Biomedical subjects
Publications and source records attributed to M Mosihuzzaman.
Quinovic acid-3-O-alpha-L-rhamnopyranoside (1), quinovic acid-3-O-beta-D-fucopyranoside (2), quinovic acid-3-O-beta-D-glucopyranosyl (1 --> 4)-beta-D-fucopyranoside (3), methyl gallate (4) and ethyl gallate (5) were isolated from the ethyl acetate extract of Bridelia ndellensis barks by fractionation. Compounds 1-3 showed significant inhibitory activity against snake venom phosphodiesterase-I.
Three compounds namely, (7S,8R)-dihydrodehydrodiconiferyl alcohol-9'-O-beta-D-glucopyranoside (1), 10-hydroxy-4,7-megastigmadien-3-one-9-O-beta-D-glucopyranoside (2) and 9-hydroxy-4,7-megastigmadien-3-one-10-O-beta-D-glucopyranoside (3) were isolated from the methanol extract of Pterospermum semisagittatum. The structures of these compounds were elucidated by spectroscopic methods. While glycosides 2 and 3 appear to be new, this is the third report of isolation of compound 1 from any natural source.
Caesalpinia bonducella F., is a shrub widely distributed throughout the coastal region of India and is ethnically used by the tribal people of Andaman and Nicober Island as a remedy of symptoms of diabetes mellitus. This ethnic report prompted the detail investigation of hypoglycemic activity of Caesalpinia bonducella seeds, initially on physiological hyperglycemic model and then on type 1 and type 2 sub-acute diabetic animal models which has already been reported. Evaluation of different extracts from Caesalpinia bonducella in chronic type 2 diabetic model alongwith insulin secretagogue activity of five fractions isolated from the Caesalpinia bonducella seed kernel are presented in this paper. Both the aqueous and ethanolic extracts showed potent hypoglycemic activity in chronic type 2 diabetic model. Two fractions BM 169 and BM 170 B could increase secretion of insulin from isolated islets.
Six new diterpenoids were isolated from a CH(2)Cl(2)-MeOH extract of the bark of Suregada multiflora. The structures were established on the basis of one- and two-dimensional NMR and other spectroscopic studies and chemical derivatizations. Two compounds, suregadolides C (1) and D (2), were identified as new diterpene lactones of two antipodal series, containing a cyclopropane ring bridging C-3 and C-4 of the basic abietane skeleton. Suremulide A (3) was found to be a new abietene diterpene lactone. Bannaringaolide A (4), a diterpene lactone, based on a novel carbon skeleton with a seven-membered ring, possibly formed by the rearrangement of the exocyclic C-17 in ring C of an ent-pimarane framework, has also been isolated. A kaurane triol, suremulol A (5), and a kaurane diol, suremulol B (6), were also identified as new metabolites.
Caesalpinia bonducella, widely distributed throughout the coastal region of India and used ethnically by the tribal people of India for controlling blood sugar was earlier reported by us to possess hypoglycemic activity in animal model. This prompted us to undertake a detail study with the aqueous and ethanolic extracts of the seeds of this plant in both type 1 and 2 diabetes mellitus in Long Evans rats. Significant blood sugar lowering effect (P < 0.05) of C. bonducella was observed in type 2 diabetic model. Special emphasis was given on the mechanistic study by gut absorption of glucose and liver glycogen.
The soluble dietary fibre (SDF) fraction of Trigonella foenum graecum (Tf-sdf) has previously been shown to reduce postprandial elevation in blood glucose level of Type 2 model diabetic rats by delaying the digestion of sucrose. The Tf-sdf has now been investigated for its chronic effect on serum fructosamine, insulin and lipid levels, and on platelet aggregation in Type 2 diabetic rats. Tf-sdf was administered orally twice daily at a dose of 0.5 g kg(-1) for 28 days. It lowered the serum fructosamine level (P<0.05) with no significant change in the insulin level as compared with the control. Atherogenic lipids, i.e. triglycerides, cholesterol and LDL-cholesterol were found to decrease significantly in Tf-sdf fed rats (P<0.01). HDL-cholesterol showed an opposite trend (P=0.024), but serum non-esterified fatty acid (NEFA) values paralleled the atherogenic lipids (P=0.001). No significant effect on platelet aggregation (%) was found although there was a tendency to lower the aggregation (P=0.069). It is concluded that Tf-sdf has a beneficial effect on dyslipidemia and has a tendency to inhibit platelet aggregation in Type 2 model diabetic rats.
