Development of biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes inducible in aerobic and anaerobic conditions.

We developed biocatalysts carrying naphthalene dioxygenase and dihydrodiol dehydrogenase genes cloned from plasmid pN3 of Pseudomonas fluoresceins N3 involved in naphthalene degradation, as an alternative approach to the production of hydroxylated compounds by chemical synthesis. Naphthalene dioxygenase is responsible for hydroxylation of the hydrocarbon into the corresponding 1,2-dihydro-1,2-dihydroxy derivative and dihydrodiol dehydrogenase is involved in the subsequent transformation into the 1,2-dihydroxy derivative. The first reaction strictly requires the presence of oxygen, essential for the dioxygenation reaction, while the second one can also be performed in anaerobic conditions that are optimal to avoid the easy oxidation of bioconversion products. Consequently, we constructed biocatalysts carrying the genes responsible for the biotransformation of hydrocarbons, inducible under aerobic and anaerobic conditions. We cloned the dioxygenase gene under its promoter, inducible by salicylic acid and the dihydrodiol dehydrogenase under the Pnar promoter of Escherichia coli, inducible by nitrate, in a nitrogen atmosphere, in order to develop biological systems with the possibility of controlling the expression of the cloned genes by the shift from aerobic to anaerobic conditions. Bioconversion experiments performed in aerobic conditions showed dihydrodiol production and dehydrogenase repression; as soon as cultures were switched to nitrogen, dihydrodiol dehydrogenation with an efficient production of 1,2-dihydroxyderivatives was observed.

Polyphenolic glycosides from african proteaceae

The phytochemical investigation of members of the genus Protea afforded a series of polyphenolic compounds (1-5) that were identified by 1D and 2D NMR experiments. Of these, 2-5 are new compounds. Chemical syntheses of 1-3 were performed in order to confirm the structures and to prepare additional material for biological evaluation.

A new biocatalyst for production of optically pure aryl epoxides by styrene monooxygenase from Pseudomonas fluorescens ST.

We developed a biocatalyst by cloning the styrene monooxygenase genes (styA and styB) from Pseudomonas fluorescens ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant Escherichia coli was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals.

Isolation, synthesis, and antiplatelet aggregation activity of resveratrol 3-O-beta-D-glucopyranoside and related compounds.

Resveratrol 3-O-beta-D-glucopyranoside (1) has been isolated from the seeds of Erythrophleum lasianthum (Caesalpinioidae, Leguminosae), a South African plant used in traditional medicine, and has shown antiplatelet aggregation activity. The synthesis of 1, related hydroxystilbenes, and their glucosides has been undertaken to provide larger quantities, for further biological evaluation, and has been accomplished via Wittig reactions followed by glucosylation under phase transfer catalysis.

Synthesis of biologically active polyphenolic glycosides (combretastatin and resveratrol series).

(E)-3-(beta-D-Glucopyranosyloxy)-4',5-dihydroxystilbene (resveratrol 3-beta-D-glucoside, piceid), (Z)-2',3'-dihydroxy-3,4,4',5-tetramethoxystilbene (combretastatin A-1), (Z)-3'-hydroxy-3,4,4',5-tetramethoxystilbene (combretastatin A-4), (Z)-2'-hydroxy-3-4-4'-5-tetramethoxystilbene (combretastatin iso-A-4), alpha, beta-dihydro-2',3'-dihydro-2',3'-dihydroxy-3,4,4',5-tetramethoxystilb ene (combretastatin B-1), the corresponding glucosides, and related compounds have been synthesized via Wittig reactions followed by glucosylation under phase-transfer catalysis. Most of the compounds synthesized have been tested with respect to biological activity (cytostatic, cytotoxic, antimitotic, neurotoxic, antiplatelet, aggregation activity).

Production of substituted naphthalene dihydrodiols by engineered Escherichia coli containing the cloned naphthalene 1,2-dioxygenase gene from Pseudomonas fluorescens N3.

