Antiviral activities of some Ethiopian medicinal plants used for the treatment of dermatological disorders.

Acokanthera schimperi (Apocynaceae), Euclea schimperi (Ebenaceae), Inula confertiflora (Asteraceae), Melilotus elegans (Leguminosae), and Plumbago zeylanica (Plumbaginaceae), are some of the medicinal plants used in Ethiopia for treatment of various skin disorders. In this study, the antiviral activities of the 80% methanolic extracts of these plants have been examined against coxsackievirus B3 (CVB3), influenza A virus and herpes simplex virus type1 Kupka (HSV-1) using cytopathic effect (CPE) inhibitory assays in HeLa, MDCK, and GMK cells, respectively. In parallel, the cytotoxicity was quantified using a crystal violet uptake assay. The antiviral activity of the most active compound was confirmed with plaque reduction assays. The results revealed that the extracts of Acokanthera schimperi and Euclea schimperi showed antiviral activity against all three tested viruses albeit with unequal efficacy. Whereas the Acokanthera schimperi extract exhibited the strongest activity against CVB3, the extract of Euclea schimperi inhibited influenzavirus A replication most effectively. A weak anti-influenzavirus A activity was also exhibited by the other plant extracts tested. In addition, CVB3 was inhibited by the extracts of Plumbago zeylanica and HSV-1 by Inula confertiflora. Thus, the extracts of these plants, particularly those of Acokanthera schimperi, Euclea schimperi and Inula confertiflora which showed activity against CVB3 and HSV-1 support their traditional use in the treatment of skin diseases of viral origin.

Visualization and analysis of the release mechanism of shellac coated ascorbic acid pellets.

Shellac coated sustained release ascorbic acid containing pellets were investigated using scanning electron microscopy in order to visualize the release mechanism and to establish a correlation to dissolution data. Scanning electron micrograph pictures revealed different drug release profiles of individual pellets. Single pellet dissolution measurements demonstrated that the release profile of the encapsulated dosage form, containing approximately 400 pellets per capsule, is a combination of different release profiles of all individual pellets. The release of ascorbic acid occurred only in some small spots on the surface area of the pellets and could be visualized by the reduction of silver ions from an aqueous silver nitrate solution. These spots could be identified as defects in the shellac sustained release film using scanning electron microscopy. In further trials, the dissolution rate of an individual pellet could be related to the number and dimension of holes in its membrane. In conclusion, the release is characterized by surface defects and scanning electron microscopy studies are a useful tool to get new information for a better understanding of the drug release.

Comparison between HPLC and HPTLC-densitometry for the determination of harpagoside from Harpagophytum procumbens CO(2)-extracts.

Carbon dioxide (CO(2)) extracts of the secondary roots of Harpagophytum procumbens were quantified by high performance liquid chromatography (HPLC) and high performance thin layer chromatography (HPTLC). An isocratic HPLC method was used for the quantification of the iridoid glucoside harpagoside at 278 nm. A HPTLC assay was developed for the determination of harpagoside after coloration at 509 nm. The diode array detection of both analytical assays were used to examine the purity of harpagoside peaks and compared with the standards, respectively. The assays provide good accuracy, reproducibility and selectivity for the quantitative analysis of harpagoside. The harpagoside contents of 15 different CO(2)-extracts were compared by HPLC and HPTLC-densitometry. The quantitative results of both analytical methods did not show any statistical significance between each other, although a trend to slightly lower mean values could be found for the HPTLC method.

Decreased systemic thromboxane A2 biosynthesis in normal human subjects fed a salmon-rich diet.

