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Dive into the research topics where Arnab K. Ojha is active.

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Featured researches published by Arnab K. Ojha.


Carbohydrate Research | 2008

Structural assignment of a heteropolysaccharide isolated from the gum of Cochlospermum religiosum (Katira gum)

Arnab K. Ojha; Debabrata Maiti; Krishnendu Chandra; Subhas Mondal; Debsankar Das Sadhan K. Roy; Kaushik Ghosh; Syed S. Islam

A heteropolysaccharide isolated from the gum (Katira) of Cochlospermum religiosum was found to consist of D-galactose, D-galacturonic acid and L-rhamnose in a molar ratio 2:1:3. Structural assignment of the polysaccharide was carried out using total acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation and NMR studies (1H, 13C, DQF-COSY, TOCSY, NOESY, HMBC and HSQC) and the repeating unit of the polysaccharide was established as [Formula: see text].


Carbohydrate Research | 2008

Structural investigation of a polysaccharide (Fr. I) isolated from the aqueous extract of an edible mushroom, Volvariella diplasia

Kaushik Ghosh; Krishnendu Chandra; Sadhan K. Roy; Subhas Mondal; Debabrata Maiti; Debsankar Das; Arnab K. Ojha; Syed S. Islam

A water-soluble polysaccharide, (Fr. I) isolated from the aqueous extract of an edible mushroom, Volvariella diplasia, is composed of D-glucose, D-mannose, and D-galactose in a molar ratio 3:1:1. Compositional analysis, methylation analysis, periodate oxidation study, Smith degradation, and NMR studies (1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC) revealed the presence of the following repeating unit in the polysaccharide: [Formula: see text].


Carbohydrate Research | 2009

Chemical analysis of a polysaccharide of unripe (green) tomato (Lycopersicon esculentum)

Krishnendu Chandra; Kaushik Ghosh; Arnab K. Ojha; Syed S. Islam

A polysaccharide (PS-I) isolated from the aqueous extract of the unripe (green) tomatoes (Lycopersicon esculentum) consists of D-galactose, D-methyl galacturonate, D-arabinose, L-arabinose, and L-rhamnose. Structural investigation of the polysaccharide was carried out using total acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of above-mentioned experiments the structure of the repeating unit of the polysaccharide (PS-I) was established as: [structure: see text].


Carbohydrate Research | 2009

Structural identification and cytotoxic activity of a polysaccharide from the fruits of Lagenaria siceraria (Lau)

Kaushik Ghosh; Krishnendu Chandra; Arnab K. Ojha; Siddik Sarkar; Syed S. Islam

A water-soluble polysaccharide, isolated from fruiting bodies of Lagenaria siceraria, is composed of methyl-alpha-d-galacturonate, 3-O-acetyl methyl-alpha-d-galacturonate, and beta-d-galactose in a ratio of nearly 1:1:1. Compositional analysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, 2D-COSY, TOCSY, NOESY, HMQC, and HMBC) revealed the presence of the following repeating unit in the polysaccharide: [carbohydrate structure: see text] This polysaccharide showed cytotoxic activity in vitro against human breast adenocarcinoma cell line (MCF-7).


Carbohydrate Research | 2010

Glucans from the alkaline extract of an edible mushroom, Pleurotus florida, cv Assam Florida: isolation, purification, and characterization

Arnab K. Ojha; Krishnendu Chandra; Kaushik Ghosh; Syed S. Islam

Three different glucans (PS-I, PS-II, and PS-III) were isolated from the alkaline extract of the fruiting bodies of an edible mushroom Pleurotus florida, cultivar Assam Florida. On the basis of total acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR experiments ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these polysaccharides was established as follows: [Formula: see text].


Carbohydrate Research | 2008

Chemical analysis of a new fucoglucan isolated from an edible mushroom, Termitomyces robustus.

Subhas Mondal; Krishnendu Chandra; Debabrata Maiti; Arnab K. Ojha; Debsankar Das; Sadhan K. Roy; Kaushik Ghosh; Indranil Chakarborty; Syed S. Islam

A water-soluble fucoglucan, isolated from alkali-treated edible mushroom, Termitomyces robustus, consists of L-fucose and D-glucose in a molar proportion of 1:4. Structural investigation of the polysaccharide was carried out by using total hydrolysis, methylation analysis, and periodate oxidation followed by GLC-MS, and the final structure was determined using NMR experiments (1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above experiments it is concluded that the following repeating unit is present in the polysaccharide: [Formula: see text].


Carbohydrate Research | 2008

NMR and MALDI-TOF analysis of a water-soluble glucan from an edible mushroom, Volvariella diplasia.

Kaushik Ghosh; Krishnendu Chandra; Arnab K. Ojha; Syed S. Islam

A polysaccharide (Fr. II) has been isolated from the hot aqueous extract of the fruit bodies of an edible mushroom, Volvariella diplasia. The polysaccharide contains glucose only. On the basis of total acid hydrolysis, methylation analysis, NMR studies ((1)H, (13)C, 2D-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC), and MALDI-TOFMS analysis, the structure of the repeating unit of the polysaccharide was established as formula see text.


Carbohydrate Research | 2008

NMR and MALDI-TOFMS analysis of a heteroglycan isolated from hot water extract of edible mushroom, Volvariella bombycina.

Debsankar Das; Debabrata Maiti; Krishnendu Chandra; Subhas Mondal; Arnab K. Ojha; Sadhan K. Roy; Kaushik Ghosh; Syed S. Islam

A water-soluble polysaccharide, isolated from the hot aqueous extract of an edible mushroom, Volvariella bombycina, consists of d-glucose, d-mannose, and d-galactose in a molar ratio 2:1:1. On the basis of total hydrolysis, methylation analysis, periodate oxidation, and NMR studies ((1)H, (13)C, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC), and MALDI-TOFMS analysis, the repeating unit of the polysaccharide is established as [table in text].


Carbohydrate Research | 2008

Isolation and characterization of a heteroglycan from the fruits of Astraeus hygrometricus

Debabrata Maiti; Krishnendu Chandra; Subhas Mondal; Arnab K. Ojha; Debsankar Das; Sadhan K. Roy; Kaushik Ghosh; Indranil Chakraborty; Syed S. Islam

A water-soluble polysaccharide was isolated from an alkaline extract of the fruits of the ectomycorrhizal fungus, Astraeus hygrometricus. It was found to contain D-mannose, D-glucose, and L-fucose in a molar ratio of 1:2:1. On the basis of total hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies (1H, 13C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC) the structure of the repeating unit of the polysaccharide was established as [Formula: see text]


Carbohydrate Research | 2009

Structural analysis of an immunoenhancing heteropolysaccharide isolated from the green (unripe) fruits of Solenum melongena (Brinjal)

Arnab K. Ojha; Krishnendu Chandra; Kaushik Ghosh; Bibhas Bhunia; Tapas K. Maiti; Syed S. Islam

A water-soluble polysaccharide (SMPS) isolated from the aqueous extract of the green (unripe) fruits of Solenum melongena (Brinjal) contains D-galactose, D-methyl galacturonate, 3-O-acetyl D-methyl galacturonate, and L-arabinose in a molar proportion of nearly 1:1:1:1. Structural investigation of the polysaccharide was carried out using total acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above experiments the structure of the repeating unit of the polysaccharide (SMPS) was established as -->5)-alpha-L-Araf-(1-->4)-beta-D-Galp-(1-->2)-alpha-D-3-O-Ac-GalpA6Me-(1-->2)alpha-D-galpA6Me-(1--> This molecule showed splenocyte and thymocyte activations.

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