Correction to: Roles and action mechanisms of herbs added to the emulsion on its lipid oxidation.

[This corrects the article DOI: 10.1007/s10068-020-00800-z.].

Roles and action mechanisms of herbs added to the emulsion on its lipid oxidation.

Quality of food emulsions is mainly determined by their physicochemical stability such as lipid oxidation, and herbs as antioxidative food materials are added to improve their quality and shelf-life. Despite the extensive researches, the chemistry and implications of herb addition in the lipid oxidation of emulsions are still confusing. This review intended to provide the information on the roles and action mechanisms of herbs in the lipid oxidation of food emulsions, with focuses on polyphenols. Polyphenols act as antioxidants mainly via reactive oxygen species scavenging and metal chelating; however, their oxidation products and reducing capacity to more reactive metal ions increase the lipid oxidation. Factors such as structure, concentration, and distribution determine their anti- or prooxidant role. Interactions, synergism and antagonism, among polyphenol compounds and the effects of tocopherols derived from oil on the antioxidant activity of herbs were also described with the involving action mechanisms.

Interaction effect of tocopherol homologs with peppermint extract on the iron-catalyzed oxidation of soybean oil-in-water emulsion.

Interaction between tocopherol homologs and peppermint extract added to oil-in-water emulsions was studied during iron-catalyzed oxidation. Emulsions consisted of tocopherol-stripped soybean oil and citrate buffer (4:6, w/w) with/without addition of peppermint extract (400 mg/kg) and α-, γ-, or δ-tocopherol (600 mg/kg), and were oxidized in the iron presence at 25 °C. Lipid oxidation of emulsions was evaluated based on hydroperoxide contents and p-anisidine values. Lipid oxidative stability of emulsions was improved by added peppermint extract, and co-added γ- and δ-tocopherols further reduced lipid oxidation, however, α-tocopherol increased it. Tocopherol contents did not change during oxidation. Polyphenol degradation in the emulsion with added peppermint extract was lower and slower by γ- and δ-tocopherols, however, α-tocopherol showed opposite results. The results suggest that co-addition of tocopherols to the emulsion containing peppermint extract shift a major role of polyphenols as antioxidants from scavenging lipid (peroxy) radicals to tocopherol radical scavenging.

Effects of jupcheong (soaking in syrup) with ginger powder on the lipid oxidation and antioxidant stability of yakgwa (Korean deep-fried confection).

This study evaluated the effect of jupcheong (soaking in syrup) with/without ginger on lipids and antioxidants of yakgwa (Korean deep-fried confection) during storage. Yakgwa was prepared with a dough consisting of wheat and rice flour (1:1, w/w), sesame oil, and sugar syrup. Shaped dough pieces were consecutively deep-fried in soybean oil at 90 and 150 °C, soaked in syrup with/without ginger powder, and stored at 30 °C in the dark for 8 weeks. Lipid oxidation was evaluated by peroxide and p-anisidine values, and antioxidants were determined spectrophotometrically. Jupcheong reduced lipid oxidation and antioxidant degradation during yakgwa storage, and increased stability by jupcheong was higher in lignans or tocopherols than polyphenols. The results suggest that jupcheong especially with ginger could improve the lipid oxidative stability of yakgwa by higher protection of tocopherols and lignans than polyphenols from degradation, and tocopherols were the most important antioxidants in reducing lipid oxidation of yakgwa.

Effect of the pH on the lipid oxidation and polyphenols of soybean oil-in-water emulsion with added peppermint (Mentha piperita) extract in the presence and absence of iron.

This study evaluated the pH effect on the lipid oxidation and polyphenols of the emulsions consisting of soybean oil, citric acid buffer (pH 2.6, 4.0, or 6.0), and peppermint (Mentha piperita) extract (400 mg/kg), with/without FeSO4. The emulsions in tightly-sealed bottles were placed at 25 °C in the dark, and lipid oxidation and polyphenol contents and composition were determined. The lipid oxidation was high in the emulsions at pH 4.0 in the absence of iron, however, iron addition made them more stable than the emulsions at pH 2.6 or 6.0. Total polyphenols were remained at the lowest content during oxidation in the emulsions at pH 4.0, and iron reduced and decelerated polyphenol degradation. The results strongly suggest that polyphenols contributed to decreased lipid oxidation of the emulsion via radical scavenging and iron-chelation, and rosmarinic acid along with catechin, caffeic acid, and luteolin were key polyphenols as radical scavengers in the extract.

