Essential oils (EOs) and extracts of rose geranium (Pelargonium graveolens) and petals of rose (Rosa damascena) have been fully characterized in terms of composition, safety, antimicrobial, and antiviral properties. They were analyzed against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, Aspergillus niger, and Adenovirus 35. Their toxicity and life span were also determined. EO of P. graveolens (5%) did not retain any antibacterial activity (whereas at 100% it was greatly effective against E. coli), had antifungal activity against A. niger, and significant antiviral activity. Rose geranium extract (dilutions 25−90%) (v/v) had antifungal and antibacterial activity, especially against E. coli, and dose-dependent antiviral activity. Rose petals EO (5%) retains low inhibitory activity against S. aureus and S. Typhimurium growth (about 20−30%), antifungal activity, and antiviral activity for medium to low virus concentrations. Rose petals extract had significant antibacterial activity at dilutions of 25−90%, especially against E. coli and S. Typhimurium, antifungal, and the most potent antiviral activity. None of the EOs and extracts were toxic in dilutions of up to 5% and 90%, respectively. Finally, all materials had a life span of more than eight weeks. These results support the aspect that rose petals and rose geranium EOs, and extracts, have beneficial antimicrobial and antiviral properties and they can be used as natural preservatives.

Rosmarinus officinalis L. (rosemary) is in high demand in the food and drink industries due to its distinct organoleptic properties. With the aim of evaluating the rosemary leaves as drink ingredients, both the essential oil and alcoholic (38%, v/v) extract were studied in terms of chemical composition, genotoxicity, antimicrobial, antiviral, and antioxidant properties. GC–MS analysis showed that the main volatile compounds in the essential oil were eucalyptol (40.1%), camphor (12.4%), and α-pinene (12.9%). LC–MS analysis revealed gallocatechin and rosmarinic acid as the main extract ingredients. Both the essential oil and the extract were not genotoxic (Ames test) against TA98 and TA100 at the dilutions of 5% and 90%, respectively; those dilutions were selected as the maximum possible ones in the drink industry. Their activity was investigated against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, Aspergillus niger, and Adenovirus 35. Both were effective against Adenovirus and A. niger, even the essential oil at 5% (v/v). The extract at dilutions of 25–90% had more pronounced activity against tested bacteria than the essential oil at the dilutions of 5–100%; the essential oil at the dilution of 5% inhibited S. aureus growth. The antioxidant activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, the 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid decolorization assay, and the ferric reducing antioxidant power assay. Both exhibited good antioxidant activity, but rosemary essential oil was far more effective than the extract. Our results demonstrate that rosemary essential oil and extract are safe and have beneficial biological properties. Therefore, they could serve as health-promoting ingredients in the drink industry.

Microalgae may produce a range of high-value bioactive substances, making them a promising resource for various applications. In this study, the antibacterial activity of twelve microalgae species isolated from lagoons in western Greece was examined against four fish pathogenic bacteria (Vibrio anguillarum, Aeromonas veronii, Vibrio alginolyticus, and Vibrio harveyi). Two experimental approaches were used to evaluate the inhibitory effect of microalgae on pathogenic bacteria. The first approach used bacteria-free microalgae cultures, whereas the second approach used filter-sterilized supernatant from centrifuged microalgae cultures. The results demonstrated that all microalgae had inhibitory effects against pathogenic bacteria in the first approach, particularly 4 days after inoculation, where Asteromonas gracilis and Tetraselmis sp. (red var., Pappas) exhibited the highest inhibitory activity, reducing bacterial growth by 1 to 3 log units. In the second approach, Tetraselmis sp. (red var., Pappas) showed significant inhibition against V. alginolyticus between 4 and 25 h after inoculation. Moreover, all tested cyanobacteria exhibited inhibitory activity against V. alginolyticus between 21 and 48 h after inoculation. Statistical analysis was performed using the independent samples t-test. These findings suggested that microalgae produce compounds with antibacterial activity, which could be useful in aquaculture.