scholarly journals Natural plant enzyme inhibitors. Characterization of an unusual α-amylase/trypsin inhibitor from ragi (Eleusine coracana Geartn.)

1981 ◽  
Vol 193 (1) ◽  
pp. 29-36 ◽  
Author(s):  
B Shivaraj ◽  
T N Pattabiraman
Keyword(s):  
Trypsin Inhibitor ◽  
Inhibitory Activity ◽  
Enzyme Inhibitors ◽  
Complete Recovery ◽  
Alpha Amylase ◽  
Protein Factor ◽  
Wide Ph Range ◽  
Arginine Residues ◽  
Inhibitory Activities ◽  
Antitryptic Activity

An inhibitor I-1, capable of acting on both alpha-amylase and trypsin, was purified to homogeneity from ragi (finger-millet) grains. The factor was found to be stable to heat treatment at 100 degrees C for 1 h in the presence of NaCl and also was stable over the wide pH range 1-10. Pepsin and Pronase treatment of inhibitor I-1 resulted in gradual loss of both the inhibitory activities. Formation of trypsin-inhibitor I-1 complex, amylase-inhibitor I-1 complex and trypsin-inhibitor I-1-amylase trimer complex was demonstrated by chromatography on a Bio-Gel P-200 column. This indicated that the inhibitor is ‘double-headed’ in nature. The inhibitor was retained on a trypsin-Sepharose 4B column at pH 7.0. Elution at acidic pH resulted in almost complete recovery of amylase-inhibitory and trypsin-inhibitory activities. alpha-Amylase was retained on a trypsin-Sepharose column to which inhibitor I-1 was bound, but not on trypsin-Sepharose alone. Modification of amino groups of the inhibitor with 2,4,6-trinitrobenzenesulphonic acid resulted in complete loss of amylase-inhibitory activity but only 40% loss in antitryptic activity. Modification of arginine residues by cyclohexane-1,2-dione led to 85% loss of antitryptic activity after 5 h, but no effect on amylase-inhibitory activity. The results show that a single bifunctional protein factor is responsible for both amylase-inhibitory and trypsin-inhibitory activities with two different reactive sites.

scholarly journals Arginine is essential for the α-amylase inhibitory activity of the α-amylase/subtilisin inhibitor (BASI) from barley seeds

1993 ◽  
Vol 293 (1) ◽  
pp. 151-155 ◽  
Author(s):  
J Abe ◽  
U Sidenius ◽  
B Svensson
Keyword(s):  
Inhibitory Activity ◽  
Enzyme Inhibitor ◽  
Three Dimensional ◽  
Order Rate Constant ◽  
Alpha Amylase ◽  
Three Dimensional Model ◽  
Pseudo First Order Reaction ◽  
Arginine Residues ◽  
Subtilisin Inhibitor ◽  
Target Enzyme

Treatment of barley alpha-amylase/subtilisin inhibitor (BASI) with reagents specific for arginine, histidine, methionine and tyrosine residues and amino and carboxyl groups indicates that an arginine residue(s) is essential for its action on the target enzyme barley alpha-amylase 2. Phenylglyoxal modified eight out of 12 arginine residues in BASI. Kinetic analysis shows that the inactivation of BASI follows a pseudo-first-order reaction and is due to reaction with one molecule of phenylglyoxal; the second-order rate constant is determined to be 2.95 M-1.min-1. At pH 8.0, BASI and barley alpha-amylase 2 form an inactive 1:1 complex. The Ki value of this association is 2.2 x 10(-10) M. The alpha-amylase protects four arginine residues and also the alpha-amylase inhibitory activity of BASI against phenylglyoxal. When BASI from the phenylglyoxal-modified target enzyme-inhibitor complex is isolated and subjected to a second treatment with phenylglyoxal, four additional arginine residues are modified, with concomitant loss of the inhibitory activity. These results are discussed in relation to a three-dimensional model of BASI based on the known structure of the corresponding inhibitor from wheat.

scholarly journals Antimicrobial and Alpha-Amylase Inhibitory Activities of Organic Extracts of Selected Sri Lankan Bryophytes

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Annalingam Kirisanth ◽  
M. N. M. Nafas ◽  
Ranga K. Dissanayake ◽  
Jayantha Wijayabandara
Keyword(s):  
Inhibitory Activity ◽  
Pathogenic Fungus ◽  
Fungal Species ◽  
Biologically Active ◽  
Alpha Amylase ◽  
Diffusion Method ◽  
Bacterial Strains ◽  
Plant Materials ◽  
Natural Product Research ◽  
Inhibitory Activities

