Abstract
Numerous studies have demonstrated that aged black garlic (ABG) has strong anti-oxidant activity. Little is known however regarding the anti-inflammatory activity of ABG. This study was performed to identify and compare the anti-oxidant and anti-inflammatory effects of ABG extract (ABGE) with those of fresh raw garlic (FRG) extract (FRGE). In addition, we investigated which components are responsible for the observed effects. Hydrogen peroxide (H2O2) and lipopolysaccharide (LPS) were used as a pro-oxidant and pro-inflammatory stressor, respectively. ABGE showed high ABTS and DPPH radical scavenging activities and low ROS generation in RAW264.7 cells compared with FRGE. However, inhibition of cyclooxygenase-2 and 5-lipooxygenase activities by FRGE was stronger than that by ABGE. FRGE reduced PGE2, NO, IL-6, IL-1β, LTD4, and LTE4 production in LPS-activated RAW264.7 cells more than did ABGE. The combination of FRGE and sugar (galactose, glucose, fructose, or sucrose), which is more abundant in ABGE than in FRGE, decreased the anti-inflammatory activity compared with FRGE. FRGE-induced inhibition of NF-κB activation and pro-inflammatory gene expression was blocked by combination with sugars. The lower anti-inflammatory activity in ABGE than FRGE could result from the presence of sugars. Our results suggest that ABGE might be helpful for the treatment of diseases mediated predominantly by ROS.
Highlights
It has been suggested that the production of excessive reactive oxygen species (ROS), which causes oxidative stress [1] and protein oxidation [2], is involved in the pathogenesis of many types of inflammatory disease, including atherosclerosis, rheumatoid arthritis, cancer, and allergies
To determine the optimal concentration of garlic extracts for H2 O2 - or LPS-stimulated cellular response, RAW264.7 cells were incubated with different concentrations of garlic extracts
FRG extract (FRGE), we investigated the effects of allicin, pyruvate, and anti-inflammatory effects compared with FRGE, we investigated the effects of allicin, pyruvate, sugars on the production of ROS, NO, and
Summary
It has been suggested that the production of excessive reactive oxygen species (ROS), which causes oxidative stress [1] and protein oxidation [2], is involved in the pathogenesis of many types of inflammatory disease, including atherosclerosis, rheumatoid arthritis, cancer, and allergies. Molecules 2016, 21, 430 garlic (ABG), an aged garlic formulation containing high levels of organosulfur compounds, has strong anti-oxidant effects compared with fresh raw garlic (FRG) [10,11]. Diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide (DATS), and diallyl tetrasulfide are lipid-soluble compounds in AGE These organosulfur compounds derived from allicin contribute to the anti-oxidant activity of AGE [17,18]. The heating processes used to prepare ABG increase the concentration of sugars as well as of compounds with anti-oxidant activity [16,22,23] Other than their sweet flavor, little is known regarding the anti-oxidant and/or anti-inflammatory effects of the sugars in ABG. We analyzed NF-κB activation and the expression of pro-inflammatory genes to identify the mechanism underlying the anti-oxidant and anti-inflammatory effects of garlic extracts
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