Oak ellagitannins suppress the phosphorylation of the epidermal growth factor receptor in human colon carcinoma cells

The ellagitannins castalagin and vescalagin, and the C-glycosides grandinin and roburin E as well as ellagic acid were found to potently inhibit the growth of human colon carcinoma cells (HT29) in vitro. In a cell-free system these compounds were identified as potent inhibitors of the protein tyrosine kinase activity of the epidermal growth factor receptor (EGFR) with IC 50 values in the low nanomolar range. To address the question of whether the interference with the activity of the isolated EGFR also plays a role within intact cells, effects on the phosphorylation status of the EGFR, as a measure for its activity, were determined in HT29 cells. As exemplified for castalagin and grandinin, both the nonglycosylated and the glycosylated ellagitannins effectively suppressed EGFR phosphorylation, but only at concentrations > or =10 microM, thus, in a concentration range where growth inhibition was observed. These results indicate that the suppression of EGFR-mediated signaling might contribute to the growth inhibitory effects of these compounds present in oak-matured wines and spirits such as whiskey. In contrast, despite substantial growth inhibitory properties, ellagic acid did not significantly affect EGFR phosphorylation in HT29 cells up to 100 microM.     

Imbibition of soybean seeds in warm water results in the release of copious amounts of Bowman-Birk protease inhibitor, a putative anticarcinogenic agent

Protease inhibitors play a protective role against pathogenic microorganisms and herbivorous insects. The two predominant protease inhibitors of soybean seeds are the Kunitz trypsin inhibitor (KTI) and Bowman-Birk protease inhibitor (BBI). In this study, we report that soybean seeds incubated in warm water release large amounts of proteins into the surrounding media. Two-dimensional gel electrophoresis analysis of the seed exudates resulted in the separation of 93 distinct protein spots out of which 90 spots were identified by LC-MS/MS. The basic 7S globulin and the BBI are the two predominant proteins found in the soybean seed exudates. In addition to 7S and 11S seed storage proteins, others known to protect the seeds against pathogens and pests including KTI, peroxidase, α-galactosidase, and endo-1.3-β-glucanase were also identified in the seed exudates. Soybean seed exudate obtained by incubating the seeds in warm water was also able to inhibit the growth of human breast cancer cell line MCF-7. Since soybean seeds release large amounts of enzymatically active BBI when immersed in warm water, our procedure could be exploited as a simplified alternative method for the preparation of BBI concentrate which is being used as a cancer chemoprotective agent.     

In vitro digestibility of the cancer-preventive soy peptides lunasin and BBI

Lunasin and BBI (Bowman Birk protease inhibitor) are bioactive soy peptides that have been shown to be effective suppressors of carcinogenesis in in vitro and in vivo model systems. Since they are subject to digestion in the gastrointestinal tract, we investigated here the stabilities of lunasin and BBI to digestion in vitro by simulated intestinal fluid (SIF) and simulated gastric fluid (SGF). Samples containing lunasin and BBI of varying purities were subjected to in vitro digestion by SIF and SGF at different times and analyzed by Western blot. While the pure BBI reaction is stable after SIF and SGF digestions, the purified lunasin from soybean and synthetic lunasin are easily digested after 2 min in both in vitro digestions. In contrast, lunasin from soy protein containing BBI is comparatively stable after SIF and SGF digestions. Both lunasin and BBI are able to internalize into the cell and localize in the nucleus even after digestion, suggesting that some of the peptides are intact and bioactive. These data suggest that BBI plays a role in protecting lunasin from digestion when soy protein is consumed orally. The role of other soy protease inhibitors such as Kunitz Trypsin Inhibitor (KTI) cannot be excluded from these experiments.     

