Junsoo Lee

Assessment of phenolics-enriched extract and fractions of olive leaves and their antioxidant activities

Recent studies suggest that olive leaf is a significant source of bioactive phenolic compounds comparable to olive oil and fruits. Identifying appropriate extraction methods is thus an important step to increase the yield of such bioactive components from olive leaf, which is otherwise agricultural waste. The present study evaluates phenolic contents and compositions of olive leaf extracted by several solvent methods and to further establish their antioxidant activities using various radical scavenging systems. Total flavonoid and phenolic contents were significantly higher in the 80% ethanol extract, butanol, and ethylacetate fractions than hexane, chloroform and water fractions (p<0.05). Oleuropein was identified as a major phenolic compound with considerable contents in these major three fractions and the extract that correlated with their higher antioxidant and radical scavenging. These results indicate that olive leaf contains significant amounts of oleuropein and phenolics, important factors for antioxidant capacity, which can be substantially modified by different extraction methods.

Protective effects of oligomeric and polymeric procyanidin fractions from defatted grape seeds on tert-butyl hydroperoxide-induced oxidative damage in HepG2 cells.

Oligomeric and polymeric procyanidins have been reported to possess different antioxidant capacities. However, the intracellular antioxidant mechanisms of oligomeric and polymeric procyanidins are still poorly understood. In this study, we evaluated the cytoprotective effects of the oligomeric procyanidin fraction (OPF) and the polymeric procyanidin fraction (PPF) from grape seeds against the oxidative damage induced by tert-butyl hydroperoxide (TBHP) in HepG2 cells. The levels of cellular reactive oxygen species (ROS), cellular lipid peroxidation, glutathione (GSH), and antioxidant enzyme activities were measured as biomarkers of cellular oxidative status. HepG2 cells were treated with different concentrations of procyanidin samples (0-20 μg/ml) for 6h prior to treatment with TBHP for 3h. The incubation of HepG2 cells with TBHP led to an approximately 60% decrease in cell viability. However, pretreatment of the cells with the samples, at 5-20 μg/ml, rescued cell viability in a dose-dependent manner. Cellular generation of ROS, formation of malondialdehyde (MDA), and depletion of GSH were reduced by OPF and PPF. Moreover, TBHP treatment increased the activities of glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD). However, a 6h pretreatment with each of the samples at 20 μg/ml significantly decreased the activities of these enzymes. These results clearly showed that treatment with OPF and PPF protected against oxidative damage by modulating ROS production, GSH levels, MDA generation, and antioxidant enzyme activities in HepG2 cells.

Effects of Different Cooking Methods on the Antioxidant Properties of Red Pepper (Capsicum annuum L.)

We investigated the effect of various cooking methods (boiling, steaming, stir-frying, and roasting) and three cooking times (5, 10, and 15 min) on the antioxidant properties of red pepper. Raw and cooked peppers were measured for proximate composition, ascorbic acid (AsA) content, total carotenoid content (TCC), total polyphenol content (TP), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities. Results showed that the proximate composition, AsA content, TCC, TP, and antioxidant activities were significantly (p<0.05) affected by the cooking procedure; the loss rate varied among individual compounds. Boiling and steaming significantly reduced AsA content (24.3~66.5%), TP (13.9~ 54.9%), and antioxidant activity (21.7~60.5%) in red pepper, while stir-frying and roasting slightly reduced AsA content (2.7~25.9%), TP (1.8~4.9%), and antioxidant activity (4.9~17.9%). The highest loss was observed after boiling, followed by steaming, roasting, and stir-frying. Stir-frying and roasting better preserved AsA content, TCC, TP, and antioxidant activity. In conclusion, dry-heat cooking methods such as stir-frying and roasting may be preferred to retain the nutrient compositions and antioxidant properties of red pepper.

