ABSTRACT
Turmeric (Curcuma longa L.), a widely used spice, has anti-inflammatory properties and other health benefits, but the detailed mechanisms of these effects are still poorly understood. Recent advances in assessment of cellular energy metabolism have revealed that macrophage mitochondrial respiration is critical in inflammatory responses. In an effort to enhance the anti-inflammatory function of turmeric with a simple processing method, extract of puffed turmeric was investigated for effect on macrophage energy metabolism. The high-performance liquid chromatography analysis revealed that puffing of turmeric significantly induced the degradation of curcumin to smaller active compounds including vanillic acid, vanillin and 4-vinylguaiacol. The in vitro consumption of oxygen as expressed by the oxygen consumption rate (OCR) was significantly downregulated following lipopolysaccharides stimulation in RAW 264.7 macrophages. Puffed turmeric extract, but not the non-puffed control, reversed the LPS-induced decrease in OCR, resulting in downregulated transcription of the pro-inflammatory genes cyclooxygenase-2 and inducible nitric oxide synthase. Dietary intervention in high-fat diet-induced obese mice revealed that both control and puffed turmeric have anti-obesity effects in vivo, but only puffed turmeric exhibited reciprocal downregulation of the inflammatory marker cluster of differentiation (CD)11c and upregulation of the anti-inflammatory marker CD206 in bone marrow-derived macrophages. Puffed turmeric extract further modulated the low-density lipoprotein/high-density lipoprotein cholesterol ratio toward that of the normal diet group, indicating that puffing is a simple, advantageous processing method for turmeric as an anti-inflammatory food ingredient.
ABSTRACT
Curcuma longa L. (turmeric) is used as a food spice; however, its strong taste restricts wider applications as a food ingredient despite its well-known health benefits. To develop an effective yet simple process for enhancing its antioxidant and anti-inflammatory activities, turmeric was gun-puffed at various pressures. Puffed turmeric exhibited an increase in its brown color and porous structures, indicating the occurrence of the Maillard reaction and vaporization during the process. Proximal analysis revealed that puffing did not alter the major constituents, although a very small decrease in crude fat extraction was observed under some circumstances. Total phenolic compounds in the extract were significantly increased after puffing, and subsequent assessment of antioxidant capacity, as determined using independent 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays, demonstrated enhanced antioxidant capacity in a puffing-pressure-dependent manner. Turmeric extract was further tested for the regulation of inflammatory responses in the murine macrophage RAW264.7 cell line. Suppression of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α in lipopolysaccharides (LPS)-induced macrophages was amplified using puffed-turmeric extracts compared to the control extract. Furthermore, macrophage-activation assessment revealed downregulated expression of inflammation-relevant cluster of differentiation (CD)80 and CD86 using puffed-turmeric extract in a puffing-pressure-dependent manner. However, expression of major histocompatibility complex (MHC)-II, which controls adoptive immunity, was not affected by treatment with any of the turmeric extracts. Overall, the current study demonstrated that puffing is a promising and simple method for enhancing the antioxidant and anti-inflammatory properties of turmeric.
