Combination of Chemically-Characterized Essential Oils from Eucalyptus polybractea, Ormenis mixta, and Lavandula burnatii: Optimization of a New Complete Antibacterial Formulation Using Simplex-Centroid Mixture Design

This study aims to identify the volatile profile of three essential oils obtained from Eucalyptus polybractea cryptonifera (EPEO), Ormenis mixta (OMEO), and Lavandula burnatii briquet (LBEO) and to examine their combined antibacterial activity that affords the optimal inhibitory ability against S. aureus and E. coli using simplex-centroid mixture design and checkerboard assay. Essential oils (EOs) were isolated by hydrodistillation and characterized using gas chromatography-mass spectrometry (GC-MS) and gas chromatography coupled with flame-ionization detector (GC-FID). The antibacterial activity was performed using disc diffusion and microdilution assays. The chemical analysis revealed that 1,8-cineole (23.75%), p-cymene (22.47%), and α-pinene (11.20%) and p-menthane-1,8-diol (18.19%), α-pinene (10.81%), and D-germacrene (9.17%) were the main components detected in E. polybractea and O. mixta EOs, respectively. However, L. burnatii EO was mainly represented by linalool (24.40%) and linalyl acetate (18.68%). The EPEO, LBEO, and OMEO had a strong antibacterial effect on S. aureus with minimal inhibitory concentrations (MICs) values ranging from 0.25 to 0.5% (v/v). Furthermore, the combination of 1/2048 MICEPEO + 1/4 MICLBEO showed a synergistic antibacterial effect on S. aureus with a FIC index of 0.25, while the formulation of 1/4 MICEPEO + 1/4 MICOMEO demonstrated an antibacterial synergistic activity on E. coli with a FIC index of 0.5. Moreover, the simplex-centroid mixture design reported that the most effective combinations on E. coli and S. aureus correspond to 32%/28%/40% and 35%/30%/35% of E. polybractea, O. mixta, and L. burnatii, respectively. Presented information highlights the action of antibacterial formulations of these EOs and suggests their potential applications as alternatives to commercialized drugs to contract the development of bacteria causing serious infections and food deterioration.

Antioxidant, Volatile Compounds; Antimicrobial, Anti-Inflammatory, and Dermatoprotective Properties of Cedrus atlantica (Endl.) Manetti Ex Carriere Essential Oil: In Vitro and In Silico Investigations

Cedrus atlantica (Endl.) Manetti ex Carriere is an endemic tree possessing valuable health benefits which has been widely used since time immemorial in international traditional pharmacopoeia. The aim of this exploratory investigation is to determine the volatile compounds of C. atlantica essential oils (CAEOs) and to examine their in vitro antimicrobial, antioxidant, anti-inflammatory, and dermatoprotective properties. In silico simulations, including molecular docking and pharmacokinetics absorption, distribution, metabolism, excretion, and toxicity (ADMET), and drug-likeness prediction were used to reveal the processes underlying in vitro biological properties. Gas chromatography-mass spectrophotometry (GC-MS) was used for the chemical screening of CAEO. The antioxidant activity of CAEO was investigated using four in vitro complementary techniques, including ABTS and DPPH radicals scavenging activity, ferric reductive power, and inhibition of lipid peroxidation (β-carotene test). Lipoxygenase (5-LOX) inhibition and tyrosinase inhibitory assays were used for testing the anti-inflammatory and dermatoprotective properties. GC-MS analysis indicated that the main components of CAEO are β-himachalene (28.99%), α-himachalene (14.43%), and longifolene (12.2%). An in vitro antimicrobial activity of CAEO was examined against eleven strains of Gram-positive bacteria (three strains), Gram-negative bacteria (four strains), and fungi (four strains). The results demonstrated high antibacterial and antifungal activity against ten of them (>15 mm zone of inhibition) using the disc-diffusion assay. The microdilution test showed that the lowest values of MIC and MBC were recorded with the Gram-positive bacteria in particular, which ranged from 0.0625 to 0.25 % v/v for MIC and from 0.5 to 0.125 % v/v for MBC. The MIC and MFC of the fungal strains ranged from 0.5 to 4.0% (MIC) and 0.5 to 8.0% v/v (MFC). According to the MBC/MIC and MFC/MIC ratios, CAEO has bactericidal and fungicidal activity. The results of the in vitro antioxidant assays revealed that CAEO possesses remarkable antioxidant activity. The inhibitory effects on 5-LOX and tyrosinase enzymes was also significant (p < 0.05). ADMET investigation suggests that the main compounds of CAEO possess favorable pharmacokinetic properties. These findings provide scientific validation of the traditional uses of this plant and suggest its potential application as natural drugs.