Imidacloprid, a Neonicotinoid Insecticide, Potentiates Adipogenesis in 3T3-L1 Adipocytes

There is emerging evidence that organochlorine and organophosphorus insecticide exposure may be linked to excessive weight gain and symptoms of diabetes. However, there is a lack of knowledge for other types of insecticides with potential influence on obesity and diabetes. Thus, the purpose of this investigation was to determine the role of imidacloprid, a neonicotinoid insecticide, in lipid metabolism by use of 3T3-L1 adipocytes. Imidacloprid treatment potentiated lipid accumulation in 3T3-L1 adipocytes and significantly increased expression of a key regulator of adipocyte differentiation and key regulators of lipogenesis. These results imply the involvement of imidacloprid in altered adipogenesis, resulting in increased fat accumulation. This finding is the first report of a potential link between neonicotinoid insecticide exposure and lipid accumulation in adipocytes. Further in vivo as well as epidemiological studies will be required before we can extrapolate these findings to a potential contribution of imidacloprid in human obesity.

Quality Characteristics and Changes in GABA Content and Antioxidant Activity of Noodle Prepared with Germinated Brown Rice

This study was to investigate the quality characteristics of noodles prepared with germinated brown rice and rice bran, and to determine the changes in GABA content and antioxidant activity of the noodles. These noodles were evaluated for cooking properties (cooking loss, swelling index, water holding capacity), total polyphenols, antioxidant activities (radical scavenging of ABTS and DPPH), and GABA contents. The addition of germinated rice bran in the range of 5, 10, and 15% showed a significant influence on cooking loss, although no effect on swelling index was observed. The raw and cooked noodles containing germinated brown rice and rice bran contained more GABA contents (2751.6~4176.7 and 5522.0~9617.8 nmol/20 g of fresh noodle, respectively) than those of non-germinated brown rice and rice bran. Noodles made with germinated brown rice and rice bran had similar total polyphenolics contents and antioxidant activities compared to noodles made with non-germinated brown rice and rice bran. Overall, the germinated brown rice could be used as a good ingredient to increase the nutritional value and antioxidant properties of wheat flour noodle without affecting the cooking properties.

Synthesis of Phytosteryl Ester Containing Pinolenic Acid in a Solvent-Free System Using Immobilized Candida rugosa Lipase

Phytosteryl ester synthesized with pinolenic acid (PLA) from pine nut oil is expected to have features of both phytosterol and PLA. In this study, lipase from Candida rugosa (CRL) was immobilized and then used to optimize conditions for synthesis of phytosteryl ester containing PLA. Lewatit VP OC 1600, a macroporous hydrophobic resin, was selected as the best carrier, and the optimum condition for the immobilization of CRL was established. With immobilized CRL prepared, synthesis of phytosteryl ester with fatty acid from pine nut oil was carried out. Parameters investigated were temperature, molar ratio (phytosterol to fatty acid), enzyme loading, and vacuum. Optimum conditions for synthesis of phytosteryl ester were a temperature of 60 °C, molar ratio of 1:4, enzyme loading of 10% (based on the total weight of the substrate), and pressure of 80 kPa. The maximum conversion of phytosteryl ester was ca. 93 mol % at the optimum condition.

Involvement of heme oxygenase-1 in the anti-inflammatory activity of Chrysanthemum boreale Makino extracts on the expression of inducible nitric oxide synthase in RAW264.7 macrophages

