Gano oil: A novel antinociceptive agent extracted from Ganoderma lucidum inhibits paw oedema and relieves pain by hypnotic and analgesic actions of fatty acid amides

Ethnopharmacological relevance: Lingzhi or Reishi - Ganoderma lucidum (Fr.) P. Karst is an extensively used medicinal mushroom in folklore and traditional medicine in south East Asia to treat a number of diseases. Lingzhi is known as 'mushroom of immortality' in Chinese folklore. In Traditional Chinese Medicine it is considered as a panacea to cure all diseases.

Aim of the study: This study aims to evaluate antinociceptive effect of Gano oil, a novel fatty acid rich extract obtained from G. lucidum and identification of the active principle.

Materials & methods: Gano oil extracted from Ganoderma lucidum was evaluated for inhibition of formalin-induced paw oedema on Swiss albino mice by oral administration as well as topical application. Antinociceptive activity of Gano oil was tested by acetic acid - induced abdominal writhing test as well as hot plate test. Free radical scavenging activity was determined by DPPH assay. COX enzyme inhibiting activity was assayed using different concentrations of Gano oil exposed to LPS stimulated RAW 264.7 cell line. NF-kB inhibiting activity of Gano oil was assayed using Lentix-293T P65 Ds Red stable cell line by fluorescent imaging and flow cytometry analysis. Chemical profile of Gano oil was ascertained by HPTLC analysis and active principle was identified by HRLCMS analysis.

Results: The oral administration of Gano oil at doses of 10,25, 50 mg/kg b.wt showed 42, 58 and 73% inhibition of paw oedema while topical applications at dose of 1,5 and 10% reduced 33, 50 and 58% oedema respectively. Acetic acid writhing test showed that Gano oil inhibited 44.44% contortions (p < 0.001) and while in hot plate method Gano oil at 25 mg/kg b. wt showed response latency of 30.0 ± 2.08 s for 120 min compared to base 1.65 ± 0.32 s (p < 0.01). Gano oil at 100 μg/ml inhibited 50% COX enzyme activity (p < 0.01). High throughput flurescent imaging and flow cytometry assay revealed marked ability of Gano oil to inhibit NF-kB activity. Gano oil was found to possess dose dependent free radical scavenging activity as evident from DPPH assay. HPTLC analysis of Gano oil indicated the chemical figure print. HR LC-MS analysis showed the major chemical components were fatty acid amides namely, Oleamide, C₁₈H₃₅NO, M⁺281, Hexadecanamide, C₁₆H₃₃NO, M⁺255 and 9-oxo-10 (E) Octadecadienoic acid, C₁₈H₃₀O₃ M⁺294.

Conclusion: Fatty acid rich Gano oil extracted from G.lucidum is a novel antinociceptive agent capable to inhibit oedema by oral administration as well as topical application. The results indicate the pharmacological interest, clinical significance and therapeutic use. The finding suggests that Gano oil might be a potent natural product based analgesic. The effect might be assigned to the fatty acid amide constituents especially oleamide which has been demonstrated to have analgesic and hypnotic actions.