Nine normal male subjects were fed a reference diet typical of that consumed in the United States and a diet containing approximately 450 g salmon (salmon-rich diet). The salmon diet contained approximately 6 g omega 3 fatty acids that comprised 2.0% energy intake/d for each individual. The percent energy contribution of protein, carbohydrate, and fat (19%, 56%, and 25%, respectively) was identical for the two diets. Urinary excretion of 2,3-dinor-thromboxane B2 was significantly lower (0.74 +/- 0.26 ng/24 h) with the salmon diet compared with the reference diet (0.95 +/- 0.31 ng/24 h). In addition, in vitro generation of thromboxane B2 in response to collagen-stimulated aggregation of platelet-rich plasma from subjects consuming the salmon diet was reduced (1.87 +/- 0.79 ng/mL) compared with subjects consuming the reference diet (3.10 +/- 1.81 ng/mL). Urinary 2,3-dinor-6-oxo-prostaglandin F1 alpha excretion in subjects was not significantly different between the salmon diet (0.69 +/- 0.33 ng/24 h) and the reference diet (0.81 +/- 0.44 ng/24 h).

Salmon diet and human immune status.

We examined the effect of feeding a salmon-containing diet on the immune status of nine healthy men (age 30-65 years) who lived at the metabolic suite of the Western Human Nutrition Research Center for 100 days. During the first 20 days all nine subjects consumed a basal diet (BD). For the next 40 days, three subjects continued to consume BD, while the diet of remainder six subjects was modified to contain 500 g salmon every day. During the last 40 days, the diets of the two groups were crossed over. Feeding 500 g salmon daily for 40 days did not significantly suppress the blastogenesis of peripheral blood mononuclear cells cultured with phytohemagglutinin, Concanavalin A, protein A or pokeweed when compared to the corresponding pre-salmon diet values. It also did not significantly affect the delayed hypersensitivity skin response to seven recall antigens, serum concentrations of immunoglobulins G, M, and A, and complement fractions C3 and C4. Our results indicate that the short-term consumption of a high fish (salmon)-containing diet does not adversely affect the immune system, as has been reported with fish oil supplements.

Surface acidity of solid pharmaceutical excipients III. Excipients for solid dosage forms.

The surface acidities of pharmaceutical excipients are detected by color changes of acid-base indicators on the substrate's surface. To quantify the indicator's transition interval on the surface of hydrophilic excipients, as an organic solvent methanol is introduced for the preparation of indicator-excipient mixtures. The influence of the particle size on the determination of the surface acidity is investigated and particle size did not influence the determination within the particle size range investigated. Surface acidities of common excipients used in preparation of solid dosage forms are presented.

Optimization of an effervescent tablet formulation containing spray dried L-leucine and polyethylene glycol 6000 as lubricants using a central composite design.

A rotatable central composite design is used to evaluate the effects of lubricants and compression force on the physical characteristics of effervescent tablets. Effervescent tablets lubricated with a combination of spray dried L-leucine and polyethylene glycol 6000 are prepared by direct compression and examined. Residual force, crushing strength and disintegration time are considered as response variables and related to the L-leucine and polyethylene glycol concentrations and to the compression force. The calculated models are used to assess the influence of the production factors on tablet properties. As increasing amounts of L-leucine, showing good lubricating properties, reduce the crushing strength and prolong tablet disintegration, the L-leucine concentration is kept at a low level. An optimum tablet formulation contains 2% L-leucine and 3% polyethylene glycol 6000. The tablets have a tensile strength of 0.47 MPa and disintegrate in less than 2 min. Predicted and experimental results are in agreement within a 95% CI.

Investigation of the pellet-distribution in single tablets via image analysis.

The influence of five different microcrystalline cellulose filler-binders on the pellet-distribution in tablets was investigated under production-scale conditions. Coloured coated pellets were tableted on an instrumented high speed rotary tablet press at four machine speed levels. The pellet-distribution on the upper and the lower tablet surfaces was detected via image analysis and correlated with the disintegration time and the crushing strength of the tablets. Filler-binders with a large surface area and a fibrous texture, like Avicel PH 101, enable the production of disintegrating tablets with an approximately homogeneous pellet-distribution within a large range of machine speeds, while pellet-containing tablets prepared with coarse microcrystalline cellulose granules showed an inhomogeneous pellet-distribution, depending on machine speed.

