Melissa officinalis essential oil as an antimicrobial agent against Listeria monocytogenes in watermelon juice.

The burden of foodborne illness has a negative effect on public health, but also in countries' economy. Melissa officinalis is an aromatic plant known for its biological properties, including antioxidant and antimicrobial effects. This work highlighted M. officinalis essential oil's antioxidant potential and antimicrobial activity against L. monocytogenes, presenting a bactericidal action and being able to inhibit some virulence attributes, such as biofilm formation. The pre-exposure of the bacterium to subinhibitory levels of essential oil (0.125 µL/mL) did not induce high tolerance to stresses (such as high temperature, low pH, osmotic stress and desiccation) or cross-resistance with antibiotics, while not modifying the invasion ability to Caco-2 cells. When applied in food model media (lettuce, chicken and milk) and watermelon juice, the essential oil showed to have antimicrobial activity in a lettuce leaf model medium, further diminishing L. monocytogenes contamination and inhibiting the natural microbiota present in watermelon juice. M. officinalis essential oil shows potential to be used as control of L. monocytogenes in watermelon juice, while increasing the food's microbial shelf life.

Phytochemical Characterization, Bioactivities Evaluation and Synergistic Effect of Arbutus unedo and Crataegus monogyna Extracts with Amphotericin B.

The increased resistance to drugs by pathogens is a serious problem, with plants showing to be promising sources for the development of new drugs or the improvement of the effect of existing antimicrobial agents. Considering this, we aimed to evaluate the bioactivities of Arbutus unedo and Crataegus monogyna. Thus, the leaves were first extracted with methanol and then fractionated with different solvents. Phenolic compound profiles were assessed by HPLC-PDA-MSn and the antioxidant activity was evaluated using DPPH method and ß-carotene bleaching assay. The antimicrobial activity of extracts was tested against several microorganisms. A. unedo contained mainly galloyl esters, hydrolysable tannins, and flavonoids, while in C. monogyna, 5-caffeoylquinic acid and flavonoids were the most representative polyphenols. Crude extracts showed antioxidant activity and the extracts and fractions displayed a weak antibacterial activity; however inhibiting the growth of Candida tropicalis and C. lusitaniae to which A. unedo extract showed higher activity. Most of the extracts and fractions demonstrated synergistic or additive interactions with amphotericin B against Candida spp. Therefore, the present study revealed significant bioactive properties of the extracts and fractions of A. unedo and C. monogyna, such as antioxidant and antifungal activities.

Genus Ruta: A natural source of high value products with biological and pharmacological properties.

ETHNOPHARMACOLOGICAL RELEVANCE: Ruta genus is constituted by ten species, of which the most commonly described are R. chalepensis and R. graveolens. Ruta plants are perennial shrubs belonging to the family Rutaceae, which are traditionally used in folk medicine, since ancient times mostly for the treatment of various ailments of the womb. AIM OF THE STUDY: To provide a review of the different uses of Ruta species in traditional medicine, as well as, on their multifactorial biological and pharmacological properties. MATERIAL AND METHODS: A search of the literature on genus Ruta and Ruta species was performed using various scientific databases and search engines and the information of articles were reviewed and compiled. RESULTS: Different parts of the plants belonging to Ruta genus are used in folk medicine to treat a wide range of different diseases. The principal use of these is in gynaecological field, but the treatment of pain, fever, nausea, inflammation, infections, nervous disorders, among others, are also described. These plants have been used to fertility regulation, as anti-fertility agent, to control menstrual flux and bleedings, as abortifacient and as contraceptive. The phytochemical composition of these plants consists mainly in essential oil (EO), but phenolic compounds were also reported, like coumarins and flavonoids, as well as alkaloids. Ruta species products like extracts and EOs have shown broad pharmacological activities, such as antimicrobial and antifungal activities, as well as, antiviral and antiparasitic. Moreover, Ruta plants products present antioxidant, neuroprotective, anti-inflammatory, anti-cancer and anti-diabetic activities and demonstrated contraceptive and abortifacient effects. These plants were also tested to be used for non-therapeutic approaches, as bio-insecticides in the control of different insect pests showing to be able to reduce infestation. CONCLUSIONS: Ruta species could be a potential source of natural products with biological activities. Ruta extracts, essential oils and isolated compounds have shown a diverse potential for use in the treatment of different diseases, as well as, for pests control, contributing to the valorisation of these plants. Nonetheless, this review indicates that more studies are needed to demonstrate the full potential of Ruta species, and to further explore the toxicology and safety of these plants.