Enzymatic extraction of anthocyanins from the pomace of aronia (Aronia melanocarpa)

Efficient extraction of natural pigments is a key focus in enhancing the utilization of by-products for applications in the food industry. In this study, an enzymatic extraction method using Pectinex Ultra SP-L, Pectinex XXL, Novoshape, and Celluclast was used to investigate natural pigment production from the pomace of aronia, a commercially important plant. The method's performance was monitored using high-performance liquid chromatography with diode-array detection by measuring total and individual anthocyanin levels. Pectinex XXL (0.5%) yielded the highest total anthocyanin extraction (2082.41 ± 85.69 mg/100 g) in the single enzyme treatment, followed by Pectinex Ultra SP-L (0.05%), Celluclast (0.01%), and Novoshape (0.1%). Combining Pectinex XXL (0.25%) with Celluclast (0.01%) increased the extraction ratio of total anthocyanins (2 323.04 ± 61.32 mg/100 g) by ∼50.7% compared with that obtained using the solvent extraction method. This study demonstrated an effective enzymatic extraction method for application in the food industry.

β-Carotene and β-apo-8'-carotenal contents in processed foods in Korea

A robust and rapid HPLC method for β-carotene and β-apo-8'-carotenal analyses in various processed foods was developed. The analysis method was validated for low-fat, moderate-fat, and high-fat food matrices. The two carotenoids were identified by LC-MS/MS. The detection limits for β-carotene and β-apo-8'-carotenal in the three food matrices were 0.08-0.27 µg/g and 0.09-0.18 µg/g, respectively. The inter- and intra-day accuracy and precision were in accordance with the Codex guidelines. The validated method was applied to 57 processed food samples, possibly containing β-carotene and β-apo-8'-carotenal, obtained in Korea. The detected β-carotene and β-apo-8'-carotenal levels in the samples ranged from not detected (ND) to 6.92 µg/g and ND to 1.63 µg/g, respectively. Chocolate and cheese samples had the highest β-carotene and β-apo-8'-carotenal levels, respectively. Notably, several samples with no labeled carotenoid additives contained β-carotene. Moreover, the developed analytical method was compatible with various processed food matrices.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01285-2.

High-performance liquid chromatography using diode array detector and fluorescence detector for hydrogen peroxide analysis in processed fishery foods

Hydrogen peroxide (H2O2) is a food additive for bleaching and sterilization, owing to its strong oxidizing effect. The current study aimed to develop analytical methods to detect trace amounts of residual H2O2 in diverse foods using high-performance liquid chromatography (HPLC) equipped with diode array detector (DAD) or fluorescence detector (FLD). The vanadium(V)-peroxo complex, derived from the reaction of H2O2 with ammonium metavanadate, was used for the detection of H2O2 with DAD. H2O2 was indirectly analyzed using FLD via the detection of 7-hydroxycoumarin, derived by Fenton reaction, followed by verification using liquid chromatography with tandem mass spectrometry analysis. Both the detection methods showed good linearity with R2 > 0.997. Limit of detection and limit of quantification were 0.30 and 0.91 mg/L (8.82 and 26.76 μM) with HPLC-DAD and 0.001 and 0.003 mg/L (0.03 and 0.09 μM) with HPLC-FLD, respectively. Applicability of both the methods was successively tested through sample analysis.

Determination of Polyvinyl Acetate in Chewing Gum Using High-Performance Liquid Chromatography-Evaporative Light Scattering Detector and Pyrolyzer-Gas Chromatography-Mass Spectrometry

