Thymus algeriensis and Artemisia herba-alba Essential Oils: Chemical Analysis, Antioxidant Potential and In Vivo Anti-Inflammatory, Analgesic Activities, and Acute Toxicity

The study of bioactive molecules of natural origin is a focus of current research. Thymus algeriensis and Artemisia herba-alba are two medicinal plants widely used by the Moroccan population in the traditional treatment of several pathologies linked to inflammation. This study aimed to evaluate the single and combined antioxidant, anti-inflammatory and analgesic effects of the essential oils extracted from these two medicinal plants, and also their potential toxicity. Essential oils were extracted using hydro-distillation in a Clevenger-type apparatus. The antioxidant activity was evaluated by two methods: the scavenging of the free radical DPPH, and the reduction in iron. Anti-inflammatory activity was evaluated by evaluating the edema development induced by carrageenan injecting, while the analgesic power was evaluated according to the number of abdominal contortions induced by the intraperitoneal injection of acetic acid (0.7%). The acute oral toxicity was performed to assess the potential toxicity of the studied EOs, followed by an analysis of the blood biochemical parameters. The results of the two antioxidant tests indicated that our extract mixture exhibits good iron reduction capacity and very interesting DPPH free radical scavenging power, with an IC50 of around 4.38 ± 0.98 μg/mL higher than that of the benchmark antioxidant, BHT. The anti-inflammatory test demonstrated that the mixture administered orally at a dose of 150 mg/kg has a better activity, exceeding that of 1% Diclofenac, with a percentage of maximum inhibition of the edema of 89.99 ± 4.08. The number of cramps in the mice treated with the mixture at a dose of 150 mg/kg is significantly lower (29.80 ± 1.92) than those of the group treated with Tramadol (42.00 ± 2.70), respectively. The toxicity results show no signs of toxicity with an LD50 greater than 150 mg/Kg. These interesting results show that the two plants’ EOs had an important anti-inflammatory, analgesic, and antioxidant activity, and also a powerful synergistic effect, which encourages further in-depth investigations on their pharmacological proprieties.

Essential Oils from Thymus capitatus and Thymus algeriensis as Antimicrobial Agents to Control Pathogenic and Spoilage Bacteria in Ground Meat

The antibacterial effects of essential oils (EOs) extracted from Thymus capitatus and Thymus algeriensis were assessed and evaluated against four pathogenic bacteria (Escherichia coli (ATCC 25922), Listeria monocytogenes (ATCC 19118), Staphylococcus aureus (ATCC 25923), and Salmonella typhimurium (ATCC 1402)) and one spoilage bacterium (Pseudomonas aeruginosa (ATCC 27853)). Both investigated EOs presented significant antimicrobial activities against all tested bacteria with a greater antibacterial effect of T. capitatus EO. In fact, the results indicated that the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of T. capitatus EO are in the range of 0.006–0.012% and 0.012–0.025%, respectively, while those of T. algeriensis EO ranged between 0.012 and 0.025% and 0.05%, respectively. Furthermore, the inhibitory effects of both EOs were appraised against the spoilage bacterium P. aeruginosa, inoculated in minced beef meat, at two different loads (105 and 108 CFU) mixed with different concentrations of EOs (0.01, 0.05, 1, and 3%) and stored at 4°C for 15 days. The obtained data demonstrated that the antibacterial effect of tested EOs varies significantly in regard to the levels of meat contamination and the concentrations of EOs. In fact, in the presence of 0.01 and 0.05% of oils, a decrease in bacterial growth p < 0.01 was observed; but, such an effect was more pronounced in the presence of higher concentrations of EOs (1 and 3%), regardless the level of meat contamination. Besides, at the low contamination level, both EOs exerted a rapid and a more pronounced antibacterial effect, as compared to the high contamination level. The results illustrated the efficacy of both EOs as preservatives in food against well-known pathogens of food-borne diseases and food spoilage, particularly in P. aeruginosa in beef meat. As regards sensory evaluation, the presence of T. capitatus EO proved to improve the sensory quality of minced beef meat.

