Chemical analysis and biological potential of Valerian root as used by herbal practitioners in the Eastern Cape Province, South Africa

Abstract

Background: Herbal practitioners in the Eastern Cape of South Africa use valerian root (Valeriana  capensis, Valerianaceae) to manage pains, arthritis and inflammation. The herb prepared from this plant was studied to determine the chemical composition of its essential oil, carried out phytochemical  screening and biological activities on its infusion extract as used by the herbal practitioner.
Materials and Methods: Essential oil of Valerian root was obtained by hydrodistillation and subjected to chemical analyses. Infusion extract of the Valerian root was screened to determine its secondary  metabolites and the relative abundance of some major metabolites. The infusion extract was further evaluated for acute toxicity (LD50), anti-inflammatory and analgesic activities in rodents.
Results: The yield of the essential oil was 0.18% w/w. The GC/MS analysis indicated the presence of 42 compounds with major ones being caryophyllene oxide (18.11%), viridiflorol (9.37%) and bornyl acetate (8.84%). Phytochemicals found in the infusion extract were alkaloids, saponins, tannins and flavonoids while quantitative screenings showed saponins and flavonoids accounted for 6.39% and 7.40%  respectively. The LD50 of the extract was found to be 3808 mg/kg per oral. The infusion extract of the root  (250-500 mg/kg, p.o.) caused significant (p<0.01) activity in the carrageenan-induced rat paw oedema model comparable to aspirin, indicating anti-inflammatory activity; but lacked analgesic activity on the acetic acid-induced writhing test.
Conclusion: The infusion extract possessed significant anti-inflammatory but lacked analgesic activity; the present data justify the use of this herbal agent by the herbal practitioners from the Eastern Cape  region of South Africa.

Key words: Valeriana capensis, essential oil, caryophyllene oxide, infusion extract, anti-inflammatory, analgesic