoma cell line (HT-29) by the sulforhodamine B (SRB) assay. The extracts which gave high anti-proliferative activity were tested for apoptotic activity by acridine orange and ethidium bromide double staining and anti-oxidative activities including free radical scavenging and lipid peroxidation inhibition activities. The extract from the hull of Thai Black Loei roasted before extracting by hot methanol (M-HTBL-R2) showed the highest anti-proliferative activity on HT-29 with the IC₅₀ values of 11.61 ± 0.95 μg/ml, while the extract from the non-cooked hull of Thai Black Loei by cold methanol extraction (M-HTBL-N1) gave the highest apoptosis (8.17 ± 1.18%) with no necrosis. In addition, M-HTBL-R2 and M-HTBL-N1 indicated free radical scavenging activity at the SC₅₀ values of 0.48 ± 0.12 and 2.47 ± 1.15 mg/ml, respectively. This study has demonstrated the anti-colorectal cancer potential of the M-HTBL-R2 and M-HTBL-N1 extracts.