A serine proteinase inhibitor isolated from Tamarindus indica seeds and its effects on the release of human neutrophil elastase

Tamarind genus chemical composition and biological activities

Tamarindus indica L., the sole species in the genus Tamarind, which is a member of the subfamily Caesalpiniaceae in the family Leguminosae (Fabaceae), is extensively dispersed in many tropical and subtropical regions. This plant's Arabic name, Tamr Al-Hindi, is the basis for its English name, Tamarind. In traditional medicine, this genus has played a major role since the time of the ancient Egyptians. Folkloric medicine has traditionally used Tamarind to treat a variety of conditions, including diabetes mellitus, fever, malaria, ulcers, diarrhoea, dysentery and wounds. The primary bioactive components of this species, which have a variety of biological functions, have been identified as flavonoids, phenolic contents, sterols, triterpenes, fatty acids, sugars and other substances. Genus Tamarind has been shown to have anti-inflammatory, analgesic, anti-pyretic, antibacterial, hypolipidemic, anti-diabetic, hepatoprotective, anti-ulcerogenic and antioxidant properties. This article provides an overview of the identified chemicals from T. indica together with their stated biological activities.

Mechanistic study on the anti-proinflammatory activity of Kunitz type inhibitor from Caesalpinia decapetala seeds

The study reports the biochemical characterization and mechanism of action of a novel 19.6 kDa protease inhibitor (PIs) isolated from the seeds of Caesalpinia decapetala belonging to the Fabaceae family. A systematic study was performed to ascertain the purity, specificity, biochemical and structural characterization, and its potential in curbing inflammation in vitro conditions. A two-step chromatography technique was used to purify the PIs. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and matrix-assisted laser desorption ionization time of flight were employed to detect the molecular mass of the protein. N-terminal sequence analysis of the inhibitor showed sequence similarity with the Kunitz family PIs. The in vitro test tube assay was performed for determining the anti-inflammatory activity and the inhibitor is antiproliferative against macrophage (RAW264.7) and lung cancer cell lines (A549). An effective decrease in the release of inflammatory mediators (NO, IL-6, TNF-α) and on the activity of elastase was observed in macrophage cell lines (RAW264.7) which were treated with PIs. The purified inhibitor shows promising results against inflammation.

Anti-Inflammatory Protein Isolated from Tamarind Promotes Better Histological Aspects in the Intestine Regardless of the Improvement of Intestinal Permeability in a Preclinical Study of Diet-Induced Obesity

Obesity is associated with metabolic and physiological effects in the gut. In this study, we evaluated the anti-inflammatory effect of trypsin inhibitor isolated from tamarind seeds (TTI) in vitro (interaction with lipopolysaccharide (LPS) and inhibitory activity against human neutrophil elastase (HNE)), and using intestinal co-cultures of Caco-2:HT29-MTX cell lines inflamed with TNF-α (50 ng/mL) and a Wistar rat model of diet-induced obesity (n = 15). TTI was administered to animals by gavage (10 days), and the treated group (25 mg/kg/day) was compared to animals without treatment or treated with a nutritionally adequate diet. In the in vitro study, it showed inhibitory activity against HNE (93%). In co-cultures, there was no protection or recovery of the integrity of inflamed cell monolayers treated with TTI (1.0 mg/mL). In animals, TTI led to lower plasma concentrations of TNF-α and IL-6, total leukocytes, fasting glucose, and LDL-c (p < 0.05). The intestines demonstrated a lower degree of chronic enteritis, greater preservation of the submucosa, and greater intestinal wall thickness than the other groups (p = 0.042). Therefore, the better appearance of the intestine not reflected in the intestinal permeability added to the in vitro activity against HNE point to possibilities for new studies and applications related to this activity.

The anti-Alzheimer potential of Tamarindus indica: an in vivo investigation supported by in vitro and in silico approaches

