Naslov (srp)

Hemijska karakterizacija i analiza biološke aktivnosti izolata iz breze (Betula pendula Roth.)

Autor

Vladimirov, Marijana S., 1989-

Doprinosi

Nikolić, Vesna, 1965-
Stanojević, Ljiljana, 1976-
Dinić, Ana D., 1988-
Stanojević, Jelena S., 1987-
Stojanović, Sanja T., 1988-

Opis (srp)

Research conducted within this doctoral dissertation includes theexamination of the chemical composition, biological activities, as well asthe potential for improving the properties of bioactive compounds derivedfrom birch (Betula pendula Roth). For this purpose, different types ofstarting plant material were used, including birch buds, sap, leaves, andbark. In addition, inclusion complexes of standards of bioactive triterpenesfrom birch bark, betulin (BE) and betulinic acid (BA), withhydroxypropyl-β-cyclodextrin (HP-β-CD) were prepared, and theirbiological activity was also evaluated.Essential oils from birch buds and leaves were isolated by Clevenger-typehydrodistillation. Isolation of bioactive compounds from birch bark andleaves was performed by Soxhlet extraction, using 96% ethanol. The sapobtained from the birch tree was extracted by diethyl-ether and ethylacetate,after which the extracts were evaporated to dryness under reducedpressure using a rotary vacuum evaporator. The characterization of birchisolates was performed by gas chromatography–mass spectrometry (GC–MS). The bioactive triterpenes betulin and lupeol (LU) were identified inthe birch bark extract.The content of micro- and macroelements in birch sap was determinedusing ICP-OES method. The mineral composition of birch sap indicated arelatively high content of the macroelements potassium (58.79 μg/cm³)and calcium (47.21 μg/cm³), while the most abundant microelement wasmanganese (25.72 μg/cm³). The total phenolic and flavonoid content inbark and leaf extracts, as well as in birch sap, were determined using theFolin-Ciocalteu method. It was found that the leaf extract contained thehighest amount of total phenolics, whereas the lowest content of totalphenolics was recorded in the sap extract. Total flavonoids were detectedonly in the birch leaf extract.Inclusion complexes of betulin and betulinic acid with hydroxypropyl-β-cyclodextrin were prepared by the coprecipitation method, in order toimprove their water solubility. The complexes were characterized usingvarious instrumental techniques (FTIR, SEM, XRD, DSC), whichconfirmed the successful inclusion of BE and BA into the cavities ofcyclodextrin. Due to the increased water solubility, the BE:HP-β-CDinclusion complex exhibited stronger antioxidant activity compared topure betulin. In contrast, betulinic acid showed lower antioxidant accitvityin the inclusion complex, which may be attributed to stronger interactionsof its functional groups with HP-β-CD.The antimicrobial activity of essential oils was determined by the diskdiffusion method, while the antimicrobial activity of extracts andinclusion complexes was detremined using the microdilution method.Birch leaf essential oil exhibited a broader spectrum of antimicrobialactivity compared to birch bud essential oil. Birch bark extracts showedstronger antimicrobial activity compared to leaf extracts, while birch sapdid not exhibit antimicrobial activity against the tested microorganisms.Betulin, betulinic acid, and their inclusion complexes did not showantibacterial activity against the tested bacterial strains. However,antimicrobial activity of betulinic acid and the BA:HP-β-CD complex wasobserved against the fungus Candida albicans, with more pronouncedactivity of betulinic acid in the inclusion complex.The antioxidant activity of isolates and formulations was evaluated by theDPPH assay. The obtained EC₅₀ values indicate that that the birch leafextract exhibits the highest antioxidant activity, followed by the birch barkextract, while the lowest antioxidant activity was recorded in the birch sapextract.The effects of birch bark extract, birch sap, BE, BA, and the inclusioncomplexes of BE and BA on the viability and proliferation of MDCK cellsin vitro were examined using the MTT assay. A stimulatory effect of thetested concentrations of birch sap on cell viability and proliferation wasobserved, whereas the birch bark extract exhibited cytotoxic andantiproliferative effects, at certain concentrations. Betulin and betulinicacid showed cytotoxic and anti-proliferative concentration-dependenteffect, with a more pronounced effect observed for betulin. This trend wasalso observed in the case of inclusion complexes BE:HP-β-CD andBA:HP-β-CD, while the complexing agent (HP-β-CD) did not exhibitsuch effects at the tested concentrations.

Opis (srp)

Biografija autora sa bibliografijom: list 150-154.Bibliografija: list. 128-147. Datum odbrane: 28.09.2026. Chemistry and chemical technology

Jezik

srpski

Datum

2026

Licenca

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Creative Commons CC BY-NC-ND 3.0 AT - Creative Commons Autorstvo - Nekomercijalno - Bez prerada 3.0 Austria License.

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