Development of disintegrating multiple-unit tablets on a high-speed rotary tablet press.

Enteric coated bisacodyl pellets were compressed into divisible disintegrating tablets on a high speed rotary tablet press and investigated for pellet damages. The degree of pellet damages was examined via the bisacodyl dissolution during the acid treatment of' the drug release test for enteric coated articles according to USP 23. The damages depended on the type of filler-binder used and settings of the tablet press. Avicel PH 101 proved to be the most suitable filler-binder, effecting homogeneous distribution of the pellets within the tablets, as could be shown by image analysis of coloured pellets. The speed of the tablet press had noo influence on the pellet damages using Avicel PH 101 as a filler-binder, however, tablets containing 70% (w/w) of coated pellets did not fulfil the requirements of USP 23, despite optimum elasticity and coating thickness of a new Eudragit FS 30 D coating. Reducing the proportion of pellets to 60% per tablet, less than 10% of bisacodyl were released within 2 h during acid treatment thus fulfilling the requirements of the USP 23.

Phase solubility studies of pure (-)-alpha-bisabolol and camomile essential oil with beta-cyclodextrin.

(-)-Alpha-bisabolol was found to form an inclusion complex with beta-cyclodextrin (beta-CD) in solution as well as in the solid state. To investigate molecular associations of beta-CD with pure (-)-alpha-bisabolol or (-)-alpha-bisabolol as a component of camomile essential oil, phase solubility studies were undertaken. A B(s) type solubility with an apparent complex constant of 273 M(-1) for the pure (-)-alpha-bisabolol and 304 M(-1) for (-)-alpha-bisabolol as a constituent of the essential oil were obtained. The two curves in the phase solubility diagram reach their plateau at different concentrations of (-)-alpha-bisabolol, 7.04 x 10(-4) M for the pure substance and 2.88 x 10(-4) M for the substance as a component of the essential oil. Although the shapes of the curves are almost similar, the intrinsic solubility's of pure (-)-alpha-bisabolol (4.85 x 10(-4) M) and (-)-alpha-bisabolol as a component of the essential oil (1.82 x 10(-4) M) differ significantly. An inclusion complex having a stoichiometric composition of 2:1 (beta-CD: drug) was obtained. A mechanism of complexation has been proposed on the basis of the stability constant calculated from phase solubility data and the stoichiometric ratio of the solid state complexation.

Comparison of three new spectrophotometric methods for simultaneous determination of aspirin and salicylic acid in tablets without separation of pharmaceutical excipients.

Simultaneous analysis of aspirin (ASA) and salicylic acid (SA) in pharmaceutical tablet preparations was performed by two multicomponent UV-spectrophotometric methods utilizing principal component regression and classical least square algorithm. Additionally, an assay procedure based on second-derivative spectroscopy was developed. The analysis was performed in turbid solutions without separation of interfering excipients. The range, as determined by the second-derivative methods, was 0.2 to 103.2 micrograms/mL for ASA and 0.07 to 44.5 micrograms/mL for SA. Sensitivity for determination of SA was 0.004% of ASA content for the second-derivative method and 0.2% of ASA content for both multicomponent methods. The methods were applied to laboratory mixtures and commercial tablet formulations containing ASA and SA. The advantage of the second-derivative method in determining small amounts of SA in commercial tablet preparations is shown in comparison with a conventional HPLC method. All UV-spectrophotometric methods are rapid, accurate, and reproducible.

Interactions during aqueous film coating of ibuprofen with aquacoat ECD.

