Mehmet Cemil Uren

Metal concentration and antioxidant activity of edible mushrooms from Turkey.

This study presents information on the antioxidant activity and heavy metal concentrations of Polyporus sulphureus, Macrolepiota procera, Lycoperdon perlatum and Gomphus clavatus mushrooms collected from the province of Mugla in the South-Aegean Region of Turkey. Antioxidant activities of mushroom samples were evaluated by four complementary tests. All tests showed L. perlatum and G. clavatus to possess extremely high antioxidant potential. Antioxidant activity of the samples was strongly correlated with total phenolic-flavonoid content. In terms of heavy metal content, L. perlatum exceeded the legal limits for daily intake of Pb, Fe, Mn, Cr, Ni and Co contents (0.461, 738.00, 14.52, 1.27, 1.65, 0.417 mg/day, respectively) by a 60-kg consumer. Co contents of M. procera (0.026 mg/day) and P. sulphureus (0.030 mg/day) and Cd contents of G. clavatus (0.071 mg/day) were also above the legal limits. According to these results, L. perlatum should not be consumed, despite the potentially beneficial antioxidant activity. Additionally, M. procera and G. clavatus should not be consumed daily due to their high levels of Cd and Co.

A significant by-product of the industrial processing of pistachios: shell skin – RP-HPLC analysis, and antioxidant and enzyme inhibitory activities of the methanol extracts of Pistacia vera L. shell skins cultivated in Gaziantep, Turkey

The aim of this study is to evaluate the antioxidant and enzyme inhibitory activities of the methanol extracts of immature and mature shell skins of Pistacia vera L. As well as biological activity tests, phytochemical compositions of the extracts were also investigated. The total phenolic and flavonoid content was determined in addition to the amounts of gallic acid, protocatechuic acid, (+)-catechin, p-hydroxybenzoic acid, caffeic acid, (−)-epicatechin, syringic acid, p-coumaric acid, hesperidin, quercetin, kaempferol, and apigenin. The immature shell skin was found to be rich in both phenolic and flavonoid compounds (52.29 mg of gallic acid equivalent (GAE) per g of extract and 16.78 mg of rutin equivalent (RE) per g of extract). In immature shell skins, the amounts of protocatechuic acid (4335 μg per g of extract), p-hydroxybenzoic acid (12 925 μg per g of extract), p-coumaric acid (120 μg per g of extract), quercetin (620 μg per g of extract), and apigenin (190 μg per g of extract) were higher than those of the mature one. In parallel to these findings, immature shell skins exhibited a higher antioxidant activity in all test systems than that of the mature one. The samples did not show any inhibitory activity on butyrylcholinesterase and α-glucosidase. Mature shell skins exhibited considerable inhibitory activity on acetylcholinesterase (2.15 mg of galantamine equivalent (GALAE) per g of extract). The tyrosinase inhibitory activity of the mature shell skin was also found as 3.14 mg kojic acid equivalent (KAE) per g of extract. The immature shell skin remained inactive on this enzyme. The samples also showed remarkable inhibitory activity of α-amylase.

Chemical composition, antioxidant, and enzyme inhibitory activities of the essential oils of three Phlomis species as well as their fatty acid compositions

This study aimed to investigate the chemical composition, antioxidant, and enzyme inhibitory activities of the essential oils of Phlomis armeniaca WILLD., P. nissolii L., and P. pungens WILLD. var. pungens as well as their fatty acid contents. Germacrene D was found as the major compound in the oils (24.7, 15.1, and 7.2%, respectively). Additionally, n-hexadecanoic acid, hexahydrofarnesyl acetone, β-caryophyllene, and linalool were the other main compounds in the oils. Among the fatty acids, C18:3 ω3 and C18:2 ω6 were determined in high quantities in P. armeniaca (23.14 and 18.01%, respectively) and P. pungens var. pungens (24.64 and 17.51%, respectively). The essential oils of P. armeniaca and P. pungens var. pungens showed remarkable antioxidant and metal chelating activities as well as great reducing power potentials. These oils also showed a moderate scavenging effect on ABTS radicals. The oils also exhibited various degrees of inhibitory activities on AChE, BChE, α-amylase, α-glucosidase, and tyrosinase.

Phenolic content, antioxidant and enzyme inhibitory capacity of two Trametes species

The phenolic composition, antioxidant and enzyme inhibitory activities of methanolic and water extracts of Trametes gibbosa (TG) and Trametes hirsuta (TH) were characterised for the first time. Reversed-phase high-performance liquid chromatography (RP-HPLC) analysis revealed that TG and TH methanolic extracts contained (+)-catechin, chlorogenic acid and caffeic acid. Methanolic extracts of TG and TH showed significantly (p < 0.05) high inhibition rates on acetyl (1.87 and 1.60 mg galantamine equivalents (GALAEs) per g extract respectively) and butyryl cholinesterase (1.71 and 1.90 mg GALAEs per g extract respectively). Low and insignificant inhibition was observed against α-amylase. α-Glucosidase inhibitory activity of TG (0.93 mmol acarbose equivalents (ACEs) per g extract) and TH (1.18 mmol ACEs per g extract) methanolic extracts were significantly (p < 0.05) high. Methanolic extract of TG (16.85 ± 0.29 TEs per g extract) and TH (13.86 ± 0.03 mg TEs per g extract) showed the most effective cupric reducing power. This study tends to support the potential use of these mushrooms species for designing new functional food formulations.

Phenolic composition, enzyme inhibitory, and antioxidant activity of Bituminaria bituminosa

This study aimed to evaluate the in vitro antioxidant and enzyme inhibitory activities of ethyl acetate, methanol, and water extracts of Bituminaria bituminosa. In phosphomolybdenum assay, the methanol extract showed the highest activity (166.78 μmol TEs/g dry plant). The water extract exhibited the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH∙) and 2,2-azino-bis (3-ethylbenzothiazloine-6-sulphonic acid) (ABTS∙+). In addition, it exhibited the highest activity in cupric ion reducing (CUPRAC) and ferric reducing antioxidant power (FRAP) assays (41.26 and 46.82 μmol TEs/g dry plant). The extracts did not show cholinesterase and tyrosinase inhibitory activity. However, α-glucosidase inhibition assay resulted in the superiority of water extract (1233.86 μmol ACEs/g dry plant). In the case of α-amylase inhibitory assay, the ethyl acetate extract showed the highest activity (53.65 μmol ACEs/g dry plant). The water extract exhibited the highest phenolic content (31.70 μmol GAEs/g dry plant). In contrast, the methanol extract was found rich in flavonoid compounds (5.29 μmol REs/g dry plant). The water extract contained considerable amounts of rosmarinic acid, luteolin, quercetin, and rutin. Therefore, it can be used as a source of new and alternative antioxidant and enzyme inhibitory agents.