In Vitro Antibacterial Activity of Aqueous and Acetone Extracts Obtained from Epiphytic Lichens

Öz

Lichens produce a wide variety of biologically active secondary metabolites that contribute to their ecological adaptation and pharmacological potential. This study was conducted to investigate the antibacterial effects of acetone and water extracts obtained from the lichen species Pseudevernia furfuracea (L.) Zopf, Platismatia glauca (L.) W.L. Culb, and Ramalina farinacea (L.) Ach on bacterial species such as Listeria innocua (Gram positive), Staphylococcus epidermidis (Gram positive), and Escherichia coli (Gram negative). The findings highlight the antibacterial potential of macrolichen species and suggest that they are promising natural sources for the development of plant-based antibacterial agents. The minimum inhibitory concentration (MIC) method was used to determine the antibacterial properties of lichens. MIC assessment revealed significant differences in antibacterial performance depending on both the lichen species and the solvent used for extraction. Among the analyzed samples, Ramalina farinacea (L.) Ach exhibited the broadest inhibitory activity range and effectively suppressed the growth of all tested bacterial strains at comparatively low concentrations. Pseudevernia furfuracea (L.) Zopf showed significant activity mainly against S. epidermidis, while Platismatia glauca (L.) W.L. Culb exhibited a narrower activity limited to the same microorganism. In contrast, all water-based extracts were found to be inactive, and visible bacterial growth was detected in each test well. These results indicate that acetone provides a more suitable medium for the isolation of lipophilic antibacterial compounds from lichen materials. Overall, the findings suggest that solvent polarity and species-specific metabolite composition play a critical role in shaping the antimicrobial potential of lichen-derived extracts.

Anahtar Kelimeler

• Antibacterial
• minimum inhibitory concentration (MIC)
• tree lichen
• Ramalina farinacea (L.) Ach

Epifitik Likenlerden Elde Edilen Su ve Aseton Ekstraktlarının İn Vitro Koşullarda Antibakteriyel Aktivitesi

Öz

Likenler, ekolojik adaptasyonlarına ve farmakolojik potansiyellerine katkıda bulunan çok çeşitli biyolojik olarak aktif ikincil metabolitler üretirler. Bu çalışma, Pseudevernia furfuracea (L.) Zopf, Platismatia glauca (L.) W.L. Culb ve Ramalina farinacea (L.) Ach liken türlerinden elde edilen aseton ve su ekstraktların, Listeria innocua (Gram pozitif), Staphylococcus epidermidis (Gram pozitif) ve Escherichia coli (Gram negatif) gibi bakteri türleri üzerindeki antibakteriyel etkilerini araştırmak amacıyla yürütülmüştür. Bulgular, makroliken türlerinin antibakteriyel potansiyelini vurgulamakta ve bitki temelli antibakteriyel ajanların geliştirilmesi için umut verici doğal kaynaklar olduklarını göstermektedir. Likenlerin antibakteriyel özelliklerinin belirlenmesi için, minimum inhibitör konsantrasyonları (MIC) yöntemi kullanılmıştır. MIC değerlendirmesi, hem liken türüne hem de ekstraksiyonda kullanılan çözücüye bağlı olarak antibakteriyel performansta belirgin farklılıklar ortaya koymuştur. Analiz edilen örnekler arasında, Ramalina farinacea (L.) Ach en geniş inhibitör etki aralığını sergilemiş ve test edilen tüm bakteri suşlarının büyümesini karşılaştırmalı olarak düşük konsantrasyonlarda etkili bir şekilde baskılamıştır. Pseudevernia furfuracea (L.) Zopf esas olarak Staphylococcus epidermidis’e karşı belirgin aktivite gösterirken, Platismatia glauca (L.) W.L. Culb aynı mikroorganizmayla sınırlı daha dar bir etki sunmuştur. Buna karşılık, tüm su bazlı ekstraktlar etkisiz bulunmuş ve her test kuyusunda gözle görülür bakteri üremesi tespit edilmiştir. Bu sonuçlar, asetonun liken materyallerinden lipofilik antibakteriyel bileşenlerin izole edilmesi için daha uygun bir ortam sağladığını göstermektedir. Genel olarak, bulgular çözücü polaritesinin ve türe özgü metabolit bileşiminin liken kaynaklı ekstraktların antimikrobiyal potansiyelinin şekillenmesinde kritik bir rol oynadığını ortaya koymaktadır.

Anahtar Kelimeler

• Antibakteriyel
• ağaç likeni
• minimum inhibitör konsantrasyon (MIC)
• Ramalina farinacea (L.) Ach

Kaynakça

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