Metabolic networks of the human gut microbiota

The human gut microbiota controls factors that relate to human metabolism with a reach far greater than originally expected. Microbial communities and human (or animal) hosts entertain reciprocal exchanges between various inputs that are largely controlled by the host via its genetic make-up, nutrition and lifestyle. The composition of these microbial communities is fundamental to supply metabolic capabilities beyond those encoded in the host genome, and contributes to hormone and cellular signalling that support the dynamic adaptation to changes in food availability, environment and organismal development. Poor functional exchange between the microbial communities and their human host is associated with dysbiosis, metabolic dysfunction and disease. This review examines the biology of the dynamic relationship between the reciprocal metabolic state of the microbiota-host entity in balance with its environment (i.e. in healthy states), the enzymatic and metabolic changes associated with its imbalance in three well-studied diseases states such as obesity, diabetes and atherosclerosis, and the effects of bariatric surgery and exercise.

Intravenous fluids warming by mattress is simple and efficient during pediatric surgery

BACKGROUND/AIM

Temperature control is essential during pediatric surgery. The effectiveness of two methods of warming intravenous (i.v.) fluids to preserve normothermia was compared during abdominal surgery.

METHODS

Intraoperative core temperature (CT) was measured in 59 children, 8 years of age and younger. Patients were randomly allocated to two study groups according to the method of fluids warming. In Group M (n = 30), fluids were warmed by placing the i.v. tubing under a warming mattress, and in Group T (n = 29), by using an active i.v. fluid tube warming system. Observations of CT, infusion fluid temperature (IFT) at the entry to the patient and other relevant parameters were made at 30-min intervals throughout the surgical procedure.

RESULTS

The two groups did not differ significantly by age, gender, body weight or length of surgical procedure. Although baseline IFT was significantly lower in Group M than in Group T (33.8 degrees C vs. 35.1 degrees C), it increased during the procedure by 1.2 degrees C in Group M compared to a 0.2 degrees C increase in Group T. Baseline CT was also lower by 0.5 degrees C in Group M compared to Group T (NS), but CT increased in Group M by 1.0 degrees C compared to 0.2 degrees C in Group T, resulting in similar final CTs.

CONCLUSIONS

The increase in CT was more pronounced in patients where fluids were warmed under the warming mattress (Group M) than in those with fluids warmed by a coil warming device (Group T). The elevation in CT seen in Group M is associated with an increase in infusion fluid temperature at the line just before the i.v. cannula. Both methods of fluid warming (by placing the i.v. tubing under warming mattress and by using a fluid warming system) effectively preserved normothermia during abdominal surgery in children.

Isolation of solasodine and other steroidal alkaloids and sapogenins by direct hydrolysis-extraction of Solanum plants or glycosides therefrom

Concomitant extraction and hydrolysis of Solanum steroidal glycoalkaloids in a two-phase system containing an aqueous mineral acid and an organic water immiscible solvent, and having a boiling point under 100(o)C, is described. It is essentially a "one-pot" process, combining direct acid hydrolysis of the glycosides in the plant material and in situ extraction of the released aglycones after alkali treatment, in a single step, the various ingredients being added simultaneously or sequentially, as required. Application of the process to fruits, leaves, and tissue cultures of Solanum khasianum Clarke plants, either fresh or in dried, finely ground form, using a two-phase aqueous hydrochloric acid-toluene system, proved to be very suitable for continuous production of pure solasodine which is a valuable raw steroid for the preparation of steroidal drugs. Pure Solanum glycoalkaloids were also prepared and hydrolysed accordingly. The process has analytical applications too, and could be extended in a general way to glycosides in other series for preparation of their related aglycones.

Membrane disruption and enzyme inhibition by naturally-occurring and modified chacotriose-containing Solanum steroidal glycoalkaloids

Naturally-occurring 3beta-O-chacotriosides of solasodine (solamargine), of its 22S, 25S isomer tomatidenol (beta-solamarine), and of solanidine (chaconine), as well as ring E- and F-modified derivatives of solamargine were prepared and assayed in order to assess the relevance of aglycone structural features to membrane-disruption and enzyme-inhibitory activities of the related glycoalkaloids. A ring E-opened dihydro-derivative of solasodine (the chacotrioside of dihydrosolasodine A) did not bind to cholesterol, stigmasterol or ergosterol in vitro, disrupt PC/cholesterol liposomes or mammalian erythrocytes. or inhibit acetylcholinesterase in vitro. It did not synergise with the solatrioside of dihydrosolasodine A or solasonine (nor did solamargine with dihydrosolasodine A solatrioside) in haemolysis tests. The ring F modified derivative, N-nitrososolamargine, did not inhibit acetylcholinesterase in vitro, but lysed liposomes at > or = 150 microM and pH 7. Increasing the pH to 8 (but not 9) further enhanced disruption. The combination of N-nitrososolamargine and solasonine did not cause any disruption of liposomes. Beta-solamarine showed no anti-acetylcholinesterase activity in vitro at up to 100 microM, but disrupted liposomes at 75 and 150 microM, although not to the extent caused by solamargine or chaconine. In combination with both the (inactive) solatriosides, solasonine and solanine, 75 microM beta-solamarine produced synergistic effects, with liposome disruption greater than 150 microM beta-solamarine alone. Beta-solamarine, solamargine and chaconine showed similar haemolytic activity. Beta-solamarine synergised with the solatriosides solasonine and solanine in disrupting erythrocytes. Preliminary structure-activity relationships were evaluated for the active chacotriosides in an attempt to define the scope and limitations of this model study.

