M Iqbal Choudhary

Publications (242)418.11 Total impact

• Article: Benzimidazole, coumrindione and flavone derivatives as alternate UV laser desorption ionization (LDI) matrices for peptides analysis.

  Syed Ghulam Musharraf, Aisha Bibi, Najia Shahid, Muhammad Najam-Ul-Haq, Nida Ambreen, Momin Khan, Khalid Mohammed Khan, M Iqbal Choudhary, Atta Ur Rahman
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  ABSTRACT: BACKGROUND: Matrix-assisted laser desorption/ionization (MALDI) is a soft ionization mass spectrometric technique, allowing the analysis of bio-molecules and other macromolecules. The matrix molecules require certain characteristic features to serve in the laser desorption/ionization mechanism. Therefore, only a limited number of compounds have been identified as ultraviolet- laser desorption/ionization (UV-LDI) matrices. However, many of these routine matrices generate background signals that useful information is often lost in them. We have reported flavones, coumarindione and benzimidazole derivatives as alternate UV-LDI matrices. RESULTS: Thirty one compounds have been successfully employed by us as matrices for the analysis of low molecular weight (LMW) peptides (up to 2000 Da). Two peptides, bradykinin and renin substrate tetra-decapeptide were analyzed by using the newly developed matrices. The MS measurements were made after mixing the matrix solution with analyte by using dried droplet sample preparation procedures. The synthesized matrix materials showed better S/N ratios and minimal background signals for low mass range. Furthermore, pico molar concentrations of [Glu1]-fibrinopeptide B human could be easily analyzed with these matrices. Finally, BSA-digest was analyzed and identified through database search against Swiss-Prot by using Mascot. CONCLUSIONS: These results validate the good performance of the synthesized UV-laser desorption/ionization (LDI) matrices for the analysis of low molecular weight peptides.
  Chemistry Central Journal 04/2013; 7(1):77. · 3.28 Impact Factor
• Article: New Inhibitors of ROS Generation and T-Cell Proliferation from Myrtus communis.

  M Iqbal Choudhary, Noureen Khan, Manzoor Ahmad, Sammer Yousuf, Hoong-Kun Fun, Samreen Soomro, M Asif, M Ahmed Mesaik, Farzana Shaheen
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  ABSTRACT: Phytochemical investigation on Myrtus communis Linn. afforded myrtucommuacetalone (1) with an unprecedented carbon skeleton and a new phloroglucinol-type compound, myrtucommulone M (2), along with four known constituents 3-6. Their structures were established by extensive analyses of NMR and mass spectral data as well as by single-crystal X-ray diffraction studies. These constituents were evaluated for their ability to modulate the immune response, based on their effects on various components of immune system. Compounds 1 and 5 exhibited significant inhibitory effect against nitric oxide (NO(•)) production. Compound 1 also exhibited significant antiproliferative activity (IC50 < 0.5 μg/mL) against T-cell proliferation. Myricetin (3) exerted a significant inhibition (IC50 = 1.6 μg/mL) on zymosan-stimulated whole blood phagocytes ROS production. Compounds 1 and 3 were active against PMA-stimulated ROS generation.
  Organic Letters 04/2013; · 5.86 Impact Factor
• Article: Synthesis of 2-Methoxybenzoylhydrazone and Evaluation of their Antileishmanial Activity

  Mohd Syukri Baharudin, Muhammad Taha, Nor Hadiani Ismail, Khalid Mohammed Khan, Faridahanim Mohd Jaafar, Samreen, Salman Siddiqui, M. Iqbal Choudhary
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  ABSTRACT: Compounds 1-25 showed varying degree of antileishmanial activities with IC50 values ranging between 1.95 – 88.56 M. Compounds 2, 10, and 11 (IC50 = 3.29 ± 0.07 M, 1.95 ± 0.04 M, and 2. 49 ± 0.03 M, respectively) were found to be more active than standard pentamidine (IC50 = 5.09 ± 0.04 M). Compounds 7 (IC50 = 7.64 ± 0.1 M), 8 (IC50 = 13.17 ± 0.46 M), 18 (IC50 = 13.15 ± 0.02 M), and 24 (IC50 = 15.65 ± 0.41 M) exhibited good activities. Compounds 1, 3, 4, 5, 9, 12, 15, 18, and 19 were found to be moderately active. Compounds 13, 14, 16, 17, 20-25 showed weak activities with IC50 values ranging between 57-88 M.
  Bioorganic & Medicinal Chemistry Letters 03/2013; · 2.55 Impact Factor
• Article: Microbial transformation of anti-cancer wsteroid exemestane and cytotoxicity of its metabolites against cancer cell lines.

