Chemical composition of Schinus areira essential oil and antimicrobial action against Staphylococcus aureus

Green One-Step Synthesis of Silver Nanoparticles Obtained from Schinus areira Leaf Extract: Characterization and Antibacterial Mechanism Analysis

The increased emergence of antibiotic-resistant bacteria is a serious health problem worldwide. In this sense, silver nanoparticles (AgNPs) have received increasing attention for their antimicrobial activity. In this context, the goal of this study was to produce AgNPs by a green synthesis protocol using an aqueous leaf extract of Schinus areira as biocomposite to later characterize their antimicrobial action. The nanomaterials obtained were characterized by UV‒vis spectroscopy, DLS, TEM, and Raman, confirming the presence of quasi-spherical AgNPs with a negative surface charge and diameter around 11 nm. Afterward, the minimum inhibitory and bactericidal concentration of the AgNPs against Staphylococcus aureus and Escherichia coli were obtained, showing high antibacterial activity. In both of the examined bacteria, the AgNPs were able to raise intracellular ROS levels. In E. coli, the AgNPs can harm the bacterial membrane as well. Overall, it can be concluded that it was possible to obtain AgNPs with colloidal stability and antibacterial activity against Gram-positive and Gram-negative bacteria. Our findings point to at least two separate mechanisms that can cause cell death, one of which involves bacterial membrane damage and the other of which involves intracellular ROS induction.

Antimicrobial properties of the essential oil of Schinus areira (Aguaribay) against planktonic cells and biofilms of S. aureus

The essential oil (EO) of Schinus areira L. (Anacardiaceae) leaves has shown antibacterial activity against Staphylococcus aureus. In this study we aimed to unravel the mechanisms of its antibacterial action by using bacterial cells and model membranes. First, the integrity of S. aureus membrane was evaluated by fluorescence microscopy. It was observed an increase in the permeability of cells that was dependent on the EO concentration as well as the incubation time. For a deep evaluation of the action of the EO on the lipids, its effect on the membrane fluidity was evaluated on DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine): DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-1'-rac-glycerol) (5:1) liposomes by dynamic scattering light and by using Laurdan doped liposomes. The results indicate that EO produces changes in lipid membrane packing, increasing the fluidity, reducing the cooperative cohesive interaction between phospholipids and increasing access of water or the insertion of some components of the EO to the interior of the membrane. In addition, the potential effect of EO on intracellular targets, as the increase of cytosolic reactive oxygen species (ROS) and DNA damage, were evaluated. The EO was capable of increasing the production of ROS as well as inducing a partial degradation of DNA. Finally, the effect of EO on S. aureus biofilm was tested. These assays showed that EO was able to inhibit the biofilm formation, and also eradicate preformed biofilms. The results show, that the EO seems to have several bacterial targets involved in the antibacterial activity, from the bacterial membrane to DNA. Furthermore, the antibacterial action affects not only planktonic cells but also biofilms; reinforcing the potential application for this EO.

Selected essential oil components fail to induce an immunological response in Artemia but still protect against vibriosis

In the present research, in order to screen out the best candidates from 12 different EOCs, we proposed three in vivo screening methods, namely the screening method of bioluminescence of V. campbellii associated with brine shrimp, regrowth performance of V. campbellii, and immune gene expression of brine shrimp without challenge. Our result showed that challenged with V. campbellii at 10⁷ cells/mL, the survival of the brine shrimp at 48 h was significantly increased after treatment with the EOCs (at 0.0005%, v/v) of 4-allylanisole, R-(+)-limonene, S-(-)-limonene, (-)-terpinen-4-ol, (±)-citronellal, citral, trans-cinnamaldehyde and (+)-carvone, compared to the positive control group. Also, it was observed that the EOCs- of 4-allylanisloe, R-(+)-limonene, S-(-)-limonene, (-)-β-pinene, geraniol, (±)-citronellal, citral, trans-cinnamaldehyde and (+)-carvone decreased significantly the in vivo bioluminescence of V. campbellii at 36 h after Vibrio exposure. The regrowth assay showed that independently from incubation time (1, 12 or 24 h), no difference was observed in the regrowth curve in all EOC treatment groups compared to the positive control group. The dscam gene expression in the (±)-citronellal group, and the sod gene in the citral group were observed to be significantly higher than in the negative control at 24 h, respectively. However, most of the immune genes were down-regulated in the EOC groups. Combining the survival data at 48 h with the bioluminescence result at 36 h, it was noted that the survival rate of brine shrimp was moderately correlated with in vivo bioluminescence of V. campbellii. The results indicate that the approach of determining in vivo bioluminescence of V. campbellii is a moderately reliable, fastest, and cheapest screening method for EOCs. As the regrowth performance assay of V. campbellii, and the immune genes expression assay of brine shrimp without challenge cannot predict Artemia survival properly, they cannot be used as screening methods for EOCs. Moreover, the immune genes expression assay is relatively slow, time-consuming and costly.

