Chemical composition, antibacterial and antioxidant activities of Tunisian garlic (Allium sativum) essential oil and ethanol extract

Enhancing antioxidant and antibacterial properties of olive oil through garlic enrichment: a comprehensive study

The amalgamation of garlic's antibacterial potency with olive oil's nutritional benefits provides a natural, effective way to boost health and counters microbial threats. This study explored the antioxidant and antibacterial traits of garlic-enriched virgin olive oil (VOO) samples, focusing on various garlic forms (fresh, oven-dried, freeze-dried). Comparative analysis revealed fresh garlic's highest total phenolic content, flavonoid content, and strongest DPPH scavenging activity. GC/MS analysis unveiled distinct volatile profiles. Fresh garlic oil contained elevated allyl-methy-sulfide, diallyl-trisulfide, methyl-propyl-disulfide levels. Antibacterial evaluation displayed substantial inhibition zones, especially fresh garlic oil against E. coli, and oven-dried/freeze-dried garlic oils against P. aeruginosa. Lower Minimal Inhibitory Concentration (MIC) values for fresh garlic oil and freeze-dried garlic oil against both Gram-negative and Gram-positive bacteria signify potent antibacterial activity of garlic-enriched VOO. These findings underscore garlic-enriched VOO's potential as natural antibacterial agents, fortified with antioxidant traits, while emphasizing drying methods' role in shaping volatile compounds.

A botanical reference set illustrating a weight of evidence approach for skin sensitization risk assessment

Recent years have seen an increase in the use of botanicals and natural substances (BNS) in consumer products such as cosmetics and household care products. Most work conducted to date to assess botanicals for human safety has focused their use as dietary supplements and thus on systemic toxicity. However, the induction of skin sensitization is a possible adverse effect of natural products in particular those that come into skin contact, especially for cosmetics that remain on the skin and are not rinsed off following use. Assessments of BNS ingredients are often challenging for a number of reasons: the BNS are complex mixtures that can be of mostly unknown composition; the composition can be highly variable even within the same plant species and dependent on how processed; the physical form of the BNS raw material can vary from a highly concentrated powdered extract to a liquid extract containing only a small percentage of the BNS; testing of the BNS raw materials in New Approach Methods (NAM) has uncertainty as these methods are often not developed or validated for complex mixtures. In this study, a reference set of 14 selected BNS which span the range of skin sensitization potential was complied. These data were used in a Weight of Evidence (WoE) approach to evaluate their skin sensitization potential with each of the data rich BNS being classified as either having strong evidence of inducing skin sensitization based on human topical use history, animal data, clinical data, composition data and NAM data, or having some but more limited (weak) evidence of inducing skin sensitization, or having strong evidence of no skin sensitization potential. When available data have sufficient potency related information, sensitization potency assessment is also provided based on WoE, classifying these BNS as either strong, moderate, or weak sensitizers, or non-sensitizers. An outline for a BNS skin sensitization risk assessment framework is proposed starting with exposure-based waiving and WoE assessment for higher exposures. In addition to demonstrating the application of the WoE approach, the reference set presented here provides a set of 'data rich' botanicals which cover a range of sensitization potencies that could be used for evaluating existing test methods or aid in the development of new predictive models for skin sensitization.

Assessing the In Vitro and In Vivo Effect of Supplementation with a Garlic (Allium sativum) and Oregano (Origanum vulgare) Essential Oil Mixture on Digestibility in West African Sheep

