Structural and metabolic studies of carbohydrates in algae

Investigation of the Carbohydrates synthesised by the marine green alga Ace tabulara a crenulata. By means of sequential extractions with different solvents the following carbohydrates were isolated and characterised. 1. From an alcoholic extract D-glucose, D-fructose, allulose, myo-inositol and an alcohol tentatively identified as allo-quercitol. This is only the second time allulose has been found in Nature and the first time in any alga. An homologous series of fructose-containing oligosaccharides were also separated and characterised as 2,1 linked units terminated by a molecule of sucrose at the potential reducing end.2, Aqueous extraction gave a mixture of a fructan (major) and a sulphated heteropolysaccharide.a) These two polysaccharides were separated on a column of DEAE-cellulose. Using the classical techniques the fructan was characterised as an inulin type polysaccharide,b) (i) The sulphated polysaccharide contained D-glucuronic acid, B-galactose, L-rhamnose and small proportions of xylose and 4-0-methylgalactose. Each of the sugars were separated and characterised. The presence of the last sugar has not been reported as a constituent of any green algal polysaccharide before,(ii) By extraction of stalks and caps separately with cold and hot water and elution from the DEAE-cellulose with 0.5 and 1.0 M potassium chloride similar sulphated polysaccharideswith variable proportions of the different sugars and portions of sulphate were separated.(iii) Structural studies by partial desulphation, methylation, periodate oxidation and partial hydrolysis established the essential similarity of these fractions and that the main structural features are: highly branched molecules containing1,3-linked D-galactose 4-sulphate (major) and 6-sulphate, 1,2-linked Larhamnose and glucuronic acid, galactose and rhamnose all present as end groups. Glucuronic acid is linked to both rhamnose and galactose and galactose units are mutually linked in the macromoiecule. 3. linked mannan was extracted with alkali. Methylation,periodate oxidation and gel filtration studies proved this structure and indicated some degree of branching and a higher molecular weight than those of previously reported for mannans from green algae.PART IIPhotosynthetic studies on 1. Acetabularia mediterranea, 2. Fucusvesiculosus and 3. Ulva lactuca1. Pulse labelling experiments with C0 on A.mediterraneafollowed by ethanolic extraction led to the separation of labelled sucrose, glucose, fructose and the first three oligosaccharides characterised in Part 1 (l). A possible biosynthetic inter-conversion of these carbohydrates is described from the results of these experiments. 2. a) Pulse labelling experiments with C0 on Fucus vesiculosas a marine bcrown alga, show that of the low molecular weight carbohydrates formed by photosynthesis, mannitol is formed first The possible conversion of mannitol into laminaran via mono-and di- glucosylmannitol is discussed*b) The polysaccharides, laminaran, xylogalactofucoglucuronan (A), xylogluouronogalactofucan (B), fucoidan (C) and alginic acid were extracted and separated by various fractionation techniques. The radioactivity in each was measured as was the radioactivity in the constituent sugars of the fucose-containing polysaccharides (all of which are sulphated). From the changes in the radioactivity of these polysaccharides in different samples it is postulated that (a) is synthesised first and transformed into (C) via (B).Low molecular weight carbohydrates present in the acid extract are suggested as precursors for the acid polysaccharides. The residual material after acid and alkali extraction was hydrolysed and the radioactivity of the sugars in the hydrolysate wasivmeasured. Glucose was the major radioactive sugar.3. Ulva lactuca, a marine green alga. Similar experiments on U.lactuca were carried out.a) Examination of the 80% ethanol extracts showed that sucrose is the first sugar to be synthesised and this is followed by glucose and fructose. Xylose, ribose(?) and myo-inositol also incorporated radioactivity.b) Starch and a sulphated glucuronoxylcrharrman were extractedand their radioactivities were measured. The former appears to be synthesised most rapidly and to be an active metabolite and the sulphated polysaccharide is laid down as a long term storage product or as part of the skeletal structure of the alga.c) The residual material after ethanolic and aqueous extractions was examined in the same way. Glucose is again the major sugar and the results indicate that the carbohydrate is laid down in the cell wall after other constituents.<p

Ethnopharmacological survey of six medicinal plants from Mali, West-Africa

An ethnopharmacological survey was carried out to collect information about the use of six medicinal plants in the regions around Siby and Dioila, Mali. The plants investigated were Biopyhtum petersianum, Cola cordifolia, Combretum molle, Opilia celtidifolia, Parkia biglobosa and Ximenia americana