Medicinal plants have been the main focus of natural product research. However, recent research has revealed that lower plants including bryophytes are also a major resource of biologically active compounds with novel structures. Sri Lanka is considered as a biodiversity hotspot with a higher degree of endemism flora including bryophytes. In this study, different species of bryophytes were investigated for their antimicrobial and alpha-amylase inhibitory activities. The air-dried plant materials of 6 different bryophyte species, Marchantia sp., Fissidens sp., Plagiochila sp., Sematophyllum demissum, Hypnum cupressiforme, and Calymperes motley, were subjected to sequential cold extraction with 3 different organic solvents. All three types of organic crude extracts were subjected to screening of antimicrobial bioassays using the disc-diffusion method against 3 bacterial strains and 1 fungal strain. According to the results obtained, 6 extracts out of 18 showed antibacterial activity for tested Gram-positive bacteria and 1 active against Gram-negative bacteria. Two extracts showed activity against the pathogenic fungus strain. Extracts from some plants were active against tested bacterial as well as fungal species. TLC-based bioautographic study was carried out to identify the corresponding active bands which is useful for active compound isolation. Furthermore, the ethyl acetate extracts were subjected to evaluate alpha-amylase inhibitory activity where three extracts out of six extracts showed moderate inhibitory activity for alpha-amylase with IC50 ranging 8–30%.

scholarly journals IN VITRO ANTIDIABETIC POTENTIALS OF SIDA ACUTA, ABUTILON INDICUM AND MALVASTRUM COROMANDELIANUM

2020 ◽  
pp. 87-89
Author(s):  
NANTAPORN DINLAKANONT ◽  
CHANIDA PALANUVEJ ◽  
NIJSIRI RUANGRUNGSI
Keyword(s):  
Enzyme Inhibitors ◽  
Postprandial Glucose ◽  
Inhibitory Effect ◽  
Glucose Absorption ◽  
Alpha Amylase ◽  
Sida Acuta ◽  
Inhibitory Activities ◽  
Alpha Glucosidase ◽  
Abutilon Indicum

Objective: Starch metabolizing enzyme inhibitors are able to retard postprandial glucose absorption. This study aimed to investigate the in vitro inhibitory activities of alpha-glucosidase and alpha-amylase of three Malvaceous weeds i.e. Sidaacuta Burm. f., Abutilon indicum (Linn.) Sweet and Malvastrumcoromandelianum (Linn.) Garcke. Methods: The stems, roots and leaves of S. acuta, A. indicum and M. coromandelianum were sequentially extracted in dichloromethane and methanol, respectively. All fractions were tested for the inhibitory activities on yeast alpha-glucosidase, rat intestinal alpha-glucosidase and porcine alpha-amylase. p-Nitrophenyl-α-D-glucopyranoside and 2-chloro-4 nitrophenol-α-D- maltotrioside were used as the substrate for glucosidase and amylase respectively. Results: The dichloromethane fraction of the roots and stems from A. indicum and dichloromethane as well as methanolic fractions of the stems of M. coromandelianum could inhibit yeast alpha-glucosidase compared to 1-deoxynojirimycin with the IC50 of 0.36, 0.45, 0.48, 0.48 and 0.58 mg/ml respectively. A. indicum root methanolic fraction had the highest inhibitory effect on rat alpha-glucosidase activity compared to 1-deoxynojirimycin with the IC50 of 0.08 and 0.11 mg/ml respectively. M. coromandelianum, the dichloromethane fraction of roots and the methanolic fraction of stems, showed the strongest effect on alpha-amylase inhibition compared to acarbose with the IC50 of 0.07, 0.07 and 2.7 mg/ml, respectively. Conclusion: S. acuta, A. indicum and M. coromandelianum dichloromethane and methanolic fractions of the root, stem and leaf parts demonstrated an appreciable inhibitory activity on alpha-amylase from porcine, alpha-glucosidase from Saccharomyces cerevisiae and from rat intestine compared to 1-deoxynojirimycin and acarbose.

scholarly journals Evaluation of Xanthine Oxidase Inhibitory Activities in vitro of Gomphrena CelosiodesMart