This study assessed the impact of a mixture of garlic (Allium sativum) and oregano (Origanum vulgare) essential oils (EOGOs) on in vitro dry matter digestibility (IVDMD) and in vivo apparent nutrient digestibility. Different EOGO inclusion levels were evaluated to assess the dose response and potential effects of the mixture. Three EOGO inclusion levels (0.5, 0.75, and 1 mL/kg of incubated dry matter) were evaluated in vitro, while four treatments (0.5, 0.75, and 1 mL/day of EOGO and a control group) were tested in vivo on 12 West African sheep. A randomized controlled trial was conducted using a 4 × 4 design. Blood parameters (glucose, blood urea nitrogen, and β-hydroxybutyrate) were measured to observe the effect of EOGO on the metabolism. The results showed that the inclusion of EOGO significantly enhanced IVDMD at low levels (p < 0.052) compared with the highest levels in treatments containing 0.5 and 0.75 mL/kg of EOGO dry matter. A higher intake of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) (p < 0.05) was observed in the in vivo diets with the inclusion of EOGO. In terms of in vivo apparent digestibility, significant differences were found among treatments in the digestibility coefficients of DM, CP, and NDF. EOGO inclusion increased the digestibility of DM. CP digestibility displayed a cubic effect (p < 0.038), with the lowest values of digestibility observed at 1 mL EOGO inclusion. Additionally, NDF digestibility showed a cubic effect (p < 0.012), with the highest value obtained at 0.75 mL of EOGO inclusion. The inclusion levels above 0.75 mL EOGO showed a cubic effect, which indicates that higher concentrations of EOGO may not be beneficial for the digestibility of CP and NDF. Although no significant difference was observed in total digestible nutrients, a linear trend was observed (p < 0.059). EOGO improved the intake of DM, CP, and NDF. EOGO supplementation improved the digestibility of DM and NDF, with optimal levels observed at 0.5 mL/day. No significant effects were observed in the blood parameters. These results suggest that EOGO has the potential as an additive in ruminal nutrition to improve food digestibility and serve as an alternative to antibiotic additives. The use of EOGO potentially improves fiber digestion and may reduce the use of antibiotics in livestock production. Garlic (A. sativum) and oregano (O. vulgare) essential oils effectively modulated fiber digestibility at 0.75 mL/day. Garlic (A. sativum) and oregano (O. vulgare) essential oils have the potential to improve digestibility at low inclusion levels and serve as an alternative to antibiotic additives. The effectiveness of essential oils is greater in a mixture and at lower doses.

In Vitro Antioxidant and In Vivo Antigenotoxic Features of a Series of 61 Essential Oils and Quantitative Composition-Activity Relationships Modeled through Machine Learning Algorithms

The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures' constituents and biological properties. In this study, a series of 61 commercial EOs were first evaluated as antioxidants in vitro, following as closely as possible the cellular pathways of reactive oxygen species (ROS) generation. Hence, EOs were assessed for the ability either to chelate metal ions, thus interfering with ROS generation within the respiratory chain, or to neutralize 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and lipid peroxide radicals (LOO•), thereby halting lipid peroxidation, as well as to neutralize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radicals (ABTS•+) and hydroxyl radicals (OH•), thereby preventing the ROS species from damaging DNA nucleotides. Showing noteworthy potencies to neutralize all of the radicals at the ng/mL level, the active EOs were also characterized as protectors of DNA double strands from damage induced by peroxyl radicals (ROO•), emerging from 2,2'-azobis-2-methyl-propanimidamide (AAPH) as a source, and OH•, indicating some genome protectivity and antigenotoxicity effectiveness in vitro. The chemical compositions of the EOs associated with the obtained activities were then analyzed by means of machine learning (ML) classification algorithms to generate quantitative composition-activity relationships (QCARs) models (models published in the AI4EssOil database available online). The QCARs models enabled us to highlight the key features (EOSs' chemical compounds) for exerting the redox potencies and to define the partial dependencies of the features, viz. percentages in the mixture required to exert a given potency. The ML-based models explained either the positive or negative contribution of the most important chemical components: limonene, linalool, carvacrol, eucalyptol, α-pinene, thymol, caryophyllene, p-cymene, eugenol, and chrysanthone. Finally, the most potent EOs in vitro, Ylang-ylang (Cananga odorata (Lam.)) and Ceylon cinnamon peel (Cinnamomum verum J. Presl), were promptly administered in vivo to evaluate the rescue ability against redox damage caused by CCl4, thereby verifying their antioxidant and antigenotoxic properties either in the liver or in the kidney.

Antimicrobial activity, chemical composition and mechanism of action of Chinese chive (Allium tuberosum Rottler) extracts

Chinese chive (Allium tuberosum Rottler) is a popular food from Allium species in East and Southeast Asia. Most Allium species possess characteristic aromas and have antimicrobial activity. In this study, the antimicrobial activities of root, leaf, and scape extracts of Chinese chive at different pH levels (3.0, 5.0, 7.0, 9.0, and 10.7) were compared. The most pronounced activity was produced by the scape extract, and the greatest activity was obtained at pH 5.0. HPLC and GC-MS analysis showed that the major active ingredient was 2-amino-5-methylbenzoic acid. The mechanism of action of Chinese chive scape extracts may involve the depression or disruption of cell membrane integrity, according to our results of the leakage of electrolytes and protein, as well as scanning electron microscopy and transmission electron microscopy observations.