Polyvinyl acetate (PVAc) is used in various adhesive, paint, and transparent tape applications. It is also used as a food additive in food manufacturing to make chewing gum and fruit and vegetable glazes; however, guidelines on the amount of food additives that is used have not yet been established. In this study, a method was developed for analysis of polyvinyl acetate (PVAc) using high-performance liquid chromatography with an evaporative light scattering detector (HPLC–ELSD) and pyrolyzer–gas chromatography–mass spectrometry (Py–GC–MS). The analytical methods were applied to commercially available chewing gum. In the HPLC–ELSD analysis, the linearity was acceptable (R² > 0.999), and the limits of detection and quantification were 22.2 and 67.3 µg/mL, respectively. The accuracies of PVAc were 87–115% at spike levels of 200–1000 µg/mL for the intra- and inter-day tests. The contents of PVAc in the chewing gum samples were n.d. (not detected)—13.8 g/kg. The presence of PVAc in chewing gum was verified with Py–GC–MS analysis, finding the typical pyrolysates of PVAc, such as acetic acid, benzene, toluene, styrene, indane, naphthalene, and acenaphthene. The developed analytical methods can be applied for successful identification of PVAc in chewing gum.

Simultaneous analysis of polyethylene glycol in dietary supplement tablets using high-performance liquid chromatography and verification with liquid chromatography-electrospray ionization mass spectrometry

Polyethylene glycol (PEG) are widely applied in detergents, cosmetics, and food additives. A simultaneous analytical method was developed to detection the polyethylene glycol (100-10000 Da). High-performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) could analyze successively PEG products. The method was verified with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS/MS). The retention times of PEG 200-8000 ranged from 1.97 to 12.33 min. Method validation was performed to the International Conference on Harmonization (ICH) guidelines and the Korea Ministry of Food and Drug Safety (MFDS); linearity: R² > 0.997, LOD: 7.47-16.24 µg/mL, LOQ: 22.40-75 µg/mL, repeatability (%RSD): 0.2-2.5, recovery (%): 90.4-104.9% for film-coated tablet, 80.1-95.9% for sugar-coated tablet. A total of 115 PEG could be identified by extracted ion chromatography in mass analysis, based on the charge state represented as [M+Na⁺+H₃O⁺_n-1]. This method can be applied for successive identification of PEGs in PEG-containing products.

High-performance liquid chromatography and gas chromatography to set the analysis method of stearoyl lactylate, a food emulsifier

Stearoyl lactylates (SLs, E481/E482) and their sodium and calcium salts are emulsifiers commonly used as food additives. This study was performed to set the analytical method of SLs in Korea using high-performance liquid chromatography (HPLC) and gas chromatography (GC). A new HPLC method using C18 column with water and methanol as the eluents, and a new GC method using DB-1 column with He as the carrier gas, were developed and were compared with previously reported analytical methods. The new HPLC and GC methods indicated a coefficient of determination (r²) of 0.999 in the calibration curves. The detection and quantification limits are 0.26 and 0.78 μg/kg for the HPLC method, respectively, and 16.54 and 50.12 μg/kg for the GC method, respectively. The new HPLC and GC methods indicated precision of 0-2.0%, and accuracy of 92.7-108.5%. Therefore, they can be applied in numerous food samples to determine the level of SLs.

An Improved Analytical Method for the Determination of Brown FK in Food using HPLC

In this study, an improved analytical method for the detection of the colorant Brown FK in foods using high-performance liquid chromatography was developed. The method, which employed an RC-C18 column and diode array detection at 254 nm with sodium acetate solution and methanol as mobile phases, exhibited good linearity (R2 = 1.0), and its limits of detection and quantification were determined to be 0.06 and 0.19 μg/mL, respectively. The precision was found to be 0-1.2% and the accuracy was between 86.5% and 94.8%. Liquid chromatography-tandem mass spectrometry was also performed to identify Brown FK in peaks. The pretreatment method was optimized for three different food sample groups, i.e., seafood, noodles and other, affording recoveries of 86.5-92.8%, 90.8-94.8% and 90.0-92.3%, respectively. In addition, inter-laboratory testing was also conducted to check the precision.