AIM OF THE STUDY This study is to elucidate the involvement of anti-inflammatory heme oxygenase-1 (HO-1) in the inhibitory activity of a Chrysanthemum boreale Makino (CB) extract on nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. MATERIALS AND METHODS Cell viability and NO assay were performed. In addition, iNOS expression was detected by Western blotting and real-time PCR. HO-1 expression was also evaluated by Western blotting, and blocking HO-1 activity on NO production was performed. RESULTS The CB extract at the highest concentration (100 μg/ml) significantly inhibited NO production by approximately 90% and suppressed iNOS protein expression by approximately 84.8% compared to LPS-stimulated cells. Furthermore, the CB extract (100 μg/ml) inhibited iNOS mRNA expression in a concentration-dependant manner and suppressed iNOS mRNA expression by 94.8%. The CB extract induced the expression of HO-1 in a dose-dependent manner, and blocking HO-1 activity abolished the inhibitory effects of the CB extract. Moreover, the addition of carbon monoxide such as tricarbonyl dichlororuthenium (II) dimmer (RuCO), a byproduct derived from heme degradation, mimicked the inhibitory action of low concentrations of CB extract. CONCLUSION These results suggest that a CB extract has potent anti-inflammatory activity in RAW264.7 macrophages involving the induction of HO-1.

Black rice bran as an ingredient in noodles: chemical and functional evaluation.

This study examined the feasibility of using black rice bran (BRB) as an ingredient of noodles and evaluated the effect of BRB incorporation in noodles in terms of chemical and functional attributes. Noodles were prepared with BRB as an ingredient at different levels (2%, 5%, 10%, and 15%). Addition of BRB (5%, 10%, and 15%) significantly decreased the cohesiveness of noodles in texture evaluation. Noodles with different levels of BRB were functionally evaluated and content of polyphenolics, flavonoids, and anthocyanins were improved compared to the control. Additionally, antioxidant activity of BRB noodles was increased compared to the control. BRB can be an excellent ingredient to increase the nutritional value and antioxidant properties of noodles.

Changes in ginsenoside compositions and antioxidant activities of hydroponic-cultured ginseng roots and leaves with heating temperature

Background This study evaluated changes in ginsenoside compositions and antioxidant activities in hydroponic-cultured ginseng roots (HGR) and leaves (HGL) with heating temperature. Methods Heat treatment was performed at temperatures of 90°C, 110°C, 130°C, and 150°C for 2 hours. Results The ginsenoside content varied significantly with heating temperature. The levels of ginsenosides Rg1 and Re in HGR decreased with increasing heating temperature. Ginsenosides F2, F4, Rk3, Rh4, Rg3 (S form), Rg3 (R form), Rk1, and Rg5, which were absent in the raw ginseng, were formed after heat treatment. The levels of ginsenosides Rg1, Re, Rf, and Rb1 in HGL decreased with increasing heating temperature. Conversely, ginsenosides Rk3, Rh4, Rg3 (R form), Rk1, and Rg5 increased with increasing heating temperature. In addition, ginsenoside contents of heated HGL were slightly higher than those of HGR. The highest extraction yield was 14.39% at 130°C, whereas the lowest value was 10.30% at 150°C. After heating, polyphenol contents of HGR and HGL increased from 0.43 mg gallic acid equivalent/g (mg GAE eq/g) and 0.74 mg GAE eq/g to 6.16 mg GAE eq/g and 2.86 mg GAE eq/g, respectively. Conclusion Antioxidant activities of HGR and HGL, measured by 1,1-diphenyl-2-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging ability, increased with increasing heating temperature. These results may aid in improving the biological activity and quality of ginseng subjected to heat treatments.

Impact of Roasting on the Chemical Composition and Oxidative Stability of Perilla Oil

The impact of roasting was observed with regard to certain changes in the chemical components and oxidative stability of oil expelled from the roasted perilla seeds. The roasting times were established differently at each roasting temperature of 180, 200, and 220 °C. Trans fatty acids in perilla oil were detected, and the level detected increased as the roasting time increased. Moreover, the roasting of perilla seed led to an increase of 4 tocopherols, α-, β-, γ-, and δ-tocopherol, as well as phosphorus in the oil. The oxidative stability of the oils obtained after roasting increased during 60 d of storage at 60 °C. The rate of decrease of tocopherol in the oil from unroasted perilla seed was faster than that of the tocopherol in the oils from roasted perilla seeds during storage.