During the development of a coated ibuprofen formulation a sticking tendency occurred when applying Aquacoat ECD. This interaction indicated the formation of a eutectic mixture. The compatibility of the components of Aquacoat ECD with ibuprofen was investigated by differential scanning calorimetry. Cetyl alcohol, a stabilizing excipient in Aquacoat, was found to form a eutectic system with ibuprofen. It was characterized by the construction of a phase diagram with 33 mol% ibuprofen and an onset temperature of 40.5 degrees C. Wide-angle X-ray diffraction was used to identify the polymorphic forms of cetyl alcohol. The results confirmed the amorphous state in the aqueous dispersion in contrast to the beta(0)- and gamma(4)-polymorphs of solid cetyl alcohol.

The effect of a salmon diet on blood clotting, platelet aggregation and fatty acids in normal adult men.

This study was designed to measure the effect of dietary n-3 fatty acids (FA) on platelets and blood lipids. Healthy men (n = 9), ages 31 to 65, were fed diets in which salmon was the source of n-3 fatty acids. They were confined in a nutrition suite at this Center for 100 days. Food intake and exercise levels were rigidly controlled. Initially they were placed on a stabilization diet for 20 days, then six men were fed the salmon diet for 40 days. The others remained on the stabilization diet. The two groups switched diets for the last 40 days of the study. Both diets were isocaloric [16% protein, 54% carbohydrate, and 30% fat by energy-% (En%)]. The salmon diet contained 7.5% of calories from n-6 FA and 2% from n-3 FA, primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in a 40:60 ratio, while the stabilization diet contained 7.5% of calories from n-6 FA and less than 0.3% n-3 FA, mainly 18:3n-3. The bleeding time was unaffected by the diets in this study. The prothrombin time was shortened (11.6 sec. vs. 12.6 sec., p less than 0.01) for the subjects consuming the salmon diet as compared to that measured after 20 days of the stabilization diet. Mean platelet volume increased significantly during the period in which the volunteers consumed the salmon diet compared to the baseline diet (p less than 0.01), while the mean platelet levels decreased. Platelet aggregation (PA) was measured in platelet rich plasma before, during, and after the salmon diet using collagen, ADP, arachidonic acid (AA), and thrombin agonists. The PA threshold for ADP was significantly increased for the subjects on the salmon diet (p less than 0.05). No change in the PA threshold was detected for collagen or thrombin. The PA threshold for AA was unchanged also, but the platelets in subjects consuming the salmon diet had a prolonged time to maximum aggregation (p less than 0.01) with this reagent compared to platelets from men on the stabilization diet. Plasma, red cell, and platelet total FA composition was determined by capillary GLC. While the men consumed the salmon diets, there were marked increases (3 to 10-fold) in the EPA and DHA levels in all blood components with concomitant decreases in linoleic acid and AA levels.(ABSTRACT TRUNCATED AT 400 WORDS)

The urinary excretion of thiobarbituric acid reactive substances and malondialdehyde by normal adult males after consuming a diet containing salmon.

In this study we investigated the output of thiobarbituric acid reactive substances (TBARS) and malondialdehyde (MDA), as thiobarbituric acid (TBA)-MDA adduct, in the urine from subjects eating a diet in which the only source of n-3 long-chain, polyunsaturated fatty acids was fresh salmon. Nine healthy men, ages 30-65, were confined in the United States Department of Agriculture Western Human Nutrition Research Center, San Francisco, CA, for 100 d; food intake and exercise levels were controlled. All subjects were placed on a stabilization diet (StD) for 20 d, then six were fed the salmon diet for 40 d. The others remained on the StD. The groups switched diets for the last 40 d. Both diets were isocaloric (16% protein, 54% CHO and 30% fat by energy %). The salmon diet contained 7.5% of calories from n-6 fatty acids (FAs) and 2% from n-3 FAs, primarily eicosapentaenoic acid and docosahexaenoic acid in a 50:60 ratio, while the StD contained 7.5% from n-6 FAs and < 0.3% n-3 FAs (with presumably no significant amounts of C20 or C22 n-3 FAs). Twenty-four hour urinary output was collected, and 2% 3-d pool samples prepared for analysis of urinary TBARS and the TBA-MDA adduct. The total urinary output of each individual varied considerably, and on a daily basis the concentration of autoxidation products in an individual's urine varied also.(ABSTRACT TRUNCATED AT 250 WORDS)

Low-fat diets do not lower plasma cholesterol levels in healthy men compared to high-fat diets with similar fatty acid composition at constant caloric intake.

