Validation of a Quantification Method for Curcumin Derivatives and Their Hepatoprotective Effects on Nonalcoholic Fatty Liver Disease

Curcumin (CM), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) are major curcumin derivatives found in the rhizome of turmeric (Curcuma longa L.), and have yielded impressive properties to halt various diseases. In the present study, we carried out a method validation for curcumin derivatives and analyzed the contents simultaneously using HPLC with UV detection. For validation, HPLC was used to estimate linearity, range, specificity, accuracy, precision, limit of detection (LOD), and limit of quantification (LOQ). Results showed a high linearity of the calibration curve, with a coefficient of correlation (R²) for CM, DMC, and BDMC of 0.9999, 0.9999, and 0.9997, respectively. The LOD values for CM, DMC, and BDMC were 1.16, 1.03, and 2.53 ng/μL and LOQ values were 3.50, 3.11, and 7.67 ng/μL, respectively. Moreover, to evaluate the ability of curcumin derivatives to reduce liver lipogenesis and compare curcumin derivatives’ therapeutic effects, a HepG2 cell model was established to analyze their hepatoprotective properties. Regarding the in vivo study, we investigated the effect of DMC, CM, and BDMC on nonalcoholic fatty liver disease (NAFLD) caused by a methionine choline deficient (MCD)-diet in the C57BL/6J mice model. From the in vitro and in vivo results, curcumin derivatives alleviated MCD-diet-induced lipid accumulation as well as high triglyceride (TG) and total cholesterol (TC) levels, and the protein and gene expression of the transcription factors related to liver adipogenesis were suppressed. Furthermore, in MCD-diet mice, curcumin derivatives suppressed the upregulation of toll-like receptors (TLRs) and the production of pro-inflammatory cytokines. In conclusion, our findings indicated that all of the three curcuminoids exerted a hepatoprotective effect in the HepG2 cell model and the MCD-diet-induced NAFLD model, suggesting a potential for curcuminoids derived from turmeric as novel therapeutic agents for NAFLD.

Differences in anti-inflammatory effect of immature and mature of Rubus coreanus fruits on LPS-induced RAW 264.7 macrophages via NF-κB signal pathways

BACKGROUND

Rubus coreanus fruit (RF) has been used as a traditional medicine formulation to treat various diseases including diarrhea, asthma, and cancer in East Asia (Korea, China, and Japan). RF, which is native to Korea, has a larger fruit size than that of exotic species. In this study, we aimed to compare the anti-inflammatory activities of immature and mature RF extracted with different solvents.

METHODS

Mature and immature RF (MRF and IRF) were extracted with 30% ethanol, 70% ethanol and water at room temperature. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assays. Anti-inflammatory activity was determined by measuring nitric oxide (NO) production, expression of inflammatory proteins (inducible NO synthase [iNOS], cyclooxygenase [COX]-2, nuclear factor [NF]-κB, and inhibitor of NF-κB [IκB]), and inflammatory cytokines using polymerase chain reaction in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages.

RESULTS

The IRF 30% ethanol extract showed higher radical scavenging activity in DPPH and ABTS assays (half-maximal inhibitory concentration [IC₅₀] 16.0 ± 0.5 and 15.9 ± 0.4) than MRF did. In addition, the IRF 30% ethanol extract (200 μg/mL) significantly reduced the production of the inflammatory mediator NO by approximately 80% and inhibited iNOS, COX-2, phosphorylated (p)-IκB, and p-NF-κB activation compared with MRF. Moreover, IRF extract decreased the inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 compared with the MRF extract.

CONCLUSIONS

This study revealed that IRF showed more beneficial effects than MRF did in LPS-stimulated RAW 264.7 macrophages, suggesting that IRF may be a useful anti-inflammatory agent.

Black Raspberry Extract Increased Circulating Endothelial Progenitor Cells and Improved Arterial Stiffness in Patients with Metabolic Syndrome: A Randomized Controlled Trial

Administration of black raspberry (Rubus occidentalis) is known to improve vascular endothelial function in patients at a high risk for cardiovascular (CV) disease. We investigated short-term effects of black raspberry on circulating endothelial progenitor cells (EPCs) and arterial stiffness in patients with metabolic syndrome. Patients with metabolic syndrome (n = 51) were prospectively randomized into the black raspberry group (n = 26, 750 mg/day) and placebo group (n = 25) during the 12-week follow-up. Central blood pressure, augmentation index, and EPCs, such as CD34/KDR(+), CD34/CD117(+), and CD34/CD133(+), were measured at baseline and at 12-week follow-up. Radial augmentation indexes were significantly decreased in the black raspberry group compared to the placebo group (-5% ± 10% vs. 3% ± 14%, P < .05). CD34/CD133(+) cells at 12-week follow-up were significantly higher in the black raspberry group compared to the placebo group (19 ± 109/μL vs. -28 ± 57/μL, P < .05). Decreases from the baseline in interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were significantly greater in the black raspberry group compared to the placebo group (-0.5 ± 1.4 pg/mL vs. -0.1 ± 1.1 pg/mL, P < .05 and -5.4 ± 4.5 pg/mL vs. -0.8 ± 4.0 pg/mL, P < .05, respectively). Increases from the baseline in adiponectin levels (2.9 ± 2.1 μg/mL vs. -0.2 ± 2.5 μg/mL, P < .05) were significant in the black raspberry group. The use of black raspberry significantly lowered the augmentation index and increased circulating EPCs, thereby improving CV risks in patients with metabolic syndrome during the 12-week follow-up.