Two new diterpene lactones, suregadolides A (1) and B (2), were isolated from a dichloromethane extract of Suregada multiflora bark. These compounds possess a novel skeleton, which contains a cyclopropane ring bridging C-3 and C-4 of the abietane skeleton. The structures were established on the basis of one- and two-dimensional NMR and other spectroscopic studies. Compound 1 showed moderate inhibitory activity in a mutant yeast strain bioassay.
The whole powder of Trigonella foenum graecum seeds and its extracts were tested for their hypoglycemic effect on normal and diabetic model rats. The powder, its methanol extract, and the residue remaining after methanol extraction had significant hypoglycemic effects when fed simultaneously with glucose. The water extract of the methanol extractive-free residue of the seed powder showed significant hypoglycemic activity at different prandial states. The Soluble Dietary Fibre (SDF) fraction showed no effect on the fasting blood glucose levels of nondiabetic or NIDDM model rats. However, when fed simultaneously with glucose, it showed a significant hypoglycemic effect (p < 0.05) in NIDDM model rats. Chemical analysis showed that the major constituent of the SDF is a galactomannan. The results confirm the involvement of SDF in the hypoglycemic effect of T. foenum graecum seeds. However, compound(s) other than SDF is (are) also involved in the hypoglycemic activity.
The structure of the Shigella boydii type 5 O-antigen polysaccharide has been investigated by sugar and methylation analyses, and specific degradations. It is proposed that it is composed of hexasaccharide repeating units with the following structure. The repeating unit also contains an O-acetyl group, linked to one of the primary positions. [formula: see text]
Rhizome of Costus speciosus, tuber of Nephrolepsis tuberosa, and bulb of Stephania hernandifolia, used by the local people and traditional healers in the Eastern Himalayan belt, were studied for their effects on serum glucose levels in nondiabetic and diabetic rat models at different prandial states. The results showed that in nondiabetic rat C speciosus and N tuberosa had no significant effect in the fasting or postprandial state when freeze-dried juices were fed simultaneously with glucose. However, when fed 30 min before the glucose load both C speciosus (p < 0.05) and N tuberosa (p < 0.003) showed hypoglycemic effect. To the contrary, S hernandifolia increased the serum glucose levels of nondiabetic rats in all the series of experiments (p < 0.05 or p < 0.01). In NIDDM model rats N tuberosa opposed the rise in serum glucose level when it was fed 30 min before the glucose load (p < 0.02), whereas S hernandifolia had a tendency to raise the serum glucose level. In IDDM model rats, none of these three freeze-dried juice showed any effect in the fasting state. However, C speciosus showed significant hypoglycemic effect (p < 0.002) when the juice was fed with simultaneous glucose load. In marked contrast to the findings with nondiabetic and NIDDM model rats S hernandifolia showed significant hypoglycemic effect (p < 0.05-0.006) in both the stages (fed simultaneously with, and 30 min before the glucose load) of prandial states of the IDDM model rats. The results indicated that these three plants have interesting possibilities as a source of oral hypoglycemic agents.
The structure of the Vibrio mimicus W-26768 O-antigen polysaccharide has been investigated by sugar and methylation analyses, Smith degradation, and NMR spectroscopy. It is proposed that it is composed of chains of beta-(1-->4)-linked 3,6-dideoxy-3-[(R)-3-hydroxybutyramido]-D-glucopyranosyl residues (D-Qui(p)3NR), approximately 60% of which are substituted in the 2-position with 2-acetamido-2-deoxy-alpha-D-galactopyranosyl groups. The polysaccharide does not seem to be composed of oligosaccharide repeating units but has a less regular structure, schematically indicated below. [formula: see text]
The structure of the Vibrio fluvialis M-940 O-antigen polysaccharide has been investigated by sugar and methylation analyses, specific degradations, NMR spectroscopy, and mass spectrometry. It is proposed that it consists of a heptasaccharide unit having the following structure. alpha-L-Rhap-(1-->2)-alpha-L-Fucp-(1-->2)-alpha-D-Galp-(1--> 2)-alpha-L-Fucp- (1-->3)-beta-D-GlcpA-(1-->4)-alpha-L-Rhap-(1-->3)-beta-D-Glc pNAc-(1--> The heptasaccharide is most probably linked to the 3-position of an alpha-D-galactopyranosyl residue in the core.
