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    Assessment of free-radical scavenging activity of Gypsophila pilulifera: assay-guided isolation of verbascoside as the main active component
    (Soc Brasileira Farmacognosia, 2014) Chima, Navdeep K.; Nahar, Lutfun; Majinda, Runner R. T.; Çelik, Sezin; Sarker, Satyajit D.
    Gypsophila pilulifera, Boiss & Heldr, Caryophyllaceae, is a perennial medicinal herb that grows in the-southwestern region of Turkey. Except for only one report on the isolation-of cytotoxic. saponins from the underground parts of G. pilulifera, there are no published thorough phytochemical or bioactivity studies on this specie. In the present study; the free-radical Scavenging activity of extracts and fractions of the-stems of G. pilulifera was evaluated, using a. slightly modified and more-precise-version of the 2,2-diphenyl-1-picrylhydrazyl (DRPH) assay, :reported here for the first time. The DPPH assay-guided HPLC-PDA-purification of the active solid-phase extraction fraction (50% methanol in water) of the methanolic-extract exhibited verbascoside as the main free-radical Scavenger present in this species. The structure of this active compound was resolved by spectroscopy, and the free-radical scavenging potential of verbascoside was determined. (C) 2014 Sociedade Brasileira. de Farmacognosia. Published by Elsevier Editora Ltda. All rights reserved..
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    Bioactivity of Centaurea persica boiss. (Asteraceae)
    (Inst Bioloska Istrazivanja Sinisa Stankovic, 2012) Sarker, Satyajit D.; Nahar, Lutfun; Gujja, Srikanth; Begum, Shazi; Celik, Sezgin
    The free-radical-scavenging property, antibacterial activity and brine shrimp toxicity of petroleum ether (PE), dichloromethane (DCM) and methanol (MeOH) extracts of Centaurea persica, a Turkish medicinal plant, were assessed using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the resazurin microtiter plate based assay, and the brine shrimp lethality assay, respectively. Additionally, the disc diffusion assay was also used to assess antibacterial activity. Only the MeOH extract of C. persica exhibited a significant free-radical-scavenging property in the DPPH assay, with an RC50 value of 0.025 mg/mL. However, in the TLC-based qualitative assay, petroleum ether and DCM extracts showed an extremely low level of free-radical-scavenging property. Among the solid-phase extraction fractions of the MeOH extract, the fractions eluted with 60% and 80% MeOH in water exhibited the highest level of free-radical-scavenging activity (RC50 = 0.010 and 0.015 mg/mL, respectively). While DCM extract showed reasonable antibacterial activity against five out of the nine test strains both in the disc diffusion assay and in the resazurin assay, the MeOH extract was highly active against both Escherichia coli and ampicillin-resistant E. coli strains. Among the solid-phase extraction fractions of the MeOH extract, fractions eluted with 80% MeOH in water and 100% MeOH displayed significant antibacterial potencies against both E. coli species. None of the extracts showed any significant toxicity towards brine shrimps (LD50 = >1.00 mg/mL).
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    Bioactivity of extracts of Centaurea polyclada dc. (Asteraceae)
    (Inst Bioloska Istrazivanja Sinisa Stankovic, 2009) Granger, Melanie; Samson, Emilie; Sauvage, Severine; Majumdar, Anisha; Nigam, Poonam; Nahar, Lutfun; Sarker, Satyajit D.
    The free radical-scavenging property, antibacterial activity, and brine shrimp toxicity of n-hexane, dichloromethane (DCM), and methanol (MeOH) extracts of Centaurea polyclada, an endemic Turkish species, were assessed using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay, the resazurin microtiter plate-based assay, and the brine shrimp lethality assay, respectively. The DCM and MeOH extracts of C. polyclada exhibited free radical-scavenging ability with RC50 values 1.17 and 0.015 mg/mL, respectively. Among solid-phase extraction fractions of the MeOH extract, the fraction eluted with 60% MeOH in water demonstrated the highest level of free radical-scavenging activity (RC50 = 0.016 mg/mL). Only the DCM extract showed considerable antibacterial activity against all nine test strains except Escherichia coli, with MIC ranging from 1.25 to 2.50 mg/mL. This antibacterial activity pattern was also observed with solid-phase extraction fractions of the DCM extract with varied potencies. None of the extracts showed any significant toxicity towards brine shrimps (LD50 = >1.00 mg/mL).