In 1995, we discovered new antiherpetic antibiotics, called fattiviracins. The producing organism was classified as a strain belonging to Streptomyces microflavus. The strain produced at least 13 fattiviracin derivatives (FV-1 to FV-13). Fattiviracins were obtained as a white amorphous powder, and their molecular weights are in the range of 1400 to 1500. They are readily soluble in water, methanol, pyridine, and DMSO, but insoluble in other organic solvents. Fattiviracins have macrocyclic diesters formed by the binding of two trihydroxy fatty acids and two D-glucose residues in the molecule, and they can be divided into five families according to the length of the fatty acid moiety. Fattiviracins have potent activity against enveloped DNA viruses such as the herpes family, HSV-1, and VZV and enveloped RNA viruses such as influenza A and B viruses, and three strains of HIV-1, with EC50 values on the order of a few micrograms per milliliter. The biosynthetic pathway of fattiviracins is also becoming clearer. Using bacitracin-resistant strains, enhanced and astringent production of fattiviracin was achieved. Fattiviracin FV-13, which has the longest fatty acid chains in the molecule, was dramatically enhanced by a C55-isoprenyl phosphate metabolism. In addition, we have screened various inhibitors of enzymes such as alkaline protease, glucosyltransferase, glucuronidase, phospholipase, deoxyribonuclease, DNA methyltransferase, and DNA topoisomerase. All the inhibitors we discovered are briefly summarized in this paper.
Indole alkaloids are one of the most interesting research fields. The chemistry of monoterpenoid indole alkaloids, in particular, offers many skeletal rearrangement reactions including terpenoid rearrangements. The author describes those compounds encountered or connected with in his research, including iridoids, indole alkaloids, adamantanes found in nature, and oxyindoles that are correlated with rearrangements.
Cytotoxic drug-induced nausea and vomiting are the side effects most feared by cancer patients. Emesis is an instinctive defense reaction caused by the somato-autonomic nerve reflex, which is integrated in the medulla oblongata. Emesis caused by anticancer drugs is associated with an increase in the concentration of serotonin (5-HT) (5-HT) in the intestinal mucosa and brainstem. 5-HT released from the enterochromaffin (EC) cells, which synthesize and secrete 5-HT, stimulates the 5-HT receptors on the adjacent vagal afferent nerves. The depolarization of the vagal afferent nerves stimulates the vomiting center in the brainstem and eventually induces a vomiting reflex. 5-HT released from EC cells appears to mediate the cisplatin-induced emesis sensitive to 5-HT3 receptor antagonists. The precise role of 5-HT in the occurrence of vomiting has not been fully elucidated. The present review describes the role of 5-HT in anticancer drug-induced emesis from the viewpoint of 5-HT release and afferent vagal nerve activity. Various models and methods for predicting emesis are also evaluated.
A novel type of deprotonative functionalization of aromatics was accomplished with a phosphazene base (t-Bu-P4 base). For various nitrogen heteroaromatics and benzene derivatives, deprotonative 1,2-additions proceeded with the t-Bu-P4 base and ZnI2 as an additive in the presence of carbonyl compounds. The t-Bu-P4 base has both extremely strong Brønsted basicity and less nucleophilicity due to its huge, widely conjugated structure, and highly chemoselective deprotonations were achieved. In addition the nonmetallic t-Bu-P4 base should not function as a Lewis acid. Therefore the deprotonation with the t-Bu-P4 base is considered to proceed via a different pathway from traditional deprotonative metalation of aromatics with metallic bases. Some reactions with unique regioselectivities were observed.
In attempts to discover anti-HIV agents from natural sources, various traditional medicine extracts were tested for their inhibitory effects on HIV-1 proliferation and its protease. An extract of the seeds of Croton tiglium showed potent inhibitory effects on the proliferation of HIV-1. The active principle was determined to be phorbol esters. Several derivatives of phorbol ester were evaluated for inhibition of proliferation as well as activation of protein kinase C (PKC). Of these compounds, 12-O-acetylphorbol 13-decanoate (6) showed the most potent inhibition of proliferation without activating PKC. Some triterpenes from the stems of Cynomorium songaricum and the woody part of Xanthoceras sorbifolia showed inhibitory activity against HIV-1 protease. Various derivatives of oleanolic acid were synthesized and evaluated for their inhibitory activity against HIV-1 protease. Their inhibitory mechanism was also investigated.