Extracts of Momordica charantia fruit pulp, seed, and whole plant were tested for their hypoglycemic effects on normal and diabetic rat models. The results show that during the oral glucose tolerance test the peak blood glucose values in rats are obtained much earlier (15-45 min) than in human subjects (around 60 min). Pulp juice of M. charantia lowered fasting blood glucose levels in normal rats (p < 0.05 at 120 min); the effect was more pronounced with the saponin-free methanol extract of the pulp juice (p < 0.05 at 60 min and p < 0.01 at 120 min). The pulp juice also had a significant hypoglycemic effect in the glucose-fed normal rats when the extract was fed 45 minutes before the oral glucose load [percentage increments over basal value (M +/- SE): 85 +/- 10 in the control group vs. 54 +/- 7 in the pulp juice group, p < 0.01]. In the IDDM model rats the pulp juice had no significant effect on blood glucose levels either in fasting or postprandial states. In the NIDDM model rats the saponin-free methanol extract of juice produced a significant hypoglycemic effect both in fasting (p < 0.05 at 120 min) and in postprandial states (sum of percentage increments over basal value: 140 +/- 26 in the control vs. 71 +/- 7 in the pulp juice group, p < 0.05). Methanol extracts of seed and of whole plant, and saponin-free methanol extract of whole plant produced no hypoglycemic effects in normal or IDDM model rats either in fasting or in postprandial states.(ABSTRACT TRUNCATED AT 250 WORDS)
Six different prepared mutant strains of Shigella dysenteriae type 1 with various combinations of 'core' plasmids of 140, 6, and 2 Mdal, were cultivated separately and their lipopolysaccharide (LPS) samples were isolated, which on delipidation afforded polysaccharides and oligosaccharides. The LPS and prepared O-antigen polysaccharides were subjected to acid hydrolysis, and the constituent sugars were analysed by paper chromatography and gas liquid chromatography (GLC), using CP Sil 8 CB fused silica capillary column equipped with a flame ionization detector. The mutant strains, harbouring the 6 Mdal plasmid, contained rhamnose, galactose, and N-acetyl glucosamine in their O-antigen polysaccharides with a minor variation in the relative proportions of these sugar constituents as compared to those of the control strain. The sugar composition of the O-antigen polysaccharides prepared from the mutant stains, without the 6 Mdal plasmid but containing 2 or 140 Mdal plasmid, contained galactose and N-acetyl glucosamine but no rhamnose. However, mutant strains with none of the core plasmids contained traces of rhamnose and were devoid of N-acetyl glucosamine, but contained heptose. These results suggest that 6 Mdal plasmid is essentially required for the complete synthesis of O-antigen polysaccharides. However, the 140 and 2 Mdal plasmids might also have an association with synthesis of carbohydrate composition of the O-antigen in S. dysenteriae type 1.
Vibrio mimicus strains W-26768 (stool isolate) and N-1301 (environmental isolate) and Vibrio fluvialis strains AA-18239 (stool isolate) and M-940 (environmental isolate) were studied for virulence properties and lipopolysaccharide composition. All four strains were hydrophobic, produced cytotoxin, adhered to HeLa cells and showed mannose-sensitive agglutination of guinea pig erythrocyte. The strains were negative for enterotoxin production and were mostly susceptible to the common antibiotics. The environmental and clinical isolates of both species were antigenically unrelated to each other. Lipopolysaccharide antigen analysis showed that O-antigen polysaccharides of two strains of V. fluvialis and two strains of V. mimicus differed with respect to the sugar components. Only LPS from V. mimicus W-26768 showed the presence of an unusual sugar, 3,6-dideoxy-3-acetamido-hexose. The sugar compositions of these V. fluvialis and V. mimicus strains differed from those of previously reported Japanese isolates. These differences probably reflect differences in the serogroup of strains.
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