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1.
Cell Mol Life Sci ; 80(10): 293, 2023 Sep 16.
Article in English | MEDLINE | ID: mdl-37715850

ABSTRACT

Insulin-resistant diabetes is a common metabolic disease with serious complications. Treatments directly addressing the underlying molecular mechanisms involving insulin resistance would be desirable. Our laboratory recently identified a proteolytic-resistant cystine-dense microprotein from huáng qí (Astragalus membranaceus) called α-astratide aM1, which shares high sequence homology to leginsulins. Here we show that aM1 is a cell-penetrating insulin mimetic, enters cells by endocytosis, and activates the PI3K/Akt signaling pathway independent of the insulin receptor leading to translocation of glucose transporter GLUT4 to the cell surface to promote glucose uptake. We also showed that aM1 alters gene expression, suppresses lipid synthesis and uptake, and inhibits intracellular lipid accumulation in myotubes and adipocytes. By reducing intracellular lipid accumulation and preventing lipid-induced, PKCθ-mediated degradation of IRS1/2, aM1 restores glucose uptake to overcome insulin resistance. These findings highlight the potential of aM1 as a lead for developing orally bioavailable insulin mimetics to expand options for treating diabetes.


Subject(s)
Insulin Resistance , Humans , Proto-Oncogene Proteins c-akt , Phosphatidylinositol 3-Kinases , Insulin/pharmacology , Signal Transduction , Glucose , Lipids , Micropeptides
2.
Angew Chem Int Ed Engl ; 63(14): e202317789, 2024 Apr 02.
Article in English | MEDLINE | ID: mdl-38342764

ABSTRACT

Disulfides in peptides and proteins are essential for maintaining a properly folded structure. Their oxidative folding is invariably performed in an aqueous-buffered solution. However, this process is often slow and can lead to misfolded products. Here, we report a novel concept and strategy that is bio-inspired to mimic protein disulfide isomerase (PDI) by accelerating disulfide exchange rates many thousand-fold. The proposed strategy termed organic oxidative folding is performed under organic solvents to yield correctly folded cysteine-rich microproteins instantaneously without observable misfolded or dead-end products. Compared to conventional aqueous oxidative folding strategies, enormously large rate accelerations up to 113,200-fold were observed. The feasibility and generality of the organic oxidative folding strategy was successfully demonstrated on 15 cysteine-rich microproteins of different hydrophobicity, lengths (14 to 58 residues), and numbers of disulfides (2 to 5 disulfides), producing the native products in a second and in high yield.


Subject(s)
Cysteine , Micropeptides , Cysteine/metabolism , Protein Folding , Biomimetics , Peptides/chemistry , Protein Disulfide-Isomerases/metabolism , Oxidation-Reduction , Solvents , Disulfides/chemistry , Oxidative Stress
3.
Molecules ; 28(18)2023 Sep 10.
Article in English | MEDLINE | ID: mdl-37764332

ABSTRACT

Coffee processing generates a huge amount of waste that contains many natural products. Here, we report the discovery of a panel of novel cell-penetrating and metal ion-binding microproteins designated coffeetide cC1a-c and cL1-6 from the husk of two popular coffee plants, Coffea canephora and Coffea liberica, respectively. Combining sequence determination and a database search, we show that the prototypic coffeetide cC1a is a 37-residue, eight-cysteine microprotein with a hevein-like cysteine motif, but without a chitin-binding domain. NMR determination of cC1a reveals a compact structure that confers its resistance to heat and proteolytic degradation. Disulfide mapping together with chemical synthesis reveals that cC1a has a ginsentide-like, and not a hevein-like, disulfide connectivity. In addition, transcriptomic analysis showed that the 98-residue micrcoproten-like coffeetide precursor contains a three-domain arrangement, like ginsentide precursors. Molecular modeling, together with experimental validation, revealed a Mg2+ and Fe3+ binding pocket at the N-terminus formed by three glutamic acids. Importantly, cC1a is amphipathic with a continuous stretch of 19 apolar amino acids, which enables its cell penetration to target intracellular proteins, despite being highly negatively charged. Our findings suggest that coffee by-products could provide a source of ginsentide-like bioactive peptides that have the potential to target intracellular proteins.