Developmental toxicology of solamargine and solasonine glycoalkaloids in frog embryos

As part of an effort to improve the safety of plant foods, a need exists to define the relative toxicities of structurally different glycoalkaloids and metabolites which may be present in Solanum plant species such as potatoes, tomatoes and eggplants. The objectives of this study were to determine the relative toxicities and the modes of action of the eggplant (Solanum melongena) glycoalkaloids solamargine and solasonine in Xenopus laevis frog embryos, using membrane potential and embryo growth and teratogenicity assays. In the cell membrane assays, adverse effects on embryos were evaluated by measuring membrane potentials using an electrochromic dye, di-4-ANEPPS, as a fluorescence probe for the integrity of the membranes. In the embryo growth and teratogenesis assays, the survival of the embryos and organ malformations was used as an index of embryo toxicity. The relative potencies of glycoalkaloids are similar for frog embryo effects (survival and teratogenicities) and for membrane effects (membrane potential). Experiments with solasonine at pH 6 and 8 suggest that the unprotonated form of the glycoalkaloids appears to be involved in the membrane effects. The nature of the carbohydrate side-chains of the steroidal glycosides governs relative potencies. The possible significance of the findings to food safety and plant physiology and possible application of the membrane assays to bacterial toxins are discussed.

The effect of some Solanum steroidal alkaloids and glycoalkaloids on larvae of the red flour beetle, Tribolium castaneum, and the tobacco hornworm, Manduca sexta

Evaluation of the inhibitory effect of a series of secondary plant compounds including steroidal alkaloids and glycoalkaloids on larvae of the red flour beetle, Tribolium castaneum, was investigated. Larval growth was inhibited on artificial diets containing 1 mumol g-1 diet of the glycoalkaloids solamargine, solasonine and tomatine, whereas the corresponding aglycones solasodine and tomatidine, and also tomatidenol, were inactive. The inhibitory effect of solamargine and tomatine, but not of solasonine, was completely abolished by addition of 1 mumol g-1 diet cholesterol and/or sitosterol. Nonetheless, synthetic cholesteryl tomatide displayed significant activity at 2 mumol g-1 diet. Parallel studies with the tobacco hornworm, Manduca sexta, showed marked inhibitory activity of tomatine at a dietary concentration of 1 mumol g-1, whereas the other compounds did not affect sterol metabolism or larval development. An appraisal of the factors influencing the mode of action of the active steroidal glycoalkaloids is attempted.

Isocratic non-aqueous reversed-phase high-performance liquid chromatographic separation of capsanthin and capsorubin in red peppers (Capsicum annuum L.), paprika and oleoresin

A simple, rapid high-performance liquid chromatography method has been devised in order to separate and quantify the xanthophylls capsorubin and capasanthin present in red pepper (Capsicum annuum L.) fruits and preparations made from them (paprika and oleoresin). A reversed-phase isocratic non-aqueous system allows the separation of xanthophylls within a few minutes, with detection at 450 nm, using methyl red as internal standard to locate the various carotenoids and xanthophylls found in plant extracts. The selection of extraction solvents, mild saponification conditions, and chromatographic features is evaluated and discussed. The method is proposed for rapid screening of large plant populations, plant selection, as well as for paprika products and oleoresin, and also for nutrition and quality control studies.

Interactions between the glycoalkaloids solasonine and solamargine in relation to inhibition of fungal growth

Inhibition of mycelium development in Phoma medicaginis and Rhizoctonia solani by solamargine and solasonine generally increased with increasing pH. P. medicaginis was the more susceptible species and solamargine the more potent compound. Solasonine was inactive against R. solani over the tested pH range (5-8). Dose-response curves confirmed these differential effects. Solamargine caused 50% growth inhibition in P. medicaginis at 60 microM (at pH 7) whereas no other treatment achieved this effect at 100 microM. Combinations of 50 microM of each glycoalkaloid produced synergistic effects against both fungi, especially R. solani which was essentially unaffected by either compound, by significantly inhibited by a 1:1 mixture of the two. The magnitude of the synergism was not affected by a pH change between 6 and 7. Spore germination in Alternaria brassicicola was markedly inhibited by 100 microM solamargine but unaffected by 100 microM solasonine or either compound at 50 microM. In P. medicaginis, neither glycoalkaloid was inhibitory up to 150 microM. In combination, the two compounds caused synergistic effects in both species, but to a much greater extent in A. brassicicola.

The Effect of Water Stress on Growth and Solasodine Content in Solanum khasianum

The effect of water stress on growth and development of SOLANUM KHASIANUM (Clarke) and on the solasodine content of its fruits, was studied under mild (field experiment) and severe (pot experiment) conditions. Under field conditions, vegetative development was inhibited but fruit production or yield were not affected and fruit maturity was enhanced considerably. Solasodine content was not affected and yield per plant remained the same with and without irrigation. Under conditions of severe water stress, fruit production and yield were affected as well as vegetative development. An increase in solasodine content per dry weight was observed, however, solasodine yield per plant was lower as a result of loss in fruit yield. Under conditions of extreme water stress, more negative water and osmotic potentials were developed and turgor was maintained in the leaves.