Biological activity of ethanolic extract and fractions from Centaurea ragusina L.

Vrste roda Centaurea bogate su bioaktivnim tvarima te su dokazana njihova antioksidacijska, antibakterijska, citotoksicna i druga ljekovita svojstva. Cilj rada je odrediti antioksidacijsku, antibakterijsku i citotoksicnu aktivnost etanolnog (96%) ekstrakta lista i frakcija izoliranih iz hrvatske endemicne biljne vrste Centaurea ragusina L. sakupljene na prirodnom lokalitetu u Splitu (lokalitet Katalinic brig i Sustipan). U svrhu boljeg razumijevanja bioloske aktivnosti dubrovacke zecine proucavane su interakcije ekstrakta i frakcija s dvolancanim polinukleotidima (moguce bioloske mete) spektroskopijom cirkularnog dikroizma (CD spektroskopijom). Etanolni ekstrakt lista pokazao je znacajnu antioksidacijsku aktivnost mjerenu DPPH i ABTS metodom dok su frakcije izolirane iz etanolnog ekstrakta pokazale slabu antioksidacijsku aktivnost. Vecina testiranih frakcija i etanolni ekstrakt lista pokazali su znacajnu antibakterijsku aktivnost na Staphylococcus aureus ATCC25923 i slabu antibakterijsku aktivnost na Acinetobacter baumannii DURN. Etanolni ekstrakt i frakcije CRE01_06-10 pokazuju znacajnu citotoksicnu aktivnost na tumorskim stanicnim linijama SCCVII, FsaR i B16‐F10. Etanolni ekstrakt CRE i dio ispitivanih frakcija uzrokovali su smanjenje CD signala polinukleotida (poli A - poli U, ctDNA) i inducirane CD spektre (ICD) u podrucju od 290 - 300 nm koji ukazuju na interakciju s tim bioloskim metama. Na temelju snimljenih spektara može se zakljuciti da ekstrakt CRE i frakcije CRE01_05 i CRE01_06 sadržavaju spojeve koji se vežu na RNA i DNA. U daljnjim istraživanjima, plan je izolirati spojeve iz ekstrakata i frakcija dubrovacke zecine koji bi se mogli koristiti u prevenciji bolesti uzrokovanim slobodnim radikalima, lijecenju bakterijskih infekcija te u lijecenju tumora./ Species of the genus Centaurea are rich in bioactive substances with antioxidant, antibacterial, cytotoxic and other medicinal properties. The goal of this work was to determine antioxidant, antibacterial and cytotoxic activity in ethanolic (96%) extract of leaves and isolated fractions of Croatian endemic plant species Centaurea ragusina L. collected at two natural habitats in Split (Katalinic brig and Sustipan). The interactions of extract and fractions with double stranded polynucleotides (possible biological targets) were studied with circular dichroism spectroscopy (CD spectroscopy) to provide a better understanding of the biological activity of C. ragusina. Ethanolic extract showed significant antioxidant activity measured by DPPH and ABTS method while fractions isolated from ethanolic extract showed weak antioxidant activity. Almost all tested fractions and crude ethanolic extract of leaves showed significant antibacterial activity against Staphylococcus aureus ATCC25923 and weak antibacterial activity against Acinetobacter baumannii DURN. Ethanolic extract and fractions CRE01_06-10 showed significant cytotoxic activity on tumor cell lines SCCVII, FsaR and B16‐F10. Crude ethanolic extract CRE and several fractions caused decrease in the CD signal of polynucleotides and the induced CD spectra (ICD) in the range 290-300 nm, indicating the interaction with studied polynucleotides (ctDNA, poly A - poly U). Based on the recorded spectra we concluded that the compounds from CRE extract and CRE01_05 and CRE01_06 fractions, bind to RNA and DNA. In further investigations, pure compounds isolated from extracts and fractions of C. ragusina could find their use in the prevention of diseases caused by free radicals, treatment of bacterial infections and in the treatment of tumors.