Tamarindus indica Linn. (Tamarind, F. Fabaceae) is one of the most widely consumed fruits in the world. A crude extract and different fractions of T. indica (using n-hexane, dichloromethane, ethyl acetate, and n-butanol) were evaluated in vitro with respect to their DPPH scavenging and AchE inhibition activities. The results showed that the dichloromethane and ethyl acetate fractions showed the highest antioxidant activities, with 84.78 and 86.96% DPPH scavenging at 0.10 μg mL-1. The n-hexane, dichloromethane, and ethyl acetate fractions inhibited AchE activity in a dose-dependent manner, and the n-hexane fraction showed the highest inhibition at 20 μg mL-1. The results were confirmed by using n-hexane, dichloromethane, and ethyl acetate fractions in vivo to regress the neurodegenerative features of Alzheimer's dementia in an aluminum-intoxicated rat model. Phytochemical investigations of those three fractions afforded two new diphenyl ether derivative compounds 1-2, along with five known ones (3-7). The structures of the isolated compounds were confirmed via 1D and 2D NMR and HRESIMS analyses. The isolated compounds were subjected to extensive in silico-based investigations to putatively highlight the most probable compounds responsible for the anti-Alzheimer activity of T. indica. Inverse docking studies followed by molecular dynamics simulation (MDS) and binding free energy (ΔG) investigations suggested that both compounds 1 and 2 could be promising AchE inhibitors. The results presented in this study may provide potential dietary supplements for the management of Alzheimer's disease.

Protease Inhibitors from Plants as Therapeutic Agents- A Review

Plant-based diets are a great source of protease inhibitors (PIs). Two of the most well-known families of PIs are Bowman-Birk inhibitors (BBI) and Kunitz-type inhibitors (KTI). The first group acts mainly on trypsin, chymotrypsin, and elastase; the second is on serine, cysteine, and aspartic proteases. PIs can retard or inhibit the catalytic action of enzymes; therefore, they are considered non-nutritional compounds; nevertheless, animal studies and cell line experiments showed promising results of PIs in treating human illnesses such as obesity, cardiovascular diseases, autoimmune diseases, inflammatory processes, and different types of cancer (gastric, colorectal, breast, and lung cancer). Anticarcinogenic activity's proposed mechanisms of action comprise several inhibitory effects at different molecular levels, i.e., transcription, post-transcription, translation, post-translation, and secretion of cancer cells. This work reviews the potential therapeutic applications of PIs as anticarcinogenic and anti-inflammatory agents in human diseases and the mechanisms by which they exert these effects.

Structural insights and molecular dynamics into the inhibitory mechanism of a Kunitz-type trypsin inhibitor from Tamarindus indica L

Trypsin inhibitors from tamarind seed have been studied in vitro and in preclinical studies for the treatment of obesity, its complications and associated comorbidities. It is still necessary to fully understand the structure and behaviour of these molecules. We purifed this inhibitor, sequenced de novo by MALDI-TOF/TOF, performed its homology modelling, and assessed the interaction with the trypsin enzyme through molecular dynamics (MD) simulation under physiological conditions. We identified additional 75 amino acid residues, reaching approximately 72% of total coverage. The four best conformations of the best homology modelling were submitted to the MD. The conformation n°287 was selected considering the RMSD analysis and interaction energy (-301.0128 kcal.mol-1). Residues Ile (54), Pro (57), Arg (59), Arg (63), and Glu (78) of pTTI presented the highest interactions with trypsin, and arginine residues were mainly involved in its binding mechanism. The results favour bioprospecting of this protein for pharmaceutical health applications.

Tamarind (Tamarindus indica L.) Seed a Candidate Protein Source with Potential for Combating SARS-CoV-2 Infection in Obesity

Introduction:

Obesity and coronavirus disease (COVID)-19 are overlapping pandemics, and one might worsen the other.

Methods:

This narrative review discusses one of the primary mechanisms to initiate acute respiratory distress syndrome, uncontrolled systemic inflammation in COVID-19, and presents a potential candidate for adjuvant treatment. Blocking the S protein binding to angiotensin-converting enzyme 2 (ACE-2) and the 3C-like protease (3CL ^pro) is an effective strategy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Results:

Host proteases such as FURIN, trypsin, and transmembrane serine protease 2 (TMPRSS) act in S protein activation. Tamarind trypsin inhibitor (TTI) shows several beneficial effects on the reduction of inflammatory markers (tumor necrosis factor α [TNF-α], leptin) and biochemical parameters (fasting glycemia, triglycerides, and very low-density lipoprotein [VLDL]), in addition to improving pancreatic function and mucosal integrity in an obesity model. TTI may inhibit the action of proteases that collaborate with SARS-CoV-2 infection and the neutrophil activity characteristic of lung injury promoted by the virus.

Conclusion:

Thus, TTI may contribute to combating two severe overlapping problems with high cost and social complex implications, obesity and COVID-19.

