Search

Tam Metin / Full Text ESCI he present study aimed to determine the phenolic compounds present in the water-soluble extracts of Thymus munbyanus subsp. ciliatus using high pressure liquid chromatography-time-of-flight mass spectrometry (MS). These phenolic compounds were further isolated and characterized for their antioxidant activities. Materials and Methods: The aerial parts of T. munbyanus subsp. ciliatus were air dried, powdered, and extracted using water:methanol three times. The concentrated hydromethanolic extract was further dissolved in H2 O, filtered, and successively extracted using ethyl acetate, chloroform, and n-butanol. T. munbyanus extracts were further purified using column chromatography, and the purified extracts were subjected to in vitro antioxidant assays. Results: Two previously undescribed compounds, namely methyl 2,3,5,6-tetrahydroxybenzoate and 4-hydroxy-5-methoxy-2-oxo-2H-pyran3-carboxylic acid, and 14 known compounds, including 3 flavonoids; namely 3’,5,5’,7-tetrahydroxyflavanone, luteolin, and isorhamnetin-3-O-βglucoside; a sterol glucoside named daucosterol; and 10 phenolic compounds, namely salicylic acid, ferulic acid, pluchoic acid, ethyl caffeate, methyl caffeate, protocatechuic acid, rosmarinicacid, p-coumaric acid, tyrosol, and protocatechuic aldehyde, were isolated from ethyl acetate and n-butanol extracts. The isolated compounds were characterized using 1D-2D-1H-13C nuclear magnetic resonance and MS methods. Conclusion: The compounds isolated from ethyl acetate and n-butanol extracts exhibited excellent antioxidant and 2,2-diphenyl-1-picrylhydrazyl scavenging activities. All these results highlighted the antioxidant potential of the isolated phenolic compounds and extracts, which could be further utilized for different pharmacological applications. Bu çalışmanın amacı, yüksek basınçlı sıvı kromatografisi-uçuş zamanlı-kütle spektrometresi (MS) kullanılarak Thymus munbyanus subsp. ciliatus’un suda çözünür ekstraktından fenolik bileşiklerin belirlenmesi, bileşiklerin izolasyonu, karakterizasyonu ve antioksidan aktivitelerinin belirlenmesidir. Gereç ve Yöntemler: Thymus munbyanus subsp. ciliatus bitkisi küçük parçalar halinde kesilmiş ve üç kez metanol/su ile ekstre edilmiştir. Konsantre hidrometanolik ekstrakt saf su içerisinde tekrar çözünmüş; daha sonra süzülmüş ve art arda kloroform, etil asetat ve n-bütanol ile ekstre edilmiştir. T. munbyanus ekstreleri, kolon kromatografisi kullanılarak daha da saflaştırılmış ve saflaştırılmış ekstrelerde in vitro antioksidan deneyler yapılmıştır. Bulgular: Önceden tanımlanmamış iki bileşik olan metil 2,3,5,6-tetrahidroksibenzoat ve 4-hidroksi-5-metoksi-2-okso-2H-piran-3-karboksilik asit ve 3 flavonoid dahil 14 bilinen bileşik; yani 3’,5,5’,7-tetrahidroksiflavanon, luteolin ve isorhamnetin-3-0-p-glukozit; daucosterol adlı bir sterol glikozit; ve etil asetat ve n-bütanol ekstraktlarından salisilik asit, ferulik asit, plukoik asit, etil kafeat, metil kafeat, protokateşik asit, rosmarinik asit, p-kumarik asit, tirosol ve protokateşik aldehit olmak üzere 10 fenolik bileşik izole edilmiştir. İzole edilen bileşikler, 1D-2D-1H-13C nükleer manyetik rezonans ve MS yöntemleri kullanılarak karakterize edilmiştir. Sonuç: Etil asetat ve n-bütanol ekstraktlarından izole edilen bileşikler, mükemmel antioksidan ve 2,2-difenil-1-pikrilhidrazil süpürme aktiviteleri sergilemiştir. Tüm bu sonuçlar, farklı farmakolojik uygulamalar için daha fazla kullanılabilecek izole fenolik bileşiklerin ve ekstraktların antioksidan potansiyelini vurgulamıştır.

The polyphenol oxidase was extracted and purified from truffles (Terfezia arenaria) and it exhibited a molecular weight of 67 kDa. The truffle PPO was able to oxidize monophenolic, o-diphenolic and triphenolic substrates. Thus, the enzyme seems to be stable under wide range of pH and temperature. Best catalytic efficiency was observed for catechol as substrate (Kcat/km; 674.2 S−1 mM−1).The effect of detergents, chaotropic agents, metal ions and eleven different inhibitors on relative activity of Truffles PPO was also investigated. A latent form of enzyme was observed and its activity was stimulated using 4 mM of SDS. Likewise, the type of inhibition and the values of KI and IC50 were reported for L-cysteine, Sodium fluoride, sodium metabisulfite and kojic acid. Besides, the effect of four concentrations of kojic acid(0.05.,0.1.,0.2 and 0.3 mM) on thermal inactivation of PPO was performed in temperature range “ 60–75° C”. The use of Kojic acid increase the rate of inactivation process and disrupt enzymatic activity. Moreover, the combined effect of temperature and kojic acid prevent from enzymatic browning reaction and maintain high antioxidant activities including ABTS scavenging activity, FRAP, and total phenolic contents.