Olivera Politeo

Composition and Antimicrobial Activity of Helichrysum italicum Essential Oil and Its Terpene and Terpenoid Fractions

The essential oil of Helichrysum italicum (Roth) G. Don from Croatia has been fractionated into terpene and terpenoid fractions and analyzed using GC/MS. Fifty-two compounds were identified. The main hydrocarbons of the oil were α-pinene (10.2%), α-cedrene (9.6%) aromadendrene (4.4%), β-caryophyllene (4.2%), and limonene (3.8%), while the main oxygen-containing compounds were neryl acetate (11.5%), 2-methylcyclohexyl pentanoate (8.3%), 2-methylcyclohexyl octanoate (4.8%), and geranyl acetate (4.7%). The essential oil and its terpene and terpenoid fractions were evaluated for antibacterial and antifungal activities. The screening of antimicrobial activity was conducted by a disc diffusion test and the minimum inhibitory concentration was determined against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The essential oil and its terpenoid fraction exhibited higher antimicrobial activity with respect to the terpene fraction. The antimicrobial activities of the oil and its terpenoid fraction were more pronounced against Staphylococcus aureus and Candida albicans.

Phenolic Composition and Antioxidant Activity of Aqueous Infusions from Capparis spinosa L. and Crithmum maritimum L. before and after Submission to a Two-Step in Vitro Digestion Model

This study investigated the phenolic composition and antioxidant activities of aqueous infusions from wild-grown caper (Capparis spinosa L.) and sea fennel (Crithmum maritimum L.) from the Dalmatia region (Croatia) before and after their submission to an in vitro digestion process. HPLC/UV-vis-DAD/ESI-MS analysis of the caper infusion identified rutin, kaempferol 3-O-rutinoside, and isorhamnetin 3-O-rutinoside as dominant flavonoids in the matrix together with a series of cinnamoylquinic acid derivatives, whereas in the sea fennel aqueous infusion chlorogenic acid (5-caffeoylquinic acid), its isomers, and higher derivatives were identified as almost the sole class of phenolics. Both infusions exhibited good and dose-dependent antioxidant activity before in vitro digestion by the DPPH method, the β-carotene bleaching method, and copper-induced oxidation of human LDL. The amount of total phenolics (Folin-Ciocalteu assay) strongly decreased in digested samples (from 3.0 and 2.2% in caper and sea fennel infusions, respectively, to <1.0%), as did their antioxidant activity as measured by the three aforesaid methods. The results showed that the majority of phenolic compounds detected in both infusions are not stable under applied simulated gastrointestinal conditions and that the stability of these secondary metabolites strongly depends on the nature of the corresponding matrix.

Molecular and chemical characterization of the most widespread Ocimum species

DNA fingerprinting (AFLP) and chemical analyses of essential oils were utilized to define the extent of variation existing in the genus Ocimum. Research was carried out on 22 Ocimum accessions representing seven species. Concerning the essential oil composition of all investigated accessions, 115 compounds were identified. UPGMA cluster analysis, based on Euclidian distances of essential oil constituents between all pairs of accessions, showed four well-supported clusters (O. tenuiflorum, O. basilicum/O. africanum, O. basilicum, and O. americanum/O. africanum). Relating to the essential oil composition of all of the investigated accessions, 17 compounds were identified as the main ones, and according to them 13 chemotypes were determined. AFLP relationships were determined by neighbor-joining (NJ) cluster analysis based on Dice’s distance matrix and by maximum parsimony (MP) analysis. O. basilicum, O. americanum/O. africanum, O. tenuiflorum, and O. gratissimum represented four clusters supported with high bootstrap values. A neighbor-net diagram allowed the visualization of apparently conflicting data by revealing relationships between genotypes and chemotypes. Concerning the O. africanum species, two distinct chemotypes, geranial/neral (accession 11) and estragol (accession 10), have been established, while all the studied O. americanum accessions belong to the geranial/neral chemotype. This could be additional evidence that O. americanum is one of the parents of O. africanum. Furthermore, the fact that the O. africanum accession (10) as well as O. basilicum ‘Purpurascens’ and O. basilicum ‘Erevanskii’ accessions belong to the estragol chemotype supports the theory that O. africanum is one of the parents of these two O. basilicum accessions.

Chemical characterization and genetic relationships among Ocimum basilicum L. cultivars.