Breakfast eating patterns and the metabolic syndrome: the Korea National Health and Nutrition Examination Survey (KNHANES) 2007-2009

OBJECTIVE

The purpose of this study is to find out the association between eating breakfast, breakfast patterns, and the metabolic syndrome.

METHODS

We used the fourth Korean National Health and Nutrition Examination Survey from 2007 to 2009. A total of 16,734 subjects were included. Breakfast dietary patterns were extracted by factor analysis. Multiple logistic regression was used to assess the relationship between breakfast consumption, breakfast dietary patterns, and the metabolic syndrome.

RESULTS

We found that breakfast consumption itself reduced the risk of the metabolic syndrome (odds ratio=0.82, 95% confidence interval=0.69-0.98). We identified two breakfast dietary patterns: the traditional Korean pattern and the dairy-cereal pattern. The dairy-cereal pattern was associated with a reduction in the risk of the metabolic syndrome among breakfast consumers. Compared to no breakfast consumption, the strongest traditional Korean pattern and the highest quartiles for the dairy-cereal pattern were associated with a reduced risk of the metabolic syndrome.

CONCLUSIONS

Breakfast consumption is associated with the metabolic syndrome. Not all breakfast consumption patterns are associated with a reduced risk of having the metabolic syndrome. In particular, eating either a dairy-cereal breakfast or high energy and fiber breakfast are associated with a reduced risk of the metabolic syndrome.

Effects of a 2-, 3- and 4-electrode stimulator design on current dispersion on the surface and into the limb during electrical stimulation in controls and patients with wounds

Electrical stimulation is a widely used modality in the field of physical therapy and exercise physiology. The most common method for the application of electrical stimulation is a two-electrode system where one electrode is the source and the other is a reference. However, recent studies report that a more effective delivery system can be achieved if more than two electrodes are used. In the present investigation, the circuitry to deliver electrical stimulation through a 2-, 3- or 4-electrode delivery system was designed. The system was evaluated by its ability to deliver current on the surface of the skin as well as deep into the quadriceps muscle in six control subjects and in and around wounds in six other subjects. The results of the experiments showed that much better depth of penetration was achieved in a 4-electrode system (one electrode was on the opposite side of the limb and three electrodes were on top of the limb) than in either a 2- or a 3-electrode delivery system. In non-wounded skin, given the same current from the stimulator, the current in the quadriceps muscle was found to be double with a 4-electrode versus a 2-electrode system. In wounds, this same finding was seen. Here, blood flow, an indicator of the effectiveness of electrical stimulation in wounds, was three times higher if a multi-channel stimulator was used versus a 2-channel stimulator. Thus a multi-channel electrical stimulation system is more effective than a 2-electrode system.

A multi-channel stimulator and electrode array providing a rotating current whirlpool for electrical stimulation of wounds

When electrical stimulation is used on wounds, the electrical current has difficulty penetrating areas where there is necrotic tissue. Further, for an irregularly shaped wound, current distribution is poor in some areas of the wound since conventional two-electrode delivery systems provide the greatest current in a line directly between the electrodes. A new stimulator and electrode system is described which uses three electrodes spaced around a wound to disperse current more evenly. The stimulator senses tissue impedance and then redirects current by altering its Thevenin's output impedance for each electrode; each of the three electrodes becomes the active one in sequence while the remaining are the sink electrodes. Eight subjects were examined to test the stimulator. Electrical stimulation was applied to the skin above the quadriceps muscle at currents of 15 mA in six subjects without wounds and in two subjects with wounds. The relationship between electrode position and current dispersion on the skin was examined with a two-electrode vs. a three-electrode system to set stimulation parameters for the computer. The results showed that the three-electrode system could (1) detect areas of the skin with high impedance; (2) compensate by altering the Thevenin's output impedance at each of the three electrodes to shift current to high impedance areas; (3) provide uniform current across the skin as assessed by skin current and blood flow measurements with a laser Doppler flow imager.