Pretreatment with an ethanolic extract of Taiwanofungus camphoratus (Antrodia camphorata) enhances the cytotoxic effects of amphotericin B

Taiwanofungus camphoratus, a well-known Chinese medicine used in Taiwan, possesses several pharmacological functions, including anticancer effects. In the present study, we aimed to investigate a novel anticancer effect by pretreating cancer cells with an ethanolic extract of T. camphoratus (TCEE) followed by the administration of an antifungal agent amphotericin B (AmB). Both TCEE and AmB showed significant dose-dependent cytotoxicity in HT29 cells. Pretreatment with a nontoxic dose of TCEE enhanced the cytotoxicity of AmB. Furthermore, significant apoptotic cell death was found in cells treated with TCEE and AmB. A combination treatment with AmB plus TCEE resulted in a significant repression of tumor growth in HT29 xenografts. Collectively, our results indicated that combined treatment with AmB and TCEE effectively induced apoptosis and inhibited tumor growth. In the future, TCEE may serve as a potential complementary and alternative medicine to treat patients suffering from colorectal cancer.     

Bowman-Birk and Kunitz Protease Inhibitors among Antinutrients and Bioactives Modified by Germination and Hydrolysis in Brazilian Soybean Cultivar BRS 133

Soybean contains constituents that have antinutritional and bioactive properties. Enzymatic hydrolysis and germination can enhance the biological activity of these compounds in soybean. The objective of this study was to investigate the effect of germination, Alcalase (protease) hydrolysis, and their combination on the concentrations of antinutritional and bioactive compounds in Brazilian soybean cultivar BRS 133. A combination of germination and Alcalase hydrolysis resulted in the degradation of Bowman-Birk inhibitor (BBI), Kunitz trypsin inhibitor (KTI), and lunasin by 96.9, 97.8, and 38.4%. Lectin was not affected by any of the processing treatments when compared to nongerminated and nonhydrolyzed soy protein extract. Total isoflavones (ISF) and total saponins (SAP) increased by 16.2 and 28.7%, respectively, after 18 h of germination, while Alcalase hydrolysis led to the reduction of these compounds. A significant correlation was found between concentrations of BBI and KTI, BBI and lunasin, BBI and ISF, KTI and lunasin, KTI and ISF, KTI and SAP, lunasin and ISF, and ISF and SAP. Germination and Alcalase hydrolysis interacted in reducing BBI, ISF, and SAP. This study presents a process of preparing soy flour ingredients with lower concentrations of antinutritional factors and with biologically active constituents, important for the promotion of health associated with soybean consumption. In conclusion, 18 h of germination and 3 h of Alcalase hydrolysis is recommended for elimination of protease inhibitors, while bioactives are maintained by at least 50% of their original concentrations.     

beta-Conglycinins among sources of bioactives in hydrolysates of different soybean varieties that inhibit leukemia cells in vitro

Soybean is a complex matrix containing several potentially bioactive components. The objective was to develop a statistical model to predict the in vitro anticancer potential of soybean varieties based on the correlation between protein composition and bioactive components after simulated gastrointestinal enzyme digestion with their effect on leukemia mouse cells. The IC 50 values of the hydrolysates of soy genotypes (NB1-NB7) on L1210 leukemia cells ranged from 3.5 to 6.2 mg/mL. Depending on genotype, each gram of soy hydrolysates contained 2.7-6.6 micromol of total daidzein, 3.0-4.7 micromol of total genistein, 0.5-1.3 micromol of glycitein, 2.1-2.8 micromol of total saponins, 0.1-0.2 micromol of lunasin, and 0.1-0.6 micromol of Bowman-Birk inhibitor (BBI). The IC 50 values calculated from a partial least-squares (PLS) analysis model correlated well with experimental data ( R (2) = 0.99). Isoflavones and beta-conglycinin positively contributed to the cytotoxicity of soy on L1210 leukemia cells. Lunasin and BBI were potent L1210 cell inhibitors (IC 50 = 13.9 and 22.5 microM, respectively), but made modest contributions to the activity of defatted soy flour hydrolysates due to their relatively low concentrations. In conclusion, the data demonstrated that beta-conglycinins are among the major protein components that inhibit leukemia cell growth in vitro. Furthermore, it was feasible to differentiate soybean varieties on the basis of the biological effect of their components using a statistical model and a cell-based assay.     

