Marija Marin

Antimicrobial Activity of Methanol Extracts of Mosses from Serbia

Antibacterial and antifungal activity of methanol extracts of the mosses Pleurozium schreberi (Willd. Ex Brid.) Mitt. (Hylocomiaceae), Palustriella commutata (Hedw.) Ochyra (Amblystegiaceae), Homalothecium philippeanum (Spruce) Schimp. (Brachytheciaceae), Anomodon attenuatus (Hedw.) Huebener (Anomodontaceae), Rhytidium rugosum (Hedw.) Kindb. (Rhytidiaceae), Hylocomium splendens (Hedw.) Schimp. (Hylocomiaceae), Dicranum scoparium Hedw. (Dicranaceae), and Leucobryum glaucum (Hedw.) Ångstr. (Leucobryaceae), were tested against six bacterial and seven fungal species by microdilution and disc diffusion methods. The extract of A. attenuatus possessed the highest antibacterial activity (MIC of 1.25–5.0 mg/ml and MBC of 2.5–5.0 mg/ml), while L. glaucum extract showed the lowest activity (MIC of 20.0–25.0 mg/ml and MBC of 25.0 mg/ml). The best antifungal activity was obtained from P. schreberi extract (MIC of 0.5 mg/ml and MFC of 2.5–5.0 mg/ml, while the lowest antifungal potential was obtained from A. attenuatus (MIC 2.5–5 mg/ml and MFC 10 mg/ml). The extracts proved to be more active against Gram (+) bacteria than Gram (−) and showed strong antifungal activity.

Micromorphology of trichomes of Thymus malyi (Lamiaceae)

Micromorphological, ultrastructural and morphometric investigations of the trichomes of Thymus malyi were carried out using a light microscope, a scanning electron microscope and a transmission electron microscope. Unbranched non‐glandular trichomes, peltate and capitate glandular trichomes were described. The leaves of Thymus malyi bear non‐glandular and glandular trichomes on both sides. Estimates of the volume density (i.e. their volume fraction per unit volume) of non‐glandular trichomes were higher as compared to volume density of peltate and capitate glandular trichomes. Estimates of the number of these trichomes per area on sections showed that the capitate trichomes were the most abundant. Ultrastructural analyses of cell inner structure have shown numerous mitochondria, big nuclei and plastids with lipid globules and starch grains.

Physiological and cell ultrastructure disturbances in wheat seedlings generated by Chenopodium murale hairy root exudate

Chenopodium murale L. is an invasive weed species significantly interfering with wheat crop. However, the complete nature of its allelopathic influence on crops is not yet fully understood. In the present study, the focus is made on establishing the relation between plant morphophysiological changes and oxidative stress, induced by allelopathic extract. Phytotoxic medium of C. murale hairy root clone R5 reduced the germination rate (24% less than control value) of wheat cv. Nataša seeds, as well as seedling growth, diminishing shoot and root length significantly, decreased total chlorophyll content, and induced abnormal root gravitropism. The R5 treatment caused cellular structural abnormalities, reflecting on the root and leaf cell shape and organization. These abnormalities mostly included the increased number of mitochondria and reorganization of the vacuolar compartment, changes in nucleus shape, and chloroplast organization and distribution. The most significant structural changes were observed in cell wall in the form of amoeboid protrusions and folds leading to its irregular shape. These structural alterations were accompanied by an oxidative stress in tissues of treated wheat seedlings, reflected as increased level of H2O2 and other ROS molecules, an increase of radical scavenging capacity and total phenolic content. Accordingly, the retardation of wheat seedling growth by C. murale allelochemicals may represent a consequence of complex activity involving both cell structure alteration and physiological processes.

Wild Thymus capitatus Hoff. Et Link. Chemical Composition, Antioxidant and Antimicrobial Activities of the Essential Oil

Abstract The composition of the essential oil (EO) obtained by hydrodistillation from the leaves of Thymus capitatus Hoff. et Link. growing wild in Sythonia (Greece) was analysed by GC-FID, GC-MS and quantitative 1H NMR spectroscopy. Thirty nine compounds were identified, representing approximately 99.0% of the oil. Major component determined by GC-FID was carvacrol (81.8%), followed by linalool (3.5%) and (E)-caryophyllene (3.5%). Abundance of carvacrol determined by quantitative 1H NMR spectroscopy was 74.9% and was in reasonable agreement with GC-FID result. The oil was tested for the antioxidant activity in DPPH assay and showed a dose dependent free radical scavenging activity with EC50 value of 1.03 μg/ml. Antimicrobial effect of the EO was tested against Gram negative, Gram positive bacteria, and fungi. The tested EO showed significant activity against fungi, especially S. cerevisiae. The most sensitive bacteria were E. coli ATCC 25922, E. fecalis and S. epidermidis. Human pathogen Burkholderia cepacia, ATCC 25416 was used in the investigation of T. capitatus for the first time.

THE HISTOCHEMICAL ANALYSIS OF THYMUS MALYI RONNINGER GLANDULAR TRICHOMES

ABSTRACT The genus Thymus L. belongs to the family Lamiaceae, and comprises numerous aromatic species which are used for medical purposes and also as culinary herbs. Thymus malyi Ronninger is an endemic species from central Balkan which grows on serpentine hills. Histochemical analyses of the peltate and capitate glandular trichomes of Thymus malyi were carried out using light microscopy. Results of histochemical tests showed positive reaction to phenol compounds in the secretory heads of peltate trichomes. Positive reaction for terpenes was obtained in capitate trichomes and in the subcuticular spaces of peltate trichomes. Lipid reaction was positive in the stalk cell of the capitate trichomes, and in the peltate trichomes heads. Positive reaction for polysaccharides was observed in the secretory head of both types of glandular trichomes, with more intensive reaction in the capitate trichomes.