M. Mosihuzzaman

Variation of carbohydrate composition of two forms of fruit from jack tree (Artocarpus heterophyllus L.) with maturity and climatic conditions

Abstract Soft and firm varieties of jackfruit of three stages of maturity (7–8, 10–12, and 14–16 weeks), harvested from the central, western and eastern parts of Bangladesh, were analysed. The dry matter content of perianth and seed of the soft and firm varieties increased from 10.0 to 32.0% and 19.0 to 52.0%, respectively, while the ash content decreased from 5.7 to 2.0% and 4.9 to 1.5%, respectively, on a dry matter basis. The free sugars of jackfruit samples increased with maturity from 1.5 to 10.5% and 1.4 to 5.2% of their dry matter for the soft and firm varieties, respectively. In all cases varying proportions of glucose, fructose and sucrose were the major sugar constituents. The starch content of the perianth samples increased from 7.8 to 47.0% and from 9.0 to 50.5%, on a dry matter basis for the soft and firm varieties, respectively, whereas, that for seed increased up to 65.0 and 59.0%, respectively. Microscopic examination of the samples showed the perianth to contain thin-walled cells packed with starch granules, some organized into distinct clusters. From both the chemical and histological studies, it appeared that the starch content of both perianth and seed of soft and firm varieties of jackfruit samples gradually increased with the increase of maturity. The total dietary fibre varied from 42.0 to 55.0% in the perianth. However, that of seed changed very little. The results show that the starch and total dietary fibre contents of jackfruit are higher than those of other fruits and vegetables of Bangladesh. ©

An unusual (4-O-methyl-d-glucurono)-d-xylan isolated from the mucilage of seeds of the quince tree (Cydonia oblonga)

Abstract The major water-soluble polysaccharide in the mucilage of the seeds of the quince tree, Cydonia oblonga , is a partially O -acetylated(4- O -methyl- d -glucurono)- d -xylan having an exceptionally high proportion of glycuronic acid residues. The 4- O -methyl-α- d -glucopyranosyluronic and α- d -glucopyranosyluronic acid groups are linked to positions 2 of a (1 → 4)-β- d -xylan that is somewhat branched through the 2-positions. The O -acetyl groups are linked to the β- d -xylopyranosyl residues. The molar proportions of d -Xyl, 4- O -Me- d -GlcA, d -GlcA, and O -Ac are ∼ 2:0.8:0.2:1.

Hypoglycaemic and antioxidant activities of Ficus racemosa Linn. fruits

The effects of Ficus racemosa Linn. fruit extract and fraction on fasting serum glucose levels of normal, type 1 and type 2 diabetic model rats are presented. The aqueous 80% EtOH extract and its water soluble fraction of F. racemosa fruit did not show any serum glucose lowering effect on non-diabetic and type 2 diabetic rats at the fasting condition, whereas the extract showed significant hypoglycaemic effect on the type 1 diabetic model rats. Both the extract and fraction were consistently active in both non-diabetic and types 1 and 2 diabetic model rats when fed simultaneously with glucose load. On the contrary, they were ineffective in lowering blood glucose levels when fed 30 min prior to glucose load. The 1-BuOH soluble part of the ethanol extract exhibited significant antioxidant activity in DPPH free radical scavenging assay. 3-O-(E)-Caffeoyl quinate (1) was isolated for the first time from this plant, which also showed significant antioxidant activity.

Structural studies of the Vibrio mimicus W-26768 O-antigen polysaccharide.

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]

Free radical scavenging phenylethanoid glycosides from Leucas indica Linn.

A new phenylethanoid glycoside, 2-(3,4-dihydroxyphenyl)-ethyl-O-α-L-rhamnopyranosyl-(1 → 3)-O-α-L-rhamnopyranosyl-(1 → 6)-4-O-E-feruloyl-β-D-glucopyranoside (3-O-methyl poliu-moside, 1) along with five known phenylethanoid glycosides (2–6) were isolated from the aerial parts of Leucas indica Linn. The structure of compound 1 has been elucidated on the basis of spectral data. Compounds 1–6 exhibited significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay method. These compounds were also found to be moderate inhibitors of xanthine oxidase (XO) enzyme.

Phosphodiesterase-I inhibitor quinovic acid glycosides from Bridelia ndellensis.

Quinovic acid-3-O-α-l-rhamnopyranoside (1), quinovic acid-3-O-β-d-fucopyranoside (2), quinovic acid-3-O-β-d-glucopyranosyl (1 → 4)-β-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.

Structural studies of Vibrio fluvialis M-940 O-antigen polysaccharide

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.

Lipopolysaccharide Composition and Virulence Properties of Clinical and Environmental Strains of Vibrio fluvialis and Vibrio mimicus

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 anti‐genically 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.

Analysis of free sugar and dietary fibre of some vegetables of Bangladesh

Abstract Free sugar and dietary fibre (DF) contents and compositions of the edible parts of seven vegetables of Bangladesh were determined. Total free sugars in the fresh vegetables varied from 0.2 to 1.8% whereas dietary fibre ranged from 3.4 to 6.1%. Among the seven vegetables, elongated bean had the best combination of low free sugar and high dietary fibre. Glucose was the main constituent of the total polysaccharide of the vegetables but galactose was the major component of the soluble DF.

Novel flavonoid glycosides from the bulbs of Urginea indica Kunth.

Three novel flavonoid glycosides, 5,6-dimethyoxy-3′,4′′-dioxymethylene-7-O-(6′′-β-D-glucopyranosyl-β-D-glucopyranosyl) flavanone (1), 5,4′-dihydroxy-3-O-α-L-rhamnopyranosyl-6-C-glucopyranosyl-7-O-(6′′-para-coumaroyl-β-D-glucopyranosyl) flavone (2) and 5,4′-dihydroxy-3-O-(2′′′′′-β-glucopyranosyl-α-L-rhamnopyranosyl)-6-C-glucopyranosyl-7-O-(6′′-para-coumaroyl-β-D-glucopyranosyl) flavone (3) were isolated from the 1-butanol soluble fraction of the bulbs of the plant Urginea indica (Indian squill). The structures of the compounds were elucidated on the basis of spectral analysis, including homo- and heteronuclear correlation NMR experiments (COSY, NOESY, HSQC and HMBC) and mass spectra.