Aleksandra Đorđević

Xanthine Oxidase: Isolation, Assays of Activity, and Inhibition

Xanthine oxidase (XO) is an important enzyme catalyzing the hydroxylation of hypoxanthine to xanthine and xanthine to uric acid which is excreted by kidneys. Excessive production and/or inadequate excretion of uric acid results in hyperuricemia. This paper presents a detailed review of methods of isolation, determination of xanthine oxidase activity, and the effect of plant extracts and their constituents on it. Determining the content and activities of XO can be used for diagnostic purposes. Testing inhibition of XO is important for detection of potentially effective compounds or extracts that can be used to treat diseases that are caused by increased activity of XO. In vitro bioassays are used to examine test material for XO inhibition, as inhibitors of XO may be potentially useful for the treatment of gout or other XO induced diseases. Several authors reported on the XO inhibitory potential of traditionally used medicinal plants.

GC-MS analyses of flower ether extracts of Prunus domestica L. and Prunus padus L. (Rosaceae)

Volatiles of fresh flowers of Prunus domestica L. and Prunus padus L. (their diethyl ether extracts) were analyzed by GC and GC-MS. 110 and 33 constituents were identified in P. domestica and P. padus extracts, respectively. 32 of the identified constituents were previously unreported as metabolites of taxa belonging to the genus Prunus. Six of them (4-methoxybenzyl palmitate, isoamyl stearate, isoamyl eicosanoate, isoamyl docosanoate and penta-O-acetyl-α- and β-D-glucopyranoses) are compounds reported for the first time from a natural source and one (isoamyl tetracosanoate) is a new compound in general. The major component of P. domestica extract was kaempferol (35.0 %), while P. padus extract was found to be rich in (Z)-8-hydroxylinalool (30.4 %), benzaldehyde (19.8 %) and 2-phenylethanol (15.1 %). Both extracts (P. domestica and P. padus) contained rather large amounts of shikimate metabolites (51.7 % and 39.1 %, respectively) and anther related odd-carbon numbered alkanes (23.2 % and 27.0 %, respectively). The observed differences between P. domestica and P. padus extracts corroborate the placement of P. domestica and P. padus in separate subgenera (Prunus and Cerasus, respectively) of the genus Prunus.

The case of Hypericum rochelii Griseb. & Schenk and Hypericum umbellatum A. Kern. essential oils: chemical composition and antimicrobial activity.

The chemical composition and antimicrobial activity studies on the essential oils of Hypericum rochelii Griseb. & Schenk and Hypericum umbellatum A. Kern. have been carried out for the first time. Seventy-nine compounds were identified in the essential oil of H. rochelii with n-nonane (24.7%), β-pinene (22.4%), germacrene D (7.5%), n-undecane (6.8%) and α-pinene (5.8%) as main constituents. One hundred and twenty-six compounds were identified in H. umbellatum essential oil with germacrene D (6.1%), (E)-nerolidol (4.4%), n-nonane (4.0%), (E)-caryophyllene (3.0%) and caryophyllene oxide (3.0%) as the most abundant components. Both oils were characterized by the presence of many components which could have numerous applications in food, pharmaceutical and perfume industries. Taxa studied herein belong to the section Drosocarpium Spach, and their intrasectional placement based on the essential oil profiles was discussed. The oils were tested in a broth microdilution assay against five bacterial and two fungal strains and found to have mainly moderate antimicrobial effects.

Essential Oil Composition of Hypericum annulatum Moris (Hypericaceae) from Serbia

Abstract The essential oil of fresh aerial parts of Hypericum annulatum Moris obtained by hydrodistillation was analyzed by GC and GC/MS. One-hundred-sixteen constituents identified accounted for 98.9% of the total oil. The major components of the oil were: α-pinene (56.3%), (E)-β-ocimene (10.2%), undecane (6.3%), myrcene (4.3%) and β-pinene (4.2%). The volatile profile of H. annulatum differs significantly from that of the rest of the taxa belonging to the section Adenosepalum, as well as from previously investigated Hypericum species growing in the same region (southeastern Serbia).

Ramalina capitata (Ach.) Nyl. acetone extract: HPLC analysis, genotoxicity, cholinesterase, antioxidant and antibacterial activity

In the present investigation, effects of Ramalina capitata acetone extract on micronucleus distribution on human lymphocytes, on cholinesterase activity and antioxidant activity (by the CUPRAC method) were examined, for the first time as well as its HPLC profile. Additionally, total phenolic compounds (TPC), antioxidant properties (estimated via DPPH, ABTS and TRP assays) and antibacterial activity were determined. The predominant phenolic compounds in this extract were evernic, everninic and obtusatic acids. Acetone extract of R. capitata at concentration of 2 μg mL-1 decreased a frequency of micronuclei (MN) for 14.8 %. The extract reduces the concentration of DPPH and ABTS radicals for 21.2 and 36.1 % (respectively). Values for total reducing power (TRP) and cupric reducing capacity (CUPRAC) were 0.4624 ± 0.1064 μg ascorbic acid equivalents (AAE) per mg of dry extract, and 6.1176 ± 0.2964 μg Trolox equivalents (TE) per mg of dry extract, respectively. The total phenol content was 670.6376 ± 66.554 μg galic acid equivalents (GAE) per mg of dry extract. Tested extract at concentration of 2 mg mL-1 exhibited inhibition effect (5.2 %) on pooled human serum cholinesterase. The antimicrobial assay showed that acetone extract had inhibition effect towards Gram-positive strains. The results of manifested antioxidant activity, reducing the number of micronuclei in human lymphocytes, and antibacterial activity recommends R. capitata extract for further in vivo studies.