Subject(s)
Coffea , Coffee , Cysteine , Disulfides , Micropeptides
4.
J Integr Plant Biol ; 65(6): 1442-1466, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36807520

ABSTRACT

Plants accumulate a vast array of secondary metabolites, which constitute a natural resource for pharmaceuticals. Oldenlandia corymbosa belongs to the Rubiaceae family, and has been used in traditional medicine to treat different diseases, including cancer. However, the active metabolites of the plant, their biosynthetic pathway and mode of action in cancer are unknown. To fill these gaps, we exposed this plant to eight different stress conditions and combined different omics data capturing gene expression, metabolic profiles, and anti-cancer activity. Our results show that O. corymbosa extracts are active against breast cancer cell lines and that ursolic acid is responsible for this activity. Moreover, we assembled a high-quality genome and uncovered two genes involved in the biosynthesis of ursolic acid. Finally, we also revealed that ursolic acid causes mitotic catastrophe in cancer cells and identified three high-confidence protein binding targets by Cellular Thermal Shift Assay (CETSA) and reverse docking. Altogether, these results constitute a valuable resource to further characterize the biosynthesis of active metabolites in the Oldenlandia group, while the mode of action of ursolic acid will allow us to further develop this valuable compound.


Subject(s)
Oldenlandia , Oldenlandia/chemistry , Transcriptome , Metabolomics , Genomics , Ursolic Acid
5.
Molecules ; 26(19)2021 Sep 29.
Article in English | MEDLINE | ID: mdl-34641455

ABSTRACT

Chitin-binding hevein-like peptides (CB-HLPs) belong to a family of cysteine-rich peptides that play important roles in plant stress and defense mechanisms. CB-HLPs are ribosomally synthesized peptides that are known to be bioprocessed from the following two types of three-domain CB-HLP precursor architectures: cargo-carrying and non-cargo-carrying. Here, we report the identification and characterization of chenotides biosynthesized from the third type of precursors, which are cleavable hololectins of the quinoa (Chenopodium quinoa) family. Chenotides are 6-Cys-CB-HLPs of 29-31 amino acids, which have a third type of precursor architecture that encompasses a canonical chitin-binding domain that is involved in chitin binding and anti-fungal activities. Microbroth dilution assays and microscopic analyses showed that chenotides are effective against phyto-pathogenic fungi in the micromolar range. Structure determination revealed that chenotides are cystine knotted and highly compact, which could confer resistance against heat and proteolytic degradation. Importantly, chenotides are connected by a novel 18-residue Gly/Ala-rich linker that is a target for bioprocessing by cathepsin-like endopeptidases. Taken together, our findings reveal that chenotides are a new family of CB-HLPs from quinoa that are synthesized as a single multi-modular unit and bioprocessed to yield individual mature CB-HLPs. Importantly, such precursors constitute a new family of cleavable hololectins. This unusual feature could increase the biosynthetic efficiency of anti-fungal CB-HLPs, to provide an evolutionary advantage for plant survival and reproduction.


Subject(s)
Antimicrobial Cationic Peptides/pharmacology , Chenopodium quinoa/chemistry , Peptide Fragments/pharmacology , Plant Lectins/metabolism , Plant Proteins/metabolism , Amino Acid Sequence , Plant Lectins/chemistry , Plant Lectins/pharmacology , Plant Proteins/chemistry , Protein Conformation , Sequence Homology
6.
J Biol Chem ; 294(11): 4000-4011, 2019 03 15.
Article in English | MEDLINE | ID: mdl-30674551

ABSTRACT

Mitochondria are attractive therapeutic targets for developing agents to delay age-related frailty and diseases. However, few promising leads have been identified from natural products. Previously, we identified roseltide rT1, a hyperstable 27-residue cysteine-rich peptide from Hibiscus sabdariffa, as a knottin-type neutrophil elastase inhibitor. Here, we show that roseltide rT1 is also a cell-penetrating, mitochondria-targeting peptide that increases ATP production. Results from flow cytometry, live-cell imaging, pulldown assays, and genetically-modified cell lines supported that roseltide rT1 enters cells via glycosaminoglycan-dependent endocytosis, and enters the mitochondria through TOM20, a mitochondrial protein import receptor. We further showed that roseltide rT1 increases cellular ATP production via mitochondrial membrane hyperpolarization. Using biotinylated roseltide rT1 for target identification and proteomic analysis, we showed that human mitochondrial membrane ATP synthase subunit O is an intramitochondrial target. Collectively, these data support our discovery that roseltide rT1 is a first-in-class mitochondria-targeting, cysteine-rich peptide with potentials to be developed into tools to further our understanding of mitochrondria-related diseases.


Subject(s)
Energy Metabolism , Hibiscus/chemistry , Hibiscus/metabolism , Mitochondria/metabolism , Plant Proteins/metabolism , Cells, Cultured , Flow Cytometry , Hibiscus/cytology , Humans
7.
J Biol Chem ; 294(51): 19604-19615, 2019 12 20.
Article in English | MEDLINE | ID: mdl-31727740