Biological Properties of Essential Oils from Thymus algeriensis Boiss

This study describes the chemical composition, antitumor, antioxidant, and antimicrobial activities of the plant Thymus algeriensis Boiss. Essential oils (EOs) were collected in different periods (before, during, and after flowering stage) from the El-Guetfa region, M’sila, Algeria. The EOs extraction was achieved using three distinguishing techniques: hydro (Clevenger trap), steam, and microwave distillations, targeting different aerial parts of the plant (stems, flowers, and leaves). The EOs chemical components were estimated using GC-FID and GC-MS apparatuses. The resulting yield of the extracted oil was moderate and ranged between 0.84 and 1.53% (wt/vol). In total, eighty-five components were identified, in which the oxygenated monoterpenes family formed the main portion, starting from 40.56 up to 70.66%. The obtained essential oil was dominated by five major components that varied from low to quite moderate percentages: camphor (17.45–32.56%), borneol (11.16–22.2%), camphene (7.53–12.86%), 1.8-cineole (5.16–11.21%), and bornyl acetate (3.86–7.92%). The biological results of this oil pointed out that the EOs extracted from the leaves part exposed a weak radical scavenging activity afterward using two well-known antioxidant assays DPPH (IC50 = 8.37 mg/mL) and ABTS (10.84 mg/mL). Meanwhile, this oil presented strong inhibition activity against colon cancer cell line HCT116 (LC50 = 39.8 µg/mL) and a moderate inhibitory against hepatocellular cancer cells HePG2 (LC50 > 100 µg/mL). In addition, this oil antimicrobial activity was quite important against Micrococcus luteus (M. luteus), Staphylococcus aureus CIP 7625, Escherichia coli ATCC 10536, Saccharomyces cerevisiae ATCC 4226, Candida albicans IPA200, Candida tropicalis (Ct), and Candida glabrata (Cg) after using Amoxicillin and Itraconazole as references.

Thymus algeriensis and Thymus fontanesii exert neuroprotective effect against chronic constriction injury-induced neuropathic pain in rats

We have previously demonstrated that the Thymus algeriensis and Thymus fontanesii extracts have powerful anti-inflammatory, antipyretic, and analgesic effects against acute pain models. We profiled their chemical composition and found many phenolic acids, flavonoids, and phenolic diterpenes. In this work, we investigated their antioxidant properties on HaCaT cells exposed to UVA-induced oxidative stress and examined their effects against chronic neuropathic pain and the underlying mechanisms. Through a rat chronic constriction injury (CCI) model, we induced chronic neuropathic pain by placing 4 loose ligatures around the right sciatic nerve for 14 days. Thermal and mechanical hyperalgesia in addition to cold and dynamic allodynia were tested on the day before surgery and on the 7th and 14th post-surgery days. Key markers of the nitrosative and oxidative stresses, in addition to markers of inflammation, were measured at day 14 post surgery. Histopathological examination and immunostaining of both synaptophysin and caspase-3 of sciatic nerve and brain stem were also performed. Results of this study showed that T. algeriensis extract suppresses UVA oxidative stress in HaCaT cells via activation of the Nrf-2 pathway. Both extracts attenuated hyperalgesia and allodynia at 7- and 14-days post-surgery with more prominent effects at day 14 of surgery. Their protective effects against neuropathic pain were mediated by inhibiting NOX-1, iNOS, by increasing the enzyme activity of catalase, and inhibition of inflammatory mediators, NF-κB, TNF-α, lipoxygenase, COX-2 enzymes, and PGE2. Furthermore, they improved deleterious structural changes of the brainstem and sciatic nerve. They also attenuated the increased caspase-3 and synaptophysin. The data indicate that both extracts have neuroprotective effects against chronic constriction injury-induced neuropathic pain. The observed protective effects are partially mediated through attenuation of oxidative and nitrosative stress and suppression of both neuroinflammation and neuronal apoptosis, suggesting substantial activities of both extracts in amelioration of painful peripheral neuropathy.

Evaluation of phenolic contents and antioxidant activities of some medicinal plants growing in Algerian Aurès Mountains

The objective of this study is to evaluate the antioxidant activities of six medicinal plants growing in Algerian Aurès Mountains. Total phenolic and flavonoids contents were measured using colorimetric methods, and the antioxidant capacities were evaluated using the DPPH radical scavenging and β-carotene bleaching tests. Juniperus phoenica L. had significantly the higher total phenolic compounds (53.6±3.86 mg GAE.g−1 DM) (p<0.05); followed by Romarinus officinalis L. (26.1±3.15 mg GAE.g−1 DM) and Artemisia campestris L. (20.5±1.99 mg GAE.g−1 DM). Artemisia campestris L. had significantly the higher flavonoid contents (11.1±0.56 mg QE.g−1 DM) than other studied plants (p<0.05). The best antiradical activity was observed in Thymus algeriensis extracts (EC50=11.1±0.33 µg.ml−1) and Romarinus officinalis L. (EC50=15.3±0.9 µg.ml−1). β-carotene bleaching test showed that the herbs’ phenolic compounds Antioxidant Activity (AA%) value was found in the range of 64-84%, whereas that of the standard antioxidant ascorbic acid was 51±2.4%. The present results indicate that medicinal plants from the Algerian Aurès mountains could be explored in food and pharmaceutical industries for development of natural’s antioxidant agents.