Milan S. Stanković

Antioxidant, Antimicrobial and Antiproliferative Activities of Five Lichen Species

The antioxidative, antimicrobial and antiproliferative potentials of the methanol extracts of the lichen species Parmelia sulcata, Flavoparmelia caperata, Evernia prunastri, Hypogymnia physodes and Cladonia foliacea were evaluated. The total phenolic content of the tested extracts varied from 78.12 to 141.59 mg of gallic acid equivalent (GA)/g of extract and the total flavonoid content from 20.14 to 44.43 mg of rutin equivalent (Ru)/g of extract. The antioxidant capacities of the lichen extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging. Hypogymnia physodes with the highest phenolic content showed the strongest DPPH radical scavenging effect. Further, the antimicrobial potential of the lichen extracts was determined by a microdilution method on 29 microorganisms, including 15 strains of bacteria, 10 species of filamentous fungi and 4 yeast species. A high antimicrobial activity of all the tested extracts was observed with more potent inhibitory effects on the growth of Gram (+) bacteria. The highest antimicrobial activity among lichens was demonstrated by Hypogymnia physodes and Cladonia foliacea. Finally, the antiproliferative activity of the lichen extracts was explored on the colon cancer adenocarcinoma cell line HCT-116 by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) viability assay and acridine orange/ethidium bromide staining. The methanol extracts of Hypogymnia physodes and Cladonia foliacea showed a better cytotoxic activity than the other extracts. All lichen species showed the ability to induce apoptosis of HCT-116 cells.

Teucrium Plant Species as Natural Sources of Novel Anticancer Compounds: Antiproliferative, Proapoptotic and Antioxidant Properties

This study deals with total phenolic content, antiproliferative and proapoptotic activity of methanolic extracts from different Teucrium species and the effect on the prooxidant/antioxidant status in HCT-116 cells. The total phenolic content of the extracts was measured spectrophotometricaly and the obtained results ranged from 56.62 mg/g to 172.50 mg GA/g. The antiproliferative activity of methanolic extracts from different Teucrium species was determined using MTT cell viability assay, where IC50 value was used as a parameter for cytotoxicity. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. MTT assay showed that all extracts significantly reduced cell viability in a dose-dependent manner, with very low IC50 values. The highest content of phenolic compounds and the best cytotoxic activity on HCT-116 cells after 24 h of exposure was in T. chamaedrys extract, with IC50 values of 5.48 × 10−9 μg/mL. After 72 h, methanolic extract of T. arduini appeared to have the best cytotoxic activity on HCT-116, with IC50 values of 0.37 μg/mL. Treatments caused typical apoptotic morphological changes in HCT-116 cells and showed a high percentage of apoptotic cells. The results of the presented research indicate that some Teucrium extracts are a very rich source of phenols, which may directly contribute to high antiproliferative and proapoptotic activity.

TOTAL PHENOLIC CONTENT, FLAVONOID CONCENTRATIONS AND ANTIOXIDANT ACTIVITY, OF THE WHOLE PLANT AND PLANT PARTS EXTRACTS FROM TEUCRIUM MONTANUM L. VAR. MONTANUM, F. SUPINUM (L.) REICHENB.

ABSTRACT The aim of this study was to determine the total phenolic content, concentrations of flavonoids and in vitro antioxidant activity of twenty different extracts from the plant and plant parts (leaves, flowers and stems) of Teucrium montanum L. var. montanum, f. supinum (L.) Reichenb. The total phenolic content in the extracts was determined using Folin-Ciocalteu reagent and their amounts ranged between 8.33 to 169.06 mg GA/g. The concentrations of flavonoids in plant extracts varied from 3.96 to 88.31 mg RU/g. Antioxidant activity was analyzed in vitro using DPPH reagent, activity expressed as IC50 and obtained results ranged from 29.41 to 2408.47 μg/mL. Parallel to the analysis of T. montanum, Ginkgo biloba L. and Green tea (Camellia sinensis (L.) Kuntze) extracts were analyzed for comparison, and the results indicated that some extracts of T. montanum were equal in activity with Ginkgo or Green tea and some appeared to have greater activity. Based on these results of investigation, it could be concluded that T. montanum is a rich source of phenolic compounds as natural antioxidans of high value.

Antiproliferative and proapoptotic activities of methanolic extracts from Ligustrum vulgare L. as an individual treatment and in combination with palladium complex.