Chemical Composition of Ballota macedonica Vandas and Ballota nigra L. ssp. foetida (Vis.) Hayek Essential Oils - The Chemotaxonomic Approach.

The essential oils isolated from fresh aerial parts of Ballota macedonica (two populations) and Ballota nigra ssp. foetida were analyzed by GC and GC/MS. Eighty five components were identified in total; 60 components in B. macedonica oil (population from the Former Yugoslav Republic of Macedonia), 34 components in B. macedonica oil (population from the Republic of Serbia), and 33 components in the oil of B. nigra ssp. foetida accounting for 93.9%, 98.4%, and 95.8% of the total oils, respectively. The most abundant components in B. macedonica oils were carotol (13.7 – 52.1%), germacrene D (8.6 – 24.6%), and (E)‐caryophyllene (6.5 – 16.5%), while B. nigra ssp. foetida oil was dominated by (E)‐phytol (56.9%), germacrene D (10.0%), and (E)‐caryophyllene (4.7%). Multivariate statistical analyses (agglomerative hierarchical cluster analysis and principal component analysis) were used to compare and discuss relationships among Ballota species examined so far based on their volatile profiles. The chemical compositions of B. macedonica essential oils are reported for the first time.

Chemical Profile of Satureja Kitaibelii Wierzb. ex Heuff. Essential Oils: Composition of Satureja Kitaibelii Essential Oils

The essential oils from dried aerial parts of Satureja kitaibelii Wierzb. ex Heuff., collected at three various sites in Serbia, were analyzed by gas chromatography and gas chromatography/mass spectrometry. One hundred sixty-three components were identified in all investigated samples, 132 components in the oil from the site Devojački grob, 124 components in the oil coming from Sićevačka klisura site, and 146 components in the oil from the site Visočka Ržana, accounting 97.3, 93.9, and 95.6% of the total oils, respectively. The most abundant component in the essential oils was geraniol amounting from 24.0 to 30.3%, making up about one-quarter of the total oils. Other representative compounds were identified as linalool (5.0–14.8%), limonene (4.3–7.9%), and caryophyllene oxide (4.4–5.2%) in all tested samples. The results suggested that essential oils of S. kitaibelii belong to the aliphatic monoterpene chemotype.

Phenolics, Antioxidant Potentials, and Antimicrobial Activities of Six Wild Boletaceae Mushrooms

ABSTRACT Since mushrooms are important sources of bioactive compounds such as phenolic acids, their identification and quantification were performed by high-performance liquid chromatography resulting in total concentrations between 2.9161 ± 0.0829 mg/kg (Boletus fechtneri) and 51.4480 ± 1.0333 mg/kg (Boletus appendiculatus). The antioxidant properties of methanol extracts and corresponding hydrolysates were estimated using 2,2-diphenyl-1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), total reducing power, ferric-reducing antioxidant power, cupric-reducing antioxidant capacity, and total phenolic content assays. The Xerocomus badius methanol extract showed the highest antioxidant potential, while among hydrolysates, the highest antioxidant potential was observed for Xerocomellus chrysenteron. The antimicrobial activities of methanol extracts of studied mushrooms against pathogenic bacterial and fungal strains were measured and the highest values were obtained for B. fechtneri and B. appendiculatus extracts against Pseudomonas aeruginosa. Principal component analyses and agglomerative hierarchical clustering were used to display the correlation between the parameters and their relationships with the mushroom species.

Secondary Metabolites of Hypericum L. Species as Xanthine Oxidase Inhibitors

Summary Nine Hypericum species (H. barbatum, H. hirsutum, H. linarioides, H. olympicum, H. perforatum, H. rochelii, H. rumeliacum, H. tetrapterum and H. umbellatum) collected in Serbia were assayed for inhibitory potential against xanthine oxidase in vitro, on the commercial enzyme, and compared with allopurinol. Seven studied Hypericum species (H. barbatum, H. rochelii, H. rumeliacum, H. umbellatum, H. perforatum, H. tetrapterum and H. olympicum) inhibit commercial xanthine oxidase with an IC50 below 100 μg/mL. H. barbatum exerted the most potent inhibitory effect (IC50 = 31.84 ± 6.64 μg/mL), followed closely by H. perforatum (IC50 = 37.12 ± 4.06 μg/mL).

Chemical composition and antibacterial activity of the essential oils isolated from leaves and fruits of Peucedanum austriacum (Jacq.) W.D.J. Koch

Chemical composition and antibacterial activity of the essential oils isolated from fruits and leaves of Peucedanum austriacum (Jacq.) W.D.J. Koch were determined in order to define their medical potential. An analysis of leaf and fruit essential oils by gas chromatography (GC) and GC/mass spectrometry (GC/MS) resulted in identification of 141 different components, representing 93.6% and 96.1% of the total oils. The most abundant class of compounds in fruit essential oil was monoterpenoids (64.0%) and in the leaf essential oil sesquiterpenoids (82.0%). The major contributors of fruit essential oil were β-phellandrene (45.2%) and α-pinene (10.1%). The major constituents of leaf essential oil were caryophyllene oxide (23.1%), germacrene D (12.2%) and (E)-caryophyllene (10.2%). Minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC) were determined by performing broth microdilution assay. In the antibacterial activity assay, both samples showed moderate activity against Bacillus subtilis and Staphylococcus aureus with inhibitory effect at 0.625 and 1.25 mg/mL, weak activity against Pseudomonas aeruginosa with inhibitory effect at 5.00 mg/mL and no effect on the growth of bacteria Escherichia coli and Salmonella typhimurium. The results showed that essential oils composition of P. austriacum leaves and fruits differed considerably. Tested oils were proved selective antibacterial agents.