Franko Burčul

Influence of the phenophase on the phenolic profile and antioxidant properties of Dalmatian sage.

This study aimed to research the influence of phenophase on the phenolic profile (phenolic acids, flavonoids and stilbenes) and related antioxidant properties of sage, one of the most characteristic plants of Dalmatian karst. The total phenol and flavonoid contents in sage leaves were determined spectrophotometrically, while the principal phenolics were determined using HPLC-RP-DAD. Antioxidant properties of this well known medicinal plant were determined as free radical scavenging activity (DPPH), ferric reducing/antioxidant power (FRAP) and by Briggs-Rauscher oscillating reaction (BR). The results strongly indicate that Dalmatian sage leaves are rich source of valuable phenolics, mainly phenolic acids, with extremely good antioxidant properties. The presence of resveratrol or its derivatives was confirmed in all extracts. The best results for total phenols and flavonoids, as well as the best antioxidant properties were obtained for May sage, while the highest amounts of catechin monomers and compounds from group of stilbenes were found in February extract.

Antiphytoviral activity of sesquiterpene-rich essential oils from four croatian teucrium species.

The purpose of this study was to compare the essential oil profiles of four Croatian Teucrium species (Lamiaceae), as determined by GC and GC/MS, with their antiphytoviral efficiency. A phytochemical analysis showed that T. polium, T. flavum, T. montanum and T. chamaedrys are characterized by similar essential oil compositions. The investigated oils are characterized by a high proportion of the sesquiterpene hydrocarbons β-caryophyllene (7.1–52.0%) and germacrene D (8.7–17.0%). Other important components were β-pinene from T. montanum and α-pinene from T. flavum. The investigated essential oils were proved to reduce lesion number in the local host Chenopodium quinoa Willd. infected with Cucumber Mosaic Virus (CMV), with reductions of 41.4%, 22.9%, 44.3% and 25.7%, respectively.

Chemical composition and evaluation of acetylcholinesterase inhibition and antioxidant activity of essential oil from Dalmatian endemic species Pinus nigra Arnold ssp. dalmatica (Vis.) Franco

In the present study, the chemical composition and biological activity (acetylcholinesterase inhibition and antioxidant activity) of essential oil from endemic species Pinus nigra Arnold ssp. dalmatica (Vis.) Franco was investigated. α-Pinene, β-pinene, germacrene D and β-caryophyllene were identified by GC-FID and GC-MS as dominant components of the oil. P. nigra ssp. dalmatica essential oil showed relatively high inhibitory activity on acetylcholinesterase (AChE), which can be in relation with good AChE inhibitory activity of pure main monoterpene components of the oil (S-α-pinene) and their mixtures (S-α-pinene:S-β-pinene and R-α-pinene:S-β-pinene, in ratio 3:2). Essential oil from P. nigra ssp. dalmatica did not show significant antioxidant activity tested by three methods: DPPH radical scavenging method, Ferric Reducing Antioxidant Potential (FRAP) and Thiobarbituric Acid Reactive Species (TBARS) assays.

Screening for acetylcholinesterase inhibition and antioxidant activity of selected plants from Croatia

The methanol, ethyl acetate and chloroform extracts of selected Croatian plants were tested for their acetylcholinesterase (AChE) inhibition and antioxidant activity. Assessment of AChE inhibition was carried out using microplate reader at 1 mg mL−1. Antioxidant capacities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test and ferric reducing/antioxidant power assay (FRAP). Total phenol content (TPC) of extracts were determined using Folin–Ciocalteu colorimetric method. Out of 48 extracts, only methanolic extract of the Salix alba L. cortex exerted modest activity towards AChE, reaching 50.80% inhibition at concentration of 1 mg mL−1. All the other samples tested had activity below 20%. The same extract performed the best antioxidative activity using DPPH and FRAP method, too. In essence, among all extracts used in the screening, methanolic extracts showed the best antioxidative activity as well as highest TPC.

Glucosinolates, volatile constituents, and acetylcholinesterase inhibitory activity of Alyssoides utriculata

Glucosinolates (GLs) and volatiles from all plant parts of Alyssoides utriculata (L.) Medik were determined for the first time. Total GLs determined by ferricyanide assay were 45.7, 12.2, 7.3, 12.5 and 15.7 μmol/g dry weight in the seed, root, stem, leaf and flower, respectively. Qualitative determination of individual GLs was done indirectly by GC/MS analysis of volatiles isolated by hydrodistillation, as well as by CH2Cl2 extraction after enzyme hydrolysis. The extracts were shown to contain mostly volatiles originating from degradation of gluconapin, glucoerucin, and glucoraphanin. The volatile isolates, tested for their acetylcholinesterase inhibition according to Ellman method, were dose-dependent reaching 53.9% and 53.3% at the final concentration of 320 μg/mL, for seed CH2Cl2 extract and hydrodistillate of the whole plant, respectively.

Isothiocyanates: cholinesterase inhibiting, antioxidant, and anti-inflammatory activity

Abstract Finding a new type of cholinesterase inhibitor that would overcome the brain availability and pharmacokinetic parameters or hepatotoxic liability has been a focus of investigations dealing with the treatment of Alzheimer’s disease. Isothiocyanates have not been previously investigated as potential cholinesterase inhibitors. These compounds can be naturally produced from their glucosinolate precursors, secondary metabolites widely distributed in our daily Brassica vegetables. Among 11 tested compounds, phenyl isothiocyanate and its derivatives showed the most promising inhibitory activity. 2-Methoxyphenyl ITC showed best inhibition on acetylcholinesterase with IC50 of 0.57 mM, while 3-methoxyphenyl ITC showed the best inhibition on butyrylcholinesterase having 49.2% at 1.14 mM. Assessment of the antioxidant efficacy using different methods led to a similar conclusion. The anti-inflammatory activity was also tested using human COX-2 enzyme, ranking phenyl isothiocyanate, and 3-methoxyphenyl isothiocyanate as most active, with ∼99% inhibition at 50 μM.

Campanula portenschlagiana Roem. et Schult.: Chemical and Antimicrobial Activities

The phytochemical profile and the antimicrobial effects of the volatile oil and the aqueous extract of Campanula portenschlagiana, a wild growing plant endemic to Croatia, were described. In the volatile oil, 53 compounds were identified by GC‐FID and GC/MS analyses. Diterpene alcohols constituted the major compound class with labda‐13(16),14‐dien‐8‐ol as the main compound. The aqueous extract was characterized by the total phenolic content. The antimicrobial potential of the volatile oil and the aqueous extract was evaluated against a diverse range of microorganisms comprising food‐spoilage and food‐borne pathogens. The volatile oil exhibited interesting and promising antimicrobial effects against the tested species, which were generally more pronounced against Gram‐negative bacteria. In addition, the inhibitory effect of this volatile oil was also evaluated against eleven extended‐spectrum β‐lactamase (ESBL)‐producing isolates. The results suggest that the C. portenschlagiana volatile oil might be used as antimicrobial agent against ESBL‐producing isolates and Gram‐negative bacteria.