Phytochemical Variability, In Vitro and In Vivo Biological Investigations, and In Silico Antibacterial Mechanisms of Mentha piperita Essential Oils Collected from Two Different Regions in Morocco

Chemical composition, antioxidant, antimicrobial, and wound healing effects of Trachyspermum roxburghianum (DC.) H. Wolff essential oil: An in vivo and in silico approach

ETHNOPHARMACOLOGICAL RELEVANCE

Trachyspermum roxburghianum (DC.) H. Wolff, commonly known as 'Ajamoda,' is a neglected Indian spice highly used in Ayurveda and folklore remedies as an antimicrobial for chronic wounds and discharges, along with many other disease conditions.

AIM OF THE STUDY

The objective of the study was to explore chemical composition and to investigate the antioxidant, antimicrobial, analgesic, and wound healing activities of T. roxburghianum fruit essential oil from India.

MATERIALS AND METHODS

The phytochemical characterization of the oil was determined through standard qualitative procedures and the gas chromatography-mass spectrometry (GC-MS) technique. The in vitro antioxidant aptitude was assessed by scavenging DPPH and ABTS radicals. The antimicrobial potential of the oil was investigated using the disc diffusion method, followed by the determination of minimum inhibitory concentration against Gram-positive and Gram-negative bacterial and fungal strains. The analgesic potential was evaluated using thermal and chemically induced pain models in Swiss albino mice. Wound healing was assessed in vivo, including determining wound contraction rates, histopathology, and hydroxyproline estimation, using the excision wound model in Swiss albino mice.

RESULTS

GC-MS analysis identified 55 compounds with major terpenoids, including thymol (13.8%), limonene (11.5%), and others. Substantial radical-scavenging activity was exhibited by T. roxburghianum fruit essential oil (TREO) (IC50 94.41 ± 2.00 μg/mL in DPPH assay and 91.28 ± 1.94 μg/mL in ABTS assay). Microorganisms were inhibited with low MIC (2 μL/mL for the inhibition of Staphylococcus aureus and Bacillus subtilis; 4 μL/mL against Salmonella typhi and 16 μL/mL against Candida albicans). In the cytotoxicity study, no cytotoxicity was observed on the Monkey Normal Kidney Cell line (Vero). Significant antinociceptive effects were observed (25.47 ± 1.10 % of inhibition at 100 mg/kg and 44.31 ± 1.69 % at 200 mg/kg). A remarkable rate of wound closure and epithelization, along with a marked increase in hydroxyproline content, were observed for the oil during wound healing in mice.

CONCLUSIONS

The results suggested that oil could be utilized as a potential source of wound healing therapeutics.

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.

Inhibitory Activity of Saussurea costus Extract against Bacteria, Candida, Herpes, and SARS-CoV-2

Medicinal herbs have long been utilized to treat various diseases or to relieve the symptoms of some ailments for extended periods. The present investigation demonstrates the phytochemical profile, molecular docking, anti-Candida activity, and anti-viral activity of the Saussurea costus acetic acid extract. GC-MS analysis of the extract revealed the presence of 69 chemical compounds. The chemical compounds were alkaloids (4%), terpenoids (79%), phenolic compounds (4%), hydrocarbons (7%), and sterols (6%). Molecular docking was used to study the inhibitory activity of 69 identified compounds against SARS-CoV-2. In total, 12 out of 69 compounds were found to have active properties exhibiting SARS-CoV-2 inhibition. The binding scores of these molecules were significantly low, ranging from -7.8 to -5.6 kcal/mol. The interaction of oxatricyclo [20.8.0.0(7,16)] triaconta-1(22),7(16),9,13,23,29-hexaene with the active site is more efficient. Furthermore, the extract exhibited significant antimicrobial activity (in vitro) against Candida albicans, which was the most susceptible microorganism, followed by Bacillus cereus, Salmonella enterica, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, respectively. On the other hand, its antiviral activity was evaluated against HSV-1 and SARS-CoV-2, and the results showed a significant positive influence against HSV-1 (EC₅₀ = 82.6 g/mL; CC₅₀ = 162.9 g/mL; selectivity index = 1.9). In spite of this, no impact could be observed in terms of inhibiting the entry of SARS-CoV-2 in vitro.