Hypolipidemic effect of lactobacillus ferment as a functional food supplement

The Lactobacillus ferment used in this study was composed of Lactobacillus fermented wheat, barley and kefir grains. Fermentation increased the CFU of lactic acid bacteria with a reduction in pH value and in the contents of dietary fi ber and glucan. Male SD rats were fed a high fat diet with or without 10% Lactobacillus ferment for 4 weeks. In the Lactic-F group (group fed high-fat diet with Lactobacillus ferment) there was a significantly reduced increase of body weight compared with the HF-control (group fed high-fat diet without Lactobacillus ferment). The food efficiency ratio (FER) tended to be decreased in the Lactic-F group, but there was no significant difference between the Lactic-F and HF-control groups. The perirenal and the epididymal fat weights in the normal dietary group (control) and in the Lactic-F group were significantly lower than those of the HF-control. The serum HDL-cholesterol and the total cholesterol in the Lactic-F group were similar to the control group, and were significantly different from those of the HF-control. These results indicated that the Lactobacillus ferment is a functional material having antiobesity effects, with use as a supplement in functional, health-favoring food.

Macrophage-stimulating activity of exo-biopolymer from cultured rice bran with Monascus pilosus

To find a new use of rice bran, five fungi were examined for the production of exo-biopolymer with macrophage-stimulating activity from rice bran. Among the exo-biopolymers produced from the cultures, Monascus pilosus had the most potent macrophage stimulating activity in a liquid culture rather than in a solid culture. In order to improve the yield of exo-biopolymer with macrophage-stimulating activity, a suitable medium for exo-biopolymer was tested in submerged culture of M. pilosus. The highest amount of exo-biopolymer (13.9 mg/mL) was obtained in a medium containing rice bran as an only carbon source followed by media with additional maltose and sucrose (13.8 and 13.7 mg/mL, respectively). The addition of peptone resulted in the production of high amount of exo-biopolymer (15.1 mg/mL), meanwhile the addition of ammonium chloride resulted in 264.0 microg/mL of glucosamine content. Among eight different kinds of inorganic salts tested, potassium phosphate (0.1%) was the most effective inorganic salt for the mycelial growth and exo-biopolymer production. Therefore the optimal medium composition was as follows (g/L): 20 g of rice bran, 5 g of peptone, and 1 g of KH2PO4. The optimal culture pH and time for mycelial growth and exo-biopolymer production was pH 5.0 and 25 degrees C, respectively. The maximum exo-biopolymer (20.1 mg/mL) was observed at the fourth day of cultivation. Exo-biopolymer, a crude polysaccharide fraction, mainly contained neutral sugar (81.8%) with considerable amounts of uronic acid (18.2%). Component sugar analysis showed that the active fraction consisted mainly of arabinose, galactose, glucose, which was digested from starch of rice bran during cultivation, and uronic acid (molar ratio; 0.8:1.0:0.7:0.8).

Pharmacological effects of fermented red pepper

The pharmacological effects were investigated of fermented red pepper (HF-S), which consisted of 14.7% carbohydrate, 1.5% lipid, 4.9% protein, 0.3% ash, 78.2% moisture content, with 0.15% capsaicin and 0.06% dihydrocapsaicin. Oral administration of 0.25 mL HF-S for 3 weeks produced significant changes of the perirenal fat pad weight compared with the HF-control group, suggesting a suppressive effect on lipid accumulation and a significant decrease in the risk of arteriosclerosis. The HF-S (0.25 mL) group also showed a lower plasma TG, TC level and atherogenic index than that of the HF-control. In addition, the HF-S (0.25 mL) group showed a marked increase in the production of glutathione, which is the major endogenous antioxidant, and a decrease in the production of lipid peroxide as the product of chemical damage by oxygen free radicals. It is assumed that the effect of HF-S might relate to high glutathione production on the suppression of lipid peroxidation. HF-S stimulated not only the proliferation of macrophages (as high as the positive control, LPS at 1000 microg/mL) but also mitogenic activity (1.2-fold of LPS at 100 microg/mL).

