Inhibitory Activity of Avocado Seed Fatty Acid Derivatives (Acetogenins) Against Listeria Monocytogenes

Abstract

High standards regarding Listeria monocytogenes control and consumer demands for food products without synthetic additives represent a challenge to food industry. We determined the antilisterial properties of an enriched acetogenin extract (EAE) from avocado seed, compared it to two commercial antimicrobials (one enriched in avocado acetogenins), and tested purified molecules. Acetogenin composition in pulp and seed of Hass avocado was quantified. EAE were obtained by two sequential centrifuge partition chromatography separations and molecules purified by preparative chromatography and quantified by HPLC-MS-TOF and HPLC-PDA. Avocado seed extracts which are the following two: 1) EAE and 2) the commercially available antimicrobial Avosafe®, presented similar inhibition zones and chemical profiles. Minimum inhibitory concentration (MIC) values of extracts and two isolated acetogenins varied between 7.8 and 15.6 mg/L, were effective at 37 and 4 °C, and showed a bactericidal effect probably caused by increased membrane permeability and lytic effects, evidenced by flow cytometry at 10 and 100× MIC. Activity was comparable to Mirenat®. Most potent acetogenins were Persenone C (5) and A (6), and AcO-avocadenyne (1), the latter exclusively present in seed. Common features of bioactive molecules were the acetyl moiety and multiple unsaturations (2 to 3) in the aliphatic chain, some persenones also featured a trans-enone group. Seeds contained 1.6 times higher levels of acetogenins than pulp (5048.1 ± 575.5 and 3107.0 ± 207.2 mg/kg fresh weight, respectively), and total content in pulp was 199 to 398 times higher than MIC values. Therefore, acetogenin levels potentially consumed by humans are higher than inhibitory concentrations. Results document properties of avocado seed acetogenins as natural antilisterial food additives.

Synergistic Antimicrobial Effects of Silver/Transition-metal Combinatorial Treatments

“…Flow cytometry with a propidium iodide dye was used to detect differences in membrane permeability 10 . A double-stain procedure with two fluorescent nucleic acid stains was followed as previously described 41 . Briefly, 10 6 bacteria were directly labeled and incubated (15 min, dark, room temperature) with propidium iodide 4 μg (PI, Sigma Aldrich, St. Louis, MO., USA) and SyBR-G 1X (Life Technologies, Carlsbad, CA., USA) in 250 μL PBS.…”

Avocado (Persea americana Mill.) by‐products and their impact: from bioactive compounds to biomass energy and sorbent material for removing contaminants. A review

“…In fact, these by‐products possess interesting biological properties and mainly avocado seed extracts exhibit high activity as antiprotozoal, antimycobacterial (Jiménez‐Arellanes et al ., ) and antimicrobial agents (Rodríguez‐Carpena et al ., ; Guil‐Guerrero et al ., ; Salinas‐Salazar et al ., ; Araújo et al ., ). This would suggest their use as an alternative to the use of veterinary antibiotics, very common in farm animals.…”

“…Different avocado seed extracts (water, ethanol and chloroform) exhibit an antimicrobial activity against Listeria monocytogenes, Staphylococcus epidermidis and Mycobacterium avium . An interesting inhibitory activity against Listeria monocytogenes was more recently pointed out by enriched acetogenin (fatty acid derivatives) extract from avocado seed (Guil‐Guerrero et al ., ; Salinas‐Salazar et al ., ; Fig. ).…”

“…Comparison of antilisterial properties (37 °C, 24 h) among different acetogenins isolated from avocado seeds and a commercial antimicrobial (Mirenat ® ) (Salinas‐Salazar et al ., ).…”

Stability of the antimicrobial activity of acetogenins from avocado seed, under common food processing conditions, against Clostridium sporogenes vegetative cell growth and endospore germination

“…The use of natural additives and the discovery of new antimicrobial molecules is a necessity of the food industry to respond to the growing trend towards clean food labels with no addition or minimal use of synthetic additives (Tiwari et al ., ; Negi, ). Acetogenins from avocado fruit are fatty acid derivatives, with a long unsaturated aliphatic chain (C19‐C23) and a highly oxygenated end (Kashman et al ., ; Rodriguez‐Saona & Trumble, ), that possess antimicrobial, antifungal and insecticidal activities (Prusky et al ., ; Rodriguez‐Saona & Trumble, ; Rodriguez‐Carpena et al ., ; Lu et al ., ; Rodríguez‐Sánchez et al ., b; Salinas‐Salazar et al ., ). In particular, seeds contain 1.6 times higher concentrations of acetogenins than the pulp representing a good source of these molecules and a waste management solution for the processing industry (Salinas‐Salazar et al ., ).…”