Naphthalene dioxygenase, a key enzyme in the dihydroxylation of naphthalene, is encoded by the plasmid pN3, responsible for naphthalene metabolism in Pseudomonas fluorescens N3. The naphthalene dioxygenase, including all the sequences for its expression and the regulatory region, has been localized on the 4.3-kb HindIII-ClaI fragment and on the 3.5-kb HindIII fragment of the plasmid pN3, by Southern analysis using as probes nahA and nahR genes, the homologous genes of the plasmid NAH7 from Pseudomonas putida G7. We cloned in Escherichia coli JM109 the dioxygenase gene and its regulatory region and developed an efficient bacterial system inducible by salicylic acid, able to produce dihydrodiols. E. coli containing recombinant plasmids carrying the dioxygenase gene were analysed for their potential as a biocatalytic tool to produce dihydrodiols from different naphthalenes with the substituent on the aromatic ring at the alpha or beta position. The dihydrodiols, identified by HPLC (high-performance liquid chromatography) and 1H-NMR (nuclear magnetic resonance) were produced with yields ranging from 50 to 94%. The degree of bioconversion efficiency depends on the nature and the position of the substituent and indicates the broad substrate specificity of this dioxygenase and its potential for the production of a wide variety of fine chemicals.

A novel K+ channel blocker isolated from 'hiccup nut' toxin.

Combretastatin B1, a polyhydroxybibenzyl compound extracted from the fruit of Combretum kraussii, known to contain 'hiccup nut' toxin, reversibly increased the duration, but not the peak or the rate of rise, of the action potential in rat sensory neurones by approximately 300%. This effect was only seen when it was applied to the extracellular side of the membrane. No effects on the resting potential were observed. K+ delayed rectifier currents were inhibited in neurones and in human myotubes with an IC50 of about 300 microM; the HERG-type inward rectifier channels in tumour cells were inhibited to a greater degree. Due to its selective action and the similarity of its blockade to that produced by class III antiarrhythmic drugs, the toxin could be the origin of compounds of potentially significant pharmacological interest.

Prevention of cytokine-induced hypotension in cancer patients by the pineal hormone melatonin.

Hypotension is a frequent side-effect of cancer biotherapies with cytokines. Cytokine-induced hypotension would mainly depend on the stimulation of nitric oxide (NO) production, which represents the most effective endogenous vasodilator. Moreover, it has been proven that both biological activity and toxicity of cytokines are influenced by the psychoneuroendocrine system, in particular by the pineal hormone melatonin. To investigate the possible modulatory effect of melatonin on cytokine cardiovascular toxicity, we evaluated the influence of a concomitant melatonin administration on interleukin-2(IL-2)- and tumour-necrosis-factor-alpha(TNF)-induced hypotension in advanced cancer patients. The study included 116 patients with advanced solid tumour, for whom no effective standard anticancer therapy was available, who underwent cancer biotherapy with IL-2 (3 x 10(6) IU/ day s.c. every day, 6 days/week for 4 weeks) or with TNF (0.75 mg/day i.v. for 5 days) as compassionate treatment for their disease. Patients were randomized to be treated with or without a concomitant melatonin administration (40 mg/day orally in the evening, starting 7 days prior to cytokine injection). The occurrence of hypotension was significantly less frequent in patients concomitantly treated by melatonin than in those who received the cytokine alone, during either IL-2: or TNF immunotherapy (IL-2; 11/45 versus 2/46, P < 0.05; TNF: 10/23 versus 1/12, P < 0.01). This study shows that melatonin may prevent hypotension occurring during cancer immunotherapy with IL-2 or TNF. Since the pineal hormone has appeared to inhibit the activity of NO synthase from the endothelial cells, we suggest that melatonin may prevent cytokine-induced hypotension by inhibiting NO production, which plays an essential role in inducing hypotension during IL-2 and TNF biotherapies.

Immunomodulatory properties of a pineal indole hormone other than melatonin, the 5-methoxytryptophol.

Several experiments have suggested that the pineal gland has an antitumor immunomodulatory action. Melatonin (MLT), the best known pineal hormone, has been shown to stimulate anticancer immune defenses during the night, corresponding to the period of its maximum blood levels, whereas it has no effect during the light phase of the day. At present, no study has been performed to investigate possible immunomodulating properties of other pineal indoles, such as 5-methoxytryptophol (5-MTL), whose circadian secretion would be opposite with respect to that of MLT, since it reaches its highest levels during the light phase of the day. In an attempt to analyze possible effects of 5-MTL on anticancer immunity, we have evaluated the action of 5-MTL (1 mg/ day orally at noon for 5 days) in 10 healthy volunteers on the two fundamental suppressive and immunostimulatory cytokines, consisting of IL-6 and IL-2, respectively. Serum levels of IL-2 and IL-6 were measured by an immunoradiometric method. Mean serum concentrations of IL-2 significantly increased on 5-MTL therapy, whereas those of IL-6 significantly decreased in response to 5-MTL. This preliminary study would suggest that the less known pineal indole 5-MTL, as well as MLT, has important immunomodulatory effects on cytokine secretions, including those involved in the antitumor immune response, by further confirming the essential role of the pineal as a central regulation of biological response modifier system. Several pineal alterations have been described in advanced cancer patients. According to the results of this study, the simultaneous administration of MLT during the dark phase and of 5-MTL during the light period of the day could further contribute to correcting pineal functions and to pilot the host anticancer immune reaction in an antitumor direction with respect to MLT alone.

