Vittorio Alonzo

Modifications of hydrophobicity, in vitro adherence and cellular aggregation of Streptococcus mutans by Helichrysum italicum extract

Aims:  The purpose of the present study was to examine whether sublethal concentrations of Helichrysum italicum extract could affect some of the cariogenic properties of Streptococcus mutans.

Effects of Helichrysum italicum extract on growth and enzymatic activity of Staphylococcus aureus

Helichrysum italicum G. Don (Compositae) is a shrub commonly found in dry, sandy and stony areas of Mediterranean regions. This plant is known for its anti-inflammatory, anti-allergic and antimicrobial activity. The aim of this study was to evaluate the effect of the diethyl ether extract on growth of Staphylococcus aureus (ATCC 6538P, MRSA and MSSA isolates) and the influence of subminimum inhibitory concentrations (subMICs) on some enzymes which are considered virulence factors. The results indicate that the H. italicum extract had an inhibitory effect on S. aureus strains reducing both their growth and some of the enzymes such as coagulase, DNAse, thermonuclease and lipase. Helichrysum italicum extract could be a novel antimicrobial agent, less toxic to human skin and tissues, worthy of further studies.

The effect of Nepeta cataria extract on adherence and enzyme production of Staphylococcus aureus

Nepeta cataria L., commonly known as catnip, is a perennial herb with a considerable folkloric reputation. A diethyl ether extract of this plant has been shown to have antimicrobial activity against fungi and Gram-positive bacteria. The aim of this work was to study the activity of N. cataria extract on 44 Staphylococcus aureus strains, some resistant to methicillin, and S. aureus 6538P (American Type Culture Collection) by evaluating the effect of subminimum inhibitory concentrations on coagulase, DNAse, thermonuclease and lipase production, and on in-vitro adherence. DNAse, thermonuclease and lipase were inhibited by concentrations equal to 1/2 and 1/4 MIC. A reduction of adherence was also observed.

Helichrysum italicum extract interferes with the production of enterotoxins by Staphylococcus aureus

Aims: The purpose of this work was to evaluate the effect of Helichrysum italicum extract on enterotoxin (A–D) production by Staphylococcus aureus strains. 
Methods and Results: The production of enterotoxins A–D in the presence or absence of H.italicum diethyl ether extract was estimated in microtiter plates using a reversed passive latex agglutination (SET‐RPLA) kit (Oxoid, Basingstoke, UK). The results indicate that, in culture medium, inhibition of staphylococcal growth and enterotoxins appeared with 250–125 µg ml−1 of the extract. Lower concentrations of the extract (62·5–31·25 µg ml−1) did not affect the final viable count of Staph. aureus but reduced the production of enterotoxins B and C. 
Conclusions: H. italicum interferes with growth and production of enterotoxins by Staph. aureus.
Significance and Impact of the Study: There is considerable interest in the use of natural compounds as alternative methods to control undesirable pathogenic micro‐organisms.

Preservative properties of Calamintha officinalis essential oil with and without EDTA.

Aims: This study was focused on the preserving properties of Calamintha officinalis essential oil, a plant known for its diaphoretic, expectorant and aromatic properties.

Efficiency of Calamintha officinalis essential oil as preservative in two topical product types

Aims:  To verify the efficiency of Calamintha officinalis essential oil as natural preservative in two current formulations.

Erratum to “Effects of Helichrysum italicum extract on growth and enzymatic activity of Staphylococcus aureus”

Erratum Erratum to ‘‘Effects of Helichrysum italicum extract on growth and enzymatic activity of Staphylococcus aureus ’’ [Int. J. Antimicrob. Agents 17 (2001) 517–520] Antonia Nostro *, Giuseppe Bisignano, Maria Angela Cannatelli, Giuseppe Cris, Maria Paola Germano, Vittorio Alonzo Dipartimento Farmaco-Biologico, Facolta di Farmacia, Uni ersita degli Studi di Messina, Villagio Annunziata, 98168 Messina, Italy Received 19 December 2000; accepted 9 January 2001 www.ischemo.org