Contribution of minor compounds present in the peppermint (Mentha piperita) to the iron-catalyzed lipid oxidation of soybean oil-in-water emulsion.

This study evaluated contribution of minor compounds naturally present in peppermint (Mentha piperita) to the iron-catalyzed lipid oxidation of oil-in-water emulsion. Emulsions consisted of tocopherol-stripped soybean oil and pH 4.0 citrate buffer (4:6, w/w) with iron. Minor compounds included α-tocopherol, rosmarinic acid, caffeic acid, ß-carotene, and chlorophyll b at natural concentration in 400 ppm of the peppermint extract. The emulsions were oxidized in the dark, and headspace oxygen contents, hydroperoxide contents, and p-anisidine values were determined. Addition of phenolic compounds decreased headspace oxygen consumption and hydroperoxide and p-anisidine values of emulsions, however, ß-carotene or chlorophyll b tended to increase them. The results suggest that tocopherols at low concentration were the most important to reduce lipid oxidation of emulsions via radical scavenging, followed by high contents of polyphenols via radical scavenging and iron-chelation. Carotenoids and chlorophylls should be precisely controlled even in the dark, possibly due to their oxidation products.

Improvement of the lipid oxidative stability of soybean oil-inwater emulsion by addition of daraesoon (shoot of Actinidia arguta) and samnamul (shoot of Aruncus dioicus) extract.

The effect of 75% ethanol extract of daraesoon and samnamul (200 mg/kg) on the lipid oxidation of soybean oil-in-water (4:6, w/w) emulsion containing iron (5 mg/kg) in dark conditions at 25°C was studied by determining headspace oxygen and hydroperoxide contents. Polyphenol, carotenoid, and chlorophyll contents were also evaluated using spectrophotometry. The headspace oxygen contents were higher and hydroperoxide contents were lower (p<0.05) in the emulsions with added daraesoon and samnamul extracts compared with the control emulsion without the extract. The antioxidant activity of the daraesoon and samnamul extracts in the lipid oxidation of the emulsions was comparable to that of dibutylhydroxytoluene at 200mg/kg. Polyphenols, carotenoids, and chlorophylls were degraded during oxidation of the emulsions, possibly due to a role of the antioxidants. The results suggest that contribution to the improved lipid oxidative stability of the emulsion with added samnamul and daraesoon would be due to polyphenols and pigments, respectively.

Lipid oxidation-related characteristics of gim bugak (Korean fried cuisine with Porphyra) affected by frying oil.

The effect of frying oil on the lipid oxidation, antioxidants, and in vitro antioxidant activity of gim bugak was studied. Bugak was prepared by pan-frying at 180 °C in unroasted sesame, soybean, extra virgin olive, or palm oil. The degree of lipid oxidation based on conjugated dienoic acid and p-anisidine values was higher in the bugak fried in soybean or sesame oil with high contents of polyunsaturated fatty acids and tocopherols. However, the oil oxidation was lower in olive and palm oils, which showed higher degradation of tocopherols and polyphenols than in sesame or soybean oil during frying. Although the bugak fried in palm oil contained less antioxidants than that fried in soybean or sesame oil, the in vitro antioxidant activity was not different (p > 0.05). Results suggest that palm oil can replace unroasted sesame oil for the preparation of gim bugak with improved lipid oxidative stability and health functionality.

Effects of selected herb extracts on iron-catalyzed lipid oxidation in soybean oil-in-water emulsion.

