Variation in Yield, Chemical Composition and Biological Activities of Essential Oil of Three Curcuma Species: A Comparative Evaluation of Hydrodistillation and Solvent-Free Microwave Extraction Methods

Abstract

The essential oils of three medicinally important Curcuma species (Curcuma alismatifolia, Curcuma aromatica and Curcuma xanthorrhiza) were extracted using conventional hydro-distillation (HD) and solvent free microwave extraction (SFME) methods. The volatile compounds from the rhizome essential oils were subsequently analysed by GC-MS. The isolation of essential oils of each species was carried out following the six principles of green extraction and comparison was made between their chemical composition, antioxidant, anti-tyrosinase and anticancer activities. SFME was found to be more efficient than HD in terms of energy savings, extraction time, oil yield, water consumption and waste production. Though the major compounds of essential oils of both the species were qualitatively similar, there was a significant difference in terms of quantity. The essential oils extracted through HD and SFME methods were dominated by hydrocarbon and oxygenated compounds, respectively. The essential oils of all Curcuma species exhibited strong antioxidant activity, where SFME was significantly better than HD with lower IC₅₀ values. The anti-tyrosinase and anticancer properties of SFME-extracted oils were relatively better than that of HD. Further, among the three Curcuma species, C. alismatifolia essential oil showed the highest rates of inhibition in DPPH and ABTS assay, significantly reduced the tyrosinase activity and exhibited significant selective cytotoxicity against MCF7 and PC3 cells. The current results suggested that the SFME method, being advanced, green and fast, could be a better alternative for production of essential oils with better antioxidant, anti-tyrosinase and anticancer activities for application in food, health and cosmetic industries.

Keywords: Curcuma species; GC-MS; anti-tyrosinase activity; anticancer activity; antioxidant activity; hydrodistillation; solvent free microwave extraction.

Figure 1

Essential oil yield (%v/w) of the studied Curcuma species obtained by HD and SFME. Oil yield values with distinct superscript letters (a–e) differ significantly at p < 0.05 (Tukey test).

Figure 2

Hydrodistillation (HD) and solvent-free microwave extraction (SFME) classified according to the six green extraction principles. The graph represents the percentage equivalents of each principle’s value.

Figure 3

Percentage composition of major compounds in C. alismatifolia, C. aromatica and C. xanthorrhiza essential oils obtained using HD and SFME methods. Different letters denote a significant difference in the mean value of constituents at (p < 0.05).

Figure 4

Antioxidant activity of Curcuma essential oils obtained by HD and SFME methods along with standard antioxidants using (A) DPPH assay. Data are represented as mean ± S.D. (n = 3).

Figure 5

Antioxidant activity of Curcuma essential oils obtained by HD and SFME along with standard antioxidants using (B) ABTS assay. Data are represented as mean ± S.D. (n = 3).

Figure 6

Anti-tyrosinase activity of Curcuma essential oils obtained by HD and SFME methods. Figure shows percent inhibition of mushroom tyrosinase enzyme by Kojic acid and (A) C. alismatifolia, (B) C. aromatica and (C) C. xanthorrhiza essential oils. Data are represented as mean ± SD (n = 3).

Figure 7

Anticancer activity of Curcuma essential oils extracted using HD (A,C) and SFME (B,D) methods, showing cell viability on 3T3-L1 non-cancer cells and HepG2 cancer cells using the MTT assay after 24 h. The results of three independent experiments are presented as means ± SD (n = 3). ^## p < 0.01 and ^### p < 0.001 compared with the untreated group; ^ns p > 0.05, * p < 0.05, ** p < 0.01 and *** p < 0.001 compared with the untreated group as determined by Dunnett’s multiple comparison test.

Figure 8

Anticancer activity of Curcuma essential oils extracted using HD (A,C) and SFME (B,D) methods showing cell viability on MCF-7 and PC-3 cancer cells using the MTT assay after 24 h. The results of three independent experiments are presented as means ± SD (n = 3). ^### p < 0.001 compared with the untreated group; ^ns p > 0.05, * p < 0.05, ** p < 0.01 and *** p < 0.001 compared with the untreated group as determined by Dunnett’s multiple comparison test.

Figure 9

(A) Milestone ETHOS X advanced microwave green extraction chamber; (B) integrated glass vessel of 2 L capacity and glass lid; (C) glass reactor containing sample inside the extraction chamber; (D) condensed Curcuma essential oil in the burette.