Twenty‐seven Ocimum basilicum cultivars were subjected to a chemical characterization of essential oil components by gas chromatography/mass spectrometry (GC/MS) and a genetic characterization using the amplified fragment‐length polymorphism (AFLP) technique. Since the same 27 accessions had previously been classified into six morphotypes, these analyses allowed us to make detailed comparisons of chemistry, genetics, and morphology. The chemical composition and morphology of the studied cultivars appeared to have a strong genetic component. The AFLP analysis revealed a distinction between the green and purple morphotypes. The green morphotypes predominantly utilized the terpene biosynthetic pathway, while most purple morphotypes primarily utilized the phenylpropene biosynthetic pathway. The GC/MS analysis led to identification of 87 volatiles. Among the 27 cultivars, five chemotypes were identified. A detailed characterization of the essential oil constituents indicated the existence of both specific combinations of compounds and ‘private’ compounds with the potential to be used in many aspects of human life. The established relationship between a genetic profile, chemical composition, and morphology represents an important step in future breeding programs and in the cultivation of this species.

Contribution to the Analysis of the Essential Oil of Helichrysum italicum (Roth) G. Don. - Determination of Ester Bonded Acids and Phenols

The essential oil of Helichrysum italicum (Roth) G. Don (everlasting or Immortelle essential oil) was isolated by hydrodistillation and analysed by GC and GC-MS. Forty four compounds were identified. The main components were α-pinene (12.8%), 2-methyl-cyclohexyl pentanoate (11.1 %), neryl acetate (10.4%), 1,7-di-epi-α-cedrene (6.8%) and other compounds. The oil was fractionated and ester-containing fraction was hydrolysed with KOH/H2SO4. The liberated volatiles were analysed by GC and GC-MS: three phenols and twenty seven volatile carboxylic acids were identified [70% low fatty acids (C2-C5), 15% C10-C12 acids and 15% other acids]. The main acids were acetic acid (24.3%) propanoic acid (17.2%), 2-methylpropanoic acid (11.4%), dodecanoic acid (8.7%), 2-methylbutanoic acid (8.3%), (Z)-2-methylbutenoic acid (5.1%) and decanoic acid (4.6%). With respect to the identified bonded carboxylic acids, the minimal number of esters in the oil was twenty seven, but their overall quantity was probably larger due to different possible combinations of alcohols with acids to form esters. On the other hand, only six main esters were identified in the oil before fractionation and hydrolysis.

Chemical composition and antimicrobial activity of the essential oil of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica).

The chemical composition and the antimicrobial activity of the essential oil isolated from the needles of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica) from Croatia were investigated. The chemical composition of the essential oil was determined by GC and GC/MS analyses, and the main compounds identified were α‐pinene, β‐pinene, germacrene D, and β‐caryophyllene. Disc‐diffusion and broth‐microdilution assays were used for the in vitro antimicrobial screening. The Dalmatian black pine essential oil exhibited a great potential of antibacterial activity against Gram‐positive bacteria (MIC=0.03–0.50% (v/v)) and a less pronounced activity against Gram‐negative bacteria (MIC=0.12–3.2% (v/v)). The volatile compounds also inhibited the growth of all fungi tested, including yeast.

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.

Phytochemical and Cytogenetic Characterization of Centaurea solstitialis L. (Asteraceae) from Croatia

The cytogenetic characterization of Centaurea solstitialis L. (Asteraceae) showed a chromosome number of 2n = 16. Karyotype is composed by four pairs of metacentric, two pairs of submetacentric and two pairs of subtelocentric chromosomes. Physical mapping of two rDNA probes revealed two loci of 35S and one locus of 5S rRNA genes. Chromomycin fluorochrome banding revealed that all rDNA loci were GC rich. The genome size (2C‐value) of 1.95 pg classes this species in the group of very small genomes. Chemical composition of C. solstitialis volatile oil (VO) from Croatia, studied with gas chromatography–mass spectrometry showed dominant components as it follows: hexadecanoic acid, α‐linolenic acid, germacrene D and heptacosane. Antioxidant capacity, measured by ferric reducing power assay and 2,2‐diphenyl‐1‐picrylhydrazyl methods, as well as inhibition of acetyl‐ and butyrylcholinesterase of VO was lower comparing to a standard solutions. Volatile oil tested with disc diffusion method showed good inhibitory potential against Pseudomonas aeruginosa, Escherichia coli and all tested fungi: Candida albicans, Penicillium funiculosum and Aspergillus fumigatus. The microdilution method showed best activity against Chronobacter sakazakii and A. fumigatus.

Effects of Ocimum spp. essential oil on Monilinia laxa in vitro

One of the most important postharvest diseases of peach and nectarine is brown rot caused by the fungus Monilinia laxa. Increasing concern related to the toxic effect of the pesticide residues on fruits has enhanced the interest for the control of postharvest pathogenic fungi using biologically active constituents of plants such as essential oils. Species from genus Ocimum are known to possess essential oils with antifungal and fungicidal properties. The present paper reports the results of essential oil composition of four basil taxa and preliminary screening of their antifungal activity against M. laxa. The greatest effectiveness was achieved by the essential oils from Ocimum basilicum var. purpurascens and Ocimum tenuiflorum, whose activity was high throughout the testing period of twenty-three days.

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.