Phytochemical analysis and evaluation of antimicrobial, antioxidant, and antidiabetic activities of essential oils from Moroccan medicinal plants: Mentha suaveolens, Lavandula stoechas, and Ammi visnaga

Mentha suaveolens, Lavandula stoechas, and Ammi visnaga are widely used in Moroccan folk medicine against several pathological disorders, including diabetes and infectious diseases. This work was designed to determine the chemical profile of M. suaveolens (MSEO), L. stoechas (LSEO), and A. visnaga (AVEO) essential oils and assess their antimicrobial, antioxidant, and antidiabetic effects. The volatile components of LSEO, AVEO, and MSEO were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The in vitro antidiabetic activity was assessed using α-amylase and α-glucosidase enzymes, while DPPH, FRAP, and β-carotene/linoleic acid methods were used to determine the antioxidant capacity. The antimicrobial activities were investigated using disc diffusion and broth-microdilution assays. GC-MS investigation revealed that the main components were fenchone (29.77 %) and camphor (24.9 %) for LSEO, and linalool (38.29 %) for AVEO, while MSEO was mainly represented by piperitenone oxide (74.55 %). The results of the antimicrobial evaluation showed that all examined essential oils (EOs) had noticeable antimicrobial activity against both bacteria and yeast, especially Micrococcus luteus and Bacillus subtilis. The MIC, MBC, and MFC values were ranged from 0.015 % to 0.5 %. The MBC/MIC and MFC/MIC ratios were less than or equal to 4.0 % (v/v), indicating their noticeable bactericidal and candidacidal efficacy. Moreover, the three EOs showed significant inhibitory effects on α-amylase and α-glucosidase (p < 0.05). It also exerted remarkable activity on FRAP, β-carotene, and DPPH radicals. These findings demonstrated that the tested plants have promising biological activities, validating their ethnomedicinal value and providing potential applications as natural drugs.

Simplex-centroid design as innovative approach in the optimization of antimicrobial effect of Thymus satureioides, Myrtus communis and Artemisia herba alba essential oils against Escherichia coli, Staphylococcus aureus and Candidatropicalis

Essential Oils (EOs) known since Antiquity, and initially obtained by maceration of aromatic plants, are used as diseases' remedies because they contain valuable therapeutic components. Antimicrobial effect's evaluation of formulations established by an augmented centered mixing plan for three Moroccan medicinal and aromatic plants' essential oils (EOs): Thymus satureioides (T. satureioides), Myrtus communis (M. communis) and Artemisia herba alba (A. herba alba) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida tropicalis (C. tropicalis). The identification of E.Os chemical compounds was made using Gaz chromatography (GC) and Gaz chromatography coupled to Mass spectrometry (GC/MS).Whereas, the optimization of their antimicrobial effect was performed by experimental design methodology (mixture design) coupled to microdilution method based on Minimal Inhibitory Concentrations (MICs) determination. Results showed that the main components are borneol (34.26%) and α-pinene (31.21%); borneol (27.15%) and 1,8-cineole (21.33%); camphor (14.67%), chrysanthenone (14.10%), and β-thujone (12.60%) for T. satureioides, M. communis and A. herba alba respectively. Optimal mixtures composed of 60% and 40% of T. satureioides and M. communis E.Os; 72% and 28% of T. satureioides and A. Herba alba E.Os; 75% of thyme E.O and 25% of mugwort E.O; predicted the highest antimicrobial effect against E. coli, S. aureus and C. tropicalis, respectively. This study highlights the antimicrobial effect of EOs tertiary mixtures through using mixture design methodology, which may contribute to a successful application in pharmaceutical, food, or cosmetic industries.

