Isolation and antibacterial activity of phenylpropanoid derivatives from Ballota nigra.

In addition to the previously isolated phenylpropanoid glycosides verbascoside 1, forsythoside B 2, arenarioside 3 and ballotetroside 4, another four compounds were isolated from generative aerial parts of Ballota nigra: three phenylpropanoid glycosides, alyssonoside 5, lavandulifolioside 6 and angoroside A 7 and a non-glycosidic derivative (+)-(E)-caffeoyl-L-malic acid 8. The antibacterial activity of the five major compounds (1-4 and 8) was tested against gram-positive and gram-negative bacteria. Three of them (1-3) exhibited a moderate antimicrobial activity against Proteus mirabilis and Staphylococcus aureus including one methicillin-resistant strain.

Antimicrobial activity of aerial parts of Drosera peltata Smith on oral bacteria.

The antimicrobial activity of extracts of aerial parts of Drosera peltata Smith against oral bacteria was investigated using agar diffusion and dilution micromethods. The chloroformic extract, active against all the bacteria tested, showed the most significant antimicrobial properties. Plumbagin, isolated from the extract, is the active principle. Results obtained suggest that Drosera peltata extract could be used in the treatment of oral infectious diseases like dental caries and periodontitis.

Activity of anthraquinonic and naphthoquinonic compounds on oral bacteria.

The activity of anthraquinonic compounds and naphthoquinones was tested by micromethods against oral bacteria. The more significant results were obtained with naphthoquinones. Plumbagin, juglone and lawsone possess a wide spectrum of activity. The lowest MIC values were observed with plumbagin and the combination of juglone and lawsone results in a synergism against cariogenic bacteria. Among the eight anthraquinonic compounds investigated only rhein showed significant antimicrobial properties. Results obtained could suggest the use of rhein and plumbagin alone or juglone and lawsone combined for treatment of oral infectious diseases.

Activity of thymol, carvacrol, cinnamaldehyde and eugenol on oral bacteria.

The antimicrobial activity of thymol, carvacrol, cinnamaldehyde and eugenol alone or combined was tested by micromethods on eight oral bacteria. The compounds showed an inhibitory activity on seven microorganisms and a synergistic effect was observed with certain combinations. The four compounds can be used alone or combined, as eugenol and thymol, eugenol and carvacrol, thymol and carvacrol, during the treatment of oral infectious diseases.

[Antibacterial activity of thymol, carvacrol and cinnamaldehyde alone or in combination]. / Activité antibactérienne du thymol, du carvacrol et de l'aldéhyde cinnamique seuls ou associés.

The antimicrobial activity of thymol, carvacrol and cinnamaldehyde was tested by several methods on bacteria involved in upper respiratory tract infections. Their combinations were investigated too. The broad spectrum of activity and the synergistic effect observed with some combinations (specially thymol and carvacrol) could allowed the use of the three compounds alone or, like thymol an carvacrol, combined during the treatment of respiratory infections.

Antimicrobial activity of naphtoquinones and Allium extracts combined with antibiotics.

Combinations of antibiotics and known antimicrobial natural products, naphtoquinones and Allium extracts, were investigated. The chessboard broth method was applied to assess the activity of these combinations against aerobic and anaerobic bacteria. If no antagonism was observed, the combinations studied lead from partial to total synergism, mainly against aerobic bacteria.

New procedure for direct bioautographic TLC assay as applied to a tincture of Ranunculus bulbosus.

A new procedure for TLC bioautographic assay using a flooding method to inoculate the developed plates is described. Details about several microbiological parameters allow good reproducibility for this method which appears rapid, easy to perform and requiring no specialized equipment. Significantly results obtained with a commercial tincture of Ranunculus bulbosus illustrate this method which can be extended to complex mixtures of natural products in order to isolate active fractions.

[Antibacterial activity of species of the genus Allium]. / Activité antibactérienne d'espèces du genre Allium.

Garlic, onion and shallot were tested for antimicrobial activity against pathogenic aerobic and anaerobic bacteria. The MIC of aqueous and petroleum ether extracts were determined. Garlic showed the greater activity; the combination garlic-antibiotic is synergistic against Acinetobacter calcoaceticus and leads to indifference against anaerobic bacteria. The active constituent is not probably allicin alone.