Yeast hydrolysate reduces body fat of dietary obese rats

The purpose of this study was to assess the antiobesity effect of the yeast hydrolysate (DNF) on the body weight, body fat and plasma lipids levels of high-fat fed rats. The weight gain of the HF (high fat diet) (162.58 +/- 6.68 g) was significantly (p < 0.05) greater than that of DNF-1, DNF-2, (high fat diet with DNF of 0.5 and 1.0 g/kg body weight, respectively) and control groups (143.19 +/- 7.33 g, 139.20 +/- 8.36 g, 130.23 +/- 8.02 g, respectively). The wet weight of the epididymal fat and the perirenal fat pads of the DNF-1, DNF-2 and control groups were reduced significantly (p < 0.05). A significant (p < 0.05) increase of HDL-cholesterol level of the DNF-2 and control groups was observed. However, there was no significant difference between DNF-1 and DNF-2. It was also found that the triacylglycerol (TG) levels decreased significantly (p < 0.05) in the DNF-2 group from that of the HF, but there was no significant (p < 0.05) difference between DNF-1 and DNF-2.

Pharmacological activities of stromata of Cordyceps scarabaecola

The chemical components of freeze-dried stromata from Cordyceps scarabaecola were examined. The stromata consisted of crude carbohydrates (55.1%) and crude proteins (14.2%). The stromata were also composed of a low content of crude ash (6.6%) and fat (1.5%). The composition of the carbohydrate in the stromata included a large quantity of glucose (46.6%), mannose (35.4%) and galactose (18.0%). The acidic amino acids such as glutamic acid (32.1 mg/g) and aspartic acid (24.7 mg/g) were present in a large quantity. The extracts of stromata did not reveal any inhibitory activity for AChE in vitro. It was observed that a hot-water extract (HW) of the stromata contributed significantly to the anticoagulant activity (60 s coagulating time) and anticomplementary activity (62% of ITCH50 value). The MeOH-soluble fraction (M) from the freeze-dried stromata inhibited TPA-induced O2- generation as effectively as the positive control, genistine 27%. The hot-water extract (HW) showed the most potent intestinal immune system modulation activity and the MeOH-soluble fraction (M) had intermediate activity.

Anti-stress and anti-fatigue effect of fermented rice bran

The anti-stress and anti-fatigue effects of a hot water extract of fermented rice bran (FRB) were investigated with Saccharomyces cerevisae IFO 2346 on rats or mice. Oral administration (1 g/kg/day) of a hot water extract of FRB inhibited major changes in weight of the adrenal, thymus, spleen and thyroid, showing the anti-stress effect. A hot water extract of FRB also inhibited the increase of GPT and LDH activity, cholesterol and serum glucose levels. Administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase of the anti-fatigue effect. From these results, it can be considered that FRB has an anti-stress and anti-fatigue effect.

Optimization of submerged culture conditions for the production of angiotensin converting enzyme inhibitor from Flammulina velutipes

The angiotensin-converting enzyme (ACE) inhibitory effect was tested in the culture broth from submerged mycelial cultures of 20 basidiomycetes. The ACE inhibitory effect of culture broth from Flammulina velutipes strain 414 was the highest (52.8%), followed by Lentinus edodes strains 2 (44.4%) and 16 (41.3%). Nutritional requirements for the production of ACE inhibitory substance from F. velutipes were studied. Sucrose, ammonium acetate, and glutamic acid were chosen for the maximum production of ACE inhibitory substance. The optimal medium composition was (g/l): sucrose 20, ammonium acetate 5, glutamic acid 2, KH(2)PO(4) 3, MgSO(4).7H(2)O 0.8, and yeast extract 0.5. Under optimal culture conditions, the ACE inhibitory effect was more than 80%.