Effect of herb extracts on the oil oxidation of an oil-in-water emulsion containing iron was studied. The emulsion comprised tocopherol-stripped soybean oil (40 g), citrate buffer (60 g, pH 4.0), xanthan gum (35mg), and FeSO4 (0.5mg) with 80% ethanol extracts of rosemary (Rosmarinus officinalis), basil (Ocimum basilicum), peppermint (Mentha piperita), thyme (Thymus vulgaris), or oregano (Origanum vulgare). Hydroperoxide contents and p-anisidine values were significantly (p<0.05) lower in the emulsions with the added herb extracts compared with the control emulsions. The antioxidant activity of the basil and peppermint extracts containing higher proportions of rosmarinic acid was significantly higher (p<0.05) than that of the other herb extracts, but the polyphenol degradation rate was not significantly different. The antioxidant activity of the basil and peppermint extracts showed concentration-dependence within 400 mg/kg. This study suggests that the oxidative stability of oil-inwater emulsion containing iron can be improved by addition of basil or peppermint extract.

Effects of gardenia seed, green tea, and cactus pear in rice batter on the chemical quality of lotus root bugak and frying oil.

This study investigated the effects of the addition of gardenia seed, green tea, or cactus pear (Opuntia ficus-indica) to rice batter at 10% on the lipid oxidation, pigments, antioxidants, and antioxidant activity of lotus root bugak and frying oil. Lipid oxidation was evaluated based on the conjugated dienoic acid and p-anisidine values. Lipid oxidation and tocopherol degradation were significantly reduced in the gardenia seed-added bugak and frying oil, whereas the cactus pear-added bugak and frying oil showed an increase. The addition of green tea had no significant effects on the lipid oxidation of bugak and frying oil. The in vitro antioxidant activity of lotus root bugak significantly increased with the addition of gardenia seed, green tea, or cactus pear. The results suggested that green tea and gardenia seed could improve the health and food functionality of antioxidation for lotus root bugak, respectively.

Hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus.

BACKGROUND/OBJECTIVES: The primary objective of the treatment of diabetes mellitus is the attainment of glycemic control. Hyperglycemia increases oxidative stress which contributes to the progression of diabetic complications. Thus, the purpose of this study was to investigate the hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus. MATERIALS/METHODS: Rats with streptozotocin-induced diabetes received an oral administration of a starch solution (1 g/kg) either with or without a 70% ethanol extract of Daraesoon (400 mg/kg) or acarbose (40 mg/kg) after an overnight fast and their postprandial blood glucose levels were measured. Five-week-old C57BL/6J mice were fed either a basal or high-fat/high-sucrose (HFHS) diet with or without Daraesoon extract (0.4%) or acarbose (0.04%) for 12 weeks after 1 week of adaptation to determine the effects of the chronic consumption of Daraesoon on fasting hyperglycemia and antioxidant status. RESULTS: Compared to the control group, rats that received Daraesoon extract (400 mg/kg) or acarbose (40 mg/kg) exhibited a significant reduction in the area under the postprandial glucose response curve after the oral ingestion of starch. Additionally, the long-term consumption of Daraesoon extract or acarbose significantly decreased serum glucose and insulin levels as well as small intestinal maltase activity in HFHS-fed mice. Furthermore, the consumption of Daraesoon extract significantly reduced thiobarbituric acid reactive substances and increased glutathione levels in the livers of HFHS-fed mice compared to HFHS-fed mice that did not ingest Daraesoon. CONCLUSIONS: Daraesoon effectively suppressed postprandial hyperglycemia via the inhibition of α-glucosidase in STZ-induced diabetic rats. Chronic consumption of Daraesoon alleviated fasting hyperglycemia and oxidative stress in mice fed a HFHS diet.

Effect of soybean lecithin on iron-catalyzed or chlorophyll-photosensitized oxidation of canola oil emulsion.