  Elias Baydoun, Marium Bibi, Muhammad Asif Iqbal, Atia-Tul Wahab, Dina Farran, Colon Smith, Samina A Sattar, Atta-Ur Rahman, M Iqbal Choudhary
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  ABSTRACT: BACKGROUND: Microbial transformation of steroids has been extensively used for the synthesis of steroidal drugs, that often yield novel analogues, which are not easy to obtain by chemical synthesis. We report here fungal transformation of a synthetic steroidal drug, exemestane, used for the treatment of breast cancer and function through inhibition of aromatase enzyme. RESULTS: Microbial transformation of anti-cancer steroid, exemestane (1), was investigated by using two filamentous fungi. Incubation of 1 with fungi Macrophomina phaseolina, and Fusarium lini afforded three new, 11alpha-hydroxy-6-methylene-androsta-1,4-diene-3,17-dione (2), 16beta, 17beta-dihydroxy-6-methylene-androsta-1,4-diene-3-one (3), and 17beta-hydroxy-6-methylene-androsta-1,4-diene-3,16-dione (4), and one known metabolites, 17beta-hydroxy-6-methylene-androsta-1,4-diene-3-one (5). Their structures were deduced spectroscopically. Compared to 1 (steroidal aromatase inactivator), the transformed metabolites were also evaluated for cytotoxic activity by using a cell viability assay against cancer cell lines (Hela and PC3). Metabolite 2 was found to be moderately active against both the cell lines. CONCLUSIONS: Biotransformation of exemestane (1) provides an efficient method for the synthesis of new analogues of 1. The metabolites were obtained as a result of reduction of double bond and hydroxylation. The transformed product 2 exhibited a moderate activity against cancer cell lines (Hela and PC3). These transformed products can be studied for their potential as drugs candidates.
  Chemistry Central Journal 03/2013; 7(1):57. · 3.28 Impact Factor
• Article: Biotransformation of clerodane diterpenoids by Rhizopus stolonifer and antibacterial activity of resulting metabolites.

  M Iqbal Choudhary, Mohammad Yasin Mohammad, Syed Ghulam Musharraf, Ismail Onajobi, Akhtar Mohammad, Itrat Anis, Muhammad Raza Shah, Atta-Ur-Rahman
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  ABSTRACT: Microbial transformation of clerodane lactone (1) by a plant pathogen fungus, Rhizopus stolonifer, resulted in the production of metabolites 3 and 4. While incubation of clerodane methyl ester (2) by R. stolonifer yielded metabolites 5-8. The structures of the transformed products were determined by the spectroscopic techniques and compounds 4, 7 and 8 were found. The antibacterial activity of clerodane diterpenoids 1 and 2 and their metabolites 3-8 were also studied. The metabolites 3-7 showed moderate activities against both Gram-positive and Gram-negative organisms. While metabolite 8 showed a moderate activity against Gram-positive organisms and a good activity against Gram-negative organisms.
  Phytochemistry 03/2013; · 3.35 Impact Factor
• Article: (E)-Ethyl 2-anilino-5-[3-(dimethyl-amino)-acrylo-yl]-4-phenyl-thio-phene-3-carboxyl-ate.