2017 ◽  
Vol 33 (2) ◽  
Author(s):  
Dang Kim Thu ◽  
Vu Thi Hoa ◽  
Chu Ngoc Khanh ◽  
Bui Thanh Tung
Keyword(s):  
Uric Acid ◽  
Xanthine Oxidase ◽  
Inhibitory Activity ◽  
Final Stage ◽  
Enzyme Inhibitors ◽  
The Body ◽  
Prevention And Treatment ◽  
Etoac Fraction ◽  
Inhibitory Activities

Xanthine oxidase (XO) is an enzyme that has an improtant role in the synthesis of uric acid. XO is an enzyme allowscatalyzing the hydroxylation of hypoxanthine to xanthine and xanthine to uric acid. These are two reactions in the final stage of metabolism of the purines in the body. Offal, XO enzyme inhibitors reduce biosynthesis of uric acid have been used to prevent and treat gout. In this study, Gompherena celosiodes is extracted by ultrasonic with ethanol 80 % (EtOH)solvents and fractionated with n-hexane, ethyl acetate (EtOAc) and n-butanol (n-BuOH) solvents. These fractions were evaluated xanthine oxidase inhibitory activities in vitro. The results show that n-BuOH fraction from roots bark had the strongest XO enzyme inhibitory activity (IC50: 27,39 ± 0,31µg/mL), followed by EtOH fraction (IC50: 47,37 ± 0,26 µg/mL) and EtOAc fraction (IC50: 33,36 ± 0,51µg/mL) and the lowest is n-hexan fraction (IC50: 81,59 ± 0,21µg/mL). The research results indicated that the n-BuOH fraction and the EtOAc fraction from tree-hatched soil have a potential in the prevention and treatment of gout.

scholarly journals GC-MS Metabolic Profile and α-Glucosidase-, α-Amylase-, Lipase-, and Acetylcholinesterase-Inhibitory Activities of Eight Peach Varieties

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4183
Author(s):  
Dasha Mihaylova ◽  
Ivelina Desseva ◽  
Aneta Popova ◽  
Ivayla Dincheva ◽  
Radka Vrancheva ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Enzyme Inhibitors ◽  
Amylase Activity ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
New Approach ◽  
Natural Agents ◽  
Patients With Diabetes ◽  
Inhibitory Activities ◽  
Inhibitory Potential

The inhibition of certain digestive enzymes by target food matrices represents a new approach in the treatment of socially significant diseases. Proving the ability of fruits to inhibit such enzymes can support the inclusion of specific varieties in the daily diets of patients with diabetes, obesity, Alzheimer’s disease, etc., providing them with much more than just valuable micro- and macromolecules. The current study aimed atidentifying and comparing the GC-MS metabolic profiles of eight peach varieties (“Filina”, “Ufo 4, “Gergana”, “Laskava”, “July Lady”, “Flat Queen”, “Evmolpiya”, and “Morsiani 90”) grown in Bulgaria (local and introduced) and to evaluate the inhibitory potential of their extracts towards α-glucosidase, α-amylase, lipase, and acetylcholinesterase. In order to confirm samples’ differences or similarities, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were also applied to the identified metabolites. The results provide important insights into the metabolomic profiles of the eight peach varieties and represent a first attempt to characterize the peels of the peach varieties with respect to α-glucosidase-, α-amylase-, lipase-, and acetylcholinesterase-inhibitory activities. All of the studied peach extracts displayed inhibitory activity towards α-glucosidase (IC50: 125–757 mg/mL) and acetylcholinesterase (IC50: 60–739 mg/mL), but none of them affected α-amylase activity. Five of the eight varieties showed inhibitory activity towards porcine pancreatic lipase (IC50: 24–167 mg/mL). The obtained results validate the usefulness of peaches and nectarines as valuable sources of natural agents beneficial for human health, although further detailed investigation should be performed in order to thoroughly identify the enzyme inhibitors responsible for each activity.

scholarly journals Alpha-Glucosidase and Alpha-Amylase Inhibitory Activities, Molecular Docking, and Antioxidant Capacities of Salvia aurita Constituents