The effect of soybean lecithin addition on the iron-catalyzed or chlorophyll-photosensitized oxidation of emulsions consisting of purified canola oil and water (1:1, w/w) was studied based on headspace oxygen consumption using gas chromatography and hydroperoxide production using the ferric thiocyanate method. Addition levels of iron sulfate, chlorophyll, and soybean lecithin were 5, 4, and 350 mg/kg, respectively. Phospholipids (PLs) during oxidation of the emulsions were monitored by high performance liquid chromatography. Addition of soybean lecithin to the emulsions significantly reduced and decelerated iron-catalyzed oil oxidation by lowering headspace oxygen consumption and hydroperoxide production. However, soybean lecithin had no significant antioxidant effect on chlorophyll-photosensitized oxidation of the emulsions. PLs in soybean lecithin added to the emulsions were degraded during both oxidation processes, although there was little change in PL composition. Among PLs in soybean lecithin, phosphatidylethanolamine and phosphatidylinositol were degraded the fastest in the iron-catalyzed and the chlorophyll-photosensitized oxidation, respectively. The results suggest that addition of soybean lecithin as an emulsifier can also improve the oxidative stability of oil in an emulsion.

Superiority of traditional cooking process for bugak (Korean traditional fried dish) for plasma lipid reduction.

In this study, the efficacy and mode of action of the Korean traditional fried dish bugak for reducing plasma lipids are investigated. Three different studies were performed as follows: lipid-lowering effects of bugak compared with (1) different preparation methods, (2) different batters, and (3) different frying oils. Traditionally, bugak is prepared with fermented glutinous rice batter (FGR) and pan-fried in unroasted sesame oil (USSO; this preparation of bugak is referred to as FGRUSSO). FGR is prepared by placing the glutinous rice and water in a crock for 7 days at room temperature. For the study, wheat flour batter (WF) and soybean oil (SBO) were alternatively used. Low-density lipoprotein receptor knockout (LDLr⁻/⁻) mice (n=24) were fed atherogenic diets with bugak (20 g/100 g of feed) for 10 weeks. Plasma triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) concentration and hepatic lipid accumulations decreased significantly in mice fed FGRUSSO, compared with bugak made with WF and fried in SBO (WFSBO). Protein expression of fatty acid synthesis (FAS) and 3-hydroxyl-3-methylglutaryl coenzyme A reductase (HMGCR) in the FGRUSSO group was decreased, although sterol regulatory element-binding proteins (SREBP-1 and -2) were not different. When batter differences were compared, TG concentration of mice fed bugak prepared with FGR and fried in SBO (FGRSBO) was lower than the WFSBO group due to suppression of hepatic FAS expression. In the oil comparison study, TC and LDL-C concentrations in the FGRUSSO group were lower due to attenuated HMGCR activity. In conclusion, bugak prepared by traditional cooking methods was most effective for lowering plasma TG, TC, and LDL-C via suppressing hepatic FAS and HMGCR activity, although transcription factors for regulating lipogenic enzyme expression were not significantly different.

Chamnamul [Pimpinella brachycarpa (Kom.) Nakai] ameliorates hyperglycemia and improves antioxidant status in mice fed a high-fat, high-sucrose diet.

Chronic consumption of a high-fat, high-sucrose (HFHS) diet increases insulin resistance and results in type 2 diabetes mellitus in C57BL/6J mice. Hyperglycemia in diabetics increases oxidative stress, which is associated with a high risk of diabetic complications. The purpose of this study was to examine the hypoglycemic and antioxidant effects of chamnamul [Pimpinella brachycarpa (Kom.) Nakai] in an animal model of type 2 diabetes. The α-glucosidase inhibitory activity of a 70% ethanol extract of chamnamul was measured in vitro. Five-week-old male C57BL/6J mice were fed a basal or HFHS diet with or without a 70% ethanol extract of chamnamul at a 0.5% level of the diet for 12 weeks after 1 week of adaptation. After sacrifice, serum glucose, insulin, adiponectin, and lipid profiles, and lipid peroxidation of the liver were determined. Homeostasis model assessment for insulin resistance (HOMA-IR) was determined. Chamnamul extract inhibited α-glucosidase by 26.7%, which was 78.3% the strength of inhibition by acarbose at a concentration of 0.5 mg/mL. Serum glucose, insulin, and cholesterol levels, as well as HOMA-IR values, were significantly lower in the chamnamul group than in the HFHS group. Chamnamul extract significantly decreased the level of thiobarbituric acid reactive substances and increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver compared with the HFHS group. These findings suggest that chamnamul may be useful in prevention of hyperglycemia and reduction of oxidative stress in mice fed a HFHS diet.