Biological activities of Saccharomyces cerevisiae and fermented rice bran as feed additives

AIMS

The objective of the present study was to examine for the various biological activities for feed additives of Saccharomyces cerevisiae and fermented rice bran.

METHODS

The feed additives (100 g of each: YE, brewery yeast; PM, mixture of YE and SF; SF, fermented rice bran) were decocted with 2 l water at 100 degrees C to a half volume.

RESULTS

The hot-water extract of PM was found to increase the stimulation of the macrophage activation (2.0-fold) and the intestinal immune modulating activity (1.8-fold), compared with those of control. When the hot-water extracts of PM, SF and YE were fed to the rats for 8 d (1 g kg-1 d-1), PM and SF showed the more effective anti-stress effect on spleen, thyroid and thymus gland.

SIGNIFICANCE AND IMPACT OF THE STUDY

The hot-water extract of PM can have a significant impact on strengthening the living body's immune system and proliferating anti-stress activities with relation to enhance immunity.

Characterization of a keratinolytic metalloprotease from Bacillus sp. SCB-3

A keratinolytic protease-producing microorganism was isolated from soybean paste waste and was identified as a strain of Bacillus sp. The keratinase was purified by polyethylene glycol precipitation and two successive column chromatographies with DEAE-Toyopearl 650C and Sephacryl S-200 HR. The purified enzyme had overall 11 purification folds with an 18% yield. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration on Sephacryl G-200 indicated that the purified enzyme was monomeric and had a molecular weight of 134 kDa. The optimum temperature and pH were 40 degrees C and 7.0, respectively. This enzyme was completely inhibited by EDTA and EGTA, and it was restored by the addition of Ca2+ and Mg2+. These results suggested that it is a metalloprotease. The stimulated enzyme activity by reducing agents indicated that the reducing condition was important in the expression of the activity.

Anti-stress and anti-fatigue effects of fermented rice bran

The anti-stress and anti-fatigue effects on rats and mice of a hot water extract of rice bran fermented with Saccharomyces cerevisae IFO 2346 were investigated. Oral administration (1 g/kg/day) of the hot water extract of fermented rice bran (FRB) inhibited major changes in the weight of the adrenal, thymus, spleen and thyroid, showing an anti-stress effect. The hot water extract of FRB also inhibited increases in the GPT and LDH activity, cholesterol and glucose in the serum. The administration (1 g/kg/day) for 2 weeks significantly prolonged the swimming time, resulting in an increase in the anti-fatigue effect. It is considered from these results that FRB had anti-stress and anti-fatigue effects.

Microinvasive video-assisted thoracoscopic sympathicotomy for primary palmar hyperhidrosis

BACKGROUND

Although video-assisted thoracoscopic surgery for palmar hyperhidrosis is now widely accepted as the approach of choice, the optimal technique has remained a subject of controversy. We have used 2-mm dual port video-assisted thoracoscopic sympathicotomy for primary palmar hyperhidrosis. This study evaluates the short-term results of the technique.

METHODS

A retrospective review was carried out of 45 patients, 20 men and 25 women, with a mean age of 24.2 years. In the period from April 1998 to August 1999, 90 consecutive video-assisted sympathicotomy for primary palmar hyperhidrosis either in isolation (n = 56) or in combination with axillary and plantar hyperhidrosis (n = 34) was performed. The mean follow-up period was 11.3 months. Attention was focused on patient's satisfaction, complications, and morbidity.

RESULTS

Dry limbs were immediately achieved in all patients after surgery. There was no operative mortality and one case of transient Horner's syndrome developed. Eight of 20 with plantar hyperhidrosis showed simultaneous improvement. The overall mean satisfaction rate was 92% +/- 2% with a median 93% improvement using a visual linear analogue scale from 0% (poor) to 100% (excellent). Only 2 patients were dissatisfied with the operative results owing to compensatory hyperhidrosis, which occurred in 25 patients and improved in 20 patients within the follow-up period.