Traditional uses, phytochemistry, pharmacology and toxicology of garlic (Allium sativum), a storehouse of diverse phytochemicals: A review of research from the last decade focusing on health and nutritional implications

Allium sativum L. (Garlic) is a fragrant herb and tuber-derived spice that is one of the most sought-after botanicals, used as a culinary and ethnomedicine for a variety of diseases around the world. An array of pharmacological attributes such as antioxidant, hypoglycemic, anti-inflammatory, antihyperlipidemic, anticancer, antimicrobial, and hepatoprotective activities of this species have been established by previous studies. A. sativum houses many sulfur-containing phytochemical compounds such as allicin, diallyl disulfide (DADS), vinyldithiins, ajoenes (E-ajoene, Z-ajoene), diallyl trisulfide (DATS), micronutrient selenium (Se) etc. Organosulfur compounds are correlated with modulations in its antioxidant properties. The garlic compounds have also been recorded as promising immune-boosters or act as potent immunostimulants. A. sativum helps to treat cardiovascular ailments, neoplastic growth, rheumatism, diabetes, intestinal worms, flatulence, colic, dysentery, liver diseases, facial paralysis, tuberculosis, bronchitis, high blood pressure, and several other diseases. The present review aims to comprehensively enumerate the ethnobotanical and pharmacological aspects of A. sativum with notes on its phytochemistry, ethnopharmacology, toxicological aspects, and clinical studies from the retrieved literature from the last decade with notes on recent breakthroughs and bottlenecks. Future directions related to garlic research is also discussed.

Anti-Methanogenic Effect of Phytochemicals on Methyl-Coenzyme M Reductase-Potential: In Silico and Molecular Docking Studies for Environmental Protection

Methane is a greenhouse gas which poses a great threat to life on earth as its emissions directly contribute to global warming and methane has a 28-fold higher warming potential over that of carbon dioxide. Ruminants have been identified as a major source of methane emission as a result of methanogenesis by their respective gut microbiomes. Various plants produce highly bioactive compounds which can be investigated to find a potential inhibitor of methyl-coenzyme M reductase (the target protein for methanogenesis). To speed up the process and to limit the use of laboratory resources, the present study uses an in-silico molecular docking approach to explore the anti-methanogenic properties of phytochemicals from Cymbopogon&nbsp;citratus, Origanum vulgare, Lavandula officinalis, Cinnamomum zeylanicum, Piper betle, Cuminum cyminum, Ocimum gratissimum, Salvia sclarea, Allium sativum, Rosmarinus officinalis and Thymus vulgaris. A total of 168 compounds from 11 plants were virtually screened. Finally, 25 scrutinized compounds were evaluated against methyl-coenzyme M reductase (MCR) protein using the AutoDock 4.0 program. In conclusion, the study identified 21 out of 25 compounds against inhibition of the MCR protein. Particularly, five compounds: rosmarinic acid (-10.71 kcal/mol), biotin (-9.38 kcal/mol), α-cadinol (-8.16 kcal/mol), (3R,3aS,6R,6aR)-3-(2H-1,3-benzodioxol-4-yl)-6-(2H-1,3-benzodioxol-5-yl)-hexahydrofuro[3,4-c]furan-1-one (-12.21 kcal/mol), and 2,4,7,9-tetramethyl-5decyn4,7diol (-9.02 kcal/mol) showed higher binding energy towards the MCR protein. In turn, these compounds have potential utility as rumen methanogenic inhibitors in the proposed methane inhibitor program. Ultimately, molecular dynamics simulations of rosmarinic acid and (3R,3aS,6R,6aR)-3-(2H-1,3-benzodioxol-4-yl)-6-(2H-1,3-benzodioxol-5-yl)-hexahydrofuro[3,4-c]furan-1-one yielded the best possible interaction and stability with the active site of 5A8K protein for 20 ns.

Antimicrobial Effect and the Mechanism of Diallyl Trisulfide against Campylobacter jejuni