  Yahia Nasser Mabkhot, Assem Barakat, Fatima Alatibi, M Iqbal Choudhary, Sammer Yousuf
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  ABSTRACT: In the title compound, CHNOS, the phenyl rings form dihedral angles of 55.65 (11) and 79.60 (11)° with the plane of the thio-phene ring. The mol-ecular conformation is stabilized by an intra-molecular N-H⋯O hydrogen bond, generating an (6) ring motif. In the crystal, centrosymmetrically related mol-ecules are linked into dimers by two pairs of C-H⋯O inter-actions.
  Acta Crystallographica Section E Structure Reports Online 03/2013; 69(Pt 3):o351. · 0.35 Impact Factor
• Article: Hepatoprotection by chemical constituents of the marine brown alga Spatoglossum variabile: A relation to free radical scavenging potential.

  Talat Makhmoor, Suad Naheed, Shahida Shujaat, Saima Jalil, Safdar Hayat, M Iqbal Choudhary, Khalid M Khan, Junaid M Alam, Samina Nazir
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  ABSTRACT: Context: In the course of searching hepatoprotective agents from natural sources, the protective effect of chemical constituents of the marine brown alga Spatoglossum variabile Figaro et DE Notar (Dictyoaceae) against CCl(4)-induced liver damage in Wistar rats was investigated. The compounds were first investigated for in vitro radical scavenging potential and were also tested for β-glucuronidase inhibition to further explore the relationship between hepatoprotection and antiradical potential. Methods: The compounds cinnamic acid esters 1 and 2 and aurone derivatives 3 and 4 were first investigated for in vitro radical scavenging potential against 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), and superoxide anion radicals. In vivo hepatoprotective studies were performed in seven groups (n = 6) of Wistar rats. The test groups were pretreated with compounds (10 mg/kg body weight, po) orally for 30 min before the intraperitoneal administration of a dose of 20% CCl(4) diluted with dietary cooking oil. Moreover, compounds were also tested for β-glucuronidase inhibition to explore the relationship between hepatoprotection and radical scavenging potential. Results: The test compounds 1-4 were found to exhibit antiradical activity against 1,1-diphenyl-2-picrylhydrazyl radicals with IC(50) values ranging between 54 and 138 µM, whereas aurone derivatives 3 and 4 additionally exhibited superoxide anion scavenging effects with IC(50) values of 95 and 87 µM, respectively. In addition, these compounds were found to be weak inhibitors of xanthine oxidase (IC(50) ≥1000 µM). In animal model, pretreatment with compounds 2-4 significantly blocked the CCl(4)-induced increase in the levels of the serum biochemical markers. Conclusion: It appears that the hepatoprotection afforded by these compounds was mainly due to their radical scavenging activity that protected the cells from the free radicals generated by CCl(4)-induced hepatotoxicity.
  Pharmaceutical Biology 03/2013; 51(3):383-90. · 0.88 Impact Factor
• Article: Fungal transformation of cedryl acetate and α-glucosidase inhibition assay, quantum mechanical calculations and molecular docking studies of its metabolites.

  Sadia Sultan, M Iqbal Choudhary, Shamsun Nahar Khan, Urooj Fatima, Muhammad Atif, Rahat Azhar Ali, Atta-Ur- Rahman, M Qaiser Fatmi
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  ABSTRACT: The fungal transformation of cedryl acetate (1) was investigated for the first time by using Cunninghamella elegans. The metabolites obtained include, 10β-hydroxycedryl acetate (3), 2α, 10β-dihydroxycedryl acetate (4), 2α-hydroxy-10-oxocedryl acetate (5), 3α,10β-dihydroxycedryl acetate (6), 3α,10α-dihydroxycedryl acetate (7), 10β,14α-dihydroxy cedryl acetate (8), 3β,10β-cedr-8(15)-ene-3,10-diol (9), and 3α,8β,10β -dihydroxycedrol (10). Compounds 1, 2, and 4 showed α-glucosidase inhibitory activity, whereby 1 was more potent than the standard inhibitor, acarbose, against yeast α-glucosidase. Detailed docking studies were performed on all experimentally active compounds to study the molecular interaction and binding mode in the active site of the modeled yeast α-glucosidase and human intestinal maltase glucoamylase. All active ligands were found to have greater binding affinity with the yeast α-glucosidase as compared to that of human homolog, the intestinal maltase, by an average value of approximately -1.4 kcal/mol, however, no significant difference was observed in the case of pancreatic amylase.
  European journal of medicinal chemistry 02/2013; 62C:764-770. · 3.27 Impact Factor
• Article: Carandinol: First isohopane triterpene from the leaves of Carissa carandas L. and its cytotoxicity against cancer cell lines