Antioxidants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1149
Author(s):  
Ninon G. E. R. Etsassala ◽  
Jelili A. Badmus ◽  
Jeanine L. Marnewick ◽  
Emmanuel I. Iwuoha ◽  
Felix Nchu ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Inhibitory Activity ◽  
Biological Evaluation ◽  
Antidiabetic Drugs ◽  
Alpha Amylase ◽  
Ic50 Values ◽  
Trolox Equivalent ◽  
Inhibitory Activities ◽  
Abietane Diterpenes ◽  
Alpha Glucosidase

Diabetes mellitus (DM) is one of the most dangerous metabolic diseases with a high rate of mortality worldwide. It is well known that insulin resistance and deficiency in insulin production from pancreatic β-cells are the main characteristics of DM. Due to the detrimental side effects of the current treatment, there is a considerable need to develop new effective antidiabetic drugs, especially alpha-glucosidase and alpha-amylase inhibitors with lesser adverse effects. These inhibitors are known to be directly involved in the delay of carbohydrate digestion, resulting in a reduction of glucose absorption rate and, consequently, reducing the postprandial rise of plasma glucose, which can reduce the risk of long-term diabetes complications. Furthermore, natural products are well-known sources for the discovery of new bioactive compounds that can serve as scaffolds for drug discovery, including that of new antidiabetic drugs. The phytochemical investigation of Salvia aurita collected from Hogobach Pass, Eastern Cape Province, South Africa (SA), yielded four known abietane diterpenes namely carnosol (1), rosmanol (2), 7-methoxyrosmanol (3), 12-methoxycarnosic acid (4), and one flavonoid named 4,7-dimethylapigenin (5). Structural characterization of these isolated compounds was conducted using 1 and 2D NMR, in comparison with reported spectroscopic data. These compounds are reported for the first time from S. aurita. The biological evaluation of the isolated compound against alpha-glucosidase exhibited strong inhibitory activities for 3 and 2 with the half maximal inhibitory concentration (IC50) values of 4.2 ± 0.7 and 16.4 ± 1.1 µg/mL respectively, while 4 and 1 demonstrated strong alpha-amylase inhibitory activity amongst the isolated compounds with IC50 values of 16.2 ± 0.3 and 19.8 ± 1.4 µg/mL. Molecular docking analysis confirms the strong inhibitory activity of 3 against alpha-glucosidase. Additionally, excellent antioxidant capacities were displayed by 2, 1, and 3, respectively, with oxygen radical absorbance capacity (ORAC) (25.79 ± 0.01; 23.96 ± 0.01; 23.94 ± 0.02) mM Trolox equivalent (TE)/g; 1 and 2 as ferric-ion reducing antioxidant power (FRAP) (3.92 ± 0.002; 1.52 ± 0.002) mM ascorbic acid equivalent (AAE)/g; 5 and 2 as Trolox equivalent absorbance capacity (TEAC) (3.19 ± 0.003; 2.06 ± 0.003) mM TE/g. The methanolic extract of S. aurita is a rich source of abietane diterpenes with excellent antioxidant and antidiabetic activities that can be useful to modulate oxidative stress and might possibly be excellent candidates for the management of diabetes. This is the first scientific report on the phytochemical isolation and biological evaluation of the alpha-glucosidase and alpha-amylase inhibitory activities of Salvia aurita.

scholarly journals Alpha-glucosidase and Alpha-amylase Inhibitory Activities, Molecular Docking and Antioxidant Capacities of Salvia Aurita Constituents

2020 ◽  
Author(s):  
Ninon G.E.R Etsassala ◽  
Jelili A. Badmus ◽  
Jeanine L. Marnewick ◽  
Felix Nchu ◽  
Ahmed A. Hussein
Keyword(s):  
Molecular Docking ◽  
Inhibitory Activity ◽  
Biological Evaluation ◽  
Antidiabetic Drugs ◽  
High Rate ◽  
Alpha Amylase ◽  
Antioxidant Capacities ◽  
Inhibitory Activities ◽  
Abietane Diterpenes ◽  
Alpha Glucosidase

