The antimycotic effect of ellagitannins from raspberry (Rubus idaeus L.) on Alternaria alternata ŁOCK 0409

Abstract

Alternaria spp. fungi, characterized by a high tolerance to unfavorable environmental conditions, are one of the threats for foods of plant origin. The increasing incidence of diseases caused by a demanding lifestyle, and a higher social awareness of the role of a diet in maintaining health and good condition, results in the dynamically growing demand for natural protective measures that would be safe for consumers. Ellagitannins, i.e. a group of bio-active polyphenols, may constitute an alternative for chemical preservatives. Studies demonstrated that the raspberry (Rubus idaeus L.) ellagitannin formula limited the growth of Alternaria alternata 0409. The minimal inhibitory concentration (MIC) was determined (0.156 mg/ml), along with the minimal fungicidal concentration (MFC) (0.312 mg/ml). The fungistatic (FA) activity and the ratio of linear growth (T) were also determined for the ellagitannin formula. A strong antimycotic activity of ellagitannins was demonstrated at the formula level of 0.1 mg/ml. Unfortunately, the activity was not maintained over time and after 9 days it was only 16.0%. For the ellagitannin formula, concentrations of 0.312 mg/ml (MFC) and 0.5 mg/ml (below the MFC value), a complete arrest of growth of Alternaria alternata 0409 was observed, and it was maintained for 9 days. The antimycotic activity of the ellagitannin formula was also confirmed in food environment, with cottage cheese and cherry tomatoes used as the matrix. Results confirmed that ellagitannins from raspberry (Rubus idaeus L.) could be successfully used as a natural food preservative.

Mycobiota of berry fruits – levels of filamentous fungi and mycotoxins, composition of fungi, and analysis of potential health risk for consumers

“…Alternaria toxins have been detected by earlier researchers in raspberry and raspberry juice, but in rather low concentrations [21,43]. The reason for that could be the ability of red raspberry to produce ellagitannins, bio-active polyphenols that inhibit the growth of Alternaria alternata [44]. Juan et al [22] also detected low levels of Alternaria mycotoxins in strawberries.…”

Combined –omics framework reveals how ant symbionts benefit the Neotropical ant-plant Tococa quadrialata at different levels

“…Using untargeted metabolomics, we found that T. quadrialata produced a diversity of ellagitannins, a class of hydrolyzable tannins that are characteristic anti-herbivore defense compounds of the plant family Melastomataceae ( Serna and Martinez, 2015 ). Ellagitannins are well-known in human medicine for their anti-inflammatory ( Gatis-Carrazzoni et al., 2019 ), anti-bacterial ( Araujo et al., 2021 ; Gontijo et al., 2019 ), anti-fungal ( Klewicka et al., 2020 ), and anti-viral ( Kesharwani et al., 2017 ) activities. In the alkaline midgut of insects, these compounds act as strong oxidants ( Barbehenn et al., 2006 ) with negative consequences for herbivores.…”

Stability of ellagitannins in processing products of selected Fragaria fruit during 12 months of storage

“…Plant extracts rich in ETs show antimicrobial properties against, e.g., Escherichia coli , Salmonella enteritidis , Staphylococcus aureus , Bacillus subtilis , Klebsiella pneumoniae , Alternaria alternata , Fusarium oxysporum , and Rhizoctonia solani (Al‐Zoreky, 2009; Ascacio‐Valdés et al, 2013). These compounds have also been shown to inhibit the growth of certain viruses, fungi, and yeasts (Ascacio‐Valdés et al, 2013; Corthout et al, 1991; Klewicka et al, 2016, 2020).…”