Immunoassays of soy proteins

Proteins of soybeans (Glycine max) are widely used in animal and human nutrition. In addition to the bulk of the seed storage proteins, which are classified as albumins and globulins, approximately 6% of soybean proteins are classified as inhibitors of trypsin and chymotrypsin and approximately 0.5% are sugar-binding lectins. The two major classes of inhibitors are the Kunitz trypsin inhibitor, which inhibits trypsin, and the Bowman-Birk inhibitor (BBI), which inhibits both trypsin and chymotrypsin. Unless removed or inactivated, these inhibitors and lectins can impair the nutritional quality and safety of soy-based diets. On the other hand, several studies suggest that BBI can also function as an anticarcinogen, possibly through interaction with a cellular serine protease. Good-quality soybean proteins contribute to the nutritional value of many specialty foods including infant soy formulas and milk replacers for calves, and provide texture to many processed foods. However, they may also induce occasional allergic responses in humans. This paper outlines immunoassays developed to analyze for soy proteins in different soybean lines, in processed foods, and in nonsoy foods fortified with soy proteins. An assessment of the current status of immunoassays, especially of enzyme-linked immunosorbent assays for soybean inhibitors of digestive enzymes, soy globulins, and soy lectins, demonstrates the usefulness of these methods in plant and food sciences and in medicine.     

Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.     

Peptides from Lactobacillus hydrolysates of bovine milk caseins inhibit prolyl-peptidases of human colon cells

Prolyl-rich peptides derived from hydrolysates of bovine caseins have been previously shown to inhibit angiotensin converting enzyme (ACE) activity, suggesting that they may also be able to inhibit the enzymatic activities of prolyl-specific peptidases. This study shows that peptides derived from α(S1)-casein and β-casein inhibited the enzymatic activities of purified recombinant matrix metalloprotease (MMP)-2, MMP-7, and MMP-9. The inhibitory efficacy was sequence-dependent. These peptides also selectively inhibited the enzymatic activities of prolyl-amino-peptidases, prolyl-amino-dipeptidases, and prolyl-endopeptidases in extracts of HT-29 and SW480 human colon carcinoma cells, but not in intact cells. They were not cytotoxic or growth inhibitory for these cells. Thus, the prolyl-rich selected peptides were good and selective inhibitors of MMPs and post-proline-cleaving proteases, demonstrating their potential to control inadequate proteolytic activity in the human digestive tract, without inducing cytotoxic effects.     

Apple polyphenols affect protein kinase C activity and the onset of apoptosis in human colon carcinoma cells

Polyphenol-rich apple extracts have been reported to suppress human colon cancer cell growth in vitro. The protein kinase C (PKC) is among the signaling elements known to play an important role in colon carcinogenesis. In the present study, we investigated whether apple polyphenols affect PKC activity and induce apoptosis in the human colon carcinoma cell line HT29. A polyphenol-rich apple juice extract (AE02) was shown to inhibit cytosolic PKC activity in a cell-free system. In contrast, incubation of HT29 cells for 1 or 3 h with AE02 up to 2 mg/mL did not affect the cytosolic PKC activity. After prolonged incubation (24 h), cytosolic PKC activity was modulated, albeit a u-shaped curve of effectiveness was observed, with an initial inhibitory effect followed by the recurrence and even induction of enzyme activity. Concomitantly, in the cytosol, a significant decrease of the protein levels of PKCalpha, PKCbetaII, and PKCgamma together with a significant increase of a proapoptotic PKCdelta fragment was observed. However, the effects on the protein levels of these PKC isoforms in the cytosol were not associated with translocation between the different cellular compartments but might instead result from the onset of apoptosis. Indeed, the treatment with AE02 was shown to induce apoptosis by the activation of caspase-3, DNA fragmentation, and cleavage of poly(ADP ribose) polymerase. So far, identified and available constituents of the apple extract did not contribute substantially to the observed effects on PKC and apoptosis induction. In summary, apple polyphenols were found to inhibit PKC activity in a cell-free system. However, our results indicate that within intact cells PKC does not represent the primary target of apple polyphenols but appears to be affected in the course of apoptosis induction.     