Cycloartane triterpene glycosides from Astragalus trigonus.

Three new cycloartane glycosides, trigonoside I, II and III, and the known astragalosides I and II were isolated from the roots of Astragalus trigonus. The structures of the new glycosides were totally elucidated by high field (600 MHz) NMR analyses as cycloastragenol-6-O-beta-xylopyranoside, cycloastragenol-3-O-[alpha-L-arabinopyranosyl(1-->2)-beta-D- xylopyranosyl]- 6-O-beta-D-xylopyranoside and cycloastragenol-3-O-[alpha-L-arabinopyranosyl (1-->2)-beta-D-(3-O-acetyl)-xylopyranosyl]-6-O-beta-D-xylopyranoside.

Study of the resolution of amino acids and aminoalcohols in organic solvents.

The enzymatic resolution of racemic phenylglycine, phenylglycinol and phenylalaninol has been studied in organic solvents under a variety of experimental conditions. Subtilisin in 3-methyl-3-pentanol was effective for the resolution of phenylglycine esters, via N-acylation with trifluoroethyl butyrate. Porcine pancreatic lipase in ethyl acetate gave satisfactory results in the resolution of phenylglycinol and phenylalaninol; theα orß position of the phenyl group was found to influence both the rate and the chemioselectivity of the reaction.

Enhanced secretion of tumour necrosis factor in patients with myocardial infarction.

OBJECTIVES: Recent evidence suggests that leukocyte infiltration of myocardial tissue may extend the area of necrosis during the acute phase of myocardial infarction. Since the activation of leukocytes depends on the action of cytokines, mainly tumour necrosis factor (TNF), we evaluated TNF secretion during myocardial infarction. METHODS: The study included 12 patients with acute myocardial infarction as diagnosed on the basis of enzymatic and ECG criteria. Patients were admitted within 3 hours from onset of chest pain. Serum levels of TNF were measured by immunoradiometric assay on venous blood samples collected at time 0, and at 6, 12 and 18 hours and 1, 2, 4 and 7 days following myocardial infarction. Plasma levels of atrial natriuretic peptide-alpha (ANP) were also measured on the same samples. RESULTS: Mean TNF levels significantly increased during the myocardial infarction, with a peak within the first 24 hours (p < 0.01). They remained significantly elevated until day 4 (p < 0.05). The rise in TNF was positively correlated with creatinine kinase levels. ANP was also significantly increased with a delayed peak after that of TNF (p < 0.01). CONCLUSION: Even though limited to a small number of cases, this study shows that acute myocardial infarction is associated with increased TNF secretion. Because of its capacity of stimulating leukocyte infiltration in myocardial tissue, the increased levels of TNF might potentially have a negative prognostic significance.

[Cardioangioimmunology: the immune implications in the principle cardiovascular pathologies]. / Cardio-angio-immunologia: implicazioni immunitarie nelle principali patologie cardiovascolari.

At present, it is known that the immune system acts through the release of protein factors, so-called cytokines. In addition to their immunomodulating and endocrinometabolic effects, cytokines have appeared to be able to have an influence on the cardiovascular system by inducing important haemodynamic changes. Cytokines cause hypotension, particularly IL-2 and TNF, due at least in part to a production of nitric oxide by endothelial cells. Cytokines, such as IL-1, IL-6 and TNF, stimulate myocardial infiltration by activating leukocytes and inducing the release of cytotoxic factors during myocardial infarction; that would extend the area of necrosis. Finally, cytokines would be involved in the pathogenesis of the atherosclerosis, and cholesterol metabolism itself would be under a cytokine control. On these bases, it is possible to suggest in the near future the elaboration of new therapeutic strategies and prognostic indications, according to the bioimmunological response of patients with cardiovascular diseases.

