Javed Iqbal - Academia.edu (original) (raw)

Papers by Javed Iqbal

Research paper thumbnail of Synthesis of small cyclic peptides constrained with 3-(3-aminomethylphenyl)propionic acid linkers using free radical-mediated macrocyclization

Tetrahedron Letters, 2005

In this letter, we report that small peptides (di-and tri-) having a 3-bromobenzyl group at the C... more In this letter, we report that small peptides (di-and tri-) having a 3-bromobenzyl group at the C-termini and an acryloyl group at the N-termini undergo an efficient Bu 3 SnH-AIBN mediated intramolecular free radical cyclization to afford cyclic peptides in good yields. We also propose that these cyclizations are occurring via a pre-organized acyclic structure dictated by a reverse turn (c/b-turn).

Research paper thumbnail of A concise asymmetric route to the antibiotic macrolides patulolide A and pyrenophorin

Tetrahedron Letters, 2006

In this letter, we describe an enantiospecific route to patulolide A and pyrenophorin through the... more In this letter, we describe an enantiospecific route to patulolide A and pyrenophorin through the synthesis of known protected seco acid precursors starting from commercially available (S)-ethyl lactate.

Research paper thumbnail of Microwave-Induced, InCl 3 -CatalyzedFerrier Rearrangement of Acetyl­glycals: Synthesis of 2,3-UnsaturatedGlycopyranosides

Synlett, 2003

Carbohydrates Carbohydrates U 0500 Microwave-Induced, InCl 3-Catalyzed Ferrier Rearrangement of A... more Carbohydrates Carbohydrates U 0500 Microwave-Induced, InCl 3-Catalyzed Ferrier Rearrangement of Acetylglycals: Synthesis of 2,3-Unsaturated C-Glycosides.-InCl 3 is reported as an efficient catalyst in the presence of different silanes.

Research paper thumbnail of Recent Advances in the Synthesis of Some Bioactive Peptides and Peptidomimetics

Current Pharmaceutical Biotechnology, 2006

This review focuses on the synthetic progress of some naturally occurring cyclic peptides and dep... more This review focuses on the synthetic progress of some naturally occurring cyclic peptides and depsipeptides apart from the development of peptidomimetics incorporating unnatural amino acids that have not been covered in the earlier reviews.

Research paper thumbnail of Novel thieno oxazine analogues as antihyperglycemic and lipid modulating agents

Bioorganic & Medicinal Chemistry Letters, 2003

Oxazine derivatives Oxazine derivatives R 0595 Novel Thieno Oxazine Analogues as Antihyperglycemi... more Oxazine derivatives Oxazine derivatives R 0595 Novel Thieno Oxazine Analogues as Antihyperglycemic and Lipid Modulating Agents.-A series of phenylacetic acid and α-hydroxypropionic acid derivatives [(I) and (II)] is synthesized. Compound (IIc), the most potent one, is a dual activator of

Research paper thumbnail of Dual PPAR-α and -γ activators derived from novel benzoxazinone containing thiazolidinediones having antidiabetic and hypolipidemic potential

Bioorganic & Medicinal Chemistry, 2006

2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their P... more 2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their PPAR-alpha and -gamma dual activation. DRF-2519, a compound obtained through SAR of TZD derivatives of benzoxazinone, has shown potent dual PPAR activation. In ob/ob mice, it showed better efficacy than the comparator molecules. In fat fed rat model, it showed significant improvement in lipid parameters, which was better than fibrates.

Research paper thumbnail of Distribution, correlation and risk assessment of selected metals in urban soils from Islamabad, Pakistan

Journal of Hazardous Materials, 2011

Urban soil samples were analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr and Zn by ... more Urban soil samples were analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr and Zn by atomic absorption spectrophotometric method. Multivariate statistical approach was used to study the apportionment of selected metals in the soil samples during summer and winter. The degree of contamination along with the geoaccumulation index, enrichment factor and contamination factor was also evaluated. In water-extract of the soil samples, relatively higher levels were noted for Na, Ca, K, Fe, Mg, and Pb with average concentrations of 56.38, 33.82, 12.53, 7.127, 5.994, and 1.045mg/kg during summer, while the mean metal levels during winter were 76.45, 38.05, 3.928, 0.627, 8.726, and 0.878mg/kg, respectively. In case of acid-extract of the soils, Ca, Fe, Mg, Na, K, Mn and Sr were found at 27,531, 12,784, 2769, 999.9, 737.9, 393.5, and 115.1mg/kg, during summer and 23,386, 3958, 3206, 254.6, 1511, 453.6, and 53.30mg/kg, during winter, respectively. Most of the metals showed random distribution with diverse correlations in both seasons. Principal component analysis and cluster analysis revealed significant anthropogenic intrusions of Cd, Pb, Co, Cr, Cu, Li, Zn and Na in the soils. Geoaccumulation indices and contamination factors indicated moderate to heavy contamination for Pb and Cd in the soils, while enrichment factor exhibited significant enrichment (EF>5) of Cd, Pb, Ca, Co, Li, Mn and Zn by anthropogenic activities. Overall, on the average basis, considerable degree of contamination (C(deg)>16) was observed in both seasons, although it was higher in winter. Present metal levels were also compared with those reported from other areas around the world.