Campylobacter jejuni is an important foodborne pathogen causing campylobacteriosis. It can infect humans through the consumption of contaminated chicken products or via the direct handling of animals. Diallyl trisulfide (DATS) is a trisulfide compound from garlic extracts that has a potential antimicrobial effect on foodborne pathogens. This study investigated the antimicrobial activity of DATS on C. jejuni by evaluating the minimal inhibitory concentrations (MICs) of C. jejuni 81-168, and fourteen C. jejuni isolates from chicken carcasses. Thirteen of 14 C. jejuni isolates and 81-176 had MICs ≤ 32 μg/mL, while one isolate had MIC of 64 μg/mL. Scanning electron microscopy (SEM) analysis showed the disruption and shrink of C. jejuni bacterial cell membrane after the DATS treatment. A time-killing analysis further showed that DATS had a dose-dependent in vitro antimicrobial effect on C. jejuni during the 24 h treatment period. In addition, DATS also showed an antimicrobial effect in chicken through the decrease of C. jejuni colony count by 1.5 log CFU/g (cloacal sample) during the seven-day DATS treatment period. The transcriptional analysis of C. jejuni with 16 μg/mL (0.5× MIC) showed 210 differentially expression genes (DEGs), which were mainly related to the metabolism, bacterial membrane transporter system and the secretion system. Fourteen ABC transporter-related genes responsible for bacterial cell homeostasis and oxidative stress were downregulated, indicating that DATS could decrease the bacterial ability to against environmental stress. We further constructed five ABC transporter deletion mutants according to the RNA-seq analysis, and all five mutants proved less tolerant to the DATS treatment compared to the wild type by MIC test. This study elucidated the antimicrobial activity of DATS on C. jejuni and suggested that DATS could be used as a potential antimicrobial compound in the feed and food industry.

Investigation into SARS-CoV-2 Resistance of Compounds in Garlic Essential Oil

Eighteen active substances, including 17 organosulfur compounds found in garlic essential oil (T), were identified by GC-MS analysis. For the first time, using the molecular docking technique, we report the inhibitory effect of the considered compounds on the host receptor angiotensin-converting enzyme 2 (ACE2) protein in the human body that leads to a crucial foundation about coronavirus resistance of individual compounds on the main protease (PDB6LU7) protein of SARS-CoV-2. The results show that the 17 organosulfur compounds, accounting for 99.4% contents of the garlic essential oil, have strong interactions with the amino acids of the ACE2 protein and the main protease PDB6LU7 of SARS-CoV-2. The strongest anticoronavirus activity is expressed in allyl disulfide and allyl trisulfide, which account for the highest content in the garlic essential oil (51.3%). Interestingly, docking results indicate the synergistic interactions of the 17 substances, which exhibit good inhibition of the ACE2 and PDB6LU7 proteins. The results suggest that the garlic essential oil is a valuable natural antivirus source, which contributes to preventing the invasion of coronavirus into the human body.

Garlic (Allium sativum L.) - the content of bioactive compounds

Genus Allium belongs to the family Alliaceae, which contains more than 600 species. Garlic (Allium sativum L.) is the most popular food ingredient widely used all over the world. During the last few decades, garlic has received tremendous attention for their wide range of therapeutic properties and great health benefits. Garlic has possessed antibacterial, antifungal, antiparasitic, antiviral, antioxidant, anticholesteremic, anti-cancerous, and vasodilator characteristics. In this work the total polyphenols content, total sulfur content and antioxidant activity was compared and evaluated in four studied varieties of garlic (Mojmír, Lukan, Záhorský and Makoi). The analyzed samples of garlic were collected at the stage of full maturity in the area Bardejov. The total polyphenols content was measured using the spectrophotometric method of Folin-Ciocalteu agents. The total polyphenols content in studied varieties of garlic were determined in the range 612.23 mg.kg-1 (Mojmír) to 566.01 mg.kg-1 (Lukan). The total polyphenols content in garlic can be arranged as follows: Mojmír >Makoi >Záhorský >Lukan. The determination of the total sulfur content is based on dry combustion in the presence of oxygen and allows for the quantitative conversion of sulfur to SO2. Statistically significant highest level of total sulfur content was recorded in 0.638% (Mojmír) and the lowest level was in 0.421% (Makoi). According to determined values of total sulfur content the studied varieties of garlic can be arranged in the following order: Mojmír >Lukan >Záhorský >Makoi. Antioxidant activity was determined by the spectrophotometric method using a compound DPPH (2.2-diphenyl-1-picryhydrazyl). The highest value of antioxidant activity was measured in Mojmír (15.24%). The lowest level was observed in Makoi (11.73%). The antioxidant activity in garlic declined in the following order: Mojmír >Lukan >Záhorský >Makoi. In all studied samples of garlic was confirmed by the strong dependence of the total polyphenols content, total sulfur content and antioxidant activity.