CONCLUSIONS

The video-assisted thoracoscopic sympathicotomy with 2-mm endoscope is a speedy and safe way of controlling hyperhidrosis with excellent cosmetic results while minimizing complications.

Purification and properties of extracellular phytase from Bacillus sp. KHU-10

Bacillus species producing a thermostable phytase was isolated from soil, boiled rice, and mezu (Korean traditinal koji). The activity of phytase increased markedly at the late stationary phase. An extracellular phytase from Bacillus sp. KHU-10 was purified to homogeneity by acetone precipitation and DEAE-Sepharose and phenyl-Sepharose column chromatographies. Its molecular weight was estimated to be 46 kDa on gel filtration and 44 kDa on SDS-polyacrylamide gel elctrophoresis. Its optimum pH and temperature for phytase activity were pH 6.5-8.5 and 40 degrees C without 10 mM CaCl2 and pH 6.0-9.5 and 60 degrees C with 10 mM CaCl2. About 50% of its original activity remained after incubation at 80 degrees C or 10 min in the presence of 10 mM CaCl2. The enzyme activity was fairly stable from pH 6.5 to 10.0. The enzyme had an isoelectric point of 6.8. As for substrate specificity, it was very specific for sodium phytate and showed no activity on other phosphate esters. The Km value for sodium phytate was 50 microM. Its activity was inhibited by EDTA and metal ions such as Ba2+, Cd2+, Co2+, Cr3+, Cu2+, Hg2+, and Mn2+ ions.

Characterization of a keratinolytic serine protease from Bacillus subtilis KS-1

A keratinolytic enzyme produced by Bacillus subtilis KS-1 isolated from poultry waste was purified and characterized using ultrfiltration, DEAE-Sephadex, and Sephadex G-100 chromatographies. The specific activity of the purified protease was 538.2 units/mg. The enzyme was shown to have a relative molecular mass of 25.4 kDa. The enzyme was made completely inactive by PMSF, which indicates a serine-protease. Dithiothreitol enhanced keratinolytic activity by 1.6 times at a concentration of 5.0 mM. These results suggest that the cleavage of the disulfide bonds with reducing agents can occur directly or by excretion of sulfite, which causes the sulfitolysis of the disulfide bonds. The first 10 amino acids of the N-terminal sequence are Ala-Gin-Pro-Val-Glu-Trp-GlyIle-Ser-Gln. The enzyme hydrolyzed casein and feather, but hydrolyzed casein more effectively than it did feather.

Cytochrome b6/f complex as an indigenous photodynamic generator of singlet oxygen in thylakoid membranes

Possible association of photodynamic sensitization by cytochrome b6/f complex (cyt b6/f) via singlet oxygen (1O2) mechanism with photoinhibition damage to photosystem II (PS II) was studied using such subthylakoid preparations as photosystem I (PS I) particles, PS II core complex and cyt b6/f from spinach leaves. Upon exposure to bright light, PS II core complex lost photosynthetic electron transport activity to a certain extent, whose-spectral dependence implied that pheophytin a is likely involved in photoinactivation of PS II core complex in itself. The presence of PS I particles exerted virtually no effect on PS II core photoinactivation. However, the inclusion of cyt b6/f in samples resulted in a marked exacerbation of the photoinactivation, particularly in UV-A and blue light. Such effect of cyt b6/f was suppressed by azide and enhanced by the medium deuteration. Photogeneration of 1O2 from cyt b6/f was confirmed by ESR and spectrophotometry, chemically trapping 1O2. Action spectra for both 1O2 photoproduction and PS II core photoinactivation by cyt b6/f bore a close resemblance to each other, seemingly carrying the absorption characteristics of the Rieske Fe-S protein. A complex deficient in the Rieske protein prepared from intact cyt b6/f showed virtually no generation of 1O2 in light, whereas an efficient photoformation of 1O2 was seen in the Rieske protein preparation. The results suggest that cyt b6/f, rather specifically the Rieske center, may play a prominent role in photoinhibition processes through type II photosensitization in thylakoids.

