The Synergistic Effects of Combined Use of Mentha longifolia, Thymus carmanicus, and Trachyspermum copticum on Growth Performance, Feed Utilization, and Expression of Key Immune Genes in Rainbow Trout (Oncorhynchus mykiss)

Medicinal plants exhibit remarkable positive effects on different aspects of fish physiology. This study aimed to evaluate the possible impact of a combination of plants (Mentha longifolia, Thymus carmanicus, and Trachyspermum copticum) on growth performance, immune responses and key immune gene expression of rainbow trout. For this purpose, four diets were designed, including zero, 0.25, 0.5, and 1% of a mixture of plants per kg of diet, representing dietary treatments of control, T1, T2, and T3, respectively. Two hundred forty fish (weighing 23.11 ± 0.57 g) were fed 3% of body weight twice a day for 45 days. The results showed that growth parameters of weight gain (except for T1) and FCR were significantly improved in fish receiving all levels of plants, with T3 showing the best growth results. Digestive enzymes activities were notably increased in T1 and T2 compared to the control. Stress biomarkers (glucose and cortisol) were significantly decreased in T1 and T2, while T3 was not significantly different from the control. Immunological responses were significantly improved in T2, while T1 andT3 did not show a statistical difference in terms of lysozyme activity. Catalase activity was noticeably decreased in T1, although superoxide dismutase and malondialdehyde were highest in T2. Immune-related genes were significantly up-regulated in T3 compared to other treatments. Also, antioxidant enzyme coding genes were strongly up-regulated in T2 and T3. Overall, the present results suggest that 1% inclusion of the mixture of M. longifolia, T. carmanicus, and T. copticum (T2) can be used to improve the growth and immunity of rainbow trout.

Essential Oils from Indigenous Iranian Plants: A Natural Weapon vs. Multidrug-Resistant Escherichia coli

Aim of this study was to investigate the antimicrobial properties of herbal plant essential oils (EOs) from selected Iranian plant species such as Ferulago angulata, Zataria multiflora, Cuminum cyminum, and Mentha longifolia against antibiotic-resistant Escherichia coli (E. coli) strains. For this purpose, the Escherichia coli strains, isolated from raw cow’s milk and local dairy products (yogurt, cream, whey, cheese, and confectionery products) collected from different areas of Hamedan province, Iran, were investigated for their resistance to antibiotics (i.e., streptomycin, tetracycline, gentamicin, chloramphenicol, ciprofloxacin, and cefixime). Thus, the E. coli strains were tested for their susceptibility to the above-mentioned essential oils. Regarding antibiotics, the E. coli strains were highly sensitive to ciprofloxacin. In relation to essential oils, the most effective antibacterial activity was observed with Zataria multiflora; also, the bacteria were semi-sensitive to Cuminum cyminum and Mentha longifolia essential oils. All strains were resistant to Ferulago angulata essential oil. According to the results, the essential oil of Zataria multiflora can be considered as a practical and alternative antibacterial strategy to inhibit the growth of multidrug-resistant E. coli of dairy origin.

Correction: Chen et al. Genome-Wide Analysis of Terpene Synthase Gene Family in Mentha longifolia and Catalytic Activity Analysis of a Single Terpene Synthase. Genes 2021, 12, 518

The authors have requested that the following changes be made to their paper [...]

Impact of Four Plant Extracts on Bactrocera dorsalis a Pest on Fruits

Menthol extracts of four local plants (Ocimum tenuiflorum, Hibiscus, Mentha longifolia and Bougainvillea glabra) were analysed to check their toxicity on third instar larvae of B. dorsalis by estimating the larval mortality for four plant extracts and different times exposure (1-5 hr) and measured LT50 value for each plant extract. Larval mortality varies for extract of each studied plant as Ocimum tenuiflorum showed its highest value of 56.68% at 4.57hr, for hibiscus it was 72% at 3.5 hr., for Mentha longifolia it was 95.23% at 4 hr., while for Bougainvillea glabra it was 100% at 2 hr. exposure. The LT50 values for B. dorsalis varying from 1.011 for Bougainvillea glabra to 2.946 for Ocimum tenuiflorum whereas LT50 values were 1.402 and 1.123, forHibiscus and Mentha longifolia respectively. Present study results showed that Bougainvillea glabra was highly toxic whereas Ocimum tenuiflorum shows least toxicity.

Chemotypical diversity of Mentha longifolia L. oil

The article presents data on the content and composition of the essential oil of Mentha longifolia (L.) L. plants growing in natural phytocenoses on the territory of Crimea and Abkhazia. It was found that dry raw materials in two samples from natural phytocenoses of Crimea contain 1.27 and 1.76% of essential oil per wet weight, three samples from phytocenoses of Abkhazia contain less essential oil - 0.68, 0.98 and 1.19 %. About 60 components have been identified. Two new chemotypes were identified for Crimea: carvone-piperitone (mass fraction of carvone is 66.65%, piperitone oxide - 14.37%) and piperitone-sabinene (mass fraction of piperitone oxide - 55.19% and cis-sabinene hydrate - 23.51%), and two for Abkhazia: terpene-caryophyllene (α-terpinyl acetate - 51.48%; β-caryophyllene - 9.26%), piperitone-non-petalactone (piperitone oxide - 46.29%; nepetalactone 4aa, 7a, 7aa - 34.85%). These Mentha longifolia chemotypes are promising for use in the food, chemical, pharmaceutical and perfume industries.

Chemotypes and Their Stability in Mentha longifolia (L.) L.—A Comprehensive Study of Five Accessions

Mentha longifolia (L.) L. is the most widespread wild-growing mint species found, and its chemical composition is extremely diverse. We studied the essential oil (EO) yield, composition, and chemotaxonomy of five, northern Hungarian accessions of the species in a cultivation experiment covering two vegetation years at two parallel sites. The long-term goal is to establish the cultivation of this stress-tolerant species in Hungary as a source of flavoring and preservative agents for commercial use. Essential oil yield (1–2 mL/100 g) was observed to be dependent on both the accession and the year. Accession HV1 is assumed to be a new, presumably rare chemotype containing carvacrol (19.28–20.56%), 1,8-cineole (14.87–17.45%), thymol (13.36–13.90%), carvacryl acetate (8.81–10.40%), and para-cymene (7.24–8.01%). Only minor fluctuations occurred in concentrations of these constituents due to habitats and years. A radical change in essential oil composition was observed in accession HV2, as one batch was based on thymol (19.79%) and 1,8-cineole (14.93%), while the others were rich in dihydrocarvone isomers (up to 69%). Although this needs further investigation, it does explain the coexistence of limonene-oxo and γ-terpinene pathways in horsemint. According to the literature, the pathway leading to thymol isomers and/or esters may be rare in the entire Mentha genus. We also demonstrated that known chemotypes of horsemint may differ in variability of their EO composition. Our results also led to the conclusion that any declaration on chemotype needs detailed examination and is not realistic on the basis of a single sample. Assumptions were made about the potential areas of utilization: beside fragrance and flavoring uses of essential oils free from pulegone and menthofurane, thymol-based ones may be used as antioxidative and anti-spoilage agents.