  Sabira Begum, Saqib A. Syed, Bina S. Siddiqui, Samina A. Sattar, M. Iqbal Choudhary
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  ABSTRACT: A new triterpene carandinol (1) was isolated from the leaves of Carissa carandas L., along with five known compounds, betulinic acid (2), β-sitosterol-3-O-β-d-glucopyranoside (3), oleanolic acid (4), ursolic acid (5) and 4-hydroxybenzoic acid (6). The structure of compound 1 was deduced as 3β,21α-dihydroxyisohopane by exhaustive spectroscopic analyses. The known compounds 2–6 were identified by comparison with the reported spectral data. Compound 1 was evaluated for cytotoxicity, immunomodulatory, antiglycation, antioxidant and enzyme inhibition activity. It exhibited significant in vitro cytotoxicity to every cell line tested (HeLa, PC-3 and 3T3) and was relatively more toxic to human cervical cancer (HeLa) cell line. This is the first report of the isolation of an isohopane triterpene from the genus Carissa. Carandinol also represents the first example of a cytotoxic isohopane.
  Phytochemistry Letters 02/2013; 6(1):91-95. · 1.22 Impact Factor
• Source

  Available from: Salman Zafar

  Article: New metabolites from fungal biotransformation of an oral contraceptive agent: Methyloestrenolone.

  Salman Zafar, Marium Bibi, Sammer Yousuf, M Iqbal Choudhary
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  ABSTRACT: Fungal cell cultures were used for the first time for the biotransformation of methyloestrenolone (1), an oral contraceptive. Fermentation of 1 with Macrophomina phaseolina, Aspergillus niger, Gibberella fujikuroi, and Cunninghamella echinulata produced eleven metabolites 2-12, six of which 2-5, 11 and 12 were found to be new. These metabolites were resulted from the hydroxylation at C-1, C-2, C-6, C-10, C-11, and C-17α-CH(3), as well as aromatization of ring A of the steroidal skeleton of substrate 1. The transformed products were identified as 17α-methyl-6β,17β-dihydroxyestr-4-en-3-one (2), 17α-(hydroxymethyl)-11β,17β-dihydroxyestr-4-en-3-one (3), 17α-methyl-2α,11β,17β-trihydroxyestr-4-en-3-one (4), 17α-methyl-1β,17β-dihydroxyestr-4-en-3-one (5), 17α-methyl-11α,17β-dihydroxyestr-4-en-3-one (6), 17α-methyl-11β,17β-dihydroxyestr-4-en-3-one (7), 17α-methyl-10β,17β-dihydroxyestr-4-en-3-one (8), 17α-(hydroxymethyl)-17β-hydroxyestr-4-en-3-one (9), 17α-methylestr-1,3,5(10)-trien-3,17β-diol (10), 17α-methyl-3,17β-dihydroxyestr-1,3,5(10)-trien-6-one (11), and 17α-methyl-6β,10β,17β-trihydroxyestr-4-en-3-one (12).
  Steroids 01/2013; · 2.83 Impact Factor
• Article: Structure-fragmentation relationship and rapid dereplication of Buxus steroidal alkaloids by electrospray ionization-quadrupole time-of-flight mass spectrometry.