Anti-inflammatory and analgesic potential of Tamarindus indica Linn. (Fabaceae): a narrative review

Chronic inflammation is one of the causes of a number of non-infectious diseases in the world. Over the years, Tamarindus indica has played fundamental roles in traditional medicine as an anti-inflammatory and analgesic drug. It is a commercialized biocompatible medicinal plant species with a wide range of therapeutic window and with suggested LD50 greater than 5000 mg kg⁻¹ body weight when administered to the Wistar rats. This review examined the anti-inflammatory and analgesic potential and mechanism of various extracts from T. indica pulp, leaves, seeds, stem bark, and roots. The preclinical studies provided strong pharmacological evidence for the anti-inflammatory and analgesic activities of the different parts of T. indica and this may be attributed to the various bioactive compounds in it including alkaloids, flavonoids, tannins, phenols, saponins, and steroids. The anti-inflammatory and analgesic effects of the extracts from the different parts of T. indica may be due to its ability to inhibit a number of biological processes including cyclooxygenase-2 (COX-2) expression, inducible nitric oxide synthase (iNOS), 5-lipoxygenase biosynthesis, and tumor necrosis factor-α. The analgesic activity of T. indica may also be through the activation of the opioidergic mechanism at both the peripheral and central levels. Although further pre-clinical studies still need to be conducted, these results demonstrated that T. indica has potent anti-inflammatory and analgesic activities and hence provides justification for its use in traditional medicine to treat body pain and other inflammatory related diseases including arthritis and offers a basis for future clinical studies and possible drug development.

Anti-TNF-α Agent Tamarind Kunitz Trypsin Inhibitor Improves Lipid Profile of Wistar Rats Presenting Dyslipidemia and Diet-induced Obesity Regardless of PPAR-γ Induction

The increasing prevalence of obesity and, consequently, chronic inflammation and its complications has increased the search for new treatment methods. The effect of the purified tamarind seed trypsin inhibitor (TTIp) on metabolic alterations in Wistar rats with obesity and dyslipidemia was evaluated. Three groups of animals with obesity and dyslipidemia were formed, consuming a high glycemic index and glycemic load (HGLI) diet, for 10 days: Obese/HGLI diet; Obese/standard diet; Obese/HGLI diet + TTIp (730 μg/kg); and one eutrophic group of animals was fed a standard diet. Rats were evaluated daily for food intake and weight gain. On the 11th day, animals were anesthetized and sacrificed for blood and visceral adipose tissue collection. TTIp treated animals presented significantly lower food intake than the untreated group (p = 0.0065), TG (76.20 ± 18.73 mg/dL) and VLDL-C (15.24 ± 3.75 mg/dL). Plasma concentrations and TNF-α mRNA expression in visceral adipose tissue also decreased in obese animals treated with TTIp (p < 0.05 and p = 0.025, respectively) with a negative immunostaining. We conclude that TTIp presented anti-TNF-α activity and an improved lipid profile of Wistar rats with dyslipidemia and obesity induced by a high glycemic index and load diet regardless of PPAR-γ induction.

Biochemical characterisation of a Kunitz-type inhibitor from Tamarindus indica L. seeds and its efficacy in reducing plasma leptin in an experimental model of obesity

A trypsin inhibitor isolated from tamarind seed (TTI) has satietogenic effects in animals, increasing the cholecystokinin (CCK) in eutrophy and reducing leptin in obesity. We purified TTI (pTTI), characterised, and observed its effect upon CCK and leptin in obese Wistar rats. By HPLC, and after amplification of resolution, two protein fractions were observed: Fr1 and Fr2, with average mass of [M + 14H]⁺ = 19,594,690 Da and [M + 13H]⁺ = 19,578,266 Da, respectively. The protein fractions showed 54 and 53 amino acid residues with the same sequence. pTTI presented resistance to temperature and pH variations; IC₅₀ was 2.7 × 10⁻¹⁰mol.L⁻¹ and Ki was 2.9 × 10⁻¹¹mol.L⁻¹. The 2-DE revealed spots with isoelectric points between pH 5 and 6, and one near pH 8. pTTI action on leptin decrease was confirmed. We conclude that pTTI is a Kunitz trypsin inhibitor with possible biotechnological health-related application.

Physio-chemical Characterization and Anti-microbial Activity of Serine Protease Inhibitors Purified from the Sophora japonica Seeds

BACKGROUND AND OBJECTIVE

Protease inhibitors (PIs) regulate various cellular processes like cell cycle, differentiation, apoptosis and immune responses. Leguminous seeds are rich sources of protease inhibitors and many novel protease inhibitors have been purified from them. To isolate and purify protease inhibitors from seeds of Sophora japonica, characterize and investigate their anti- microbial activity.

