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Zhang Y, Chang SK. Trypsin inhibitor activity, phenolic content and antioxidant capacity of soymilk as affected by grinding temperatures, heating methods and soybean varieties. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2021.112424] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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2
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Adeleye OO, Awodiran ST, Ajayi AO, Ogunmoyela TF. Effect of high-temperature, short-time cooking conditions on in vitro protein digestibility, enzyme inhibitor activity and amino acid profile of selected legume grains. Heliyon 2020; 6:e05419. [PMID: 33225089 PMCID: PMC7662876 DOI: 10.1016/j.heliyon.2020.e05419] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/24/2019] [Accepted: 10/29/2020] [Indexed: 11/26/2022] Open
Abstract
African yam beans (Sphenostylis stenocarpa), Bambara groundnut (Vigna subterranean) and Pigeon pea (Cajanus cajan) flours were extruded in a single screw extruder at two extrusion temperatures; 100 °C and 140 °C, and the effect of extrusion cooking temperature on the chemical composition; crude protein, crude fibre, ether extract and nitrogen-free extracts, protein digestibility, enzyme inhibitor activity and amino acid profiles was investigated. The crude protein, amino acid profile and ether extract of the grain legumes were negatively affected (p < 0.05) by the extrusion cooking process, with a significant increase in nitrogen-free extracts for all grain legumes, and increased crude fibre of Bambara groundnut and Pigeon pea extrudates. Extrusion cooking of African yam beans and Pigeon pea produced extrudates with significantly lower trypsin, chymotrypsin and amylase inhibitor activity as well as improved protein digestibility. However, extrusion cooking did not modify the chymotrypsin and amylase inhibitor activity of Bambara groundnut extrudates. Extrusion cooking at 140 °C compared to 100 °C significantly reduced the protein quality of extrudates resulting in 22.94-51.27%, 5.11-25.18%, and 7.78-38.42% reduction in amino acid concentration of African yam beans, Bambara groundnut and Pigeon pea, respectively.
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Affiliation(s)
- Oluwafunmilayo O. Adeleye
- Agricultural Biochemistry and Nutrition Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria
| | - Seun T. Awodiran
- Agricultural Biochemistry and Nutrition Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria
| | - Atinuke O. Ajayi
- Agricultural Biochemistry and Nutrition Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria
| | - Toluwalope F. Ogunmoyela
- Agricultural Biochemistry and Nutrition Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria
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3
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Xu Q, Qu J, Song B, Liu F, Chen P, Krishnan HB. Lathyrus sativus Originating from Different Geographical Regions Reveals Striking Differences in Kunitz and Bowman-Birk Inhibitor Activities. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:8119-8129. [PMID: 31265283 DOI: 10.1021/acs.jafc.9b02604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Grass pea (Lathyrus sativus L.) is an important legume commonly grown in arid and semi-arid regions. This protein-rich legume performs well even under harsh environmental conditions and is considered to be a strategic famine food in developing countries. Unfortunately, its potential usage is greatly limited as a result of the presence of antinutritional factors, including the neuroexcitatory amino acid β-N-oxalyl-l-α,β-diaminopropionic acid (β-ODAP) and protease inhibitors. β-ODAP is responsible for a neurodegenerative syndrome that results in the paralysis of lower limbs, while protease inhibitors affect protein digestibility, resulting in reduced growth. Concerted research efforts have led to development of grass pea cultivars with reduced β-ODAP content. In contrast, very little information is available on the protease inhibitors of L. sativus. In this study, we have conducted biochemical characterization of 51 L. sativus accessions originating from different geographical regions. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analyses of seed globulins and prolamins revealed striking similarity in their protein profile, although geographic-specific variations in profiles was also evident. Measurement of Bowman-Birk chymotrypsin inhibitor (BBi) and Kunitz trypsin inhibitor (KTi) activities in accessions revealed striking differences among them. Amino acid sequence alignment of grass pea BBi and KTi revealed significant homology to protease inhibitors from several legumes. Real-time polymerase chain reaction analysis demonstrated high-level expression of BBi and KTi in dry seeds and weak expression in other organs. Our study demonstrates substantial variation in BBi and KTi among grass pea accessions that could be exploited in breeding programs for the development of grass pea lines that are devoid of these antinutritional factors.
