Hexaploid wheat (Triticum aestivum) accumulates benzoxazinones (Bxs) as defensive compounds. Previously, we found that five Bx biosynthetic genes, TaBx1-TaBx5, are located on each of the three genomes (A, B, and D) of hexaploid wheat. In this study, we isolated three homoeologous cDNAs of each TaBx gene to estimate the contribution of individual homoeologous TaBx genes to the biosynthesis of Bxs in hexaploid wheat. We analyzed their transcript levels by homoeolog-or genome-specific quantitative RT-PCR and the catalytic properties of their translation products by kinetic analyses using recombinant TaBX enzymes. The three homoeologs were transcribed differentially, and the ratio of the individual homoeologous transcripts to total homoeologous transcripts also varied with the tissue, i.e., shoots or roots, as well as with the developmental stage. Moreover, the translation products of the three homoeologs had different catalytic properties. Some TaBx homoeologs were efficiently transcribed, but the translation products showed only weak enzymatic activities, which inferred their weak contribution to Bx biosynthesis. Considering the transcript levels and the catalytic properties collectively, we concluded that the homoeologs on the B genome generally contributed the most to the Bx biosynthesis in hexaploid wheat, especially in shoots. In tetraploid wheat and the three diploid progenitors of hexaploid wheat, the respective transcript levels of the TaBx homoeologs were similar in ratio to those observed in hexaploid wheat. This result indicates that the genomic bias in the transcription of the TaBx genes in hexaploid wheat originated in the diploid progenitors and has been retained through the polyploidization.biosynthetic genes ͉ homoeolog ͉ polyploidization

Protein kinase C (PKC) is widely recognized as a therapeutic target in intractable diseases such as cancer, Alzheimer's disease (AD), and acquired immune deficiency syndrome (AIDS). While inhibition of PKC is a general therapeutic strategy for the treatment of cancer, PKC activators are potential therapeutic agents for AD and AIDS. However, concerns have been raised about their therapeutic use since PKC activators such as phorbol esters exhibit potent tumor-promoting activities. Naturally occurring bryostatin 1 (bryo-1), prostratin, and 12-deoxyphorbol 13-phenylacetate (DPP) are fascinating PKC activators without tumor-promoting activities. Bryo-1 is currently in clinical trials for the treatment of cancer and is also effective against AD. Prostratin and DPP are attractive candidates for the adjunctive treatment of human immunodeficiency virus (HIV) infection. However, their limited availability from natural sources and synthetic complexity have hampered further development as therapeutic agents. We report here easy access (22 steps) to a simple analogue (1) of the tumor-promoting aplysiatoxin (ATX) as a novel PKC activator with anticancer and anti-tumor-promoting activities. Anticancer activities of 1 against several human cancer cell lines were comparable to those of bryo-1. Moreover, 1 as well as bryo-1 significantly inhibited the Epstein-Barr virus early antigen (EBV-EA) induction by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA), whereas ATX strongly induced EBV-EA. This inhibitory effect is characteristic of antitumor promoters. Compound 1 as well as bryo-1 displayed significant binding and activation of PKCdelta and induced its translocation to the nuclear membrane in CHO-K1 cells. This study provides a synthetically accessible PKC activator with bryo-1-like activities, which could be another therapeutic lead for cancer, AD, and AIDS.

Aplog-1, a simplified analogue of tumor-promoting debromoaplysiatoxin, is antiproliferative but not tumor-promoting. Our recent study has suggested that local hydrophobicity around the spiroketal moiety is a crucial determinant for antiproliferative activity. To further clarify the structural features relevant to the activity, we synthesized two methyl derivatives of aplog-1, where a methyl group was installed at position 4 or 10 of the spiroketal moiety. 10-Methyl-aplog-1 (5) bound to the C1B domains of novel PKCs (δ, η, and θ) with subnanomolar K(i) values, approximately 10-20 times stronger than aplog-1, and markedly inhibited the growth of many human cancer cell lines, while 4-methyl-aplog-1 (4) had levels of activity similar to those of aplog-1. Interestingly, 5 showed little tumor-promoting activity unlike the tumor promoter debromoaplysiatoxin. These results suggest that 5 is a potent PKC ligand without tumor-promoting activity and could be a therapeutic lead for the treatment of cancer, like bryostatins.

An Aβ42 analog crosslinked within the molecule at the 17th and 28th amino acid residues exhibited high aggregative ability and potent neurotoxicity comparable to those of E22P-Aβ42.

The only trimer model to exhibit weak but significant neurotoxicity against SH-SY5Y cells was the one which was linked at position 38.

The CH/pi interaction between the indole ring of indolactam-V (IL-V) and the hydrogen atom at position 4 of Pro-11 of the PKCdelta C1B domain was evaluated using the mutant peptide of the PKCdelta C1B domain, in which the CH/pi interaction was inhibited by substitution of the hydrogen atom with a fluorine atom. IL-V showed about a 10 times lower binding affinity to the mutant peptide compared to the wild-type peptide, suggesting that the CH/pi interaction could play a pivotal role in the binding of IL-V to the PKCdelta C1B domain. On the other hand, benzolactam-V8 (BL-V8), with the benzene ring instead of the indole ring of IL-V, might lack the CH/pi interaction. The low binding affinity of BL-V8 could be enhanced by the effective formation of the CH/pi interaction as exemplified by the synthesis of naphtholactam-V8 (NL-V8).

Protein kinase C (PKC) isozymes are widely recognized as targets for anticancer therapy, and recent investigations demonstrated that PKC activators are potential therapeutic candidates for Alzheimer's disease and acquired immune deficiency syndrome. However, concerns exist about their therapeutic uses because most PKC activators are potent tumor promoters. Bryostatin 1 (bryo-1) is a unique PKC activator with little tumor-promoting activities. Bryo-1 is currently undergoing clinical trials for the treatment of cancer. However, its limited availability from natural sources and difficulty in the synthesis hamper further studies on its mode of action and structural optimization. Although excellent practical methods for synthesizing several bryo-1-related compounds have been developed, the identification of synthetically more accessible compounds with bryo-1-like activity also provides a promising way to circumvent the problem of supply. The authors focused on the bryo-1's unique mechanism of activating PKCδ that plays a tumor suppressor role, and found that a simple and less lipophilic analogue (aplog-1) of the tumor-promoting aplysiatoxin showed PKCδ-activating behavior similar to bryo-1. Aplog-1 was easily synthesized in only 22 steps using standard reactions. Moreover, its tumor-promoting activity in vitro was very weak, and its cell growth-inhibitory activities were comparable to those of bryo-1. These data suggest that aplog-1 could become another therapeutic lead for cancer.

Two similarly sulfated triterpene saponins from Pearsonothuria graeffei were prepared to investigate the anti-obesity effects of echinoside A (EA) and holothurin A (HA). The in vitro inhibitory activities of EA and HA toward pancreatic lipase were investigated, and two in vivo studies were performed: (i) Male Wistar rats were orally administered the lipid emulsion with or without a saponin (HA or EA). The serum's total triglyceride concentration was measured at various times. (ii) C57BL/6 mice were assigned to four groups, high fat (HF), EA (0.03%), HA (0.04%), and orlistat (0.01%), and the weight of adipose tissue and level of fatty acids excreted in the feces were determined. Both EA and HA repressed the pancreatic lipase activity and increased fatty acid excretion in the feces. Treatment with EA and HA significantly decreased the adipose tissue accumulation in mice. EA and HA manifested different inhibitory activities in vitro, but each of them dramatically inhibited lipid absorption in vivo and showed strong anti-obesity activity.