Effects of water activity on the lipid oxidation and antioxidants of dried laver (porphyra) during storage in the dark.

Lipid oxidation and antioxidant degradation in dried laver (Porphyra) were determined during storage at water activities (Aw ) of 0.11, 0.30, 0.51, 0.75, or 0.89 in the dark at 40 °C for 15 d. Lipid oxidation was evaluated by measuring peroxide value (POV) and conjugated dienoic acid (CDA) contents, and fatty acid composition was analyzed by gas chromatography. Contents of polyphenols, tocopherols, and porphyran were determined by spectrophotometry, HPLC, and gravimetry, respectively. The POV and CDA contents of the dried laver lipids increased during storage as Aw increased from 0.11 to 0.30, 0.51, 0.75, and 0.89, whereas the relative content of eicosapentaenoic acid was decreased; however, the contents of polyphenols, α-tocopherol, and porphyran in dried laver showed the reverse phenomena. Lipid oxidation and antioxidant degradation in dried laver sharply increased at an Aw of 0.51. Polyphenols, α-tocopherol, and porphyran contributed to reduction of lipid oxidation in dried laver. The degree of lipid oxidation of dried laver was more dependent on the concentration of α-tocopherol than that of either polyphenols or porphyran during storage in the dark. The results strongly suggest that the quality of dried laver can be improved by preserving tocopherols as much as possible while decreasing A(w) during storage.

Effects of fatty acid composition and ß-carotene on the chlorophyll photosensitized oxidation of W/O emulsion affected by phosphatidylcholine.

UNLABELLED: Chlorophyll photosensitized oxidation of W/O emulsion consisting of oils with different fatty acid composition was studied and ß-carotene effects on the singlet oxygen oxidation affected by phosphatidylcholine were evaluated by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. An emulsion was composed of purified oil (sunflower, soybean, canola, or olive oil), water, and xanthan gum (50:50:0.35, w/w/w) with addition of phosphatidylcholine (0 or 250 ppm) and ß-carotene (0, 1, 5, or 10 ppm). PV and CDA content of oil in the emulsion were increased with time under chlorophyll photosensitized oxidation, and the oxidation rate was higher in the emulsion consisting of sunflower or soybean oil whose polyunsaturated fatty acids content was high compared to canola or olive oil. Addition of ß-carotene to the emulsion significantly decreased the oil oxidation under chlorophyll photosensitization, however, co-addition of phosphatidylcholine decreased the antioxidant activity of ß-carotene, suggesting an antagonistic antioxidation between them. PRACTICAL APPLICATION: The results of this study can be applied to the area of emulsion foods such as salad dressing to have improved texture and stability by decreasing the oil oxidation and providing desirable color by use of ß-carotene with phosphatidylcholine as emulsifier.

Fatty acid synthase inhibitor cerulenin inhibits topoisomerase I catalytic activity and augments SN-38-induced apoptosis.

Fatty acid synthase (FASN) is overexpressed in a wide variety of human cancers, making it an attractive target for anticancer therapy. One of the most widely used inhibitors of FASN, cerulenin, is a natural product of Cephalosporium caerulens. Cerulenin is selectively toxic to human cancer cells in vitro. However, the mechanism by which FASN inhibition causes apoptosis in tumor cells remains unclear. Because of the widespread clinical interest in combining cerulenin with other chemotherapeutic agents, we performed this study to gain insight into the downstream effects of FASN inhibition that lead to apoptosis. Here, we observed the increased antitumor effect of cerulenin when combined with the topoisomerase inhibitor SN-38. We identified topoisomerase I as a potential mediator of cerulenin-induced apoptosis, possibly by upregulating intracellular polyunsaturation. Finally, we show that suppressing topoisomerase I catalytic activity results in synergistic effects between cerulenin and LY294002. Our results suggest that topoisomerase I could participate in cerulenin-induced apoptosis by upregulating intracellular polyunsaturation. These results will help determine the molecular basis of the cerulenin and SN-38 drug combination. Further investigation of this pathway will provide new insight into cancer cell metabolism and may aid in the design of additional cancer chemotherapeutic agents.