In most studies reporting the effects of high-fat (HF) and low-fat (LF) diets on human plasma fatty acids (FA) and lipoprotein levels, the design involved adding to the diet an oil that had an FA composition (FAC) very different from the FAC of the control diet. Thus, it is difficult to determine if simply reducing the fat content of the diet without changing the dietary FAC changes the tissue FAC or alters plasma lipid levels. In this study, we fed diets that contained either 22 or 39% of calories from fat, but had no differences in their FAC, for 50 d to a group (n = 11) of healthy men (20-35 y). Thus, the polyunsaturated/saturated ratios (1.0) of the diets were identical as were the n-3/n-6 ratio and the monounsaturated-to-total fat ratios. The diets contained (wt% of total fat) approximately 28% saturated FA, 33% monounsaturated cis-FA, 6% monounsaturated trans-FA, 22% n-6 polyunsaturated FA, and 7% n-3 polyunsaturated FA, and 4% other minor FA. The diets consisted of natural foods and were formulated to contain 16 en% protein, either 45 or 62 en% carbohydrate (CHO) and at least the recommended daily allowance for all micronutrients. Both diets contained 360 mg of cholesterol per day. All subjects were given the HF diet for 20 d, and then six were placed on the LF and the other five remained on the HF diet for 50 d. The two groups were crossed-over for the remaining 50 d of the study. The subjects' baseline total cholesterol level was 173 mg/dl, after 50 d on the HF diet it was 177 mg/dl and after 50 d on the LF diet, 173 mg/dl. The differences were not significant, and there were no significant changes in either the LDL or HDL cholesterol levels with either diet. Triglyceride levels, and consequently very low density lipoprotein levels, rose significantly on the LF, higher CHO diet compared to the levels found in the subjects on the HF diet (91.5 and 66.4 mg/dl respectively, P < 0.002). The linoleic acid content of the plasma, platelets, and red blood cells was significantly (P < 0.05) reduced in the LF diet compared to HF diet, without any obvious physiological effects. Hence, many earlier observations indicating reductions in plasma lipid levels when people are on LF diets may be due to changes in the FAC of the diet, not the reduction in fat calories.

Studies on the hydrogen belts of membranes: II. Non-electrolyte permeability of liposomes of diester, diether, and dialkyl phosphatidylcholine and cholesterol.

We have postulated the existence of lipid-lipid and protein-lipid hydrogen bonding in the hydrogen belts of membranes, i.e., the regions of hydrogen bond acceptors (carbonyl oxygens of esters and amides) and hydrogen bond donors (hydroxyls of cholesterol, sphingosine, proteins, water). To assess the possible effects of modifications of the hydrogen belts on membrane permeability, we prepared a diester phosphatidylcholine and two analogs lacking carbonyl oxygens, a diether and a dialkyl phosphatidylcholine, care being taken to synthesize lipids of identical efficient hydrophobic chain length. Relative permeation rates for glycerol and urea were determined by osmotic swelling of liposomes containing the phospholipids alone or with an equimolar quantity of cholesterol, with 4 mole % of dioleylphosphate added. The permeation rates of both solutes were similar for all three lipids, with Arrhenius activation energies deltaE* around 16 kcal/mole. Cholesterol reduced the permeability of all three membranes. The activation energy deltaE* of permeation did not change for diester and dialkyl phosphatidylcholine with cholesterol, but was lower by about 5 kcal/mole for the diether lipid with cholesterol. This corresponds to a reduction in the entropy of activation deltadeltaS*approximately-16 cal/mole/degree. We interpret the results as supporting the hypothesis of interaction between cholesterol hydroxyl and phospholipid carbonyl.