  Syed Ghulam Musharraf, Madiha Goher, Salma Shahnaz, M Iqbal Choudhary, Atta-Ur-Rahman
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  ABSTRACT: Tandem mass spectrometric studies of natural products revealed the identification of key fragments which can be helpful for their rapid dereplication in plant extracts utilizing a liquid chromatography/tandem mass spectrometry (LC/MS/MS) approach, particularly for the thermally labile compounds. The knowledge of the collision-induced dissociation (CID) fragmentation pattern of the molecule is essentially required prior to the analysis by LC/MS/MS. The fragmentation patterns of eleven Buxus steroidal alkaloids were studied by using a positive ion electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. Chromatographic separation of a Buxus papillosa extract was achieved using a capillary HPLC system coupled with the mass instrument. ESI-QqTOF-MS (positive ion mode) showed the presence of several characteristic fragments which can be used to rapidly identify various classes of Buxus steroidal alkaloids. The presence of a cyclopropane ring in the cycloartenol skeleton and the hydroxyl group at C-10 was found to effect on the fragmentation pattern and afford characteristic peaks. This study distinguishes between different types of Buxus steroidal alkaloids based on logical fragmentation pathways. This strategy was successfully applied in LC/ESI-QqTOF-MS/MS analysis of Buxus papillosa extract to investigate and characterize Buxus steroidal alkaloids and 14 compounds were identified as steroidal alkaloids. The knowledge of the fragmentation pattern was used for the rapid identification of this bioactive group of biosynthetically unique steroidal alkaloids in complex plant extracts of Buxus species, especially in the absence of any reference material, by combining key fragments, exact mass measurements and relative abundances of diagnostic fragment ions. Copyright © 2012 John Wiley & Sons, Ltd.
  Rapid Communications in Mass Spectrometry 01/2013; 27(1):169-78. · 2.79 Impact Factor
• Article: Synthesis of some potent immunomodulatory and anti-inflammatory metabolites by fungal transformation of anabolic steroid oxymetholone.

  Naik Tameen Khan, Marium Bibi, Sammer Yousuf, Izhar Husain Qureshi, Atta-Ur-Rahman, Abdullah Mohammad Al-Majid, Muhammad Ahmed Mesaik, Ahmed Shukralla Khalid, Samina A Sattar, Atia-Tul-Wahab, M Iqbal Choudhary
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  ABSTRACT: BACKGROUND: Biotransformation of organic compounds by using microbial whole cells provides an efficient approach to obtain novel analogues which are often difficult to synthesize chemically. In this manuscript, we report for the first time the microbial transformation of a synthetic anabolic steroidal drug, oxymetholone, by fungal cell cultures. RESULTS: Incubation of oxymetholone (1) with Macrophomina phaseolina, Aspergillus niger, Rhizopus stolonifer, and Fusarium lini produced 17beta-hydroxy-2-(hydroxy-methyl)-17alpha-methyl-5alpha-androstan-1-en-3-one (2), 2alpha,17alpha-di(hydroxyl-methyl)-5alpha-androstan-3beta,17beta-diol (3), 17alpha-methyl-5alpha-androstan-2alpha,3beta,17beta-triol (4), 17beta-hydroxy-2-(hydroxymethyl)-17alpha-methyl-androst-1,4-dien-3-one (5), 17beta-hydroxy-2alpha-(hydroxy-methyl)-17alpha-methyl-5alpha-androstan-3-one (6), and 2alpha-(hydroxymethyl)-17alpha-methyl-5alpha-androstan-3beta-17beta-diol (7). Their structures were deduced by spectral analyses, as well as single-crystal X-ray diffraction studies. Compounds 2--5 were identified as the new metabolites of 1. The immunomodulatory, and anti-inflammatory activities and cytotoxicity of compounds 1--7 were evaluated by observing their effects on T-cell proliferation, reactive oxygen species (ROS) production, and normal cell growth in MTT assays, respectively. These compounds showed immunosuppressant effect in the T-cell proliferation assay with IC50 values between 31.2 to 2.7 mug/mL, while the IC50 values for ROS inhibition, representing anti-inflammatory effect, were in the range of 25.6 to 2.0 mug/mL. All the compounds were found to be non-toxic in a cell-based cytotoxicity assay. CONCLUSION: Microbial transformation of oxymetholone (1) provides an efficient method for structural transformation of 1. The transformed products were obtained as a result of de novo stereoselective reduction of the enone system, isomerization of double bond, insertion of double bond and hydroxylation. The transformed products, which showed significant immunosuppressant and anti-inflammatory activities, can be further studied for their potential as novel drugs.
  Chemistry Central Journal 12/2012; 6(1):153. · 3.28 Impact Factor
• Source

  Available from: Momin Khan

  Dataset: Med. Chem., 2011, 7, 572-580

  Shahnaz Perveen, Momin Khan, Muhammad Taha, Khalid Mohammed Khan, Fazal Rahim, Zarbad Shah, M Iqbal Choudhary, Humera Jahan, Viqar Uddin Ahmad
• Article: Biodiesel production from microalgal isolates of southern Pakistan and quantification of FAMEs by GC-MS/MS analysis.

