Synergistic Antibacterial Effects of Polyphenolic Compounds from Olive Mill Wastewater

Abstract

Polyphenols or phenolic compounds are groups of secondary metabolites widely distributed in plants and found in olive mill wastewater (OMW). Phenolic compounds as well as OMW extracts were evaluated in vitro for their antimicrobial activity against Gram-positive (Streptococcus pyogenes and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). Most of the tested phenols were not effective against the four bacterial strains when tested as single compounds at concentrations of up to 1000 μg mL−1. Hydroxytyrosol at 400 μg mL−1 caused complete growth inhibition of the four strains. Gallic acid was effective at 200, and 400 μg mL−1 against S. aureus, and S. pyogenes, respectively, but not against the gram negative bacteria. An OMW fraction called AntiSolvent was obtained after the addition of ethanol to the crude OMW. HPLC analysis of AntiSolvent fraction revealed that this fraction contains mainly hydroxytyrosol (10.3%), verbascoside (7.4%), and tyrosol (2.6%). The combinations of AntiSolvent/gallic acid were tested using the low minimal inhibitory concentrations which revealed that 50/100–100/100 μg mL−1 caused complete growth inhibition of the four strains. These results suggest that OMW specific fractions augmented with natural phenolic ingredients may be utilized as a source of bioactive compounds to control pathogenic bacteria.

Phenolic Constituents, Antioxidant and Preliminary Antimycoplasmic Activities of Leaf Skin and Flowers of Aloe vera (L.) Burm. f. (syn. A. barbadensis Mill.) from the Canary Islands (Spain)

“…Several reports have suggested that the biological activity of the extracts is also dependent on the interaction among the phenolic compounds [33,34]. Tafesh et al [35] reported that hydroxytyrosol at 400 µg·mL −1 caused growth inhibition of the four bacterial isolate gram-positive ( Streptococcus pyogenes and Staphylococcus aureus ) together with the gram-negative ( Escherichia coli and Klebsiella pneumoniae ), while gallic acid at 200 and 400 µg mL −1 inhibited the growth of the S. aureus and S. pyogenes strains, respectively (no growth inhibition was observed for the gram-negative bacteria). However, the combination of both compound gallic acid and hydroxytyrosol at lower concentrations (100 and 200 μg·mL − 1 , respectively) caused a complete inhibition of the four bacterial strains.…”

An environmentally friendly process for the production of extracts rich in phenolic antioxidants from Olea europaea L. and Cynara scolymus L. matrices

“…The dose used in biscuits and rusks is 250 ppm of Olea OH-Tyr fraction. In a recent patent, the mixture of fractions from Olea, Cynara, and antimicrobial tannins from chestnut and grapes seeds is proposed as a new ingredient in the meat stabilization and for the decrement of the mycotoxins in food [26].…”

Agricultural by-products with bioactive effects: A multivariate approach to evaluate microbial and physicochemical changes in a fresh pork sausage enriched with phenolic compounds from olive vegetation water

“…In particular, these compounds have been found to be effective against bacteria rather than yeasts, especially Gram-positive bacteria (Fasolato et al, 2015;Obied et al, 2005). In contrast to previous studies, Tafesh et al (2011) showed that an OVW extract mixed with specific compounds (e.g. gallic acid or hydroxytyrosol) could lead to a greater antimicrobial effect than each phenol alone.…”

“…Despite some studies highlighting the in vitro antimicrobial effects of OVW extracts (Capasso et al, 1995;Tafesh et al, 2011), little information is available in food models. Moreover, little work has been published using processed meat products (ChavesLópez et al, 2015;Novelli et al, 2014).…”