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Affiliation(s)
- Quanle Xu
- College of Life Sciences , Northwest A&F University , Yangling , Shaanxi 712100 , People's Republic of China
- Plant Genetics Research, United States Department of Agriculture's Agricultural Research Service (USDA-ARS) , University of Missouri , Columbia , Missouri 65211 , United States
| | - Jinmiao Qu
- College of Life Sciences , Northwest A&F University , Yangling , Shaanxi 712100 , People's Republic of China
| | - Bo Song
- Plant Genetics Research, United States Department of Agriculture's Agricultural Research Service (USDA-ARS) , University of Missouri , Columbia , Missouri 65211 , United States
- Key Laboratory of Soybean Biology at the Chinese Ministry of Education , Northeast Agricultural University , Harbin , Heilongjiang 150030 , People's Republic of China
| | - Fengjuan Liu
- College of Life Sciences , Northwest A&F University , Yangling , Shaanxi 712100 , People's Republic of China
| | - Peng Chen
- College of Life Sciences , Northwest A&F University , Yangling , Shaanxi 712100 , People's Republic of China
| | - Hari B Krishnan
- Plant Genetics Research, United States Department of Agriculture's Agricultural Research Service (USDA-ARS) , University of Missouri , Columbia , Missouri 65211 , United States
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4
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Identification and characterization of a calcium dependent bacillopeptidase from Bacillus subtilis CFR5 with novel kunitz trypsin inhibitor degradation activity. Food Res Int 2018; 103:263-272. [DOI: 10.1016/j.foodres.2017.10.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2017] [Revised: 10/16/2017] [Accepted: 10/28/2017] [Indexed: 12/24/2022]
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5
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Pade D, Jamei M, Rostami-Hodjegan A, Turner DB. Application of the MechPeff model to predict passive effective intestinal permeability in the different regions of the rodent small intestine and colon. Biopharm Drug Dispos 2017; 38:94-114. [PMID: 28214380 DOI: 10.1002/bdd.2072] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/26/2017] [Accepted: 02/03/2017] [Indexed: 01/17/2023]
Abstract
A major component of physiologically based pharmacokinetic (PBPK) models is the prediction of the rate and extent of absorption of orally dosed drugs for which knowledge of effective passive intestinal permeability (Peff ) is essential. Single-pass intestinal perfusion (SPIP) studies are used to establish effective permeability in vivo but are difficult to perform in rodents, while mechanistic models to predict drug Peff in rat and mouse have not been published. This work evaluates the predictive performance of the 'MechPeff' model to predict Peff in the rodent intestine based upon knowledge of regional gut physiology and drug-specific physicochemical parameters. The 'MechPeff' model, built-in to the Simcyp Rat and Mouse Simulators, predicts transcellular, paracellular and mucus layer permeabilities and combines these to give the overall Peff . The jejunal and/or ileal Peff was predicted for 12 (4) acidic, 13 (12) basic, 10 (8) neutral and 2 (0) ampholytic drugs in the rat (mouse), spanning a wide range of MW and logPo:w , and compared with experimental Peff obtained using SPIP. A key input is the intrinsic transcellular permeability (Ptrans,0 ) which can be derived from modelling of appropriate in vitro permeability experiments or predicted from physicochemical properties. The Peff predictions were reasonably good when experimentally derived Ptrans,0 was used; from 42 Peff,rat values, 24 (57%) were within 3-fold, and of 19 Peff,mouse values, 12 (63%) were within 3-fold, of observed Peff . Considering the lack of alternative models to predict Peff in preclinical species, and the minimal drug-specific inputs required, this model provides a valuable tool within drug discovery and development programmes. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- D Pade
- Blades Enterprise Centre, Simcyp Ltd (A Certara Company), John Street, Sheffield, S2 4SU, UK
| | - M Jamei
- Blades Enterprise Centre, Simcyp Ltd (A Certara Company), John Street, Sheffield, S2 4SU, UK
| | - A Rostami-Hodjegan
- Blades Enterprise Centre, Simcyp Ltd (A Certara Company), John Street, Sheffield, S2 4SU, UK.,Centre for Applied Pharmacokinetic Research, Manchester Pharmacy School, Stopford Building, University of Manchester Medical School, Oxford Road, Manchester, M13 9PT, UK
| | - D B Turner
- Blades Enterprise Centre, Simcyp Ltd (A Certara Company), John Street, Sheffield, S2 4SU, UK
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6
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Oral delivery of macromolecular drugs: Where we are after almost 100years of attempts. Adv Drug Deliv Rev 2016; 101:108-121. [PMID: 26826437 DOI: 10.1016/j.addr.2016.01.010] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/11/2016] [Accepted: 01/18/2016] [Indexed: 02/08/2023]
Abstract
Since the first attempt to administer insulin orally in humans more than 90years ago, the oral delivery of macromolecular drugs (>1000g/mol) has been rather disappointing. Although several clinical pilot studies have demonstrated that the oral absorption of macromolecules is possible, the bioavailability remains generally low and variable. This article reviews the formulations and biopharmaceutical aspects of orally administered biomacromolecules on the market and in clinical development for local and systemic delivery. The most successful approaches for systemic delivery often involve a combination of enteric coating, protease inhibitors and permeation enhancers in relatively high amounts. However, some of these excipients have induced local or systemic adverse reactions in preclinical and clinical studies, and long-term studies are often missing. Therefore, strategies aimed at increasing the oral absorption of macromolecular drugs should carefully take into account the benefit-risk ratio. In the absence of specific uptake pathways, small and potent peptides that are resistant to degradation and that present a large therapeutic window certainly represent the best candidates for systemic absorption. While we acknowledge the need for systemically delivering biomacromolecules, it is our opinion that the oral delivery to local gastrointestinal targets is currently more promising because of their accessibility and the lacking requirement for intestinal permeability enhancement.