  Syed Ghulam Musharraf, Muhammad Arif Ahmed, Noureen Zehra, Nurul Kabir, M Iqbal Choudhary, Atta-Ur Rahman
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  ABSTRACT: BACKGROUND: Microalgae have attracted major interest as a sustainable source for biodiesel production on commercial scale. This paper describes the screening of six microalgal species, Scenedesmus quadricauda, Scenedesmus acuminatus, Nannochloropsis sp., Anabaena sp., Chlorella sp. and Oscillatoria sp., isolated from fresh and marine water resources of southern Pakistan for biodiesel production and the GC-MS/MS analysis of their fatty acid methyl esters (FAMEs). RESULTS: Growth rate, biomass productivity and oil content of each algal species have been investigated under autotrophic condition. Biodiesel was produced from algal oil by acid catalyzed transesterification reaction and resulting fatty acid methyl esters (FAMEs) content was analyzed by GC/MS. Fatty acid profiling of the biodiesel, obtained from various microalgal oils showed high content of C-16:0, C-18:0, cis-Delta9C-18:1, cis-Delta11C-18:1 (except Scenedesmus quadricauda) and 10-hydroxyoctadecanoic (except Scenedesmus acuminatus). Absolute amount of C-14:0, C-16:0 and C-18:0 by a validated GC-MS/MS method were found to be 1.5-1.7, 15.0-42.5 and 4.2-18.4 mg/g, respectively, in biodiesel obtained from various microalgal oils. Biodiesel was also characterized in terms of cetane number, kinematic viscosity, density and higher heating value and compared with the standard values. CONCLUSION: Six microalgae of local origin were screened for biodiesel production. A method for absolute quantification of three important saturated fatty acid methyl esters (C-14, C-16 and C-18) by gas chromatography-tandem mass spectrometry (GC-MS/MS), using multiple reactions monitoring (MRM) mode, was employed for the identification and quantification of biodiesels obtained from various microalgal oils. The results suggested that locally found microalgae can be sustainably harvested for the production of biodiesel. This offers the tremendous economic opportunity for an energy-deficient nation.
  Chemistry Central Journal 12/2012; 6(1):149. · 3.28 Impact Factor
• Source

  Available from: Asaad Khalid

  Article: Phytochemistry and antiglycation activity of Aloe sinkatana Reynolds

  Gihan O.M. ELhassan, Achyut Adhikari, Sammer Yousuf, Md. Hafizur Rahman, Asaad Khalid, Hala Omer, Hoong-Kun Fun, Humaira Jahan, M. Iqbal Choudhary, Sakina Yagi
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  ABSTRACT: A new anthraquinone along with 10 known compounds were isolated from the leaves of Aloe sinkatana Reynolds (Aloaceae), and their structures were elucidated as the new compound 2,8-dihydroxy-6-(hydroxymethyl)-1-methoxyanthracene-9,10-dione (1) and the known compounds Aloe-emodin (2), feralolide (3), 1-hydroxy-5-methoxy-3-methyl-9,10 dihydroanthracene 9,10-dione (4), β-sitosterol (5), β-sitosterol with glycosidic bond (6), microdontin (7), homoaloins A (8) and B (9) and aloins A (10) and B (11). Characterization of compounds 1–9 was based on spectral analyses and comparison with reported data, particularly the new compound 1 was identified by 1D- and 2D NMR, mass spectroscopic and X-ray crystallography analyses. Antiglycation activity of the extracts and isolated compounds were carried out using the hemoglobin-δ-gluconolactone and glucose–bovine serum albumin assays. The results obtained showed that MeOH and EtOAc extracts as well as compound 1 showed an inhibitory effect on early stage protein glycation. Compound 1 also showed significant inhibitory effects against glucose-induced advanced glycation end-products.
  Phytochemistry Letters 12/2012; 5(4):725-728. · 1.22 Impact Factor
• Article: Oxindole Derivatives: Synthesis and Antiglycation Activity.

