Vpliv nekonvencionalnih metod ekstrakcije na protimikrobno delovanje izvlečkov koprive (Urtica dioica L.) in koromača (Foeniculum vulgare)

Malin, Valentina (author), Smole Možina, Sonja (mentor), Dragović-Uzelac, Verica (co-mentor)

Namen magistrskega dela je bil ovrednotiti vpliv metod ekstrakcije na biološko aktivnost izvlečkov iz listov koprive (Urtica dioica L.) ter iz semen koromača (Foeniculum vulgare). Izvlečke smo pripravili s pospešeno ekstrakcijo (ASE), ekstrakcijo z mikrovalovi (MAE) ter refluksno ekstrakcijo. Izvlečkom smo določili vsebnost skupnih fenolnih spojin (TPC), ki je bila 504 ± 26 – 3301 ± 171 mg GAE/100 g s.s. za liste koprive ter 237 ± 10 – 860 ± 26 mg GAE/100 g s.s. za semena koromača. Fenolni profil smo analizirali z UPLC-MS/MS. V izvlečkih listov koprive smo identificirali 27 različnih spojin, med katerimi sta močno prevladovala cimetna kislina ter kemferol, v izvlečkih semen koromača pa je bila med 21 identificiranimi spojinami prevladujoča spojina kemferol-3-O-glukuronid. Optimalna metoda ekstrakcije bioaktivnih spojin iz listov koprive je bila ASE, za semena koromača pa klasični refluks, pri obeh s 30 % acetonom kot topilom. Ob upoštevanju optimalnih pogojev ekstrakcije smo pripravili nova izvlečka in jima določili antioksidativni potencial (DPPH, FRAP) in protimikrobno aktivnost z metodo mikrodilucije. Izvlečki listov koprive so izkazali boljšo antioksidativno kot tudi protimikrobno aktivnost v primerjavi z izvlečki semen koromača, kar sovpada z vrednostmi TPC. Oba izvlečka sta zavirala rast seva P. fragi (MIK = 0,5 mg/mL za izvleček listov koprive, MIK = 2 mg/mL za izvleček semen koromača), medtem ko je le izvleček listov koprive deloval inhibitorno proti sevu S. aureus (MIK = 2 mg/mL). Ostale testirane bakterije in kvasovke na izvlečka niso bile občutljive.

• Language: Slovenian
• Keywords: rastlinski izvlečki, kopriva, Urtica dioica L., koromač, Foeniculum vulgare, bioaktivne snovi, ekstrakcija z mikrovalovi, MAE, pospešena ekstrakcija, ASE, refluksna ekstrakcija, protimikrobno delovanje, antioksidativni potencial
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [V. Malin]
• Year: 2021
• PID: 20.500.12556/RUL-124825
• UDC: 579.67:579.24:547.9:66.061
• COBISS.SI-ID: 52799747
• Publication date in RUL: 21.02.2021

Secondary language

• Language: English
• Title: Influence of non-conventional extraction methods on antimicrobial activity of the extracts from nettle (Urtica dioica L.) and fennel (Foeniculum vulgare)

Abstract

The aim of this work was to evaluate the impact of different extraction methods on bioactivity of the extracts from nettle (Urtica dioica L.) leaves and fennel (Foeniculum vulgare) seeds. Extracts were obtained by using accelerated solvent extraction (ASE), microwave assisted extraction (MAE) and heat reflux extraction. Total phenolic content (TPC) was determined and ranged from 504 ± 26 to 3301 ± 171 mg GAE/100 g dw in nettle leaves extracts and from 237 ± 10 to 860 ± 26 mg GAE/100 g dw in fennel seeds extracts. Phenolic profile analyses were carried out by UPLC-MS/MS. In total, 27 different compounds were identified in nettle leaves extracts, among those cinnamic acid and kaempferol were far the most abundant in all the extracts while kaempferol-3-O-glucuronide was identified as the most dominant among 21 compounds found in fennel seeds extracts. ASE proved to be optimal method for the extraction of bioactive compounds from nettle leaves, while classical heat reflux for fennel seeds, for both using 30 % acetone as a solvent. Based on the optimal extraction conditions, new extracts were prepared for which antioxidative potential (DPPH, FRAP) and antimicrobial activity using microdilution method were determined. Nettle leaves extract showed both, better antioxidative and antimicrobial activity, compared to fennel seeds extract, which correlated also with TPC values. Both extracts had antimicrobial effect on P. fragi (MIC = 0,5 mg/mL for nettle leaves extract and MIC = 2 mg/mL for fennel seeds extract) while only nettle leaves extract had an inhibitory effect against S. aureus (MIC = 2 mg/mL). Other bacteria and yeasts tested were not sensitive to the extracts.

• Keywords: plant extracts, nettle, Urtica dioica L., fennel, Foeniculum vulgare, bioactive compounds, microwave assisted extraction, MAE, accelerated solvent extraction, ASE, heat reflux extraction, antimicrobial activity, antioxidative potential