Ethnopharmacological uses of Erythrina senegalensis: a comparison of three areas in Mali, and a link between traditional knowledge and modern biological science

This paper describes ethnopharmacological knowledge on the uses of Erythrina senegalensis DC (Fabaceae) in traditional medicine in three different areas (Dioila, Kolokani and Koutiala) in Mali. Data were collected using interviews of traditional healers selected randomly. The main reported diseases for which E. senegalensis was used by the traditional healers were amenorrhea, malaria, jaundice, infections, abortion, wound, and body pain (chest pain, back pain, abdominal pain etc). The fidelity level (which estimates the agreement of traditional healers on the same area about a reported use of the plant) was calculated to compare the results from the three areas. Certain differences were noticed, the most striking was the fact that amenorrhea was the most reported disease in Dioila and Kolokani with 21% of agreement for both areas, while this use was not reported in Koutiala at all. Similarities existed between the three areas on the use of the plant against malaria and infections, although with different degree of agreement among the healers. We also report the results of a literature survey on compounds isolated from the plant and their biological activities. A comparison of these results with the ethnopharmacological information from Mali and other countries showed that some of the traditional indications in Mali are scientifically supported by the literature. For instance, the use of E. senegalensis against infectious diseases (bilharzias, schistosomiasis, pneumonia etc.) is sustained by several antibacterial and antifungal compounds isolated from different parts of the plant. The comparison also showed that pharmacologists have not fully investigated all the possible bioactivities that healers ascribe to this plant

Ethnopharmacological survey of different uses of seven medicinal plants from Mali, (West Africa) in the regions Doila, Kolokani and Siby

An ethnopharmacological survey was carried out to collect information on the use of seven medicinal plants in rural areas in the nearby regions of Bamako, Mali. The plants were Opilia celtidifolia, Anthocleista djalonensis, Erythrina senegalensis, Heliotropium indicum, Trichilia emetica, Piliostigma thonningii and Cochlospermum tinctorium About 50 medical indications were reported for the use of these plants in traditional medicine. The most frequent ailments reported were malaria, abdominal pain and dermatitis. The highest number of usages was reported for the treatment of malaria (22%). The majority of the remedies were prepared from freshly collected plant material from the wild and from a single species only. They were mainly taken orally, but some applications were prepared with a mixture of plants or ingredients such as honey, sugar, salt, ginger and pepper. Decoction of the leaves was the main form of preparation (65%) and leaf powder was mostly used for the preparation of infusions (13%). The part of the plants most frequently used was the leaves. There was a high degree of informant consensus for the species and their medicinal indications between the healers interviewed. The results of this study showed that people are still dependent on medicinal plants in these rural areas of Mali

Chromatographic immunoassays for Helicobacter pylori detection – are they reliable in Mali, West Africa?

Introduction: Gastrointestinal diseases are major reasons for morbidity in Mali. As Helicobacter pylori is known to play a major role in gastritis and gastric ulcer we wanted to find a simple method for detection. Methods: Twenty-nine volunteers with confirmed gastric ulcer by gastroscopy and 59 randomly selected volunteers were diagnosed by using the rapid serological test Clearview®H. Pylori . The ImmunoCard STAT!® HpSA®test was applied on stool from 65 volunteers seeking help for gastrointestinal related ailments. Results: A Helicobacter pylori prevalence of 21% was found among the individuals with confirmed gastric ulcer, 44% among the randomly selected volunteers and 14% in individuals with gastrointestinal related ailments. Conclusion: According to what is already known about the aetiology of gastric ailments and the prevalence of Helicobacter pylori in neighboring countries, the infection rates in our study appear strikingly low. This might indicate that Clearview® H. Pylori and ImmunoCard STAT!® HpSA® have low sensitivities in the populations studied. Strain variability of H. Pylori may be an explanation. The tests need to be properly evaluated in Mali before they can be relied upon as diagnostic tools.Pan African Medical Journal 2013; 14: 7

NorSat-3 – Next Generation Norwegian Maritime Surveillance

The NorSat-3 mission, with expected launch Q2/Q3 2020, aims to enhance the Norwegian recognized maritime picture with an experimental ship navigational radar detector (NRD) in addition to an AIS receiver. The NRD aims to geolocate ship navigation radars within 10 km circular error probable and verify AIS positions. The 10º NRD antenna field of view will nominally be pointed towards the horizon in order to maximize the area coverage and view of the ships’ navigation radar main lobe. Operating in a near polar low earth orbit the Norwegian area of interest may be covered between 10 and 15 times per day if pointing the antenna suitably. Achieving the desired geolocation accuracy and area coverage, while minimizing polarization loss, requires a highly capable attitude determination and control system. The signal processing capabilities of the Zynq Ultrascale+ system-on-chip enables the radar signal processing in orbit, although also requiring a large platform power generation capability. The mission, payloads and platform are described in this paper, including some of the lessons learned. All flight subsystems and payloads have completed their relevant unit environmental tests, including proton irradiation of NRD electronics. Final system verification and environmental testing begins August 2019, with a target flight readiness review November 2019

