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PubMedDate not supplied

Some emulsifying and suspending properties of the mucilage extracted from kernels of Irvingia gabonensis.

The mucilage extracted from the kernels of Irvingia gabonensis was evaluated for use as suspending and emulsifying agent. The rheological behaviour of the mucilage was studied and compared to that of tragacanth. As a suspending agent, Irvingia mucilage was compared to tragacanth at various concentrations (0.5, 1.0, 1.5 and 2.0% w/v) in the formulation of sulphanilamide suspensions. At all concentrations the formulated suspensions with Irvingia mucilage gave higher Hu (final sedimentation height) and F (sedimentation volume) values. As an emulsifying agent, the properties of Irvingia mucilage was compared to tragacanth and acacia gum. The emulsions prepared with 0.6, 1.0, and 1.5% tragacanth and Irvingia 'cracked' within six days while that with 12.5% w/v acacia started showing signs of creaming at the tenth day. The emulsion prepared with 2.0% w/v Irvingia mucilage was however stable throughout the six weeks of study. The results indicate that Irvingia mucilage performed better than acacia and tragacanth even at lower concentrations in the formulation of emulsions and suspensions.

Adhesives↗
PubMedDate not supplied

Cissus stem gum as potential dispersant in pharmaceutical liquid systems 2: The emulsifying and suspending properties.

The emulsifying and suspending properties of a new gum derived from the stem of cissus rufescence family Amphelidaceae were studied. Stability of the liquid paraffin emulsions prepared using this mucilaginous substance was compared with that containing tragacanth or acacia. The rate of globule coalescence was determined using Sherman's equation for concentrated emulsions. The suspending ability of the polymer was compared with that of tragacanth or compound tragacanth. The rate of deflocculation, K, was found to obey a power law equation: beta t = beta 0 e-kt in zinc oxide suspensions. At concentrations above 0.75% w/v, cissus gum produced liquid paraffin emulsion with minimal separation. The rate of globule coalescence was in the order acacia > cissus > tragacanth and rate of creaming was tragacanth > acacia > cissus. At concentrations of 0.6 to 1.0% w/v, cissus gum produced highly flocculated zinc oxide suspensions, which exhibited good redispersibility. Stability of the agglomerated, dispersed particles was similar to that produced using tagacanth mucilage.

Chemical Phenomena↗
PubMed1992

Interaction of preservatives with macromolecules: Part I--Natural hydrocolloids.

Antibacterial activity of methyl-p-hydroxybenzoate against Ps. aeruginosa was evaluated in the presence of varying concentrations of acacia, tragacanth, sodium alginate, guar gum and carrageenin. All these hydrocolloids reduced the antibacterial activity to varying degrees. Tragacanth and guar gum inhibited the activity to a greater extent than acacia, sodium alginate and carrageenin. Hydrocolloids reduce the antibacterial activity of preservatives in two ways. Interaction of the preservative with hydrophilic macromolecules and subsequent reduction in the availability of preservative appears to be the predominant mechanism by which tragacanth and guar gum reduce the activity of methyl-p-hydroxybenzoate. Acacia, sodium alginate and carrageenin apparently act by offering physical protection to microbial cells from the action of the preservative. It is also probable that these hydrocolloids provide more favourable media for microbial growth thereby increasing the preservative requirement for adequate preservation.

Colloids↗
PubMed1995

Caecal and faecal short-chain fatty acids and stool output in rats fed on diets containing non-starch polysaccharides.

The exact mechanisms by which non-starch polysaccharides increase stool output are unknown. In the present study the hypothesis that the site of fermentation and short-chain fatty acid (SCFA) accumulation is related to the action of non-starch polysaccharides (NSP) on stool output was tested. The basal diet (45 g NSP/kg) of forty-three male Wistar rats was supplemented with 50 g/kg of either guar, karaya, tragacanth, gellan, xanthan or ispaghula for 28 d. A further twenty-three rats were maintained on the basal diet for the same time period. Faeces were then collected over 2 d and caecal contents obtained post-mortem. Caecal and faecal wet and dry weights and SCFA were measured. Each supplement had a different effect on the caecal and faecal contents but they appeared to fall into three groups when compared with the basal diet. In group 1, guar gum affected only caecal SCFA. It had no effect on stool output or faecal SCFA. In group 2, karaya increased caecal SCFA and tragacanth, karaya and xanthan increased faecal SCFA and faecal water. In group 3, ispaghula and gellan had no consistent effect on caecal or faecal SCFA concentrations but increased total faecal SCFA output and increased faecal wet and dry weight. Although the knowledge that SCFA are rapidly absorbed in the large intestine has led us to believe that they play no role in determining faecal output, these results suggest that in some cases where NSP are slowly fermented, and increase faecal SCFA, the role of the SCFA may need to be reassessed.

Animals↗
PubMed1980

Plaquing procedure for infectious hematopoietic necrosis virus.

A single overlay plaque assay was designed and evaluated for infectious hematopoietic necrosis virus. Epithelioma papillosum carpio cells were grown in normal atmosphere with tris(hydroxymethyl)aminomethane- or HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered media. Plaques were larger and formed more quickly on 1- to 3-day-old cell monolayers than on older monolayers. Cell culture medium with a 10% addition of fetal calf serum (MEM 10) or without serum (MEM 0) were the most efficient virus diluents. Dilution with phosphate-buffered saline, saline, normal broth, or deionized water reduced plaque numbers. Variations in the pH (7.0 to 8.0) of a MEM 0 diluent did not affect plaque numbers. Increasing the volume of viral inoculum above 0.15 ml (15- by 60-mm plate) decreased plaquing efficiency. Significantly more plaques occurred under gum tragacanth and methylcellulose than under agar or agarose overlays. Varying the pH (6.8 to 7.4) of methylcellulose overlays did not significantly change plaque numbers. More plaques formed under the thicker overlays of both methylcellulose and gum tragacanth. Tris(hydroxymethyl)aminomethane and HEPES performed equally well, buffering either medium or overlay. Plaque numbers were reduced when cells were rinsed after virus adsorption or less than 1 h was allowed for adsorption. Variation in adsorption time between 60 and 180 min did not change plaque numbers. The mean plaque formation time was 7 days at 16 degrees C. The viral dose response was linear when the standardized assay was used.

Adsorption↗