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Pereira de Sousa I, Bernkop-Schnürch A. Pre-systemic metabolism of orally administered drugs and strategies to overcome it. J Control Release 2014; 192:301-9. [DOI: 10.1016/j.jconrel.2014.08.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/04/2014] [Accepted: 08/05/2014] [Indexed: 01/18/2023]
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8
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Bile enhances glucose uptake, reduces permeability, and modulates effects of lectins, trypsin inhibitors and saponins on intestinal tissue. Comp Biochem Physiol A Mol Integr Physiol 2014; 168:96-109. [DOI: 10.1016/j.cbpa.2013.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 11/14/2013] [Accepted: 11/22/2013] [Indexed: 12/24/2022]
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9
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Stong DB, Carlsson SC, Bjurström S, Fransson-Steen R, Healing G, Skånberg I. Two-year carcinogenicity studies with the oral direct thrombin inhibitor ximelagatran in the rat and the mouse. Int J Toxicol 2012; 31:348-57. [PMID: 22692977 DOI: 10.1177/1091581812448881] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The results of 18 months mouse and 24 months rat carcinogenicity studies with the oral direct thrombin inhibitor ximelagatran are presented. In the mouse, gavage doses of ximelagatran up to 180 μmol/kg per d produced no neoplastic changes in any of the tissues examined. In the rat, gavage doses up to 240 μmol/kg per d produced multiple macroscopically detectable nodules in the pancreas, which are seen to be focal/multifocal acinar cell hyperplasia and focal/multifocal acinar cell adenoma upon histological evaluation. There were no other treatment-related effects on tumor incidence or distribution in the rat. The studies show a clear species difference in pancreatic effects between the rat and the mouse to long-term treatment with ximelagatran.
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Affiliation(s)
- David B Stong
- Global Safety Assessment, AstraZeneca Pharmaceuticals LP, Sodertalje, Sweden.
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10
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Abstract
Macromolecular therapeutics, in particular, many biologics, is the most advancing category of drugs over conventional chemical drugs. The potency and specificity of the biologics for curing certain disease made them to be a leading compound in the pharmaceutical industry. However, due to their intrinsic nature, including high molecular weight, hydrophilicity and instability, they are difficult to be administered via non-invasive route. This is a major quest especially in biologics, as they are frequently used clinically for chronic disorders, which requires long-term administration. Therefore, many efforts have been made to develop formulation for non-invasive administration, in attempt to improve patient compliance and convenience. In this review, strategies for non-invasive delivery, in particular, oral, pulmonary and nasal delivery, that are recently adopted for delivery of biologics are discussed. Insulin, calcitonin and heparin were mainly focused for the discussion as they could represent protein, polypeptide and polysaccharide drugs, respectively. Many recent attempts for non-invasive delivery of biologics are compared to provide an insight of developing successful delivery system.