MATERIALS AND METHODS

Protease inhibitors (SJ-pi I and SJ-pi II) were purified to homogeneity by ammonium sulfate precipitation, Ion exchange chromatography and column chromatography. The molecular mass was estimated by size exclusion chromatography and by SDS-PAGE and anti- microbial activity was tested by agar disk diffusion method.

RESULTS

Two protease inhibitors were isolated and purified from Sophora japonica seeds, SJ-pi I and SJ-pi II, with molecular weight of 15.1 and 31 kDa, respectively. Both purified inhibitors were active over a range of pH (6.0-9.0) and showed maximum activity in the temperature range of 30-40°C. They inhibited the growth of three Gram-positive bacteria.

CONCLUSION

Protease inhibitors were classified as serine protease inhibitors, however further necessary structural investigations need to be carried out so as to group them into specific class of serine protease inhibitors.

Protease inhibitor in scorpion (Mesobuthus eupeus) venom prolongs the biological activities of the crude venom

It is hypothesized that protease inhibitors play an essential role in survival of venomous animals through protecting peptide/protein toxins from degradation by proteases in their prey or predators. However, the biological function of protease inhibitors in scorpion venoms remains unknown. In the present study, a trypsin inhibitor was purified and characterized from the venom of scorpion Mesobuthus eupeus, which enhanced the biological activities of crude venom components in mice when injected in combination with crude venom. This protease inhibitor, named MeKTT-1, belonged to Kunitz-type toxins subfamily. Native MeKTT-1 selectively inhibited trypsin with a Kivalue of 130 nmol·L(-1). Furthermore, MeKTT-1 was shown to be a thermo-stable peptide. In animal behavioral tests, MeKTT-1 prolonged the pain behavior induced by scorpion crude venom, suggesting that protease inhibitors in scorpion venom inhibited proteases and protect the functionally important peptide/protein toxins from degradation, consequently keeping them active longer. In conclusion, this was the first experimental evidence about the natural existence of serine protease inhibitor in the venom of scorpion Mesobuthus eupeus, which preserved the activity of venom components, suggests that scorpions may use protease inhibitors for survival.

A Trypsin Inhibitor from Tamarind Reduces Food Intake and Improves Inflammatory Status in Rats with Metabolic Syndrome Regardless of Weight Loss

Trypsin inhibitors are studied in a variety of models for their anti-obesity and anti-inflammatory bioactive properties. Our group has previously demonstrated the satietogenic effect of tamarind seed trypsin inhibitors (TTI) in eutrophic mouse models and anti-inflammatory effects of other trypsin inhibitors. In this study, we evaluated TTI effect upon satiety, biochemical and inflammatory parameters in an experimental model of metabolic syndrome (MetS). Three groups of n = 5 male Wistar rats with obesity-based MetS received for 10 days one of the following: (1) Cafeteria diet; (2) Cafeteria diet + TTI (25 mg/kg); and (3) Standard diet. TTI reduced food intake in animals with MetS. Nevertheless, weight gain was not different between studied groups. Dyslipidemia parameters were not different with the use of TTI, only the group receiving standard diet showed lower very low density lipoprotein (VLDL) and triglycerides (TG) (Kruskal-Wallis, p < 0.05). Interleukin-6 (IL-6) production did not differ between groups. Interestingly, tumor necrosis factor-alpha (TNF-α) was lower in animals receiving TTI. Our results corroborate the satietogenic effect of TTI in a MetS model. Furthermore, we showed that TTI added to a cafeteria diet may decrease inflammation regardless of weight loss. This puts TTI as a candidate for studies to test its effectiveness as an adjuvant in MetS treatment.

Isolation and purification of trypsin inhibitors from the seeds of Abelmoschus moschatus L

Four trypsin inhibitors, AMTI-I, AMTI-II, AMTI-III, and AMTI-IV, have been isolated and purified to homogeneity from the seeds of Abelmoschus moschatus following ammonium sulphate fractionation, DEAE-cellulose ion exchange chromatography and gel permeation on Sephadex G-100, and their molecular weights were determined to be 22.4, 21.2, 20.8 and 20.2 kDa respectively by SDS-PAGE. While all the four inhibitors were very active against bovine trypsin, two of them (AMTI-III and AMTI-IV) showed moderate activity towards bovine chymotrypsin. AMTI-I and AMTI-II were found to be glycoproteins with neutral sugar content of 2.8 and 4 %, respectively, and all the four inhibitors were devoid of free sulphhydryl groups. The inhibitors were quite stable up to 80 °C for 10 min and were not affected at alkaline as well as acidic conditions tested. Treating them with 8 M urea and 1 % SDS for 24 h at room temperature did not result in any loss of their antitryptic activities. However, they lost considerable antitryptic activity when treated with 6 M guanidine hydrochloride. Activities of the inhibitors were unaffected even after their reduction with DTT suggesting that disulphide bonds are not needed for their inhibitory activities.

