Phenolic content and antioxidant capacity in different plant parts of Hypericum elongatum and Hypericum orientale: A comparative study

Yıl 2026, Cilt: 8 Sayı: 1, 9 - 19, 31.01.2026

Cansu Altuntaş

https://doi.org/10.51435/turkjac.1819405

Öz

This study investigates the phytochemical composition and antioxidant capacity of two underexplored Hypericum species, H. elongatum and H. orientale. Methanolic extracts of flowers, leaves, and stems were evaluated for total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity using DPPH, FRAP, and CUPRAC assays. 24 phenolic compounds were quantified by high-performance liquid chromatography with diode-array detection (HPLC-DAD). The TPC values ranged from 7.6 to 37.9 mg GAE/g, and TFC values from 1.9 to 10.7 mg QE/g. H. orientale generally showed higher phenolic and flavonoid levels, with its flower extract exhibiting the highest TPC (37.87 ± 1.86 mg GAE/g) and TFC (10.66 ± 0.30 mg QE/g). All extracts demonstrated notable antioxidant activity. Remarkably, the H. elongatum leaf extract had a very low DPPH IC₅₀ value (0.02 mg/mL), indicating strong radical-scavenging capacity. Its leaf also showed the highest FRAP value (299.38 ± 13.99 µmol FeSO₄·7H₂O/g) among all samples. The dominant phenolics in both species were catechin and epicatechin; kaempferol was detected only in H. orientale flowers (75.91 mg/kg). Hypericin was present in all tissues, with the highest concentration in H. orientale leaves (27.5 mg/kg). These findings highlight the significant antioxidant potential of both species, particularly in their flowers and leaves and suggest they may serve as valuable sources of natural antioxidants in phytomedicine.

Anahtar Kelimeler

Hypericum , Hypericin , Antioxidant , HPLC , Phenolic

Hypericum elongatum ve Hypericum orientale türlerinin farklı bitki kısımlarında fenolik içerik ve antioksidan kapasitenin karşılaştırmalı olarak incelenmesi

Öz

Bu çalışma, az incelenmiş iki Hypericum türü olan H. elongatum ve H. orientale’nin fitokimyasal bileşimini ve antioksidan kapasitesini araştırmaktadır. Çiçek, yaprak ve gövde kısımlarından elde edilen metanol ekstreleri; toplam fenolik içeriği (TPC), toplam flavonoid içeriği (TFC) ve DPPH, FRAP ve CUPRAC yöntemleri kullanılarak antioksidan aktivite açısından değerlendirilmiştir. Ayrıca, yüksek performanslı sıvı kromatografisi-diyot dizisi dedektörü (HPLC-DAD) kullanılarak 24 fenolik bileşik nicel olarak belirlenmiştir. TPC değerleri 7.6–37.9 mg GAE/g, TFC değerleri ise 1.9–10.7 mg QE/g aralığında bulunmuştur. H. orientale genel olarak daha yüksek fenolik ve flavonoid içerikleri göstermiş; özellikle çiçek ekstresi en yüksek TPC (37.87 ± 1.86 mg GAE/g) ve TFC (10.66 ± 0.30 mg QE/g) değerlerini vermiştir. Tüm ekstreler belirgin antioksidan aktivite göstermiştir. Dikkat çekici olarak, H. elongatum yaprak ekstresinin DPPH IC₅₀ değeri oldukça düşük bulunmuştur (0.02 mg/mL); bu durum güçlü serbest radikal süpürme kapasitesine işaret etmektedir. Aynı organsal kısım ayrıca tüm örnekler içinde en yüksek FRAP değerini göstermiştir (299.38 ± 13.99 µmol FeSO₄·7H₂O/g). Her iki türde de baskın fenolik bileşiklerin kateşin ve epikateşin olduğu belirlenmiştir; kaempferol ise yalnızca H. orientale çiçeklerinde tespit edilmiştir (75.91 mg/kg). Hiperisin tüm dokularda saptanmış olup, en yüksek konsantrasyon H. orientale yapraklarında gözlenmiştir (27.5 mg/kg). Bu bulgular, her iki türün özellikle çiçek ve yaprak kısımlarında belirgin antioksidan potansiyel taşıdığını ortaya koymakta ve bu türlerin fitoterapötik uygulamalarda doğal antioksidan kaynağı olarak değerlendirilebileceğini göstermektedir.

Anahtar Kelimeler

Hypericum , Hiperisin , Antioksidan , HPLC , Fenolik

Kaynakça

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