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Affiliation(s)
- Seung Woo Chung
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul, Korea
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Tashiro M, Samuelson LC, Liddle RA, Williams JA. Calcineurin mediates pancreatic growth in protease inhibitor-treated mice. Am J Physiol Gastrointest Liver Physiol 2004; 286:G784-90. [PMID: 14684381 DOI: 10.1152/ajpgi.00446.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
CCK acts on pancreatic acinar cells to increase intracellular Ca(2+) leading to secretion of digestive enzymes and, in the long term, pancreatic growth. Calcineurin (CN) is a serine/threonine-specific protein phosphatase activated by Ca(2+) and calmodulin that recently has been shown to participate in the growth regulation of cardiac and skeletal myocytes. We therefore tested the effect of two different CN inhibitors, cyclosporine A (CsA) and FK506, on mouse pancreatic growth induced by oral administration of the synthetic protease inhibitor camostat, a known stimulator of endogenous CCK release. Mice were fed a powdered diet with or without 0.1% camostat. Pancreatic wet weight, protein, and DNA were increased in response to camostat in a time-dependent manner over 10 days in ICR mice but not in CCK-deficient mice. Both CsA (15 mg/kg) and FK506 (3 mg/kg) given twice daily blocked the increase in pancreatic wet weight and protein and DNA content induced by camostat. The increase in plasma CCK induced by camostat was not blocked by CsA or FK506. Camostat feeding also increased the relative amount of CN protein, whereas levels of MAPKs, ERKs, and p38 were not altered. In summary, 1) CCK released by chronic camostat feeding induces pancreatic growth in mice; 2) this growth is blocked by treatment with both CsA and FK506, indicating a role for CN; 3) CCK stimulation also increases CN protein. In conclusion, activation and possibly upregulation of CN may participate in regulation of pancreatic growth by CCK in mice.
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Affiliation(s)
- Mitsuo Tashiro
- Molecular and Integrative Physiology, Univ. of Michigan Medical School, 7744 Medical Science II, Ann Arbor, MI 48109-0622, USA
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12
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Csáky I, Fekete S. Soybean: feed quality and safety. Part 2: pathology of soybean feeding in animals. A review. Acta Vet Hung 2004; 52:315-26. [PMID: 15379446 DOI: 10.1556/avet.52.2004.3.7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Various animal models in farm and laboratory animals indicate the possible pathological effect of soybean feeding. Immunity and tolerance to oral soybean intake and a generalised meta-model of effects are discussed. It seems that FAO/WHO recommendations will have to be considered in assessing the biological value of soybean feed sources. Determination of hull content, antigenic potential, conglycinin and trypsin inhibitor content is warranted in view of the future component pricing of soybean meals.
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Affiliation(s)
- I Csáky
- Institute of Animal Breeding, Nutrition and Laboratory Animal Science, Faculty of Veterinary Science, Szent István University, H-1078 Budapest, István u 2, Hungary.
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13
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Sood A, Panchagnula R. Peroral route: an opportunity for protein and peptide drug delivery. Chem Rev 2001; 101:3275-303. [PMID: 11840987 DOI: 10.1021/cr000700m] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- A Sood
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
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Vadivel V, Janardhanan K. Nutritional and anti-nutritional attributes of the under-utilized legume, Cassia floribunda Cav. Food Chem 2001. [DOI: 10.1016/s0308-8146(00)00280-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Bernkop-Schnürch A. Chitosan and its derivatives: potential excipients for peroral peptide delivery systems. Int J Pharm 2000; 194:1-13. [PMID: 10601680 DOI: 10.1016/s0378-5173(99)00365-8] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In the 1990s chitosan turned out to be a useful excipient in various pharmaceutical formulations. By modifications of the primary amino group at the 2-position of this poly(beta1-->4 D-glucosamine), the features of chitosan can even be optimised according to a given task in drug delivery systems. For peroral peptide delivery these tasks focus on overcoming the absorption (I) and enzymatic barrier (II) of the gut. On the one hand, even unmodified chitosan proved to display a permeation enhancing effect for peptide drugs. On the other hand, a protective effect for polymer embedded peptides towards degradation by intestinal peptidases can be achieved by the immobilisation of enzyme inhibitors on the polymer. Whereas serine proteases are inhibited by the covalent attachment of competitive inhibitors such as the Bowman-Birk inhibitor, metallo-peptidases are inhibited by chitosan derivatives displaying complexing properties such as chitosan-EDTA conjugates. In addition, because of the mucoadhesive properties of chitosan and most of its derivatives, a presystemic metabolism of peptides on the way between the dosage form and the absorption membrane can be strongly reduced. Based on these unique features, the co-administration of chitosan and its derivatives leads to a strongly improved bioavailability of many perorally given peptide drugs such as insulin, calcitonin and buserelin. These polymers are therefore useful excipients for the peroral administration of peptide drugs.
