A Comparative Evaluation of Solvent Effects on the Phenolic Content and in vitro Antioxidant Activity of Aerial Parts of Endemic Sideritis galatica (Lamiaceae)

Öz

Sideritis galatica Bornm. (Lamiaceae) is an endemic plant species native to Türkiye. This Türkiye-endemic species belongs to the genus Sideritis, whose members are traditionally consumed as 'mountain tea' and are rich in phenolic compounds. In this study, the total phenolic content and in vitro antioxidant activity of extracts prepared from the aerial parts of S. galatica collected from Afyonkarahisar Province using methanol, acetone, and water were comparatively investigated. Total phenolic content was determined using the Folin–Ciocalteu method, total antioxidant capacity using the phosphomolybdenum method, and radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method at concentrations of 25, 50, and 100 ppm.The data were analyzed using ANOVA, Tukey’s HSD test, Pearson correlation, linear regression, and principal component analysis (PCA). While the methanol (36.60±0.50 mg GAE/g) and acetone (36.57±1.06 mg GAE/g) extracts exhibited similar phenolic content, the aqueous extract was found to be significantly lower (22.79±0.59 mg GAE/g; p<0.001). The highest antioxidant capacity was detected in the acetone extract (125.43±10.10 μmol AAE/g). DPPH inhibition increased with concentration; the solvent×concentration interaction was non-significant (p=0.929). A strong positive correlation was observed between phenolic content and antioxidant capacity (R²=0.879). PCA and permutational multivariate analysis of variance (PERMANOVA) confirmed that the solvent groups were markedly separated (R²=0.942; p=0.010). The findings indicate that the antioxidant potential of S. galatica depends on the choice of solvent.

Anahtar Kelimeler

• Antioxidants
• Chemical fractionation
• Lamiaceae
• Phenols
• Plant extracts
• Sideritis

Endemik Sideritis galatica (Lamiaceae) Toprak Üstü Kısımlarının Fenolik İçeriği ve in vitro Antioksidan Aktivitesine Çözücülerin Karşılaştırmalı Etkisi

Öz

Sideritis galatica Bornm. (Lamiaceae), Türkiye'ye özgü endemik bir bitki türüdür. Türkiye'ye özgü bu tür, geleneksel olarak "dağ çayı" biçiminde tüketilen ve fenolik bileşiklerce zengin Sideritis cinsinin bir üyesidir. Bu çalışmada Afyonkarahisar'dan toplanan S. galatica bitkisinin toprak üstü kısımlarından metanol, aseton ve su ile hazırlanan ekstraktların toplam fenolik içeriği ve in vitro antioksidan aktivitesi karşılaştırmalı olarak incelendi. Toplam fenolik içerik Folin-Ciocalteu, toplam antioksidan kapasite fosfomolibden ve radikal süpürme aktivitesi 25, 50 ve 100 ppm konsantrasyonlarda 2-difenil-1-pikrilhidrazil (DPPH) yöntemleriyle belirlendi. Veriler ANOVA, Tukey HSD, Pearson korelasyonu, doğrusal regresyon ve temel bileşen analizi (PCA) ile değerlendirildi. Metanol (36.60±0.50 mg GAE/g) ve aseton (36.57±1.06 mg GAE/g) ekstraktları benzer fenolik içerik sunarken, sulu ekstrakt anlamlı düşük bulundu (22.79±0.59 mg GAE/g; p<0.001). En yüksek antioksidan kapasite aseton ekstraktında saptandı (125.43±10.10 μmol AAE/g). DPPH inhibisyonu konsantrasyonla arttı; çözücü×konsantrasyon etkileşimi anlamsızdı (p=0.929). Fenolik içerik ile antioksidan kapasite arasında güçlü pozitif ilişki gözlendi (R²=0.879). PCA ve permütasyonel çok değişkenli varyans analizi (PERMANOVA) çözücü gruplarının belirgin biçimde ayrıştığını doğruladı (R²=0.942; p=0.010). Bulgular S. galatica'nın antioksidan potansiyelinin çözücü seçimine bağlı olduğunu göstermektedir.

Anahtar Kelimeler

• Antioksidanlar
• Bitki ekstreleri
• Fenoller
• Kimyasal fraksiyonlama
• Lamiaceae
• Sideritis

Kaynakça

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