Effect of a salmon diet on the distribution of plasma lipoproteins and apolipoproteins in normolipidemic adult men.

The effects of n-3 fatty acids on plasma lipids, lipoproteins and apoproteins have usually been studied in humans after feeding of purified fish oil. This study describes the effect of a natural diet, containing salmon as the source of n-3 fatty acids, on these parameters as compared to a diet very low in n-3 fatty acids. The subjects were nine normolipidemic, healthy males who were confined to a nutrition suite for 100 days. During the first 20 days of the study the participants were given a stabilization diet consisting of 55% carbohydrates, 15% protein, and 30% fat. The n-3 content of this diet was less than 1%, and it contained no 20- or 22-carbon n-3 fatty acids. After the stabilization period the men were split into two groups, one group continued on the stabilization diet while the other received the salmon diet that contained approximately 2.1 energy percent (En%) of calories from 20- and 22-carbon n-3 fatty acids. Both diets contained equal amounts of n-6 fatty acids. This regime continued for 40 days, then the two groups switched diets for the remainder of the study. Plasma triglycerides were lowered significantly (p less than 0.01) and high density lipoprotein cholesterol (HDL-C) was significantly elevated (p less than 0.01) after the men consumed the salmon diet for 40 days. The very low density lipoproteins (VLDL) were lowered, but the trend did not reach statistical significance during the intervention period.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of fat-free, saturated and polyunsaturated fat diets on rat liver and plasma lipids.

The liver and plasma lipids and fatty acid composition of rats fed synthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a high carbohydrate, fat-free diet for 48 hr. They were then divided into three groups and fed for an additional 48 hrs the following: group 1, the fat-free diet; group 2, a diet containing 44% of calories from corn oil; and group 3, a diet containing 44% calories from completely hydrogenated soybean oil. The total lipid concentration of the liver in the animals on the fat-free diet was elevated at 72 and 96 hr. The addition of either saturated or unsaturated fat in the diet at 48 hr prevented this accumulation. The total phospholipid and cholesterol concentrations of the liver were relatively uninfluenced by any diet in this study. Plasma total fatty acid concentration was elevated at 72 hr in the animals on a fat-free diet compared to those fed the stock diet, starved for 48 hr or fed the fat-containing diets. By 96 hr, however, plasma fatty acid concentrations in all groups were similar to those in animals fed only the stock diet. The release of de novo synthesized fatty acids into plasma from the liver was strongly inhibited by dietary fat, either saturated or polyunsaturated. With the fat-free diet there was a significant increase in the saturated and monounsaturated fatty acids in both liver and plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of dietary fat on the lipogenic activity and fatty acid composition of rat white adipose tissue.

The in vivo fatty acid synthesis rate, selected enzyme activities and fatty acid composition of rat white adipose tissue from animals fed semisynthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a fat-free (FF) diet for 48 hr. They were then divided into three groups. One group was continued on the FF diet for 48 hr. Another group was fed a diet containing 44% of calories from corn oil (CO). The final group was fed a diet containing 44% of calories from completely hydrogenated soybean oil (HSO). The animals on the FF diet had a marked increase in adipose tissue fatty acid synthesis during the 96-hr feeding period (as measured by 3H incorporation into adipose fatty acids). Addition of either CO or HSO to the diets did not significantly inhibit fatty acid synthesis in dorsal or epididymal adipose tissue. The activities of the enzymes' fatty acid synthetase, ATP-citrate lyase and glucose-6-phosphate dehydrogenase increased on the FF diet and generally were not inhibited significantly by the addition of either fat to the diets. Linoleic acid was the major polyunsaturated fatty acid (ca. 22%) in adipose tissue. Monounsaturated fatty acids (palmitoleic, oleic, cis-vaccenic) made up ca. 38% of the total adipose fatty acids, while saturated fatty acids accounted for about 32% (myristic, palmitic and stearic). White adipose tissue in mature male rats was a major depot for n-3 fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)