Contents and bioactivities of lunasin, bowman-birk inhibitor, and isoflavones in soybean seed

It has been previously demonstrated that lunasin is a novel and promising cancer preventive peptide from soybean. The Bowman-Birk protease inhibitor (BBI) and isoflavones are well-studied substances from soy. This study evaluated the levels and bioactivities of these three compounds as affected by stages of seed development and sprouting under light and dark conditions. BBI and lunasin appear at 7 and 6 weeks, respectively, after flowering and increase as the seed matures. Daidzein and genistein both decrease during seed maturation. During sprouting under light, BBI increases up to the 6th day and decreases thereafter, disappearing at the 9th day after soaking. Under dark conditions, BBI increases up to the 7th day after soaking and decreases thereafter, disappearing at the 10th day. Lunasin starts to decrease at 2 days after soaking and disappears completely at 7 days under light and dark conditions. Daidzein and genistein increase continuously during the 10 days of soaking, and both increase more in the dark than under light conditions. Protein extracts from early seed development (2-5 weeks after flowering) suppress cell viability to a greater degree than those from later stages (6-9 weeks). Inhibition of foci formation by protein extracts from later stages is greater than those from earlier stages. Lunasin and BBI suppress foci formation more than the isoflavones. Sprouting decreases lunasin and BBI contents but increases isoflavones. Protein extracts from early soaking times inhibit foci formation more and suppress cell viability less than those from later soaking times. Light and dark conditions have no influence on the bioactivities of protein extracts. These data are useful in the preparation of soy fractions enriched in lunasin, BBI, and isoflavones and in making dietary recommendations.     

Relative abundance and inhibitory distribution of protease inhibitors in potato juice from cv. Elkana.

Protease inhibitors from potato juice of cv. Elkana were purified and quantified. The protease inhibitors represent ca. 50% of the total soluble proteins in potato juice. The protease inhibitors were classified into seven different families: potato inhibitor I (PI-1), potato inhibitor II (PI-2), potato cysteine protease inhibitor (PCPI), potato aspartate protease inhibitor (PAPI), potato Kunitz-type protease inhibitor (PKPI), potato carboxypeptidase inhibitor (PCI), and "other serine protease inhibitors". The most abundant families were the PI-2 and PCPI families, representing 22 and 12% of all proteins in potato juice, respectively. Potato protease inhibitors show a broad spectrum of enzyme inhibition. All the families (except PCI) inhibited trypsin and/or chymotrypsin. PI-2 isoforms exhibit 82 and 50% of the total trypsin and chymotrypsin inhibiting activity, respectively. A strong variation within the latter activities was shown within one family and between protease inhibitor families.     

Biochemical and biophysical changes induced by fungicide sodium diethyl dithiocarbamate (SDD), in phytocystatin purified from Phaseolus mungo (Urd): a commonly used Indian legume

Phytocystatins are the plant thiol protease inhibitors involved in several reaction mechanisms of the plant system like regulation of proteolytic activity and storage of proteins. Biochemical and biophysical changes induced by fungicide SDD in phytocystatin purified from Phaseolus mungo have been investigated in terms of mass spectroscopy, Fourier transform infrared spectroscopy, and fluorescence spectroscopy, at pH 7.0, with varying fungicide concentrations (1-9 mM) and a time of incubation ranging from 2 to 8 h at 37 degrees C, with a fixed cystatin concentration (1.5 mM). Reactive oxygen species responsible for inhibitor damage were also investigated, and thiourea was found to scavenge the free radicals generated by SDD. FTIR analysis indicates a significant conformational transition from alpha-helix to beta-sheet structure; quenching of fluorescence is evident by fluorescence spectroscopy. The activity assay showed a decrease in inhibitory activity, as well as a fragmentation of the inhibitor was observed in electrophoresis. Results obtained implicate that exposure of phytocystatins to SDD involves physicochemical changes in cystatins leading to damage and a decrease in the activity of the inhibitor.     