Research paper thumbnail of Synthesis of small cyclic peptides constrained with 3-(3-aminomethylphenyl)propionic acid linkers using free radical-mediated macrocyclization

Tetrahedron Letters, 2005

In this letter, we report that small peptides (di-and tri-) having a 3-bromobenzyl group at the C... more In this letter, we report that small peptides (di-and tri-) having a 3-bromobenzyl group at the C-termini and an acryloyl group at the N-termini undergo an efficient Bu 3 SnH-AIBN mediated intramolecular free radical cyclization to afford cyclic peptides in good yields. We also propose that these cyclizations are occurring via a pre-organized acyclic structure dictated by a reverse turn (c/b-turn).

Research paper thumbnail of A concise asymmetric route to the antibiotic macrolides patulolide A and pyrenophorin

Tetrahedron Letters, 2006

In this letter, we describe an enantiospecific route to patulolide A and pyrenophorin through the... more In this letter, we describe an enantiospecific route to patulolide A and pyrenophorin through the synthesis of known protected seco acid precursors starting from commercially available (S)-ethyl lactate.

Research paper thumbnail of Microwave-Induced, InCl 3 -CatalyzedFerrier Rearrangement of Acetyl­glycals: Synthesis of 2,3-UnsaturatedGlycopyranosides

Synlett, 2003

Carbohydrates Carbohydrates U 0500 Microwave-Induced, InCl 3-Catalyzed Ferrier Rearrangement of A... more Carbohydrates Carbohydrates U 0500 Microwave-Induced, InCl 3-Catalyzed Ferrier Rearrangement of Acetylglycals: Synthesis of 2,3-Unsaturated C-Glycosides.-InCl 3 is reported as an efficient catalyst in the presence of different silanes.

Research paper thumbnail of Recent Advances in the Synthesis of Some Bioactive Peptides and Peptidomimetics

Current Pharmaceutical Biotechnology, 2006

This review focuses on the synthetic progress of some naturally occurring cyclic peptides and dep... more This review focuses on the synthetic progress of some naturally occurring cyclic peptides and depsipeptides apart from the development of peptidomimetics incorporating unnatural amino acids that have not been covered in the earlier reviews.

Research paper thumbnail of Novel thieno oxazine analogues as antihyperglycemic and lipid modulating agents

Bioorganic & Medicinal Chemistry Letters, 2003

Oxazine derivatives Oxazine derivatives R 0595 Novel Thieno Oxazine Analogues as Antihyperglycemi... more Oxazine derivatives Oxazine derivatives R 0595 Novel Thieno Oxazine Analogues as Antihyperglycemic and Lipid Modulating Agents.-A series of phenylacetic acid and α-hydroxypropionic acid derivatives [(I) and (II)] is synthesized. Compound (IIc), the most potent one, is a dual activator of

Research paper thumbnail of Dual PPAR-α and -γ activators derived from novel benzoxazinone containing thiazolidinediones having antidiabetic and hypolipidemic potential

Bioorganic & Medicinal Chemistry, 2006

2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their P... more 2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their PPAR-alpha and -gamma dual activation. DRF-2519, a compound obtained through SAR of TZD derivatives of benzoxazinone, has shown potent dual PPAR activation. In ob/ob mice, it showed better efficacy than the comparator molecules. In fat fed rat model, it showed significant improvement in lipid parameters, which was better than fibrates.

Research paper thumbnail of Distribution, correlation and risk assessment of selected metals in urban soils from Islamabad, Pakistan

Journal of Hazardous Materials, 2011

Urban soil samples were analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr and Zn by ... more Urban soil samples were analyzed for Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr and Zn by atomic absorption spectrophotometric method. Multivariate statistical approach was used to study the apportionment of selected metals in the soil samples during summer and winter. The degree of contamination along with the geoaccumulation index, enrichment factor and contamination factor was also evaluated. In water-extract of the soil samples, relatively higher levels were noted for Na, Ca, K, Fe, Mg, and Pb with average concentrations of 56.38, 33.82, 12.53, 7.127, 5.994, and 1.045mg/kg during summer, while the mean metal levels during winter were 76.45, 38.05, 3.928, 0.627, 8.726, and 0.878mg/kg, respectively. In case of acid-extract of the soils, Ca, Fe, Mg, Na, K, Mn and Sr were found at 27,531, 12,784, 2769, 999.9, 737.9, 393.5, and 115.1mg/kg, during summer and 23,386, 3958, 3206, 254.6, 1511, 453.6, and 53.30mg/kg, during winter, respectively. Most of the metals showed random distribution with diverse correlations in both seasons. Principal component analysis and cluster analysis revealed significant anthropogenic intrusions of Cd, Pb, Co, Cr, Cu, Li, Zn and Na in the soils. Geoaccumulation indices and contamination factors indicated moderate to heavy contamination for Pb and Cd in the soils, while enrichment factor exhibited significant enrichment (EF>5) of Cd, Pb, Ca, Co, Li, Mn and Zn by anthropogenic activities. Overall, on the average basis, considerable degree of contamination (C(deg)>16) was observed in both seasons, although it was higher in winter. Present metal levels were also compared with those reported from other areas around the world.