Antifungal activity of some Sternbergia taxa: effects on germ tube and biofilm formation

Natural products are rapidly becoming the primary sources of novel antimicrobial agents, as resistance to existing antimicrobial agents is increasing. Apart from determining the antimicrobial activity of natural products, it is also important to understand their effects on the virulence factors of microorganisms. This study aimed to determine the antimicrobial activity of Sternbergia species prevalent in Turkey and investigate their role in the inhibition of germination tube and biofilm formation, both of which are known to be important virulence factors of Candida albicans. The antimicrobial activities of the plant extracts were evaluated using bore-plate and broth microdilution method. The extracts' capacity to inhibit the formation of the germ-tube was also evaluated. The findings of our study revealed that Sternbergia lutea, Sternbergia vernalis possessed antimicrobial activities, with MIC values ranging between 0.048 mg/mL and 0.39 mg/mL. The highest antimicrobial activity was observed against Candida dubliniensis (0.048 mg/mL). While evaluating the inhibition of fungal germination activities, S. vernalis extract (at a concentration of 0.09 mg/mL) was found to be the most effective against C. albicans ATCC 90028 strain. The results also indicated that S. vernalis extracts at sub-MIC levels inhibited germ tube formation and modulated the tail-length of germinated cells, both of which are important virulence factors of C. albicans. Furthermore, the inhibition of biofilm-formation was also investigated, and it was found that two Sternbergia spp. extracts at or below MIC levels inhibited biofilm formation.

Enzyme inhibitory and antioxidant activities of Viburnum tinus L. relevant to its neuroprotective potential.

In vitro neuroprotective activity of the extracts of Viburnum tinus L. was investigated via inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and tyrosinase (TYRO) by microtitre plate assays. Their antioxidant activity was tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), super oxide (SO), and nitric oxide (NO) radical-scavenging activities, ferric ion-chelation capacity, ferric- (FRAP), and phosphomolybdenum-reducing antioxidant power (PRAP) assays. Total phenol and flavonoid content of the extracts was determined spectrophotometrically. The branch-ethyl acetate and fruit-methanol extracts exerted potent anticholinesterase effects (66.4 ± 0.65% to 97.7 ± 0.47%), while the fruit-methanol extract had the highest TYRO inhibition (47.0 ± 0.68%). The methanol extracts showed higher activities in most of the antioxidant tests. All the extracts displayed notable NO-scavenging effects (47.5 ± 5.03% to 74.5 ± 1.80%). Only the fruit-ethyl acetate extract quenched SO radical (38.4 ± 1.01%) at 500 µg ml(-1). Our data indicate that the fruit and branch extracts of V. tinus may provide potential neuroprotection.

Antioxidant properties of Viburnum opulus and Viburnum lantana growing in Turkey.

In the present study, antioxidant properties of the water extracts of different parts of Viburnum opulus and Viburnum lantana (Caprifoliaceae) were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and superoxide anion scavenging methods. The extracts were prepared from the fruits, branches, and leaves of V lantana and V opulus species. The branch extracts of V lantana and V opulus inhibited superoxide anion in a concentration-dependent manner. Compared with t-tocopherol, the fruit extract of V lantana did not show any scavenging effect on superoxide anion formation. V lantana leaf extracts, however, showed a moderate scavenging effect on superoxide anion formation, whereas V lantana branch extracts showed a strong scavenging effect (IC50 = 3.1 mg/ml) on superoxide anion in higher concentration. On the other hand, all extracts exhibited a scavenging effect on the DPPH radical with various potencies. When compared with butylated hydroxytoluene, V opulus branch and V lantana leaf extracts, as well as V lantana branch, V opulus fruit and V lantana fruit extracts, showed strong DPPH radical scavenging activity with IC50 values of 0.014, 0.035, 0.052, 0.057 and 0.085 mg/ml, respectively.

Analgesic and hepatotoxic effects of Ononis spinosa L.

The present study investigated the analgesic and hepatoprotective activities of a water extract of Ononis spinosa L. (OS) in mice. Analgesic activity was based on the pain thresholds measured with the tail-flick test before administration at 30, 90 and 150 min. The results were analysed with one-way variance analysis. The extract of Ononis spinosa showed analgesic activity equivalent to aspirin at 30 and 90 min and even higher than aspirin with the 50 mg/kg dose. At a dose of 100 mg/kg OS showed an analgesic effect equivalent to aspirin at all time points.The hepatoprotective influence of OS on carbon tetrachloride (CCl(4))-induced acute liver toxicity was also studied. The extract had no significant effect on the increased levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin in CCl(4) treated animals (p > 0.05). Thus, the results reveal that the extract of OS had no hepatoprotective effect on CCl(4)-induced acute liver toxicity.