Singlet oxygen-related photooxidative stability and antioxidant changes of diacylglycerol-rich oil derived from mixture of olive and perilla oil.

UNLABELLED: This study investigated the oxidative stability and antioxidants changes in diacylglycerol (DAG)-rich oil under singlet oxygen. DAG-rich oil was derived from triacylglycerol (TAG) oil of extra virgin olive and perilla oil mixture by hydrolysis and re-esterification using lipases. The oxidation of oils was performed at 25 °C for 48 h under singlet oxygen produced with chlorophyll b under light, and was evaluated by headspace oxygen consumption and peroxide value (POV). The oxidation of DAG-rich oil was higher and faster in the co-presence of light and chlorophyll than in their single presence. DAG-rich oil was more oxidation-susceptible than TAG oil. There was no significant change in fatty acid and lipid subclass compositions in DAG-rich oil during the photooxidation. Tocopherols were degraded, whereas polyphenols weren't during phootooxidation of DAG-rich oil. The oxidation of DAG-rich oil was well-correlated with tocopherol contents, not with polyphenol contents, indicating that tocopherols were effective antioxidants in the singlet oxygen-related phootooxidation of DAG-rich oil. The results suggested that the oxidative stability of DAG-rich oil under singlet oxygen be improved by a precise control through retention of tocopherols. PRACTICAL APPLICATION: The results of this study can be applied to the utilization of diacylglycerol oils to the area of functional edible oils with good oxidative stability.

Effects of phospholipids on the antioxidant activity of α-tocopherol in the singlet oxygen oxidation of canola oil.

This study evaluated the effects of phosphatidylcholine (PC) or phosphatidylethanolamine (PE) on the antioxidative activity of α-tocopherol during oxidation of canola oil by singlet oxygen at 10°C for seven hours. Singlet oxygen was produced by chlorophyll b (4 ppm) under 1,700 lux. The oxidation of oil was evaluated by headspace oxygen consumption by gas chromatography and peroxide values (POVs). Concentrations of PC, PE, chlorophyll, and α-tocopherol were determined by HPLC. PC and PE protected chlorophyll from degradation, but they accelerated the degradation of α-tocopherol under singlet oxygen. Contents of PC and PE did not change for seven hours under singlet oxygen. α-Tocopherol significantly lowered POV and headspace oxygen consumption of canola oil under singlet oxygen, and its antioxidant activity was increased by the co-presence of PC and PE. PC and PE increased chemical quenching of singlet oxygen by tocopherol in decreasing the oil oxidation.

Interaction of phosphatidylcholine and α-tocopherol on the oxidation of sunflower oil and content changes of phosphatidylcholine and tocopherol in the emulsion under singlet oxygen.

Interaction of phosphatidylcholine (PC) and α-tocopherol (α-Toc) on the oxidation of oil in the emulsion consisting of sunflower oil and water under singlet oxygen at 25 °C was studied by determining peroxide value (PV) and conjugated dienoic acid (CDA) contents. Singlet oxygen was produced by chlorophyll b under 1700 lux. Single addition of PC or α-Toc decreased the values of peroxides and CDAs of oil in the emulsion via singlet oxygen quenching. PC and α-Toc showed simply additive interaction in decreasing the singlet oxygen oxidation of oil in the emulsion. α-Toc was a physical quencher of singlet oxygen in the emulsion, but PC involved chemical quenching in the antioxidant action. Chlorophyll and PC contents were decreased in the emulsion under singlet oxygen, while α-Toc was not. α-Toc protected chlorophyll and PC from degradation, and was a more important component than PC in the oil oxidation under singlet oxygen in the emulsion.