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Affiliation(s)
- A Bernkop-Schnürch
- Institute of Pharmaceutical Technology, Centre of Pharmacy, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria.
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Bernkop-Schnürch A, Pasta M. Intestinal peptide and protein delivery: novel bioadhesive drug-carrier matrix shielding from enzymatic attack. J Pharm Sci 1998; 87:430-4. [PMID: 9548894 DOI: 10.1021/js970410u] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We have been developing a novel bioadhesive drug-carrier matrix that protects embedded therapeutic peptides and proteins from degradation by the most abundant intestinal proteases. Increasing amounts of the Bowman-Birk inhibitor (BBI) were thereby covalently linked to chitosan-EDTA. The bioadhesive properties of the resulting polymer-BBI conjugates and their inhibitory effect toward trypsin (EC 3.4.21.4), chymotrypsin (EC 3.4.21.1), elastase (3.4.21.36), carboxypeptidase A (EC 3.4.17.1), and aminopeptidase N (EC 3.4.11.2) were evaluated in vitro. Whereas unmodified chitosan-EDTA exhibited under our experimental conditions an adhesive strength of 54.4 +/- 7.7 mN, it was determined to be 21.0 +/- 3.8 mN for the comparably most adhesive polymer-BBI conjugate (mean +/- SD; n = 5). All polymer-BBI conjugates showed a strong inhibitory activity toward the serine proteases trypsin and chymotrypsin. However, the protective effect toward elastase was markedly lower. Due to the high binding affinity of chitosan-EDTA toward zinc, which represents an essential cofactor for carboxypeptidase A and aminopeptidase N, all polymer-BBI conjugates displayed additionally a strong protective effect toward these exopeptidases. The novel bioadhesive polymer-BBI conjugates described in this study seem to be very useful drug-carrier matrixes in overcoming the enzymatic barrier to orally administered peptide and protein drugs.
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Affiliation(s)
- A Bernkop-Schnürch
- The Center of Pharmacy, Institute of Pharmaceutical Technology, University of Vienna, Austria.
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18
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Bernkop-Schnürch A. The use of inhibitory agents to overcome the enzymatic barrier to perorally administered therapeutic peptides and proteins. J Control Release 1998; 52:1-16. [PMID: 9685931 DOI: 10.1016/s0168-3659(97)00204-6] [Citation(s) in RCA: 215] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The peroral administration of peptide drugs is a major challenge to pharmaceutical science. In order to provide a sufficient bioavailability of these therapeutic agents after oral dosing, several barriers encountered with the gastrointestinal (GI) tract have to be overcome by a suitable galenic. One of these barriers is caused by proteolytic enzymes, leading to a severe presystemic degradation in the GI tract. Besides some other strategies to overcome the so-called enzymatic barrier, the use of inhibitory agents has gained considerable scientific interest, as various in vivo studies could demonstrate a significantly improved bioavailability of therapeutic peptides and proteins, due to the co-administration of such excipients. In vitro techniques to evaluate the actual potential of inhibitory agents incubation with pure proteases, freshly collected gastric or intestinal fluids, mucosal homogenates, brush border vesicles and freshly excised mucosa. In situ techniques are based on single-pass perfusion studies cannulating different intestinal segments and determining the amount of undegraded model drug in perfusion solutions or blood. For in vivo studies, insulin is mostly used as a model drug, offering the advantage of a well-established method to evaluate the biological response after oral dosing by determining the decrease in blood glucose level. Generally, inhibitory agents can be divided into: inhibitors which are not based on amino acids (I), such as p-aminobenzamidine, FK-448 and camostat mesilate; amino acids and modified amino acids (II), such acid derivatives; peptides and modified peptides (III), e.g. bacitracin, antipain, chymostatin and amastatin; and polypeptide protease inhibitors (IV), e.g. aprotinin, Bowman-Birk inhibitor and soybean trypsin inhibitor. Furthermore, complexing agents and some mucoadhesive polymers also display enzyme inhibitory activity. Drawbacks of inhibitory agents, such the risk of toxic side effects or high production costs, might be excluded by the development of advanced drug delivery systems. Initial steps in this direction can be seen in the development of delivery system containing mucoadhesive polymers providing an intimate contact to the mucosa, thereby reducing the drug degradation between delivery system and absorbing membrane, controlled release systems which provide a simultaneous release of drug and inhibitor and in the immobilisation of enzyme inhibitors on delivery systems.