Chemical Composition of Herbal Macerates and Corresponding Commercial Essential Oils and Their Effect on Bacteria Escherichia coli

This study addresses the chemical composition of some commercial essential oils (clove, juniper, oregano, and marjoram oils), as well as appropriate herbal extracts obtained in the process of cold maceration and their biological activity against selected Escherichia coli strains: E. coli ATTC 25922, E. coli ATTC 10536, and E. coli 127 isolated from poultry waste. On the basis of the gas chromatography-mass spectrometry (GCMS) analysis, it was found that the commercial essential oils revealed considerable differences in terms of the composition and diversity of terpenes, terpenoids and sesquiterpenes as compared with the extracts obtained from plant material. The commercial clove, oregano, and marjoram oils showed antibacterial properties against all the tested strains of E. coli. However, these strains were not sensitive to essential oils obtained from the plant material in the process of maceration. The tested strains of E. coli show a high sensitivity, mainly against monoterpenes (α-pinene, β-pinene, α,β,γ-terpinene, limonene) and some terpenoids (thymol, carvacrol). The commercial juniper oil contained mainly monoterpenes and monoterpenoids, while the extracts contained lower amounts of monoterpenes and high amounts of sesquiterpenes—the anti-microbiotic properties of the juniper herbal extract seem to be caused by the synergistic activity of mono- and sesquiterpenes.

Formulation development and evaluation of antimicrobial polyherbal gel

OBJECTIVE

In the recent years, there has been a gradual revival of interest in the use of medicinal plants in developing countries because herbal medicines have been reported safe with minimal adverse side effect especially when compared with synthetic drugs.

METHOD

In the present study we prepared gel formulations (formulations A and B) which comprised of ethanolic extract of Azadirachta indica, Curcuma longa, Allium sativum, Ocimum sactum, Cinnamomum zeylanicum nees and Tamarindus indica in a concentration of 0.1 and 0.5%, respectively in a base. The base was prepared by using carbapol 940, propylene glycol-400, ethanol, methyl paraben, propylparaben, EDTA, triethanolamine and required amount of water in a quantity sufficient to prepare 50g. The prepared formulations were screened for their antimicrobial activity by agar well diffusion technique against S. aureus, B. subtilis, A. niger and E. coli which are representative types of Gram positive and Gram negative organisms. The formulations were also evaluated for appearance and homogeneity, pH, viscosity and rheological studies, spreadability, drug content uniformity, skin irritation test (Patch test) and washability.

RESULT

The results of the studies revealed that both formulation under study viz A and B showed better zone of inhibition as compared with the base. However, formulation B exhibited maximum activity against the selected strains which may be attributed to its greater amount of herbal extracts as compared to formulation A.

CONCLUSION

Based on our research, it could be concluded that these formulations possess antimicrobial activity and can be used safely on human skin.

Evaluation and comparison of the content of total polyphenols and antioxidant activity in garlic (Allium sativum L.)

Garlic (Allium sativum L.) is one of the oldest cultivated plants in the world and highly valued throughout the ages as a culinary spice. It is a hardy perennial belonging to the Alliaceae family. The garlic bulb is the most commonly used portion of the plant, composed of 5 - 20 individual. It is a very good source of manganese, selenium, vitamin C and vitamin B6 (pyridoxine). In addition, garlic is a good source of other minerals, including phosphorous, calcium, potassium, iron and copper. Many of the perceived therapeutic effects of garlic are thought to be due to its active ingredient allicin. This sulphur-containing compound gives garlic its distinctive pungent smell and taste. Garlic possesses antiviral, antibacterial, anti-fungal properties allowing it to stand against all infections. This work has focused on the evaluation and comparison of total content of polyphenols and antioxidant activity in five varieties of garlic - Mojmír, Záhorský, Lukan, Havran and Makoi. Samples of plant material were collected at the stage of full maturity in the area of Nitra. The total content of polyphenols was determined using the spectrophotometric method of Folin-Ciocalteu agents. Determined the content of total polyphenols in garlic were in the range 621.13 mg.kg-1 (Záhorský) to 763.28 mg.kg-1 (Havran). Total polyphenols content in garlic declined in the following order: Havran >Mojmír >Makoi >Lukan >Záhorský. Antioxidant activity was measured by the spectrophotometric method using a compound DPPH (2.2-diphenyl-1-picryhydrazyl). Statistically significant highest value of antioxidant was recorded in 20.22% (Mojmír) and the lowest value was in 13.61% (Záhorský). The values of antioxidant activity observed in the varieties of garlic may be arranged as follows: Mojmír >Havran >Lukan >Makoi >Záhorský. In all the analysed varieties of garlic was confirmed by the strong dependence of the antioxidant activity and the total content of polyphenols.