Insecticidal activity of the essential oil of Schinus areira against Rhipibruchus picturatus (F.) (Coleoptera: Bruchinae), and its inhibitory effects on acetylcholinesterase

During the storage of Prosopis alba pods, substantial quantitative and qualitative losses were observed. One of the main factors is the seed beetle Rhipibruchus picturatus. A key strategy to develop new pest control management is the use of essential oils (EOs) due they are efficient, less toxic, and less persistent in the environment compared to synthetic pesticides. In this context, seeds and leaves of Schinus areira L. (Anacardiaceae) EOs and Citrus spp. EO were studied in the present work. In the leaves of S. areira EO, 1-epi-cadinol, sesquiterpenoid alcohol, was the major compound. On the other hand, the main compounds of the EO extracted from S. areira seeds are the monoterpenes sabinene, and α-pinene. Finally, in the Citrus EO, limonene is the principal component. The three EOs obtained exhibited insecticidal activity against R. picturatus, being the first report of the use of EOs against this insect pest. The best insecticidal results were obtained with the leaves of S. areira EO. Moreover, this EO inhibits the acetylcholinesterase enzyme in vitro assays. Molecular docking studies on acetylcholinesterase (AChE) suggest that the main components of the leaves of S, areira EOs, bind to the active site of the enzyme, in good agreement with in vitro competitive inhibition against AChE observed for this EO. The data obtained demonstrate the potential use of Schinus areira EOs in the development of new storage pest control strategies.

The genus Schinus (Anacardiaceae): a review on phytochemicals and biological aspects

The genus Schinus belongs to family 'Anacardiaceae' and includes about 29 species originating from South America, distributed to Peru, Chile, Argentina, Brazil and Paraguay and cultivated in Egypt. Traditionally, Schinus plants are used to alleviate several and diverse diseases including rheumatism, hypertension, ulcers, gastric distress, menstrual disorders, gonorrhea, bronchitis, gingivitis, conjunctivitis, dysentery, wounds, urinary tract, and eye infections. Several phytochemical studies on the Schinus plants revealed presence of diverse bioactive compounds such as flavonoids, bioflavonoids, phenolic acids, tannins, catechins, terpenoids and essential oils. Besides, some Schinus species and their isolated active compounds showed important biological activities such as antibacterial, antifungal, insecticidal, antiparasitic, analgesic, cytotoxic, antitumor, antioxidant, antihypertensive, anti-inflammatory, antimycobacterial, anti-Parkinson, anti-allergic, antiviral, wound healing, chemoprotective, anthelmintic and hepatoprotective. This review attempts to summarize the phytochemical profile and biological activities of Schinus species that could guide researchers to undertake further investigation.

Zeta potential beyond materials science: Applications to bacterial systems and to the development of novel antimicrobials

This review summarizes the theory of zeta potential (ZP) and the most relevant data about how it has been used for studying bacteria. We have especially focused on the discovery and characterization of novel antimicrobial compounds. The ZP technique may be considered an indirect tool to estimate the surface potential of bacteria, a physical characteristic that is key to maintaining optimal cell function. For this reason, targeting the bacterial surface is of paramount interest in the development of new antimicrobials. Surface-acting agents have been found to display a remarkable bactericidal effect and have simultaneously revealed a low tendency to trigger resistance. Changes in the bacterial surface as a result of various processes can also be followed by ZP measurements. However, due to the complexity of the bacterial surface, some considerations regarding the assessment of ZP must first be taken into account. Evidence on the application of ZP measurements to the characterization of bacteria and biofilm formation is presented next. We finally discuss the feasibility of using the ZP technique to assess antimicrobial-induced changes in the bacterial surface. Among these changes are those related to the interaction of the agent with different components of the cell envelope, membrane permeabilization, and loss of viability.