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Affiliation(s)
- A Bernkop-Schnürch
- Institute of Pharmaceutical Technology, Center of Pharmacy, University of Vienna, Austria.
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19
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Oates PS, Thomas C, Morgan EH. Characterization of isolated duodenal epithelial cells along a crypt-villus axis in rats fed diets with different iron content. J Gastroenterol Hepatol 1997; 12:829-38. [PMID: 9504894 DOI: 10.1111/j.1440-1746.1997.tb00380.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The intestinal mucosa is characterized by cell proliferation, commitment, differentiation, digestion and absorption. These processes occur at specified locations along the crypt to villus axis. A technique is reported for the isolation of cells along this axis which allows the study of any one of these processes in an enriched population of cells. As an example, the uptake of transferrin-bound iron by enterocytes was studied. Rats were fed diets normal, high (30% carbonyl iron) or low in iron for 12 days. Cells from either the duodenum or ileum were isolated by incubating in a Ca(2+)-, Mg2+-free, cation chelating solution for varying periods. The incorporation of thymidine into DNA was measured in these cells as a marker of the crypt region, while alkaline phosphatase and sucrase activities marked mature enterocytes. The in vivo uptake of transferrin-bound 59Fe was measured in cells isolated either 2 or 4 h after intravenous injection. This procedure resulted in the isolation of 10 fractions of viable cells. Earlier fractions were enriched at least 10-fold in villus cells and the last fractions in crypt cells. Cells in intermediate fractions were at various stages of development. Uptake of transferrin-bound iron into enterocytes was highest with feeding an iron-loaded diet compared with control or iron-deficient diets. However, with all diets uptake was highest in crypt cells and this fell at the crypt-villus junction to be only 25%, as high at the villus tip as the crypt. A technique for the reproducible isolation of viable enterocytes along a crypt-villus axis is described. Transferrin receptor activity changes with maturation of the enterocyte.
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Affiliation(s)
- P S Oates
- Department of Physiology, The University of Western Australia, Perth
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20
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Obourn JD, Frame SR, Chiu T, Solomon TE, Cook JC. Evidence that A8947 enhances pancreas growth via a trypsin inhibitor mechanism. Toxicol Appl Pharmacol 1997; 146:116-26. [PMID: 9299603 DOI: 10.1006/taap.1997.8231] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A8947 is a member of the sulfonyl urea class of compounds and is the active ingredient in a commercial broad leaf herbicide. This compound has been shown to produce pancreatic hypertrophy in rats, mice, and dogs. The objectives of this study were to investigate the mechanism(s) for the A8947 induction of pancreatic acinar cell hypertrophy and proliferation and to evaluate whether these pancreatic changes are reversible. A8947 was fed to male Crl:CD BR rats for up to 28 days (0, 300, 10,000, 30,000 ppm) or 56 days (0, 30,000 ppm). Rats were terminated on Test Days 7, 14, and 28 to assess the time course and dose response for the A8947-induced pancreatic changes, while rats terminated on Test Day 56 were used to assesss the reversibility of the pancreas effects at 30,000 ppm A8947. A8947 produced significant increases in pancreatic weight and acinar cell proliferation and diffuse acinar cell hypertrophy in 7 days at 10,000 and 30,000 ppm dose levels. By Day 14, absolute pancreas weights in the 10,000 and 30,000 ppm groups were maximally increased and remained at these levels throughout the study. In contrast, acinar cell proliferation in the 30,000 ppm group was still elevated at Test Day 14, but attenuated relative to the 7-day response, and returned to control levels by Test Day 28. No effects were observed at 300 ppm after a 28-day exposure period, while complete reversibility of A8947-induced pancreatic effects was demonstrated at 30,000 ppm following a 1-month recovery period (Test Day 56). Cholecystokinin (CCK) levels were increased by A8947 and closely followed the time course for pancreatic changes. MK-329, a specific CCKA receptor antagonist, completely ablated the ability of 30,000 ppm A8947 to increase pancreas weight following 7 days of exposure. A8947 did not bind the CCKA receptor in a receptor competition assay, negating any potential agonist mechanism. A8947 did, however, inhibit trypsin in vitro, suggesting a mechanism of action similar to that of raw soy protein, in which trypsin inhibition in vivo results in increased CCK levels followed by pancreatic acinar cell hypertrophy and proliferation.
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Affiliation(s)
- J D Obourn
- Haskell Laboratory for Toxicology and Industrial Medicine, E. I. du Pont de Nemours & Company, Elkton Road, Newark, Delaware 19714, USA
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