In this study, we investigated the induction of apoptosis by ultrasound in the presence of the novel porphyrin derivative DCPH-P-Na(I). HL-60 cells were exposed to ultrasound for up to 3 min in the presence and absence of DCPH-P-Na(I), and the induction of apoptosis was examined by analyzing cell morphology, DNA fragmentation, and caspase-3 activity. Reactive oxygen species were measured by means of ESR and spin trapping technique. Cells treated with 8 μM DCPH-P-Na(I) and ultrasound clearly showed membrane blebbing and cell shrinkage, whereas significant morphologic changes were not observed in cells exposed to either ultrasound or DCPH-P-Na(I) alone. Also, DNA ladder formation and caspase-3 activation were observed in cells treated with both ultrasound and DCPH-P-Na(I) but not in cells treated with ultrasound or DCPH-P-Na(I) alone. In addition, the combination of DCPH-P-Na(I) and the same acoustical arrangement of ultrasound substantially enhanced nitroxide generation by the cells. Sonodynamically induced apoptosis, caspase-3 activation, and nitroxide generation were significantly suppressed by histidine. These results indicate that the combination of ultrasound and DCPH-P-Na(I) induced apoptosis in HL-60 cells. The significant reduction in sonodynamically induced apoptosis, nitroxide generation, and caspase-3 activation by histidine suggests active species such as singlet oxygen are important in the sonodynamic induction of apoptosis. These experimental results support the possibility of sonodynamic treatment for cancer using the induction of apoptosis.

Cyclooxygenase‐2 (COX‐2) plays an important role in carcinogenesis. Investigation of the suppressive action of twelve flavonoids of different chemical classes on the transcriptional activity of the COX‐2 gene in human colon cancer DLD‐1 cells using a reporter gene assay have revealed quercetin to be the most potent suppressor of COX‐2 transcription (IC50=10.5 μM), while catechin and epicatechin showed weak activity (IC50=415.3 μM). Flavonoids have three heterocyclic rings as a common structure. A structure‐activity study indicated that the number of hydroxyl groups on the B ring and an oxo group at the 4‐position of the C ring are important in the suppression of COX‐2 transcriptional activity. A low electron density of the oxygen atom in the hydroxyl group of the A ring was also important. Further examination of the role of the hydroxyl group in the A ring showed that bromination of resacetophenone to give 3,5‐dibromo‐2,4‐dihydroxyacetophenone resulted in a 6.8‐fold increase in potency for suppressing COX‐2 promoter activity. These results provide a basis for the design of improved suppressors of COX‐2 transcriptional activity.

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We previously reported the presence of cytotoxic substances in extracts of the Danaid butterfly, Ideopsis similis. In the present study, we isolated cytotoxic substances against a human gastric cancer cell line, TMK-1, in I. similis pupae, with an activity similar to that of the adult butterfly. The basic fraction, prepared from a methanol extract, accounted for 83% of the cytotoxic activity. Two major cytotoxic substances were purified by HPLC, and one was determined to be a new phenanthroindolizidine alkaloid, trans-(+)-3,14alpha-dihydroxy-6,7-dimethoxyphenanthroindolizidine (1), and the other a known compound, trans-(+)-3,14alpha-dihydroxy-4,6,7-trimethoxyphenanthroindolizidine (2). The IC(50) values for TMK-1 cells were 0.5 ng/mL and 0.7 ng/mL, respectively. These two compounds showed similar cytotoxic potential with four other cancer cell lines including cervical, lung, and colon carcinomas and leukemia. Quantitative analyses indicated the presence of each of the two phenanthroindolizidine alkaloids at levels of 11-74 microg in each larva, pupa, or adult of I. similis. However, 1 was not detected in the leaves of Tylophora tanakae, a host plant for larvae of I. similis, and the level of 2 (2 microg per gram of leaves) was far less than that in the larvae. Since the leaves of T. tanakae are known to contain various phenanthroindolizidines, compounds 1 and 2 are presumably metabolically converted from such alkaloids in larvae of I. similis.

Neutrophils have an important role in the self-defense systems of organisms through the production of superoxide. On the other hand, it has been proposed that abnormal amounts of superoxide produced by neutrophils are a serious factor in tissue injury. A series of novel thiazole derivatives was prepared and evaluated inhibitory effect on superoxide production by human neutrophils in vitro. Among these compounds, 6-[2-(3,4-diethoxyphenyl)thiazol-4-yl]-pyridine-2-carboxylic acid (OPC-6535) was selected as one of the most promising compounds. The synthesis and structure-activity relationships of these compounds are reported herein.