Antioxidant activities of tamarind (Tamarindus Indica) seed coat extracts using in vitro and in vivo models

Tamarindus indica seed coat was extracted with methanol, acetone and water and screened for DPPH radical scavenging activities. Methanol extract showed higher activity than other extracts. Treatment of albino rats (Wistar strain) with CCl4 at 1.25 mL/kg of body weight decreased superoxide dismutase (55 %), catalase (73 %) and peroxidase (78 %), while lipid peroxidation increased nearly 2.5 fold in liver. Pretreatment of rats with methanol extract of T. Indica seed coat (TSCE) at 50 mg/kg (as tannic acid equivalents) followed by CCl4 treatment, caused restoration of superoxide dismutase, catalase and lipid peroxidation to values close to control while peroxidase was restored to 67 % of the control. Histopathological studies of liver of different groups supported the protective effects of TSCE by restoring the hepatic architecture. These studies could be further extended to exploit its possible application for the preservation of food products as well as a health supplement and neutraceutical.

Cloning and characterization of a novel Kunitz-type inhibitor from scorpion with unique cysteine framework

Kunitz-type proteins from animal venom are good tools for understanding structure-function relationships between serine proteases and their inhibitors. We used a cDNA library to clone and characterize the Buthus martensi Kunitz-type protease inhibitor (BmKPI) present in the venom gland of the scorpion B. martensi. The gene codes for a signal peptide of 19 residues and a mature peptide of 64 residues. The mature BmKPI peptide possesses a unique cysteine framework reticulated by four disulfide bridges, unlike many other Kunitz-type proteins with three disulfide bridges. The recombinant BmKPI peptide was functionally expressed and showed strong inhibitory activity toward trypsin (Ki 1.8 × 10⁻⁶ M), chymotrypsin (Ki 3.2 × 10⁻⁸ M), and elastase (Ki 1.6 × 10⁻⁷ M). Structure-functional relationship between elastase and BmKPI was further studied. Cysteine mutagenesis experiment showed that the unique disulfide bridge Cys53-Cys61 had little effect on its inhibiting elastase. Molecular dynamics simulation revealed that BmKPI possesses elastase inhibitory active sites similar to the classical Kunitz-type venom peptides, although their cysteine frameworks were different. These results showed that BmKPI is a new multifunctional serine protease inhibitor. To the best of our knowledge, BmKPI is the first functionally characterized Kunitz-type elastase inhibitor derived from scorpion venoms.

SjAPI, the first functionally characterized Ascaris-type protease inhibitor from animal venoms

BACKGROUND

Serine protease inhibitors act as modulators of serine proteases, playing important roles in protecting animal toxin peptides from degradation. However, all known serine protease inhibitors discovered thus far from animal venom belong to the Kunitz-type subfamily, and whether there are other novel types of protease inhibitors in animal venom remains unclear.

PRINCIPAL FINDINGS

Here, by screening scorpion venom gland cDNA libraries, we identified the first Ascaris-type animal toxin family, which contains four members: Scorpiops jendeki Ascaris-type protease inhibitor (SjAPI), Scorpiops jendeki Ascaris-type protease inhibitor 2 (SjAPI-2), Chaerilus tricostatus Ascaris-type protease inhibitor (CtAPI), and Buthus martensii Ascaris-type protease inhibitor (BmAPI). The detailed characterization of Ascaris-type peptide SjAPI from the venom gland of scorpion Scorpiops jendeki was carried out. The mature peptide of SjAPI contains 64 residues and possesses a classical Ascaris-type cysteine framework reticulated by five disulfide bridges, different from all known protease inhibitors from venomous animals. Enzyme and inhibitor reaction kinetics experiments showed that recombinant SjAPI was a dual function peptide with α-chymotrypsin- and elastase-inhibiting properties. Recombinant SjAPI inhibited α-chymotrypsin with a Ki of 97.1 nM and elastase with a Ki of 3.7 μM, respectively. Bioinformatics analyses and chimera experiments indicated that SjAPI contained the unique short side chain functional residues "AAV" and might be a useful template to produce new serine protease inhibitors.