ABSTRACT

Disulfide-rich plant peptides with molecular masses of 2-6 kDa represent an expanding class of peptidyl-type natural products with diverse functions. They are structurally compact, hyperstable, and underexplored as cell-penetrating agents that inhibit intracellular functions. Here, we report the discovery of an anionic, 34-residue peptide, the disulfide-rich roseltide rT7 from Hibiscus sabdariffa (of the Malvaceae family) that penetrates cells and inhibits their proteasomal activities. Combined proteomics and NMR spectroscopy revealed that roseltide rT7 is a cystine-knotted, six-cysteine hevein-like cysteine-rich peptide. A pair-wise comparison indicated that roseltide rT7 is >100-fold more stable against protease degradation than its S-alkylated analog. Confocal microscopy studies and cell-based assays disclosed that after roseltide rT7 penetrates cells, it causes accumulation of ubiquitinated proteins, inhibits human 20S proteasomes, reduces tumor necrosis factor-induced IκBα degradation, and decreases expression levels of intercellular adhesion molecule-1. Structure-activity studies revealed that roseltide rT7 uses a canonical substrate-binding mechanism for proteasomal inhibition enabled by an IIML motif embedded in its proline-rich and exceptionally long intercysteine loop 4. Taken together, our results provide mechanistic insights into a novel disulfide-rich, anionic, and cell-penetrating peptide, representing a potential lead for further development as a proteasomal inhibitor in anti-cancer or anti-inflammatory therapies.


Subject(s)
Cell-Penetrating Peptides/pharmacology , Hibiscus/chemistry , Plant Extracts/chemistry , Proteasome Endopeptidase Complex/metabolism , Proteasome Inhibitors/pharmacology , A549 Cells , Anti-Inflammatory Agents/pharmacology , Antimicrobial Cationic Peptides , Antineoplastic Agents, Phytogenic/pharmacology , Cysteine/chemistry , Disulfides , Endocytosis , Flow Cytometry , Humans , Magnetic Resonance Spectroscopy , Microscopy, Confocal , Molecular Conformation , Plant Lectins , Plant Proteins/chemistry , Proteomics , Structure-Activity Relationship , Ubiquitin/chemistry
8.
BMC Complement Altern Med ; 19(1): 50, 2019 Feb 21.
Article in English | MEDLINE | ID: mdl-30791910

ABSTRACT

BACKGROUND: This study investigated the protective effects of the Danshen (DS) and Sanqi (SQ) herb pair on cell survival in the human cardiovascular endothelial (EA.hy926) cell line exposed to injury. METHODS: Nine combination ratios of Danshen-Sanqi extracts (DS-SQ) were screened for their protective effects in the EA.hy926 cell line against two different cellular impairments induced by DL-homocysteine (Hcy) - adenosine (Ado) - tumour necrosis factors (TNF) and oxidative stress (H2O2), respectively. The type of interaction (synergistic, antagonistic, additive) between DS and SQ was analysed using a combination index (CI) model. The effects of key bioactive compounds from DS and SQ were tested using the same models. The compound from each herb that demonstrated the most potent activity in cell viability was combined to evaluate their synergistic/antagonistic interaction using CI. RESULTS: DS-SQ ratios of 6:4 (50-300 µg/mL) produced synergistic effects (CI < 1) in restoring cell viability, reducing lactate dehydrogenase (LDH) leakage and caspase-3 expressions against Hcy-Ado-TNF. Additionally, DS-SQ 6:4 (50-150 µg/mL) was found to synergistically protect endothelial cells from impaired cellular injury induced by oxidative damage (H2O2) by restoring reduced cell viability and inhibiting excessive expression of reactive oxygen species (ROS). In particular, the combination of salvianolic acid A (SA) and ginsenoside Rb1 (Rb1) at 4:6 (1-150 µM) showed synergistic effects in preventing cytotoxic effects caused by Hcy-Ado-TNF (CI < 1). This simplified combination also demonstrated synergistic effects on H2O2-induced oxidative damage on EA.hy926 cells. CONCLUSIONS: This study provides scientific evidence to support the traditional use of the DS-SQ combination on protecting endothelial cells through their synergistic interactions.


Subject(s)
Cell Survival/drug effects , Drugs, Chinese Herbal/pharmacology , Protective Agents/pharmacology , Cell Line , Drug Synergism , Humans , Oxidative Stress/drug effects , Reactive Oxygen Species/metabolism , Salvia miltiorrhiza
9.
J Am Chem Soc ; 137(49): 15398-401, 2015 Dec 16.
Article in English | MEDLINE | ID: mdl-26633100

ABSTRACT

Macrocyclization is a valuable tool for drug design and protein engineering. Although various methods have been developed to prepare macrocycles, a general and efficient strategy is needed. Here we report a highly efficient method using butelase 1 to macrocyclize peptides and proteins ranging in sizes from 26 to >200 residues. We achieved cyclizations that are 20,000 times faster than sortase A, the most widely used ligase for protein cyclization. The reactions completed within minutes with up to 95% yields.