Diabetes mellitus (DM) is one of the most dangerous metabolic diseases with high rate of mortality worldwide. It is well known that insulin resistance and deficiency in insulin production from pancreatic β-cells are the main characteristic of DM. Due to the detrimental side effects of the current treatment, there is a considerable need to develop new effective antidiabetic drugs, especially alpha-glucosidase and alpha-amylase inhibitors with lesser adverse effects. These inhibitors are known to be directly involved in the delay of carbohydrate digestion, resulting in a reduction of glucose absorption rate and consequently reduce the post-prandial raise of plasma glucose, which can reduce the risk of long-term diabetes complications. Hence, natural products are well-known sources for the discovery of new scaffold for drugs discovery, including new antidiabetic drugs. The phytochemical investigation of Salvia aurita collected from Hogobach pass, Eastern Cape, South Africa (SA), yielded four known abietane diterpenes namely carnosol (1), rosmanol (2), 7-methoxyrosmanol (3), 12-methoxycarnosic acid (4) and one flavonoid named 4,7-dimethylapigenin (5). Structural characterization of these isolated compounds was conducted using 1 and 2D NMR, in comparison with reported spectroscopic data. These compounds are reported for the first time from S. aurita. The biological evaluation of the isolated compound against alpha-glucosidase exhibited strong inhibitory activities for 3 and 2 with IC50 values of 4.2 ± 0.7 and 16.4 ± 1.1 µg/mL respectively, while 4 and 1 demonstrated strong alpha-amylase inhibitory activity amongst the isolated compounds with IC50 of 16.2 ± 0.3 and 19.8 ± 1.4 µg/mL. Molecular docking analysis confirms strong inhibitory activity of 3 against alpha-glucosidase. Additionally, excellent antioxidant capacities were displayed by 2, 1 and 3 respectively as ORAC (25789.9 ± 10.5; 23961.8 ± 14.1; 23939.3 ± 2.4) µM TE/g; 1 and 2 as FRAP (3917.8 ± 2.1; 1522.3 ± 0.9) µM AAE/g; 5 and 2 as TEAC (3190.4 ± 2.8; 2055.0 ± 2.6) µM TE/g. The methanolic extract of S. aurita is a rich source of abietane diterpenes with excellent antioxidant and anti-diabetic activities that can be useful to modulate oxidative stress, and might possibly be excellent candidates for the management of diabetes. This is the first scientific report on the phytochemical isolation and biological evaluation of alpha-glucosidase and alpha-amylase inhibitory activities of Salvia aurita.

Screening of Actinomycetes For α-amylase Inhibitors Production

2019 ◽  
Vol 15 (1) ◽  
pp. 41-45
Author(s):  
Shivabai Chandwad ◽  
Sudhakar Gutte
Keyword(s):  
Inhibitory Activity ◽  
Enzyme Inhibitors ◽  
Spectroscopic Method ◽  
Solid Material ◽  
Soil Samples ◽  
Assay Method ◽  
Novel Drugs ◽  
Pre Treatment ◽  
Diabetic Treatment ◽  
Amylase Inhibitors

Background:Diabetes mellitus is the most common and fastest growing disease in the world. One of the therapies to treat diabetes is the inhibition of α-amylase activity by inhibitors from microbial and plant source. Actinomycetes are potential sources of enzyme inhibitors, drugs, amino acids, vitamins etc.Objective:Our work mainly highlights the isolation of actinomycetes from soil samples of different habitats and screening of α -amylase inhibitors.Methods:Actinomycetes were isolated from soil samples of different habitats by different methods; these include a variety of pre-treatment of soil samples in combination with an appropriate supplement medium with selective antibacterial agents. Isolated actinomycetes grown in fermentation condition and metabolites were extracted with Isopropyl alcohol and concentrated to obtain solid material. The extract of each isolate was tested for α -amylase inhibition using starch Iodine plate method and DNS- spectroscopic method.Results:Total 110 actinomycetes strains were isolated from various sources. Among 110 extracts of actinomycetes, eight extracts have shown positive results for α-amylase inhibition in starch Iodine plate assay method. Extracts selected from primary results were used for the confirmation of inhibitory activity using DNS- spectroscopic method. Out of eight extracts, six extracts showed Porcine pancreatic α -amylase inhibitory activity ranging from 40-86%. The actinomycetes strains that produce α -amylase inhibitory activity are A-24, A-29, B-5, B-18, C-15 and D-24.Conclusion:These results show that actinomycetes are a potential source for α -amylase inhibitors, which may lead to valuable novel drugs for diabetic treatment.

scholarly journals Structural Characterization and Assessment of Anti-Inflammatory and Anti-Tyrosinase Activities of Polyphenols from Melastoma normale