The aim of this study is to examine the growth inhibitory effects of methanolic leaf and fruit extracts of L. vulgare on HCT-116 cells over different time periods and their synergistic effect with a Pd(apox) complex. The antiproliferative activity of plant extracts alone or in combination with the Pd(apox) complex was determined using MTT cell viability assay, where the IC50 value was used as a parameter of cytotoxicity. Results show that antiproliferative effects of L. vulgare extracts increase with extension of exposure time, with decreasing IC50 values, except for 72 h where the IC50 values for methanolic leaf extract were lower than for the fruit extract. The Pd(apox) complex alone had a weak antiproliferative effect, but combination with L. vulgare extracts caused stronger effects with lower IC50 values than with L. vulgare extracts alone. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. Treatments with plant extracts caused typical apoptotic morphological changes in HCT-116 cells and co-treatments with Pd(apox) complex caused higher levels of apoptotic cells than treatment with plant extracts alone. The results indicate that L. vulgare is a considerable source of natural bioactive substances with antiproliferative activity on HCT-116 cells and which have a substantial synergistic effect with the Pd(apox) complex.

Grewia asiatica L., a Food Plant with Multiple Uses

Grewia asiatica L., is a species native to south Asia from Pakistan, east to Cambodia, cultivated primarily for its edible fruit and well-reputed for its diverse medicinal uses. Fruits are a rich source of nutrients such as proteins, amino acids, vitamins, and minerals and contain various bioactive compounds, like anthocyanins, tannins, phenolics and flavonoids. Different parts of this plant possess different pharmacological properties. Leaves have antimicrobial, anticancer, antiplatelet and antiemetic activities; fruit possess anticancer, antioxidant, radioprotective and antihyperglycemic properties; while stem bark possesses analgesic and anti-inflammatory activities. This review focuses on the botanical description, phytochemistry, nutritional studies and pharmacological properties of this plant.

Biological Effects, Total Phenolic Content and Flavonoid Concentrations of Fragrant Yellow Onion (Allium flavum L.)

The antioxidant, antibacterial and antiproliferative activities, total phenolic content and concentrations of flavonoids of A. flavum extracts were determined. The total phenolic content was determined with Folin-Ciocalteu reagent and it ranged between 42.29 to 80.92 mg GA/g. The concentration of flavonoids in various extracts of A. flavum was determined using spectrophotometric method with aluminum chloride and obtained results varied from 64.07 to 95.71 mg RU/g. The antioxidant activity was monitored spectrophotometrically and expressed in terms of IC50 (μg/ml), and its values ranged from 64.34 to 243.34 μg/ml. The highest phenolic content and capacity to neutralize DPPH radicals were found in acetone extract. Antibacterial efficacy was defined by determining minimum inhibitory and minimum bactericidal concentrations using microdilution method. Significant antibacterial activity, especially for ethyl acetate extract, was observed. The best activity was showed against G+ bacteria, Staphylococcus aureus ATCC 25923 and Bacillus subtilis, while Escherichia coli was one of the least sensitive bacteria. Antiproliferative activity of the methanolic extract on HCT- 116 cell line was determined by MTT assay. Results showed that A. flavum has good antiproliferative activity with IC50 values of 28.29 for 24 h and 35.09 for 72 h. Based on these results, A. flavum is a potential source of phenols as natural antioxidant, antibacterial and anticancer substance of high value. Phenolic content of extracts depend on the solvents used for extraction.

Platismatia glaucia and Pseudevernia furfuracea lichens as sources of antioxidant, antimicrobial and antibiofilm agents