Effects of commercial anthocyanin-rich extracts on colonic cancer and nontumorigenic colonic cell growth

Commercially prepared grape (Vitis vinifera), bilberry (Vaccinium myrtillus L.), and chokeberry (Aronia meloncarpa E.) anthocyanin-rich extracts (AREs) were investigated for their potential chemopreventive activity against colon cancer. The growth of colon-cancer-derived HT-29 and nontumorigenic colonic NCM460 cells exposed to semipurified AREs (10-75 microg of monomeric anthocyanin/mL) was monitored for up to 72 h using a sulforhodamine B assay. All extracts inhibited the growth of HT-29 cells, with chokeberry ARE being the most potent inhibitor. HT-29 cell growth was inhibited approximately 50% after 48 h of exposure to 25 microg/mL chokeberry ARE. Most importantly, the growth of NCM460 cells was not inhibited at lower concentrations of all three AREs, illustrating greater growth inhibition of colon cancer, as compared to nontumorigenic colon cells. Extracts were semipurified and characterized by high-pressure liquid chromatography, spectrophotometry, and colorimetry. Grape anthocyanins were the glucosylated derivatives of five different anthocyanidin molecules, with or without p-coumaric acid acylation. Bilberry contained five different anthocyanidins glycosylated with galactose, glucose, and arabinose. Chokeberry anthocyanins were cyanidin derivatives, monoglycosylated mostly with galactose and arabinose. The varying compositions and degrees of growth inhibition suggest that the anthocyanin chemical structure may play an important role in the growth inhibitory activity of commercially available AREs.     

Antioxidant levels and inhibition of cancer cell proliferation in vitro by extracts from organically and conventionally cultivated strawberries

The effects of extracts from five cultivars of strawberries on the proliferation of colon cancer cells HT29 and breast cancer cells MCF-7 were investigated, and possible correlations with the levels of several antioxidants were analyzed. In addition, the effects of organic cultivation compared to conventional cultivation on the content of antioxidants in the strawberries and strawberry extracts on the cancer cell proliferation were investigated. The ratio of ascorbate to dehydroascorbate was significantly higher in the organically cultivated strawberries. The strawberry extracts decreased the proliferation of both HT29 cells and MCF-7 cells in a dose-dependent way. The inhibitory effect for the highest concentration of the extracts was in the range of 41-63% (average 53%) inhibition compared to controls for the HT29 cells and 26-56% (average 43%) for MCF-7 cells. The extracts from organically grown strawberries had a higher antiproliferative activity for both cell types at the highest concentration than the conventionally grown, and this might indicate a higher content of secondary metabolites with anticarcinogenic properties in the organically grown strawberries. For HT29 cells, there was a negative correlation at the highest extract concentration between the content of ascorbate or vitamin C and cancer cell proliferation, whereas for MCF-7 cells, a high ratio of ascorbate to dehydroascorbate correlated with a higher inhibition of cell proliferation at the second highest concentration. The significance of the effect of ascorbate on cancer cell proliferation might lie in a synergistic action with other compounds.     

Purification and identification of a protease inhibitor from glassfish (Liparis tanakai) eggs

Two protease inhibitors of 67 and 18 kDa, respectively, were purified from glassfish, Liparis tanakai, eggs by affinity chromatography. The smaller protein was purified with a yield and purity of 0.25% and 49.69-fold, respectively, and was characterized for further study. The glassfish egg protease inhibitor exhibited stability between 50 and 65 degrees C in an alkaline environment (pH 8). It was shown to be a noncompetitive inhibitor against papain, with an inhibitor constant (Ki) of 4.44 nM. Potent glassfish protease inhibitor with N-Val-Gly Ser-Met-Thr-Gly-Gly-Phe-Thr-Asp-C amino acid residues was synthesized and its inhibitory activity was compared. Moreover, the 18-kDa protein inhibited cathepsin, a cysteine protease, more effectively than did egg white protease inhibitor, whereas the reverse was true for papain. Glassfish egg protease inhibitor is classified as a member of the family I cystatins.     