Polysaccharides from the South African medicinal plant Artemisia afra: Structure and activity studies

Artemisia afra (Jacq. Ex. Willd), is an indigenous plant in South Africa and other parts of the African continent, where it is used as traditional medicine mostly for respiratory conditions. The objective of this study was to investigate the structural features of the polysaccharides from the leaves of this plant, as well as the biological activities of the polysaccharide fractions against the complement assay. Leaves of Artemisia afra were extracted sequentially with organic solvents (dichloromethane and methanol), 50% aqueous ethanol, and water at 50 and 100 °C respectively. The polysaccharide extracts were fractionated by ion exchange chromatography and the resulting fractions were tested for biological activity against the complement fixation assay. Active fractions were further fractionated using gel filtration. Monosaccharide compositions and linkage analyses were determined for the relevant fractions. Polysaccharides were shown to be of the pectin type, and largely contain arabinogalactan, rhamnogalacturonan and homogalacturonan structural features. The presence of arabinogalactan type II features as suggested by methylation analysis was further confirmed by the ready precipitation of the relevant polysaccharides with the Yariv reagent. An unusual feature of some of these polysaccharides was the presence of relatively high levels of xylose as one of its monosaccharide constituents. Purified polysaccharide fractions were shown to possess higher biological activity than the selected standard in the complement assay. Digestion of these polysaccharides with an endo-polygalacturonase enzyme resulted in polymers with lower molecular weights as expected, but still with biological activity which exceeded that of the standard. Thus on the basis of these studies it may be suggested that immunomodulating properties probably contribute significantly to the health-promoting effects of this medicinal plant

Structure of extracellular polysaccarides produced by a soil Cryptomonas Sp. (Cryptophyceae)

The Hindak strain of a Cryptomonas species (Cryptophyceae) produces extracellular polysaccharides. Because there is no information on the structure of these compounds in the Cryptophyceae we conducted structural studies. Gas–liquid chromatographic analyses showed that the polysaccharide is composed of fucose, rhamnose, xylose, mannose, glucose, galactose, galacturonic acid, glucuronic acid, and traces of 3-O-methyl galactose. The polysaccharide was separated into two subtractions by ion-exchange chromatography. Fraction A consisted mainly of 1,3-linked galactose units and 1,4-linked galacturonic acid. Unlike fraction B, fraction A did not have xylose, 3-O-methyl galactose, or glucuronic acid. Also, its degree of branching was low compared to that of fraction B. Only traces of sulfate were present infraction A, but fraction B was 10–15% sulfated. Protein was approximately 1% in both fractions. These polysaccharides appear to be a novel type of polymer in algae

Relative increase of deoxy sugars during microbial degradation of an extracellular polysaccharide released by a tropical freshwater thalassiosira sp, (bacillariophyceae)

The aim of this study was to characterize the extracellular polysaccharides (EPS) released by a freshwater Thalassiosira sp. (Bacillariophyceae) and evaluate their degradation by heterotrophic microbial populations from the same habitat of Thalassiosira sp., a tropical eutrophic reservoir. The EPS were purified by anion exchange column chromatography, the monosaccharide composition was determined by GC, and the linkages of the monosaccharides by GC-MS. The EPS is a mannose-rich heteropolysaccharide composed of two different acidic fractions. Both of these fractions are composed of mannose, rhamnose, fucose, xylose, galactose, glucose, glucuronic acid, and N-acetyl glucosamine but with different proportions. N-acetyl galactosamine occurs only in fraction 1 and galacturonic acid only in fraction 2. We monitored the concentrations of the monosaccharides in the EPS during its degradation using pulse amperometric detection in an HPLC. The decay patterns of the monosaccharides were varied and the deoxy sugars, fucose and rhamnose, were degraded at a slower rate than the other components, increasing their relative concentrations and the hydrophobic feature of the EPS. The possibility of a selective degradation, which enhances the stickiness of the EPS, promoting transparent exopolymeric particles and aggregate formation, is discussed based on the literature data