Antioxidant capacities of Gundelia tournefortii L. extracts and inhibition on glutathione-S-transferase activity

Department of Chemistry, Middle East Technical University, Engüri, Ankara, Turkey
Food Chemistry (Impact Factor: 3.26). 01/2007; 100(3):1249-1253. DOI: 10.1016/j.foodchem.2005.12.008

ABSTRACT Gundelia tournefortii L. is an important food source and a well-known medicinal plant in Eastern Anatolia. Therapeutic effects of medicinal plants are known to be closely related to their antioxidant capacities. Antioxidant activities of G. tournefortii, both for the aerial parts and seeds, were investigated by using both 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and lipid peroxidation inhibition methods. The seeds were found to have higher antioxidant potential than the aerial, with IC50 values of 0.073 mg/mL for DPPH scavenging and 0.146 mg/mL for lipid peroxidation inhibition capacities. In addition, total phenolic contents of the Gundelia tournefortii L. extracts, especially the seed extracts correlates to its high antioxidant activity with 105.1 ± 8.7 μg gallic acid equivalents (GAEs) per mg of seed extract. Plant extracts with high phenolics content are known to have important effects on various enzymes, as well as glutathione-S-transferases, which are important detoxification enzymes in phase II systems with an important role in developing multi-drug resistance to chemotherapy in tumour cells. Consequently, the effects of G. tournefortii extracts on crude cytosolic glutathione-S-transferase was also studied and the seed extracts have shown effective inhibition of cytosolic GST activity, with an IC50 of 97.51 μg/mL.

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    ABSTRACT: Asteracantha longifolia (L.) Nees belonging to the family Acanthaceae is an important medicinal plant used in traditional medicine. The plant is reported to exhibit various pharmacological activities. In the present study, we determined the antimicrobial and radical scavenging activity of leaf, fruit and root extract of Asteracantha longifolia (L.) Nees (Acanthaceae). Agar well diffusion assay was performed to determine antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, K. pneumoniae, Pseudomonas aeruginosa and Escherichia coli. The extracts inhibited Gram positive bacteria to higher extent than Gram negative bacteria. E. faecalis and P. aeruginosa were inhibited to higher extent among Gram positive and Gram negative bacteria respectively. Poisoned food technique was performed to investigate antifungal activity against two phytopathogenic fungi Colletotrichum capsici and Sclerotium rolfsii. The colony diameter of test fungi was considerably lesser in plates poisoned with extracts when compared to control plates. Among fungi, higher susceptibility was observed in case of S. rolfsii than C. capsici. Radical scavenging activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The extracts scavenged DPPH radicals dose dependently. The scavenging effect was marked in case of fruit extract followed by leaf and root extracts. Total phenolic content of extracts was estimated by Folin-Ciocalteau reagent (FCR) method. Fruit extract contained high phenolic content followed by leaf and root extracts. The plant A. longifolia can be used to treat urinary tract infections and to control phytopathogenic fungi. It can also be used against free radical induced oxidative stress.
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    ABSTRACT: In the present study, we determined the antibacterial and radical scavenging efficacy of extracts of five plants viz., Psychotria nigra (Gaert.) Alston, Flacourtia montana Graham, Aglaia roxburghiana (W.&.A) Miq. Var. beddomei, Canthium dicoccum (Gaertn.) Teys. & Binn. and Ligustrum roxburghii C.B. Clarke collected at Haniya, Western Ghat region of Hosanagar Taluk, Shivamogga district, Karnataka. The leaves were shade dried, powdered and extracted using methanol. Antibacterial activity was determined by agar well diffusion assay against two Gram positive and two Gram negative bacteria. Radical scavenging potential of extracts was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Total phenolic content of extracts was estimated by Folin-Ciocalteau Reagent (FCR) method. The extracts were able to inhibit at least one of the test bacteria. Marked inhibitory activity was observed in case of L. roxburghii whereas C. dicoccum displayed least inhibitory effect. Extracts were shown to exhibit dose dependent scavenging of DPPH radicals. Marked radical scavenging potential was observed in case of A. roxburghiana. A positive correlation was observed between total phenolic content and radical scavenging efficacy of extracts. In conclusion, the plants have been shown promising for the development of pharmacologically active drugs. Further in vivo studies are to be conducted.
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    ABSTRACT: Context: Plants and most of the plant-derived compounds have long been known for their potential pharmaceutical effects. They are well known to play an important role in the treatment of several diseases from diabetes to various types of cancers. Today most of the clinically effective pharmaceuticals are developed from plant-derived ancestors in the history of medicine. Objective: The aim of this study was to evaluate the free radical scavenging activity and total phenolic and flavonoid contents of methanol, ethanol, and acetone extracts from flowers and leaves of Onopordum acanthium L., Carduus acanthoides L., Cirsium arvense (L.) Scop., and Centaurea solstitialis L., all from the Asteraceae family, for investigating their potential medicinal values of biological targets that are participating in the antioxidant defense system such as catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPx). Materials and methods: In this study, free radical scavenging activity and total phenolic and flavonoid contents of the plant samples were assayed by DPPH, Folin–Ciocalteu, and aluminum chloride colorimetric methods. Also, the effects of extracts on CAT, GST, and GPx enzyme activities were investigated. Results and discussion: The highest phenolic and flavonoid contents were detected in the acetone extract of C. acanthoides flowers, with 90.305 mg GAE/L and 185.43 mg Q/L values, respectively. The highest DPPH radical scavenging was observed with the methanol leaf extracts of C. arvense with an IC50 value of 366 ng/mL. The maximum GPx and GST enzyme inhibition activities were observed with acetone extracts from the flower of C. solstitialis with IC50 values of 79 and 232 ng/mL, respectively.
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