TLC determination of flavonoids from different cultivars of Allium cepa and Allium ascalonicum

This study comprises the optimization and validation of a new TLC method for determination of flavonols in the bulbs of seven cultivars of onions and shallots. Separation was performed on RP-18 plates with the solvent mixture tetrahydrofuran/water/formic acid (40+60+6, V/V/V) as a mobile phase. The method was validated for precision, linearity, LOD, LOQ, accuracy and robustness. Chromatographic analysis of the extracts revealed the presence of three main flavonols, quercetin, quercetin-4’-O-glucoside and quercetin-3,4’-O-diglucoside in the majority of analyzed cultivars. The content of flavonols in the analyzed extracts of onion bulbs varied from 123 (‘Exihibition’) to 1079 mg kg–1 fresh mass (fm) (‘Hybing’) in edible parts, and from 1727 (‘Hyline’) to 28949 mg kg–1 fm (‘Red Baron’) in outer scales. The bulbs of two shallot cultivars contained 209 (‘Ambition’) and 523 mg kg–1 fm (‘Matador’) of flavonols in edible parts and 5426 and 8916 mg kg–1 fm in outer scales, respectively

TLC determination of flavonoids from different cultivars of Allium cepa and Allium ascalonicum

This study comprises the optimization and validation of a new TLC method for determination of flavonols in the bulbs of seven cultivars of onions and shallots. Separation was performed on RP-18 plates with the solvent mixture tetrahydrofuran/water/formic acid (40+60+6, V/V/V) as a mobile phase. The method was evaluated for precision, linearity, LOD, LOQ, accuracy and robustness. Chromatographic analysis of the extracts revealed the presence of three main flavonols, quercetin, quercetin-4′-O-glucoside and quercetin-3,4′-O-diglucoside in the majority of analyzed cultivars. The content of flavonols in the analyzed extracts of onion bulbs varied from 123 (‘Exihibition’) to 1079 mg kg-1 fresh mass (fm) (‘Hybing’) in edible parts, and from 1727 (‘Hyline’) to 28949 mg kg-1 fm (‘Red Baron’) in outer scales. The bulbs of two shallot cultivars contained 209 (‘Ambition’) and 523 mg kg-1 fm (‘Matador’) of flavonols in edible parts and 5426 and 8916 mg kg-1 fm in outer scales, respectively

Chemosystematic Value of the Essential Oil Composition of Thuja species Cultivated in Poland—Antimicrobial Activity

In the framework of the correlation between chemotaxonomy and chemical analysis studies, the chemical composition of the essential oils of four varieties of Thuja species cultivated in Poland − T. occidentalis ‘globosa’, T. occidentalis ‘aurea’, T. plicata and T. plicata ‘gracialis’ − were investigated by GC and GC-MS. Thirty-one compounds were identified from T. occidentalis ‘globosa’, representing 96.92% of the total oil; twenty-seven from T. occidentalis ‘aurea’ (94.34%); thirty-one from T. plicata (94.75%); and thirty compounds from T. plicata ‘gracialis’ (96.36%). The main constituents in all samples were the monoterpene ketones α- and β-thujone, fenchone and sabinene, as well as the diterpenes beyerene and rimuene.The chemosystematic value of the total ketone content of all samples (which varied from 54.30–69.18%) has been discussed and investigated. The constituents, beyerene and the mixture of α- and β-thujone, were isolated from the oils and tested against six Gram-positive and -negative bacteria and three pathogenic fungi. The oils of the two T. plicata species exhibited significant antimicrobial activity, while the mixture of α- and β-thujone showed very strong activity as well

Combination of silver nanoparticles and Drosera binata extract as a possible alternative for antibiotic treatment of burn wound infections caused by resistant Staphylococcus aureus.

Staphylococcus aureus is the most common infectious agent involved in the development of skin infections that are associated with antibiotic resistance, such as burn wounds. As drug resistance is a growing problem it is essential to establish novel antimicrobials. Currently, antibiotic resistance in bacteria is successfully controlled by multi-drug therapies. Here we demonstrate that secondary metabolites present in the extract obtained from Drosera binata in vitro cultures are effective antibacterial agents against S. aureus grown in planktonic culture and in biofilm. Moreover, this is the first report demonstrating the synergistic interaction between the D. binata extract and silver nanoparticles (AgNPs), which results in the spectacular enhancement of the observed bactericidal activity, while having no cytotoxic effects on human keratinocytes. Simultaneous use of these two agents in significantly reduced quantities produces the same effect, i.e. by killing 99.9% of bacteria in inoculum or eradicating the staphylococcal biofilm, as higher amounts of the agents used individually. Our data indicates that combining AgNPs with either the D. binata extract or with its pure compound (3-chloroplumbagin) may provide a safe and highly effective alternative to commonly used antibiotics, which are ineffective towards the antibiotic-resistant S. aureus

An isobologram depicting the bactericidal interaction between silver nanoparticles and pure 3-chloroplumbagin towards the planktonic culture of the <i>S. aureus</i> strain ATCC 13420.

<p>The Minimum Bactericidal Concentration was the measured effect.</p

An isobologram depicting the bactericidal interaction between silver nanoparticles and either the extract derived from <i>D. binata</i> or pure 3-chloroplumbagin towards planktonic cultures of <i>S. aureus</i> strains.

<p>The Minimum Bactericidal Concentration was the measured effect.</p

Eradication of <i>S. aureus</i> biofilm by A) the <i>D. binata</i> extract and by B) AgNPs.

<p>The experiment was conducted using the ATCC 13420 strain. The MBEC (Minimum Biofilm Eradication Concentration) obtained from the recovery plates after 24 h of incubation at 37°C is defined as the absorbance at 600 nm below the value of 0.1. DW – dry weight.</p

The structure of A) plumbagin, droserone, 3-chloroplumbagin and B) 3,3′-di-<i>O</i>-methylellagic acid.

<p>The structure of A) plumbagin, droserone, 3-chloroplumbagin and B) 3,3′-di-<i>O</i>-methylellagic acid.</p

Cytotoxic effect of A) AgNPs, the <i>D. binata</i> extract and various secondary metabolites present in <i>D. binata</i> tissues applied individually on human keratinocytes [n = 3. Data were analyzed by one-way ANOVA with Tukey's post hoc tests; p≤0.05 (*) indicates differences between the control and 1-treated cells] and B) combinations of AgNPs with either the <i>D. binata</i> extract or with pure 3-chloroplumbagin towards human dermal keratinocytes.

<p>Toxicity was assessed after 24 h of incubation at 37°C in the dark. Each point is the mean of three experiments ± s.d. DR – droserone (32 µg/ml); AgNPs – silver nanoparticles (6.15 µg/ml); DEA – 3,3′-di-O-methylellagic acid (32 µg/ml); Dbin – chloroform extract from tissues of <i>D. binata</i> (16 µg DW/ml); ChPL – 3-chloroplumbagin (32 µg/ml); PL- plumbagin (16 µg/ml); Combinations: ChPL + AgNPs – 1 µg/ml+1.54 µg/ml, respectively; Dbin + AgNPs (A) – 0.5 µg DW/ml+3.075 µg/ml, respectively; Dbin + AgNPs (B) – 8 µg DW/ml+0.2 µg/ml, respectively [n = 3. Data were analyzed by one-way ANOVA with Tukey's post hoc tests, p≤0.05 (*)].</p