Saponins from Albizzia lucida.

Three main saponins were isolated from the seeds of Albizzia lucida. Their structures were established by spectral analyses and chemical and enzymatic transformations as 3-O-[beta-D-xylopyranosyl(1----2)-alpha-L-arabinopyranosyl (1----6)] [beta-D-glucopyranosyl (1----2)] beta-D-glucopyranosyl echinocystic acid; 3-O-[alpha-L-arabinopyranosyl (1----6)] [beta-D-glucopyranosyl (1----2)]-beta-D-glucopyranosyl echinocystic acid and 3-O-[beta-D-xylopyranosyl (1----2)-beta-D-fucopyranosyl (1----6)-2-acetamido-2-deoxy-beta-D-glucopyranosyl echinocystic acid, characterized as its methyl ester.

Melatonin response to atrial natriuretic peptide administration in healthy volunteers.

Recent observations have demonstrated that the pineal hormone melatonin (MLT) plays a role in the neuroendocrine control of the cardiovascular system. On the other hand, it has been observed that the cardiac hormone alpha-atrial natriuretic peptide (ANP) may regulate the neuroendocrine functions. The present study was carried out to investigate the possible relationship between cardiac and pineal endocrine functions. Six healthy volunteers were treated on two different occasions with placebo or ANP at a dose of 0.1 mg i.v. as a bolus. An increase of greater than 100% in MLT serum levels was seen in 2/6 subjects. These preliminary results would suggest that ANP may play a role in the regulation of MLT secretion. Further studies will be needed to define better the cardiac-pineal interactions.

Pineal gland and tumor cell kinetics: serum levels of melatonin in relation to Ki-67 labeling rate in breast cancer.

Recent observations showed that host may regulate either endocrinologically or immunologically tumor growth and differentiation, perhaps by modulating oncogene expression. Within the endocrine system, the pineal hormone, melatonin, seems to play an important antineoplastic role. To investigate its secretion in relation to tumor growth, we have evaluated the daily serum levels of melatonin in a group of 25 untreated breast cancer patients with a locally limited disease. Tumor cell proliferation was established by measuring Ki-67 labeling rate. As controls, 46 healthy women were considered. Breast cancer patients showed significantly higher mean values of melatonin than controls. Moreover, patients with negative Ki-67 labeling rate had significantly higher levels of the pineal hormone than those with a positive Ki-67 rate. Since tumors with high growth fraction present a worse prognosis, this study would suggest that the relief of an increased melatonin secretion represents a favorable prognostic sign, because of its association with less proliferating breast cancers.

A study of heart-pineal interactions: atrial natriuretic peptide response to melatonin administration in healthy humans.

It is known that the pineal hormone melatonin plays a role in the regulation of several biological functions. In an attempt to investigate interactions between the pineal and the cardiac endocrine activity, in this preliminary study we have evaluated the effect of melatonin on the secretion of the cardiac hormone, atrial natriuretic peptide (ANP). The study included five healthy volunteers, and melatonin was given orally at a dose of 30 mg at 17:00. The results of the study show that the administration of melatonin does not influence ANP plasma concentrations. Further studies will be required to better define the cardiac-pineal interaction.

The pineal gland and breast cancer: serum levels of melatonin in patients with mammary tumors and their relation to clinical characteristics.

Several studies have suggested that the pineal gland hormone melatonin may influence the growth of breast cancer. The importance of melatonin blood concentrations in the clinical history of human breast cancer, however, has still to be defined. To further investigate this problem, we used a RIA method to assay serum levels of the pineal hormone in 74 untreated breast cancer patients, clinical stage T1-3 NO-2 MO, and in 46 age-matched healthy women as controls. Mean serum melatonin levels were significantly higher in patients than in controls. Melatonin concentrations were highest in breast cancer patients with the best prognosis (i.e. estrogen receptor-positive/node-negative cases). Mean levels of melatonin were significantly higher in estrogen receptor-positive patients than in the negative ones. They were also higher in node-negative than in node-positive cases, and in progesterone receptor-positive patients than negative ones, but none of these differences was statistically significant. No difference was observed in relation to menopausal status and to tumor histotype. These results suggest that melatonin plays a role in the hormone-dependency of human breast cancer.