Preparation, characterization, optimization, and antibacterial evaluation of nano-emulsion incorporating essential oil extracted from Teucrium polium L

Assessment of Growth Inhibition of Eugenol-Loaded Nano-Emulsions against Beneficial Bifidobacterium sp. along with Resistant Escherichia coli Using Flow Cytometry

The intestinal tract microbiota influences many aspects of the dietary components on colon health and during enteric infections, thus, playing a pivotal role in the colon health. Therefore, the eugenol (EU) nano-emulsion effective concentration reported in our previous study against cancer cells should be explored for safety against beneficial microbes. We evaluated the sensitivity of Bifidobacterium breve and B. adolescentis against EU-loaded nano-emulsions at 0, 300, 600 and 900 µm, which were effective against colon and liver cancer cells. Both B. breve and B. adolescentis showed comparable growth ranges to the control group at 300 and 600 µm, as evident from the plate count experimental results. However, at 900 µm, a slight growth variation was revealed with respect to the control group. The real-time inhibition determination through flow cytometry showed B. breve viable, sublethal cells (99.49 and 0.51%) and B. adolescentis (95.59 and 0.15%) at 900 µm, suggesting slight inhibition even at the highest tested concentration. Flow cytometry proved to be a suitable quantitative approach that has revealed separate live, dead, and susceptible cells upon treatment with EU nano-emulsion against Escherichia coli. Similarly, in the case of B. breve and B. adolescentis, the cells showed only live cells that qualitatively suggest EU nano-emulsion safety. To judge the viability of these sublethal populations of B. breve and B. adolescentis, Fourier transforms infrared spectroscopy was carried out, revealing no peak shift for proteins, lipids, DNA and carbohydrates at 900 µm EU nano-emulsion compared to the control. On the other hand, EU-loaded nano-emulsions (900 µm)-treated E. coli showed a clear peak shift for a membrane protein, lipids, DNA and carbohydrates. This study provides insights to utilize plant phenols as safe medicines as well as dietary supplements.

A study on the nutritional characteristics of some plants and their effects on ruminal microbial fermentation and protozoa population

We designed this project to determine the nutritional potential and ruminal microbial fermentation properties of eight rangeland plants (Dracocephalum moldavica L., Melissa officinalis L., Ruta graveolens L., Perovskia abrotanoides Kar., Cichorium intybus L., Borago officinalis L., Peganum harmala L., and Teucrium polium L.) collected from the semi-arid region of Iran at two consecutive years (2019 and 2020) for ruminant diets. Medicago sativa as a common forage was also considered as control. We determined the chemical-mineral composition, buffering capacity, in vitro gas yield, ruminal fermentation, and protozoa population in a culture medium with the standard laboratory methods. A significant difference in chemical-mineral compounds was observed among the studied plants (p < 0.05). A lower crude protein range (6.28% for Cichorium intybus L. to 18.4% for Melissa officinalis L.) was observed rather than Medicago sativa (20.3%). The amount of calcium was highest in Peganum harmala L. (23.5–24.2 g/kg DM) and lowest in Ruta graveolens L. (1.15–1.25 g/kg DM). Dracocephalum moldavica L. exhibited the highest acid–base buffering capacity (235–242 mEq×10⁻³) among other plants. The highest decrease in total protozoa and other protozoan populations was observed when Perovskia abrotanoides Kar. was added to the culture medium. Teucrium Polium L. had the greatest potential gas yield and its total volatile fatty acid was comparable with Medicago sativa. It seems that eight plants are nutritionally suitable for partial replacement of the conventional plants such as Medicago sativa in diets of small ruminants, however dietary supplementation of Peganum harmala L. due to its alkaloids content should be done with caution.