Tumor necrosis factor-alpha (TNF-α) has been expected to be a promising new antitumor agent, but toxic side effects by the systemic administration of TNF-α limit its clinical application. In this study, we attempted to improve the therapeutic potency of TNF-α by using our protein-drug innovation systems. Among phage libraries displaying various mutant TNF-αs, we isolated some lysine-deficient super mutant TNF-αs, typified by mTNF-α-K90R, with higher TNF-receptor affinities and stronger bioactivity in vitro, in spite of the importance of lysine residues for trimer formation and receptor binding. mTNF-α-K90R showed more than 10 times stronger in vivo antitumor effects and 1.3 times less toxicity than wild-type TNF-α (wTNF-α). Site-specifically mono-PEGylated mTNF-α-K90R (sp-PEG-mTNF-α-K90R) at N-terminus showed higher in vitro bioactivity than unmodified wTNF-α, whereas randomly mono-PEGylated wTNF-α at a lysine residue (ran-PEG-wTNF-α) had less than 6% of the bioactivity of wTNF-α. The antitumor therapeutic window of sp-PEG-mTNF-α-K90R was extended by about 5 times, 60 times and 18 times compared with those of mTNF-α-K90R, wTNF-α and ran-PEG-wTNF-α, respectively. sp-PEG-mTNF-α-K90R may, thus, be a potential systemic anti-tumor therapeutic agent. These data suggested that our fusion protein-drug innovation system composed of a creation system of functional mutant proteins based on phage display technique and a site-specific PEGylation system may open up a new avenue to the optimal protein therapy.
To date, the pharmacologic approach to cerebral vasospasm and ischemia has been hampered in part by an inability to attain sufficiently high concentrations of drugs in the cerebrospinal fluid (CSF). To overcome this limitation of current drug therapy, we have developed a sustained-release preparation of the protein kinase inhibitor fasudil. Experimental cerebral vasospasm in rats and dogs was induced by double injection of autologous arterial blood into the cisterna magna. Focal cerebral ischemia in rats was induced by middle cerebral artery occlusion using an intraluminal suture technique. A single intrathecal injection of liposomal fasudil can maintain a therapeutic the drug concentration in the CSF due to the sustained-release property of liposomes, significantly decreasing intarct size of acute ischemia and decreasing vasoconstriction of the basilar artery in cerebral vasospasm. This novel approach for the treatment of cerebral vasospasm and ischemia may have significant potential for use in the clinical setting.
Endomorphin-2 (Tyr-Pro-Phe-PheNH2) was discovered as an endogenous ligand for the μ-opioid receptor. The physiologic function of endomorphin-2 as a neurotransmitter or neuromodulator may cease after rapid enzymatic processing in the synapses of the brain, like other neuropeptides. The present study was conducted to examine the metabolism of endomorphin-2 by synaptic membranes prepared from mouse brain. Major metabolites were free tyrosine, free phenylalanine, Tyr-Pro, and PheNH2. Both the degradation of endomorphin-2 and the accumulation of major metabolites were inhibited by specific inhibitors of dipeptidyl peptidase IV, such as diprotin A and B. On the other hand, the accumulation of Phe-PheNH2 and Pro-Phe-PheNH2 was increased in the presence of bestatin, an aminopeptidase inhibitor, whereas that of free phenylalanine and PheNH2 was decreased. Furthermore, purified dipeptidyl peptidase IV hydrolyzed endomorphin-2 at the cleavage site, the Pro2-Phe3 bond. Thus degradation of endomorphin-2 by brain synaptic membranes appears to occur mainly through the cleavage of the Pro2-Phe3 bond by dipeptidyl peptidase IV, followed by the release of free phenylalanine and PheNH2 from the liberated fragment, Phe-PheNH2, by aminopeptidase. We have also examined the effects of diprotin A on the antinociception induced by intracerebroventricularly administered endomorphin-2 in the mouse paw withdrawal test. Diprotin A simultaneously injected with endomorphin-2 enhanced endomorphin-2-induced antinociception. These results indicate that dipeptidyl peptidase IV may be an important peptidase responsible for terminating endomorphin-2-induced antinociception at the supraspinal level in mice. These findings also suggest that selective dipeptidyl peptidase IV inhibitors or dipeptidyl peptidase IV-resistant endomorphin-2 analogues have the potential for the clinical use as analgesics.