Intracellular survival of Candida albicans in peritoneal macrophages from chronic peritoneal dialysis patients

Candidal peritonitis is a tenacious infection in patients undergoing chronic peritoneal dialysis. Since little is known about host defenses of the human peritoneal cavity against fungi, we investigated the interaction of peritoneal macrophages (PM phi) from uninfected dialysis patients with Candida albicans blastospores. Chemiluminescence (CL) techniques were used to assess the respiratory burst activity of these cells, and candidacidal activity was evaluated with a fluorochrome microassay. In sharp contrast to peripheral blood polymorphonuclear leukocytes (PMNs) from healthy donors, which gave a brisk luminol-enhanced CL response to opsonized blastospores and killed 35% of cell-associated organisms, PM phi produced barely detectable luminol-enhanced CL and killed only 13% of intracellular Candida. These findings appeared to be associated with a decreased level of myeloperoxidase in PM phi. The mechanism of intracellular survival of C albicans also appeared to be related to relatively poor triggering of superoxide production during phagocytosis of viable blastospores. The CL response of PMNs to C albicans was opsonin-dependent, and peritoneal dialysis effluent was devoid of opsonic activity. These studies suggest that local cellular and humoral mechanisms of defense are inadequate for protection of peritoneal dialysis patients against candidal peritonitis.

Opioid peptides rapidly stimulate superoxide production by human polymorphonuclear leukocytes and macrophages

Opioid peptides found in the general circulation can modulate several functions of phagocytic cells that are related to their microbicidal and cytotoxic activity. Since reactive oxygen species are crucial to these activities, the affect of opioid peptides on superoxide (O-2) generation was evaluated with the use of lucigenin-enhanced chemiluminesence (CL). beta-Endorphin and dynorphin stimulate the production of O-2 in human polymorphonuclear leukocytes (PMN) and peritoneal macrophages (PMO) at peptide concentrations that prevail systemically (10(-14)-10(-12)M). There is an inverse dose-response relation for PMN but not PMO. The effect is rapid and sustained in PMN (peak CL at 2-4 min, duration greater than 15 min), whereas it is rapid but brief in PMO (peak 1 min, duration less than 3 min). Naloxone inhibits CL responses by greater than 75% in both cell types.

Antimicrobial activities of dialysate-elicited and resident human peritoneal macrophages

Recent studies of the antimicrobial capacity of peritoneal macrophages (PM phi) isolated from patients undergoing chronic peritoneal dialysis have raised the question of whether these cells might be analogous to stimulated or activated murine PM phi. To explore this possibility, we compared PM phi from these patients (dialysate-elicited PM phi) with PM phi obtained from women undergoing laparoscopy (resident PM phi) in several in vitro assays of phagocyte function. Although bacterial phagocytosis by cells from both groups of donors was similar, significant differences were found in their chemiluminescence responses to opsonized zymosan. Although the mean peak luminol-enhanced chemiluminescence response of dialysate-elicited PM phi was 4.7 X 10(5) cpm, that of resident PM phi was only 1.3 X 10(5) cpm (P less than 0.05). In a lucigenin-enhanced chemiluminescence assay, dialysate-elicited PM phi again generated significantly greater chemiluminescence than did resident PM phi, suggesting that dialysate-elicited PM phi have a relatively increased capacity for O2- production. Using a fluorochrome microassay to assess the intracellular candidicidal activities of these cells, we found that dialysate-elicited PM phi killed 17% of cell-associated blastospores compared with only 1.5% killing by resident PM phi (P less than 0.05). These investigations led us to conclude that results of studies of the functional activity of dialysate-elicited PM phi cannot necessarily be extrapolated to resident PM phi and that dialysate-elicited PM phi do in some respects behave as stimulated or activated cells.