Cell death-inducing activities via Hsp inhibition of the sesquiterpenes isolated from Valeriana fauriei.

Three new sesquiterpenes, valerianaterpenes I-III, and eight known compounds have been isolated from the methanol extract of the rhizomes and roots of Valeriana fauriei. The chemical structures of the three new sesquiterpenes were elucidated based on chemical and spectroscopic evidence. The absolute stereochemistry of valerianaterpene I was determined using X-ray crystallography. The cell death-inducing activity of isolated compounds alone or combination with Adriamycin (ADR) was observed by time-lapse cell imaging. Although the isolated compounds did not affect the number of mitotic entry cells and dead cells alone, kessyl glycol, kessyl glycol diacetate, and iso-teucladiol significantly increased the number of dead cells on ADR treated human cervical cancer cells. One of the mechanisms of cell death-inducing activity for the kessyl glycol acetate was suggested to be the inhibition of heat-shock protein 105 (Hsp105) expression level. This paper first deals with the naturally occurring compounds as Hsp105 inhibitor.

Limonoids isolated from the Fortunella crassifolia and the Citrus junos with their cell death-inducing activity on Adriamycin-treated cancer cell.

From the fruits of Fortunella crassifolia and the peels of Citrus junos, two new limonoids, fortunellone and junosol were isolated together with three known compounds including nomilin. The chemical structures of the new compounds were elucidated based on chemical/physicochemical evidence. For fortunellone, the absolute configuration was established by comparison of experimental and predicted electronic circular dichroism (ECD) data. Fortunellon and nomilin significantly increased the number of dead cells on adriamycin (ADR)-treated human cervical cancer cells (HeLa). On the other hand, fortunellon and nomilin did not affects the number of dead cells alone. These results suggested that fortunellone and nomilin may have the potency as the chemotherapy enhancement agents.

Polymerization of Oxidized DJ-1 via Noncovalent and Covalent Binding: Significance of Disulfide Bond Formation.

The reactive cysteine residue at position 106 (Cys106) of DJ-1 is preferentially oxidized under oxidative stress, generating oxidized DJ-1 (oxDJ-1). Oxidation of Cys106 to sulfinic acid changes the biologic action of DJ-1 and increases its cytoprotective properties. The similar activation step is known in peroxiredoxins (Prxs), in which oxidation of reactive Cys to sulfinic acid induces polymerization of Prxs and changes its enzyme characteristic from peroxidase to molecular chaperone. In the present study, oxDJ-1 was prepared and its polymerization and related amino acid residues were investigated. We found that oxDJ-1 formed a characteristic polymer with disulfide bonds and with noncovalent and covalent binding other than disulfide. The physiological concentration of glutathione resolved the polymer form of oxDJ-1, and glutathionylation of other two Cys residues, such as Cys 46 and 53, was detected. Mutant analysis indicated the necessity not only of Cys106 but also of Cys46 for the polymer formation. The cellular experiment demonstrated that the electrophilic quinone treatment induced a high-molecular-weight complex containing oxDJ-1. Dynamic polymerization of oxDJ-1 with a ring and a stacked structure was observed by an atomic force microscope. Collectively, these results clearly demonstrated the characteristic polymer formation of oxDJ-1 with a disulfide bond and noncovalent and covalent binding other than disulfide, which might be related to the biologic function of oxDJ-1.

Oxidation and interaction of DJ-1 with 20S proteasome in the erythrocytes of early stage Parkinson's disease patients.

Parkinson's disease (PD) is a progressive, age-related, neurodegenerative disorder, and oxidative stress is an important mediator in its pathogenesis. DJ-1, the product of the causative gene of a familial form of PD, plays a significant role in anti-oxidative defence to protect cells from oxidative stress. DJ-1 undergoes preferential oxidation at the cysteine residue at position 106 (Cys-106) under oxidative stress. Here, using specific antibodies against Cys-106-oxidized DJ-1 (oxDJ-1), it was found that the levels of oxDJ-1 in the erythrocytes of unmedicated PD patients (n = 88) were higher than in those of medicated PD patients (n = 62) and healthy control subjects (n = 33). Elevated oxDJ-1 levels were also observed in a non-human primate PD model. Biochemical analysis of oxDJ-1 in erythrocyte lysates showed that oxDJ-1 formed dimer and polymer forms, and that the latter interacts with 20S proteasome. These results clearly indicate a biochemical alteration in the blood of PD patients, which could be utilized as an early diagnosis marker for PD.