Distillation time effecting on the composition of Origanum floribundum essential oils and their antioxidant and antimicrobial activities

The essential oils (EOs) of Origanum floribundum Munby, an aromatic and medicinal plant endemic in Algeria, were extracted by different hydrodistillation times (30 min, 1, 2 and 3 h) and analyzed by GC and GC-MS. The chromatographic analysis showed that thymol (32.7-45.0%), p-cymene (16.8-23.1%) and γ-terpinene (21.6-28.7%) were the most prominent components of the oils. The antioxidant ability was measured using the reductive potential, thiobarbituric acid reactive substances (TBARS) assay and the inhibition of free radicals DPPH^● and ABTS^●+. Antibacterial activity was assessed by the disc diffusion method against three bacteria (Escherichia coli, Staphylococcus aureus and Bacillus subtilis) and one fungus (Candida albicans). Minimal inhibitory concentrations (MICs) were determined using a microdilution method. Thymol is one of the compounds of EOs, which are widely reported as very biologically active. Although the oil isolated for 30 min was the less-thymol rich, it was the most active with all the antioxidant tests. In the most cases, the antimicrobial activity showed the best results with oils isolated for 30 min and 3 h (MIC = 0.25-1.75 μL/mL). These results suggest that it might be possible to isolate the EO from this plant for a minimum distillation time to obtain oil that can give maximum biological activities.

Antinociceptive and antineuropathic effects of cuminaldehyde, the major constituent of Cuminum cyminum seeds: Possible mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

In Iranian traditional medicine, Cuminum cyminum is a unique medicinal herb for pain relief. Cuminaldehyde has been distinguished as the major constituent of C. cyminum seeds; even though, the analgesic effect of cuminaldehyde has not yet been examined.

AIM OF THE STUDY

The nobility of this study was to assess cuminaldehyde effect on nociceptive and neuropathic pains; furthermore, evaluation of its possible mechanisms of action.

MATERIALS AND METHODS

Hot plate, formalin, and acetic acid-induced writhing tests were used to evaluate nociception in mice. Naloxone (opioid receptors antagonist), L-arginine (nitric oxide (NO) precursor), L-NAME (NO synthase inhibitor), sodium nitroprusside (NO donor), methylene blue (guanylyl cyclase inhibitor), sildenafil (phosphodiesterase inhibitor), and glibenclamide (K_ATP channel blocker) were used to determine the implication of opioid receptors and L-arginine/NO/cGMP/K_ATP channel pathway. Allodynia and hyperalgesia were investigated in the CCI (chronic constriction injury) model of neuropathic pain in rats. The ELISA method was used to measure the inflammatory cytokines in serum samples of rats. The entire chemicals were intraperitoneally injected.

RESULTS

Cuminaldehyde (100 and 200 mg/kg) significantly decreased the latency to nociceptive response in the hot plate test. The outcome of cuminaldehyde was completely antagonized by naloxone (2 mg/kg). Formalin- and acetic acid-induced nociception was significantly inhibited by cuminaldehyde (12.5-50 mg/kg). The antinociceptive effect of cuminaldehyde was reversed in writhing test by L-arginine (200 mg/kg), sodium nitroprusside (0.25 mg/kg), and sildenafil (0.5 mg/kg); however, L-NAME (30 mg/kg) and methylene blue (20 mg/kg) enhanced the effect of cuminaldehyde. Glibenclamide (10 mg/kg) did not alter the antinociceptive effects of cuminaldehyde. In the CCI-induced neuropathy, cuminaldehyde (25-100 mg/kg) significantly alleviated allodynia and hyperalgesia and decreased the serum levels of TNF-α and IL-1β.

CONCLUSION

It was attained magnificently that cuminaldehyde exerts antinociceptive and antineuropathic effects through the involvement of opioid receptors, L-arginine/NO/cGMP pathway, and anti-inflammatory function.

A New Method for Determination of Thymol and Carvacrol in Thymi herba by Ultraperformance Convergence Chromatography (UPC2)

Ultraperformance convergence chromatography is an environmentally friendly analytical technique for dramatically reducing the use of organic solvents compared to conventional chromatographic methods. In this study, a rapid and sensitive ultraperformance convergence chromatography method was firstly established for quantification of thymol and carvacrol, two positional isomers of a major bioactive in the volatile oil of Thymi herba, the dried leaves and flowers of Thymus mongolicus or Thymus przewalskii, known in China as "Dijiao." Using a TrefoilTM CEL1 column, thymol and carvacrol were separated in less than 2.5 min and resolution was enhanced. The method was validated with respect to precision, accuracy, and linearity according to the National Medical Products Administration guidelines. The optimized method exhibited good linear correlation (r = 0.9998-0.9999), excellent precision (relative standard deviations (RSDs) < 1.50%), and acceptable recoveries (87.29-102.89%). The limits of detection for thymol and carvacrol were 1.31 and 1.57 ng/L, respectively, while their corresponding limits of quantification were 2.63 and 3.14 ng/L. Finally, the quantities of the two compounds present in 16 T. mongolicus and four T. przewalskii samples were successfully evaluated by employing the developed method. It is hoped that the results of this study will serve as a guideline for the quality control of Thymi herba.

Carvacrol effectively protects demyelination by suppressing transient receptor potential melastatin 7 (TRPM7) in Schwann cells

Peripheral neurodegenerative processes are essential for regenerating damaged peripheral nerves mechanically or genetically. Abnormal neurodegenerative processes induce peripheral neurodegenerative diseases via irreversible nerve damage. Carvacrol, a major component in Origanum vulgare, possesses various effects on organisms, such as antibiotic, anti-inflammatory and cytoprotective effects; although transient receptor potential (TRP) ankyrin 1 (TRPA1), TRP canonical 1 (TRPC1), TRP melastatin M7 (TRPM7), and TRP vanilloid 3 (TRPV3) are carvacrol-regulated TRPs, however, effect of carvacrol on the peripheral neurodegenerative process, and its underlying mechanism, remain unclear. Here, we investigated the specificity of carvacrol for TRPM7 in Schwann cells and the regulatory effect of carvacrol on TRPM7-dependent neurodegenerative processes. To construct peripheral nerve degeneration model, we used with a sciatic explant culture and sciatic nerve axotomy. Ex vivo, in vivo sciatic nerves were treated with carvacrol following an assessment of demyelination (ovoid fragmentation) and axonal degradation using morphometric indices. In these models, carvacrol effectively suppressed the morphometric indices, such as stripe, ovoid, myelin, and neurofilament indices during peripheral nerve degeneration. We found that carvacrol significantly inhibited upregulation of TRPM7 in Schwann cells. In this study, our results suggest that carvacrol effectively protects against the peripheral neurodegenerative process via TRPM7-dependent regulation in Schwann cells. Thus, pharmacological use of carvacrol could be helpful to protect against neurodegeneration that occurs with aging and peripheral neurodegenerative diseases, prophylactically.