Essential oil from waste leaves of Curcuma longa L. alleviates skin inflammation.

BACKGROUND: Curcuma longa L. is an important industrial crop used by medicinal and cosmetic industries in the world. Its leaves are a waste material after harvesting rhizomes. The aim of the study was to evaluate the chemical and pharmacological profile of essential oil from waste leaves of Curcuma longa (EOCl) against skin inflammation.

METHODS: EOCl was subjected to gas chromatography (GC) analysis for identification of essential oil constituents and its anti-inflammatory evaluation through in vitro and in vivo models.

RESULTS: Chemical fingerprinting using GC and GC-MS analysis of EOCl revealed the presence of 11 compounds, representing 90.29% of the oil, in which terpinolene (52.88%) and α-phellandrene (21.13%) are the major components. In the in vitro testing EOCl inhibited the production of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) in lipopolysaccharide (LPS) and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in the human keratinocyte cell line (HaCaT). Topical application of EOCl produced anti-inflammatory effects by reducing ear thickness, ear weight and ameliorating the level of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) at protein and mRNA levels as well as regulating the overproduction of oxidative markers and restoring the histopathological damage in a TPA-induced mouse model of inflammation.

CONCLUSION: These findings of topical anti-inflammatory properties of EOCl provide a scientific basis for medicinal use of this plant material against inflammatory disorders.