Achillea extracts elicit anti-diabetic neuropathic pain by modulating inflammatory cytokines

Abstract

Background and aim: The Eastern-Mediterranean herbal-remedies are utilized for their immunomodulatory-potentials. Achillea species have ethno-pharmacological significance. The current-work aims to perform an in-depth phytochemical-investigation on three Eastern-Mediterranean Achillea species, mainly, Achillea kotschyi Boiss. (AK), Achillea falcata L. (AF), and Achillea aleppica DC. (AAL) essential oils (EOs), and to investigate their antidiabetic, and antineuropathic pain, and inflammation, and to have insights into their mechanisms of action.

Experimental-procedure: The methods include EO-isolation from three different samples of each of the three species examined, optimization, and validation of GC-MS method, in-vivo antioxidant-technique, HbA1c diabetes-assessment, insulin-level, thermal-hyperalgesia and tactile-allodynia experiments, anti-inflammatory, and inflammatory-markers, TNF-α, IL-6, and 10 level monitoring.

Results and conclusion: The optimized and validated GC-MS method was developed to quantify the major EO components. The highest components detected on AK-EO were thujone (35.84 ± 0.01 %), α-phellandrene (15.99 ± 0.01), and ocimene (12.31 ± 0.01 %), while those of AF were ocimene (65.11 ± 0.01 %), thujone (14.68 ± 0.01 %), and resorcinol (5.00 ± 0.01 %), and the AAL-EO were m-toluamide (49.35 ± 0.01 %), eucalyptol (21.08 ± 0.01 %), and ocimene (13.48 ± 0.01 %). AAL-EO showed superiority in normalizing HbA1c-levels. AAL-EO showed the highest improvement in both thermal-hyperalgesia and tactile-allodynia latencies. The insulin-secretagogue-potential and the improvement of the antioxidant serum-catalase levels might be their mechanism of antinociception. AAL-EO highest-dose (300 mg/kg)showed superiority in the anti-inflammatory-potentials both acutely and chronically, compared to AK and AF-EOs. The decrease in the inflammatory-mediators, TNF-α and IL-6, and the improvement of IL-10 titers proved to be their mechanism of anti-inflammation. In conclusion, AK, AF, and AAL proved to be rich in essential-oil components that can ameliorate chronic-conditions like diabetes, diabetic-neuropathy pain, and inflammation.

Keywords: Achillea; Cytokines; Essential oils; Gas chromatography mass spectrometry; Painful diabetic neuropathy.

Graphical abstract

Fig. 1

Glycated Haemoglobin (HbA1c) and Serum insulin percentages monitoring for the three Achillea species. Glycated Haemoglobin (HbA1c) percentage: (A) Achillea kotschyi (AK), (B) Achillea falcate (AF), and (C) Achillea Aleppica (AAL). GB glibenclamide (5 mg/kg) utilized as appositive control. NORM means normal non-diabetic control, and VEH means diabetic control administering solvent (DMSO) only. “*” means significant p < 0.05 compared to VEH. (D) Serum insulin percentage of the three Achillea species: Achillea kotschyi (AK), Achillea falcate (AF), and Achillea Aleppica (AAL) and all doses in mg/Kg. GB glibenclamide (5 mg/kg) utilized as appositive control. NC means normal non-diabetic control, and DC means diabetic control administering solvent (DMSO) only. “*” means significant p < 0.05 compared to DC.

Fig. 2

Thermal hyperalgesia and tactile allodynia monitoring. Comparisons of response latency in hot plate test of the three Achillea species: (A) Achillea kotschyi (AK), (B) Achillea falcate (AF), and (C) Achillea Aleppica (AAL). Comparisons of response latency in tail flick test of the three Achillea species: (D) Achillea kotschyi (AK), (E) Achillea falcate (AF), and (F) Achillea Aleppica (AAL). Comparisons of response latency in von Frey test of the three Achillea species: (G) Achillea kotschyi (AK), (H) Achillea falcate (AF), and (I) Achillea Aleppica (AAL). TRA (Tramadol, 10 mg/kg) utilized as a positive control. NORM means normal non-diabetic control, and VEH means diabetic control administering solvent (DMSO) only. “*” means significant p < 0.05 compared to VEH.

Fig. 3

In vivo catalase antioxidant potential (kU/I) of: (A) AK, (B) AF, and (C) AAL. GB glibenclamide (5 mg/kg) as a positive control. NORM means normal non-diabetic control, and VEH means diabetic control administering solvent (DMSO) only. “*” means significant p < 0.05 compared to VEH.

Fig. 4

Anti-inflammatory activity of the three Achillea species: Achillea kotschyi (AK), Achillea falcate (AF), and Achillea Aleppica (AAL) EOs each in 3 different doses 75 mg/kg (75), 150 mg/kg (150), and 300 mg/kg (300): (A) Acute anti-inflammatory evaluation: via carrageenan-induced inflammatory-pain method, and (B) Chronic anti-inflammatory evaluation: via hind-paw edema method. All tests were n = 6/group utilizing Ibuprofin 100 mg/kg (Ib 100) as a positive control. NC means Normal non-diabetic control and CTRL diabetic control administering solvent (DMSO) only. “*” means significant p < 0.05 compared to CTRL.