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3913
Author(s):  
Rui-Jie He ◽  
Jun Li ◽  
Yong-Lin Huang ◽  
Ya-Feng Wang ◽  
Bing-Yuan Yang ◽  
...  
Keyword(s):  
Enzyme Inhibitors ◽  
Enzyme Inhibitor ◽  
Structure Identification ◽  
No Production ◽  
Protective Effects ◽  
Successful Isolation ◽  
Ic50 Values ◽  
Development And Utilization ◽  
Inhibitory Activities ◽  
Anti Inflammatory

Polyphenols, widely distributed in the genus Melastoma plants, possess extensive cellular protective effects such as anti-inflammatory, anti-tyrosinase, and anti-obesity, which makes it a potential anti-inflammatory drug or enzyme inhibitor. Therefore, the aim of this study is to screen for the anti-inflammatory and enzyme inhibitory activities of compounds from title plant. Using silica gel, MCI, ODS C18, and Sephadex LH-20 column chromatography, as well as semipreparative HPLC, the extract of Melastoma normale roots was separated. Four new ellagitannins, Whiskey tannin C (1), 1-O-(4-methoxygalloyl)-6-O-galloyl-2,3-O-(S)-hexahydroxydiphenoyl-β-d-glucose (2), 1-O-galloyl-6-O-(3-methoxygalloyl)-2,3-O-(S)-hexahydroxydiphenoyl-β-d-glucose (3), and 1-O-galloyl-6-O-vanilloyl-2,3-O-(S)-hexahydroxydiphenoyl-β-d-glucose (4), along with eight known polyphenols were firstly obtained from this plant. The structures of all isolates were elucidated by HRMS, NMR, and CD analyses. Using lipopolysaccharide (LPS)-stimulated RAW2 64.7 cells, we investigated the anti-inflammatory activities of compounds 1–4, unfortunately, none of them exhibit inhibit nitric oxide (NO) production, their IC50 values are all > 50 μM. Anti-tyrosinase activity assays was done by tyrosinase inhibition activity screening model. Compound 1 showed weak tyrosinase inhibitory activity with IC50 values of 426.02 ± 11.31 μM. Compounds 2–4 displayed moderate tyrosinase inhibitory activities with IC50 values in the range of 124.74 ± 3.12–241.41 ± 6.23 μM. The structure–activity relationships indicate that hydroxylation at C-3′, C-4′, and C-3 in the flavones were key to their anti-tyrosinase activities. The successful isolation and structure identification of ellagitannin provide materials for the screening of anti-inflammatory drugs and enzyme inhibitors, and also contribute to the development and utilization of M. normale.

scholarly journals Identification and Target-Modification of SL-BBI: A Novel Bowman–Birk Type Trypsin Inhibitor from Sylvirana latouchii

Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1254 ◽  
Author(s):  
Xi Chen ◽  
Dong Chen ◽  
Linyuan Huang ◽  
Xiaoling Chen ◽  
Mei Zhou ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Trypsin Inhibitor ◽  
Inhibitory Activity ◽  
Membrane Damage ◽  
Antiproliferative Effects ◽  
Docking Simulations ◽  
Cell Membrane Damage ◽  
Action Mode ◽  
Trypsin Inhibition ◽  
Cloning Method

The peptides from the ranacyclin family share similar active disulphide loop with plant-derived Bowman–Birk type inhibitors, some of which have the dual activities of trypsin inhibition and antimicrobial. Herein, a novel Bowman–Birk type trypsin inhibitor of the ranacyclin family was identified from the skin secretion of broad-folded frog (Sylvirana latouchii) by molecular cloning method and named as SL-BBI. After chemical synthesis, it was proved to be a potent inhibitor of trypsin with a Ki value of 230.5 nM and showed weak antimicrobial activity against tested microorganisms. Modified analogue K-SL maintains the original inhibitory activity with a Ki value of 77.27 nM while enhancing the antimicrobial activity. After the substitution of active P1 site to phenylalanine and P2′ site to isoleucine, F-SL regenerated its inhibitory activity on chymotrypsin with a Ki value of 309.3 nM and exhibited antiproliferative effects on PC-3, MCF-7 and a series of non-small cell lung cancer cell lines without cell membrane damage. The affinity of F-SL for the β subunits in the yeast 20S proteasome showed by molecular docking simulations enriched the understanding of the possible action mode of Bowman–Birk type inhibitors. Further mechanistic studies have shown that F-SL can activate caspase 3/7 in H157 cells and induce apoptosis, which means it has the potential to become an anticancer agent.

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