The antioxidative, antimicrobial and antibiofilm potentials of acetone, ethyl acetate and methanol extracts of lichen species Platismatia glauca and Pseudevernia furfuracea were evaluated. The phytochemical analysis by GC, GC/MS and NMR revealed caperatic acid, atraric acid, atranorin and chloroatranorin as the predominant compounds in Platismatia glauca. Atraric acid, olivetoric acid, atranorin and chloroatranorin were the major constituents in Pseudevernia furfuracea. The strong antioxidant capacities of the Platismatia glauca and Pseudevernia furfuracea extracts were assessed by their total phenolic and flavonoid contents and DPPH scavenging activities. The methanol extracts of both species exhibited the strongest antioxidant activities with the highest IC50 value for Pseudevernia furfuracea (95.33 µg/mL). The lichen extracts demonstrated important antibacterial activities against 11 bacterial strains with detectable MIC values from 0.08 mg/mL to 2.5 mg/mL for Platismatia glauca and from 0.005 mg/mL to 2.5 mg/mL for Pseudevernia furfuracea. While the antibacterial activities of Pseudevernia furfuracea were solvent–independent, the acetone and ethyl acetate extracts of Platismatia glauca showed higher antibacterial activities compared to its methanol extract. The methanol extracts of both species demonstrated significant antifungal activities against 9 fungal strains with detectable MIC values from 0.04 mg/mL to 2.5 mg/mL. The best antifungal activities were determined against Candida species in Pseudevernia furfuracea extracts with remarkable MIC values which were lower than the MIC values of the positive contol fluconazole. The acetone and ethyl acetate extracts of Platismatia glauca showed better antibiofilm activities on Staphylococcus aureus and Proteus mirabilis with BIC value at 0.63 mg/mL then its methanol extract. On the other hand, the methanol extract of Pseudevernia furfuracea was more potent with BIC value at 1.25 mg/mL on Staphylococcus aureus and 0.63 mg/mL on Proteus mirabilis compared to other types of extracts. Our study indicates a possible use of lichens Platismatia glauca and Pseudevernia furfuracea as natural antioxidants and preservatives in food, pharmaceutical and cosmetic industry.

In Vitro Cytotoxic Activity of Origanum vulgare L. on HCT-116 and MDA-MB-231 Cell Lines.

In the present investigation, we examined the cytotoxic effect of methanolic extract from Origanum vulgare on HCT-116 and MDA-MB-231 cell line in vitro. In order to determine the cytotoxic effects we used an MTT viability assay. The results showed that cell growth is significantly lower in extract treated cells compared to untreated control. The effect of inhibition of cell growth was higher in the treatment of HCT-116 cell line than in MDA-MB-231. Based on the results it is determined that O. vulgare is a significant source of biologically active substances that have cytotoxic and antiproliferative activity in vitro.

Dropwort (Filipendula hexapetala Gilib.): potential role as antioxidant and antimicrobial agent

The aim of this study was to investigate the antioxidant activity of the methanolic extracts of Filipendula hexapetala Gilib. aerial parts (FHA) and roots (FHR) and their potential in different model systems, as well as antimicrobial activity. According to this, a number of assays were employed to evaluate the antioxidant and antimicrobial potential of F. hexapetala extracts. In addition, the antioxidant activity assays in different model systems were carried out, as well as pH, thermal and gastrointestinal stability studies. The phenolic compounds contents in FHA and FHR were also determined. The results showed that F. hexapetala extracts had considerable antioxidant activity in vitro and a great stability in different conditions. The extracts exhibited antimicrobial activity against most of the tested bacterial and fungal species. Also, the extracts contain high level of phenolic compounds, especially aerial parts extract.

Immortelle (Xeranthemum annuum L.) as a natural source of biologically active substances

Antioxidant and antimicrobial effects, total phenolic content and flavonoid concentrations of methanolic, acetone and ethyl acetate extracts from Xeranthemum annuum L. were investigated in this study. The total phenolic content was determined using Folin-Ciocalteu reagent and ranged between 101.33 to 159.48 mg GA/g. The concentration of flavonoids in various X. annuum extracts was determined using spectrophotometric method with aluminum chloride and the results varied from 22.25 to 62.42 mg RU/g. Antioxidant activity was monitored spectrophotometrically using DPPH reagent and expressed in terms of IC50 (µg/ml), and it ranged from 59.25 to 956.81 µg/ml. The highest phenolic content and capacity to neutralize DPPH radicals were found in the acetone extract. In vitro antimicrobial activity was determined by microdilution method. Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) have been determined. Testing was conducted against 24 microorganisms, including 15 strains of bacteria (standard and clinical strains) and 9 species of fungi. Statistically significant difference in activity between the extracts of X. annuum L. was observed and the acetone extract was found most active. The activity of acetone extract was in accordance with total phenol content and flavonoid concentration measured in this extract. The tested extracts showed significant antibacterial activity against G+ bacteria and weak to moderate activity against other microorganisms. Based on the obtained results, X. annuum can be considered as a rich natural source of polyphenolic compounds with very good antioxidant and antimicrobial activity.