Probing the soybean Bowman-Birk inhibitor using recombinant antibody fragments

The nutritional and health benefits of soy protein have been extensively studied over recent decades. The Bowman-Birk inhibitor (BBI), derived from soybeans, is a double-headed inhibitor of chymotrypsin and trypsin with anticarcinogenic and anti-inflammatory properties, which have been demonstrated in vitro and in vivo. However, the lack of analytical and purification methodologies complicates its potential for further functional and clinical investigations. This paper reports the construction of anti-BBI antibody fragments based on the principle of protein design. Recombinant antibody (scFv and diabody) molecules targeting soybean BBI were produced and characterized in vitro (K(D)~1.10(-9) M), and the antibody-binding site (epitope) was identified as part of the trypsin-specific reactive loop. Finally, an extremely fast purification strategy for BBI from soybean extracts, based on superparamagnetic particles coated with antibody fragments, was developed. To the best of the authors' knowledge, this is the first report on the design and characterization of recombinant anti-BBI antibodies and their potential application in soybean processing.     

第四类配合物型脲酶抑制剂对油菜生长及土壤氮素转化的影响

研究不同浓度第四类新型Schiff碱配合物型脲酶抑制剂对油菜生长及其对土壤氮素转化的影响,旨在为此类新型脲酶抑制剂在农业上的推广应用提供依据。采用室外盆栽方法,比较新型脲酶抑制剂(SU)和市售脲酶抑制剂乙酰氧肟酸(AHA)对油菜产量、品质、生长状况、氮素吸收利用和土壤表观硝化率等指标的影响。结果表明:SU和AHA均能提高油菜产量,提高油菜品质指标和养分指标,其中SU对油菜增产和养分增效的效果比AHA明显;SU平均提高油菜产量28.0%,显著降低油菜硝酸盐含量28.8%～50.8%,同时促进油菜对氮、磷的吸收,使氮肥利用率平均提高68.0%,在一定程度也能降低土壤表观硝化率,平均降低35.2%。不同浓度新型抑制剂处理的油菜指标和抑制尿素水解效果不同,表现为低中浓度的抑制剂对油菜增产和养分增效效果优于高浓度,其中抑制剂用量为纯氮施入量的1%时对尿素水解抑制的效果最好,因此施入纯氮量的1%为此类抑制剂的最佳用量。     

Nitrogen lowers the sulfur amino acid content of soybean (Glycine max [L.] Merr.) by regulating the accumulation of Bowman-Birk protease inhibitor

Soybeans in general contain 35-40% protein. Efforts are underway to increase further this protein content, thus enhancing their nutritive value. Even though higher protein is a desirable characteristic, whether such an increase will be accompanied by enhanced protein quality is not known. Soybean protein quality could be significantly improved by increasing the concentration of the sulfur-containing amino acids, cysteine and methionine. To ascertain if a correlation existed between protein quantity and quality, a comparison of the amino acids of soybeans differing in protein content was made. Soybeans with higher protein content had a significantly lower percentage of sulfur amino acids, while those with lower protein exhibited a higher content of cysteine and methionine. Nitrogen application elevated the protein content but lowered that of the sulfur amino acids. Transmission electron microscopy examination of thin sections of low protein soybean seeds revealed several protein storage vacuoles that were partially filled with storage proteins. Fluorescence two-dimensional difference gel electrophoresis of soybean seed proteins revealed that nitrogen application favored the accumulation of the beta-subunit of beta-conglycinin while decreasing the accumulation of Bowman-Birk protease inhibitor (BBI), a protein rich in cysteine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 60% 2-propanol-extracted proteins showed a drastic reduction in the accumulation of BBI with increasing protein content. Northern blot analysis indicated that nitrogen had a negative influence on the expression of the BBI gene. Our results indicate that the negative correlation between total protein and sulfur amino acid content is mostly mediated by the differential accumulation of BBI.