Miško Plazibat

HPTLC determination of flavonoids and phenolic acids in some Croatian Stachys taxa

Stachys is a large genus belonging to the family Lamiaceae. In common with many other representatives of this family, the aerial parts of plants belonging to this genus have been used in folk medicine and phytotherapy for many years. The aim of this work was to determine the amounts of biologically active compounds (flavonoids and phenolic acids) present in seven Croatian Stachys taxa (S. alpina, S. officinalis, S. palustris, S. recta subsp. recta, S. recta subsp. subcrenata, S. salviifolia, and S. sylvatica). This was achieved by establishing an appropriate extraction procedure and by analyzing the samples by HPTLC with densitometric evaluation. Plant extracts and standard solutions of flavonoids and phenolic acids were applied to silica gel 60 F254 HPTLC plates as 10 mm bands. Plates were developed in vertical glass chambers previously saturated with the mobile phase, ethyl acetate—acetic acid—formic acid—water, 100 + 11 + 11 + 26 (v/v). After drying and spraying with NP/PEG reagent, the bands were visualized under short and longwavelength UV light. By use of standard solutions, RF values and fluorescence colors of the investigated compounds were determined. Concentrations of the standard solutions were adjusted to the amounts in the samples and again chromatographed with Stachys samples. The Camag Reprostar 3 Videosystem was used for quantitative evaluation. The compound occurring in most of the samples investigated was found to be chlorogenic acid (it was not present in S. recta subsp. recta only); isoquercitrin, luteolin 7-O glucoside, rutin, and quercitrin were present in several of the samples. Although S. recta subsp. recta did not contain chlorogenic acid, it was found to be richest in the flavonoids whose presence was determined. This HPTLC method was found to be simple and convenient for rapid screening of active compounds and quantification of the investigated flavonoids and phenolic acids in Stachys taxa.

Thin-layer chromatographic analysis of flavonoids, phenolic acids, and amino acids in some Croatian Hypericum taxa

The flowering tops of Hypericum hirsutum, H. montanum, H. perforatum subsp. angustifolium, H. perforatum subsp. perforatum, and H. perforatum subsp. veronense, collected from different locations in Croatia, were investigated to determine their flavonoid, phenolic acid, and amino acid composition. Thin-layer chromatography (TLC) on silica gel was used for separation and identification of the flavonoids and phenolic acids and TLC on cellulose was used for investigation of the amino acids. By use of these procedures ten flavonoids, three phenolic acids, and sixteen amino acids were detected and identified in the samples investigated. The composition of these compounds depended on the taxa investigated and the locality. Spectrophotometric analysis of the flavonoid content indicated that the three subspecies of H. perforatum are richer in flavonoids than H. hirsutum and H. montanum. H. perforatum subsp. perforatum is the richest in flavonoids, phenolic acids, and amino acids. This is the first time these biologically active compounds have been identified in the some Hypericum taxa.

Estimating plant species occurrence in MTB/64 quadrants as a function of DEM-based variables: a case study for Medvednica Nature Park, Croatia

Abstract Croatia is among those European countries without an Atlas of Flora produced till today as a result of constant lack of greater number of active botanists and inconsistency in gathering data in the field. Recently, a standard for collection of data, based on the Central European MTB (abbreviation of German term “Mestischblatter” that stands for a sheet of topographic map) grid was proposed and tested in the field on the “Medvednica Nature Park” on Medvednica mountain near the city of Zagreb. Using the data collected in 97 MTB/64 quadrants (presence/absence of plant species), we tested the potential of estimating species occurrence at the proposed grid by models in a function of the Digital Elevation Model (DEM)-based variables, namely altitude, terrain slope, terrain aspect, and flow accumulation potential. Because of significant spatial variability of environmental factors within MTB/64 quadrants, each one was represented by descriptive statistics (median, 5-, 25-, 75- and 95-percentiles) of DEM-based variables. Thirty-seven plant species were selected arbitrarily, on the basis of their frequency in the studied area (40–60% of all quadrants). Three methods for development of predictive model were used and compared: discriminant analyses, logistic regression, and classification trees. Yielded results suggest that spatial modelling could be probably applied in flora mapping, which would optimise fieldwork. However, decreasing of mapping unit area is recommended, especially for rare species. For larger areas, inclusion of other environmental predictors (macroclimatic, lithological, landuse) in models is probably needed.

Essential Oil of Teucrium flavum L. from Croatia

ABSTRACT The composition of the essential oil of Teucrium flavum L. from Croatia was investigated by GC and GC/MS. Thirty-five components were identified, of which α-pinene (17.3%), β-pinene (11.2%), β-caryophyllene (15.8%) and allo-aromadendrene (9.2%) were the major components.

Essential Oil Content and Composition of Teucrium arduini L.

ABSTRACT Two samples of plant material of Teucrium arduini L., which were collected in 1989 and 1990 were hydrodistilled to produce oil yields of 0.07% and 0.18% (v/w) respectively. GC and GC/MS analysis revealed that germacrene D (23.4% and 57.8%) and β-caryophyllene (17.3% and 13.5%) were the main components of the oils.

An evaluation of floristic diversity in Medvednica Nature Park (northwestern Croatia)

Abstract Mount Medvednica (northwestern Croatia), mostly consisting of slates and marls, rises to the north, above the Croatian capital of Zagreb, from 300 to 1,035 m a.s.l. A floristic research was carried out in the area of Medvednica Nature Park, which consists mainly of the western part of the mountain. On the whole, 1,352 taxa of vascular plants were recorded from all sources (field observations, literature and herbaria). Out of these, 48 taxa are strictly protected, 228 are protected, 67 taxa are considered threatened according to the IUCN categories, and 9 taxa are endemic for the Croatian flora. The life-form analysis of the investigated flora shows the predominance of hemicryptophytes, followed by therophytes and geophytes, while the chorological analysis has evidenced the prevalence of Euro-Asiatic, South European and cosmopolite geographical groups. The biological/chorological cross-spectrum was laid out by considering the percent of every life-form for each geographical element. In order to evaluate the floristic richness of the studied area, the α-index was calculated and then compared with the α-indices of similar regions in Croatia and several European countries. A floristic diversity map of Medvednica Nature Park is presented here for the first time.

Essential oil of Thymus bracteosus Vis. ex Benth., an Endemic Species of Dinaric Karst

Abstract The essential oils of two samples of Thymus bracteosus Vis. ex Benth. (Lamiaceae) collected in Croatia were examined by GC/MS and GC-FID. The major compounds were germacrene D (29.0%) and β-caryophyllene (13.1%), respectively.