  Khalid Mohammed Khan, Momin Khan, Nida Ambreen, Muhammad Taha, Fazal Rahim, Saima Rasheed, Sumayya Saied, Humaira Shafi, Shahnaz Perveen, M Iqbal Choudhary
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  ABSTRACT: Oxindole derivatives 3-25 have been synthesized from commercially available oxindole by refluxing with different aromatic aldehydes in good yields. Their in vitro antiglycation potential has been evaluated. They showed a varying degree of antiglycation activity with IC50 values ranging between 150.4 - 856.7 µM. 3-[(3-Chlorophenyl)methylidene]-1,3-dihydro-2H-indol-2-one (IC50 = 150.4 ± 2.5 µM) is the most active compound among the series, better than the standard rutin with an IC50 value 294.5 ± 1.50 µM. The structures of the compounds were elucidated by 1H-NMR and mass spectroscopy and elemental analysis. A limited structure-activity relationship has been developed.
  Medicinal chemistry (Shāriqah (United Arab Emirates)) 11/2012; · 1.64 Impact Factor
• Article: Solid-Phase Total Synthesis of Cherimolacyclopeptide E and Discovery of More Potent Analogues by Alanine Screening.

  Farzana Shaheen, Tania S Rizvi, Syed G Musharraf, A Ganesan, Kai Xiao, Jared B Townsend, Kit S Lam, M Iqbal Choudhary
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  ABSTRACT: Cherimolacyclopeptide E (1) is a cyclic hexapeptide obtained from Annona cherimola, reported to be cytotoxic against the KB (human nasopharyngeal carcinoma) cell line. The solid-phase total syntheses of this cyclic peptide and its analogues were accomplished by employing FMOC/tert-butyl-protected amino acids and the Kenner sulfonamide safety-catch linker. The synthetic peptide 1 was found to be weakly cytotoxic against four cell lines (MOLT-4, Jurkat T lymphoma, MDA-MB-231, and KB). Analogues 3 and 7, where glycine at positions 2 and 6 of the parent compound was replaced by Ala, exhibited enhanced cytotoxicity against KB (3, IC(50) 6.3 μM; 7, IC(50) 7.8 μM) and MDA-MB-231 breast cancer cells (3, IC(50) 10.2 μM; 7, IC(50) 7.7 μM), thereby suggesting possible selective targeting of these cancer cells by these peptides. The spectral data of synthetic peptide 1 was found to be similar to that reported for the natural product. However, a striking difference in biological activity was noted, which warrants the re-evaluation of the original natural product for purity and the existence of conformational differences.
  Journal of Natural Products 11/2012; · 3.13 Impact Factor
• Article: Electrospray tandem mass spectrometric analysis of a dimeric conjugate, salvialeriafone and related compounds.

  Syed Ghulam Musharraf, Madiha Goher, Amjad Hussain, M Iqbal Choudhary
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  ABSTRACT: BACKGROUND: Electrospray tandem mass spectrometry approach is widely used for the rapid characterization of natural products. This paper describes the gas-phased ESI-MS/MS fragmentation of abietane-type diterpenoids and their novel dimeric conjugate, salvialeriafone (1) using both positive and negative ion electrospray ionization quadropole time-of-flight mass spectrometry (ESI-QqTOF-MS/MS) hybrid instrument. Diterpenoids are widely distributed throughout the plant kingdom and posses interesting biological activities. RESULTS: ESI-QqTOF-MS (positive ion mode) of diterpenoids 1--6 under collision-induced dissociation tandem mass spectrometric analysis (CID-MS/MS) showed the characteristic losses of water, carbonmonoxide and propene molecules, while analysis in negative ion mode showed the characteristic losses of water, carbon monoxide, methane molecules and methyl radical. Results demonstrated the differences in the product ions and base peaks due to the differences in the skeleton. A novel dimeric conjugate, salvialeriafone (1) showed characteristic fragmentation pattern and was found to be more prone to form radical ions, as compared to monomeric diterpenoids. The fragmentation pathways of characteristic fragments were proposed with the aid of HRESIMS. CONCLUSIONS: Extensive tandem mass spectrometric studies of salvialeriafone (1) and related diterpenoids 2--6 were conducted and their characteristic fragments were identified. The knowledge of the fragmentation pattern of these diterpenoids will be useful for the characterization of new dimers of this class of compounds.
  Chemistry Central Journal 10/2012; 6(1):120. · 3.28 Impact Factor
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  Available from: Salman Zafar