To clarify the effectiveness and safety of azathioprine (AZA) and 6-mercaptopurine (6MP) in the induction and maintenance of remission in ulcerative colitis (UC) by using a systematic review of published studies. Studies were searched for from within the 1966 to March 2003 MEDLINE database, Cochrane Library 2003 issue 1, and the 1981 to March 2003 Japana Centra Revuo Medicina database. References from published studies and reviews were also obtained. Randomized, placebo-controlled trials of oral AZA or 6MP therapy in adult patients with active or quiescent UC were included. Ratios for the induction and maintenance of remission, the steroid-sparing effect, and the incidence of adverse drug reactions (ADRs) were compared and evaluated between the two study arms and expressed by the odds ratio (OR) specific for the individual studies and the meta-analytic summary for the OR. We could find no randomized controlled trial for 6MP therapy. However, four clinical trials for AZA therapy were included in this meta-analysis. For the induction of remission, the pooled OR of the response to AZA therapy compared with placebo in active UC was 1.45 (95% Confidence Interval (CI): 0.68 to 3.08). For the maintenance of remission, the pooled OR for AZA therapy was 2.26 (95% CI: 1.27 to 4.01). The number needed to treat (NNT) to prevent one recurrence was 6 patients. The pooled OR for AZA therapy's ADRs compared with placebo was 2.11 (95% CI: 0.92 to 4.84). From the viewpoint of effectiveness and safety, this meta-analysis suggests that AZA might be useful in the maintenance of remission in UC patients.
Multiple-chemical sensitivity (MCS) patients are presumed to be compelled to lead inconvenient and difficult lives, because unpleasant and multiorgan symptoms are caused by very small amounts of various chemicals in the living environment. Therefore we conducted a questionnaire survey of MCS patients who are members of support groups to elucidate the problems of MCS patients in using medicinal drugs. In this report, we selected 205 persons who stated that they had been “diagnosed with MCS by a physician” or “a physician suspected a diagnosis of MCS” on the questionnaire as the reason they judged themselves to have MCS. The questionnaire results showed that about 60% of MCS patients have difficulty in using medicinal drugs and that the difficulties are more likely to occur in women, in people 40—59 years old, and in patients who developed MCS in reaction to pesticides or medicinal drugs. The prescribed drugs and OTC drugs noted as usable or unusable by patients in the questionnaire were analyzed from the viewpoint of their medicinal constituents. The results indicated that lidocaine is likely to be unusable by MCS patients. In addition, caffeine, aspirin, chlorphenylamine maleate, minocycline hydrochloride, levofloxacin, etc. were also likely to be unusable by MCS patients. Many patients who recorded drugs containing the above-mentioned remedies as unusable had a past history of allergy, suggesting that allergy is involved in the difficulties of MCS patients in using medicinal drugs.
This research intends to clarify the protective effect of barley and its hydrolysates with respect to a water immersion stress-induced ulcer in the rat model. The β-(1→3)-glucan content of barley, and specifically β-(1→4),(1→3)-glucan content was determined and then gastric stress ulcerogenesis induced by water immersion was conducted using five-week-old male Sprague-Dawley rats (7 rats in one group). The barley diet group was fed 10% barley flour that was substituted with sucrose in the control diet. For the 3 groups fed on soluble dietary fiber (SDF), the diets were supplemented with 0.46 g of SDF, equivalent to 100 g of the control diet; 0.46 g of SDF is equivalent to 10 g of barley flour. The rats were housed in a stress-cage and immersed in a water bath (23°C) up to their necks for 21 h. The content of SDF and β-(1→3)-glucan content in barley flour were 4.6% and 3.4%, respectively. Although strongly anti-ulcer activities were observed in the barley (10%), SDF isolated and β-(1→3)-glucan fraction (Hydrolysate I) prepared from barley flour after treatment with lichenase, in other words, β-(1→4),(1→3)-glucan itself, its hydrolysate (Hydrolysate II) with β-(1→3)-glucosidase did not display any anti-ulcer activity. This finding suggests that the β-(1→3)-glucosyl-linkage on β-(1→3)-glucan is an important part of the active principle for anti-ulcerogenesis.