Health Benefits and Pharmacological Properties of Stigmasterol

Stigmasterol is an unsaturated phytosterol belonging to the class of tetracyclic triterpenes. It is one of the most common plant sterols, found in a variety of natural sources, including vegetable fats or oils from many plants. Currently, stigmasterol has been examined via in vitro and in vivo assays and molecular docking for its various biological activities on different metabolic disorders. The findings indicate potent pharmacological effects such as anticancer, anti-osteoarthritis, anti-inflammatory, anti-diabetic, immunomodulatory, antiparasitic, antifungal, antibacterial, antioxidant, and neuroprotective properties. Indeed, stigmasterol from plants and algae is a promising molecule in the development of drugs for cancer therapy by triggering intracellular signaling pathways in numerous cancers. It acts on the Akt/mTOR and JAK/STAT pathways in ovarian and gastric cancers. In addition, stigmasterol markedly disrupted angiogenesis in human cholangiocarcinoma by tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor receptor-2 (VEGFR-2) signaling down-regulation. The association of stigmasterol and sorafenib promoted caspase-3 activity and down-regulated levels of the anti-apoptotic protein Bcl-2 in breast cancer. Antioxidant activities ensuring lipid peroxidation and DNA damage lowering conferred to stigmasterol chemoprotective activities in skin cancer. Reactive oxygen species (ROS) regulation also contributes to the neuroprotective effects of stigmasterol, as well as dopamine depletion and acetylcholinesterase inhibition. The anti-inflammatory properties of phytosterols involve the production of anti-inflammatory cytokines, the decrease in inflammatory mediator release, and the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Stigmasterol exerts anti-diabetic effects by reducing fasting glucose, serum insulin levels, and oral glucose tolerance. Other findings showed the antiparasitic activities of this molecule against certain strains of parasites such as Trypanosoma congolense (in vivo) and on promastigotes and amastigotes of the Leishmania major (in vitro). Some stigmasterol-rich plants were able to inhibit Candida albicans, virusei, and tropicalis at low doses. Accordingly, this review outlines key insights into the pharmacological abilities of stigmasterol and the specific mechanisms of action underlying some of these effects. Additionally, further investigation regarding pharmacodynamics, pharmacokinetics, and toxicology is recommended.

Ruta montana (L.) L.: An insight into its medicinal value, phytochemistry, biological properties, and toxicity

Ruta montana (RM) is a medicinal and aromatic plant (MAP) used in folk medicine, especially in North Africa, to treat digestive, infectious, respiratory, neurological, gynecological, and diabetic diseases. The current work aims to review the scientifically validated ethno-medicinal usage, bioactivities and phytochemistry of RM, in order to provide data support for further investigations. Data were procured from PubMed, Scopus, Google Scholar, Web of Science, ScienceDirect, and PubChem. The present study revealed that RM could be used to manage many diseases involved in public health problems, such as diabetes, hypertension, neurological disorders, infections, reproductive system disorders, and cancer. It might also replace chemical insecticides and fungicides since it exhibits antifungal, insecticidal, and larvicidal properties. RM extracts also contain mainly coumarins and alkaloids. The volatile oil of RM is characterized by an abundance of ketone compounds and 2-undecanone as major constituents. In the case of a high-dose administration, RM infusion can cause poisoning through the oral path. Thus, in-depth in vivo pharmacological studies and clinical trials are needed to transmute the traditional applications of RM into scientific-based information.