CONCLUSIONS/SIGNIFICANCE

To our knowledge, SjAPI is the first functionally characterized animal toxin peptide with an Ascaris-type fold. The structural and functional diversity of animal toxins with protease-inhibiting properties suggested that bioactive peptides from animal venom glands might be a new source of protease inhibitors, which will accelerate the development of diagnostic and therapeutic agents for human diseases that target diverse proteases.

Tamarindus indica: Extent of explored potential

Tamarindus is a monotypic genus and belongs to the subfamily Caesalpinioideae of the family Leguminosae (Fabaceae), Tamarindus indica L., commonly known as Tamarind tree is one of the most important multipurpose tropical fruit tree species in the Indian subcontinent. Tamarind fruit was at first thought to be produced by an Indian palm, as the name Tamarind comes from a Persian word “Tamar-I-hind,” meaning date of India. Its name “Amlika” in Sanskrit indicates its ancient presence in the country. T.indica is used as traditional medicine in India, Africa, Pakistan, Bangladesh, Nigeria,and most of the tropical countries. It is used traditionally in abdominal pain, diarrhea and dysentery, helminthes infections, wound healing, malaria and fever, constipation, inflammation, cell cytotoxicity, gonorrhea, and eye diseases. It has numerous chemical values and is rich in phytochemicals, and hence the plant is reported to possess antidiabetic activity, antimicrobial activity, antivenomic activity, antioxidant activity, antimalarial activity, hepatoprotective activity, antiasthmatic activity, laxative activity, and anti-hyperlipidemic activity. Every part of the plant from root to leaf tips is useful for human needs. Thus the aim of the present review is to describe its morphology, and explore the phytochemical constituents, commercial utilization of the parts of the plant, and medicinal and pharmacologic activities so that T. indica's potential as multipurpose tree species can be understood.

New properties of the soybean trypsin inhibitor: Inhibition of human neutrophil elastase and its effect on acute pulmonary injury

Seeds from legumes including the Gilcine max are known to be a rich source of protease inhibitors. The soybean Kunitz trypsin inhibitors (SKTIs) have been well characterised and have been found to exhibit many biological activities. However their effects on inflammatory diseases have not been studied to date. In this study, SKTI was purified using anion exchange chromatography using a Resource Q column. The purified protein was able to inhibit human neutrophil elastase (HNE) and bovine trypsin. Purified SKTI inhibited HNE with an IC(50) value of 8mug or 0.3nM. At this concentration SKTI showed neither cytotoxic nor haemolytic effects on human blood cell populations. SKTI showed no deleterious effects on organs, blood cells or the hepatic enzymes ALT and AST in the mouse model of acute systemic toxicity. Human neutrophils incubated with SKTI released less HNE than control neutrophils when stimulated with PAF or fMLP (83.1% and 70% respectively). These results showed that SKTI affected both pathways of elastase release by PAF and fMLP stimuli, suggesting that SKTI is an antagonist of fMLP/PAF receptors. In an in vivo mouse model of LPS acute lung injury, SKTI significantly suppressed the inflammatory effects caused by elastase in a dose-dependent manner. Histological sections stained by hematoxylin/eosin confirmed this decrease in inflammation. These results showed that SKTI could be used as a pharmacological agent for the therapy of many inflammatory diseases.

Characterization of a Kunitz trypsin inhibitor with a single disulfide bridge from seeds of Inga laurina (SW.) Willd

Inga laurina is a tree that belongs to the Mimosoideae sub-family of the Leguminosae. A protein inhibitor of trypsin (ILTI) was isolated from its seeds by ammonium sulphate precipitation, ion-exchange chromatography and rechromatography on an HiTrap Q ion-exchange column. By SDS-PAGE, ILTI yielded a single band with a Mr of 20 kDa with or without reduction. ILTI was found to be a single polypeptide chain containing 180 amino acids, the sequence of which was clearly homologous to the Kunitz family of serine protease plant protein inhibitors, and it also showed significant similarity to the seed storage proteins, sporamin and miraculin. However, ILTI displayed major differences to most other Kunitz inhibitors in that it contained only one disulfide bridge, and did not have two polypeptide chains as for the majority of other Kunitz inhibitors purified from Mimosoideae species. ILTI inhibited bovine trypsin with an equilibrium dissociation constant (K(i)) of 6 x 10(-9)M, but did not inhibit chymotrypsin, papain and alpha-amylase. Its amino acid sequence contained a Lys residue at the putative reactive site (position 64). ILTI was stable over a wide range of temperature and pH and in the presence of DTT.