  Article: Biotransformation of oral contraceptive ethynodiol diacetate with microbial and plant cell cultures.

  Salman Zafar, Sammer Yousuf, Hammad A Kayani, Saifullah Saifullah, Saifullah Khan, Abdullah M Al-Majid, M Iqbal Choudhary
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  ABSTRACT: BACKGROUND: Biotransformation by using microbial and plant cell cultures has been applied effectively for the production of fine chemicals on large scale. Inspired by the wealth of literature available on the biotransformation of steroids, we decided to investigate the biotransformation of ethynodiol diacetate (1), by using plant and microbial cultures. RESULTS: The biotransformation of ethynodiol diacetate (1) with Cunninghamella elegans and plant cell suspension cultures of Ocimum basilicum and Azadirachta indica is being reported here for the first time. Biotransformation of 1 with Cunninghamella elegans yielded three new hydroxylated compounds, characterized as 17alpha-ethynylestr-4-en-3beta,17beta-diacetoxy-6alpha-ol (2), 17alpha-ethynylestr-4-en-3beta,17beta-diacetoxy-6beta-ol (3), and 17alpha-ethynylestr-4-en-3beta,17beta-diacetoxy-10beta-ol (4) and a known metabolite, 17alpha-ethynyl-17beta-acetoxyestr-4-en-3-one (5). The biotransformations of 1 with Ocimum basilicum included hydrolysis of the ester group, oxidation of alcohol into ketone, and rearrangement of the hydroxyl group. Thus four major known metabolites were characterized as 17alpha-ethynyl-17beta-acetoxyestr-4-en-3-one (5), 17alpha-ethynyl-17beta-hydroxyestr-4-en-3-one (6), 17alpha-ethynyl-3 beta-hydroxy-17beta-acetoxyestr-4-ene (7) and 17alpha-ethynyl-5alpha,17beta-dihydroxyestr-3-ene (8). Biotransformation of 1 with Azadirachta indica culture yielded compounds 5 and 6. Spectroscopic data of compound 8 is being reported for the first time. Structure of compound 6 was unambiguously deduced through single-crystal x-ray diffraction studies. CONCLUSION: Biotransformation of an oral contraceptive, ethynodiol diacetate (1), by using microbial and plant cell cultures provides an efficient route to the synthesis of a library of new steroids with potential contraceptive properties. These methods can be employed in the production of such compounds with high stereoselectivity.
  Chemistry Central Journal 09/2012; 6(1):109. · 3.28 Impact Factor
• Article: 2-[3-(1,3-Benzothia-zol-2-yl)-2,2-di-methyl-prop-yl]-2-methyl-2,3-di-hydro-1,3-benzothia-zole.

  Sammer Yousuf, Hina Siddiqui, Rabia Farooq, M Iqbal Choudhary
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  ABSTRACT: In the title compound, C(20)H(22)N(2)S(2), the five-membered thia-zole ring of the 2-methyl-2,3-dihydro-1,3-benzothia-zole unit has an envelope conformation. The dihedral angle between the planar [maximum deviation of 0.014 (1) Å for the S atom] benzothia-zole ring system and the benzene ring is 78.37 (12)°. Two intra-molecular C-H⋯S hydrogen bonds are observed, forming rings of graph-set motif S(6). In the crystal, the molecules are consolidated in pairs through N-H⋯N hydrogen bonds and are arranged parallel to the b axis.
  Acta Crystallographica Section E Structure Reports Online 08/2012; 68(Pt 8):o2349. · 0.35 Impact Factor