Subject(s)
Ligases/metabolism , Peptides/metabolism , Proteins/metabolism , Amino Acid Sequence , Animals , Cyclization , Humans , Ligases/chemistry , Models, Molecular , Molecular Sequence Data , Peptide Synthases/chemistry , Peptide Synthases/genetics , Peptide Synthases/metabolism , Peptides/chemistry , Plant Proteins/chemistry , Plant Proteins/genetics , Plant Proteins/metabolism , Proteins/chemistry , Rats
10.
J Pharm Pharm Sci ; 18(5): 871-81, 2015.
Article in English | MEDLINE | ID: mdl-26670373

ABSTRACT

PURPOSE: Adenosine plays an important role in the pathogenesis of homocysteine-associated vascular complications. METHODS: This study examined the effects of dipyridamole, an inhibitor for nucleoside transport, on impaired angiogenic processes caused by homocysteine and adenosine in human cardiovascular endothelial cell line (EAhy926). RESULTS: The results showed that dipyridamole restored the extracellular adenosine and intracellular S-adenosylhomocysteine concentrations disrupted by the combination of homocysteine and adenosine. Dipyridamole also ameliorated the impaired proliferation, migration and formation of capillary-like tubes of EAhy926 cells caused by the combination of homocysteine and adenosine. Mechanism analysis revealed that dipyridamole induced the phosphorylation of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinases (ERK) and its effect on cell growth was attenuated by the MEK inhibitor, U0126. CONCLUSION: Dipyridamole protected against impaired angiogenesis caused by homocysteine and adenosine, at least in part, by activating the MEK/ERK signalling pathway, and this could be associated with its effects in suppressing intracellular S-adenosylhomocysteine accumulation. NOVELTY OF THE WORK: This is the first paper showing that nucleoside transport inhibition by dipyridamole reduced impaired angiogenic process caused by homocysteine and adenosine.


Subject(s)
Adenosine , Dipyridamole/pharmacology , Homocysteine , Neovascularization, Pathologic/prevention & control , Nucleosides/metabolism , Vasodilator Agents/pharmacology , Biological Transport, Active/drug effects , Capillaries/drug effects , Capillaries/growth & development , Cell Line , Cell Movement/drug effects , Cell Proliferation/drug effects , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Humans , MAP Kinase Signaling System/drug effects , Neovascularization, Pathologic/chemically induced , Nucleosides/antagonists & inhibitors , Phosphorylation , S-Adenosylhomocysteine/metabolism , Wound Healing/drug effects
11.
J Pharm Pharm Sci ; 18(4): 424-33, 2015.
Article in English | MEDLINE | ID: mdl-26626244

ABSTRACT

PURPOSE: Circulating microparticles have been highlighted as biomarkers of cardiovascular disease state and progression. The aim of this study was to evaluate the effects of curcumin on microparticle release from endothelial cells undergoing TNF-induced cell activation and apoptosis. METHODS: This study evaluated the effects of curcumin on microparticle release, cytotoxicity, apoptosis, cell adhesion molecule expression and monocyte adhesion in EAhy926 human endothelial cells. RESULTS: The results showed that the numbers of microparticles were increased by tumour necrosis factor (TNF) or the combination of TNF and cycloheximide (CHX). Curcumin attenuated microparticle release caused by TNF or TNF plus CHX treatments. The pretreatment by curcumin not only negated the accelerated cell death and apoptosis caused by TNF and CHX, but also diminished TNF-induced cell activation, as assessed by reduced surface expression of intercellular adhesion molecule 1, and adhesion of monocytes to endothelial monolayers. CONCLUSION: Curcumin reduced microparticle release from endothelial cells undergoing cell activation and apoptosis, which supports its protective role in TNF-associated endothelial dysfunction, and highlights its potential use as a nutraceutical agent for vascular inflammatory diseases. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.


Subject(s)
Cell-Derived Microparticles/metabolism , Curcumin/pharmacology , Endothelial Cells/drug effects , Tumor Necrosis Factor-alpha/administration & dosage , Annexin A5/chemistry , Apoptosis/drug effects , Cell Adhesion/drug effects , Cell Adhesion Molecules/metabolism , Cell Line , Endothelial Cells/metabolism , Humans , Monocytes/drug effects , Monocytes/metabolism
12.
Acta Pharm Sin B ; 14(2): 653-666, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38322337

ABSTRACT

Stress and illness connection is complex and involves multiple physiological systems. Panax ginsengs, reputed for their broad-spectrum "cure-all" effect, are widely prescribed to treat stress and related illnesses. However, the identity of ginseng's "cure-all" medicinal compounds that relieve stress remains unresolved. Here, we identify ginsentides as the principal bioactives that coordinate multiple systems to restore homeostasis in response to stress. Ginsentides are disulfide-rich, cell-penetrating and proteolytic-stable microproteins. Using affinity-enrichment mass spectrometry target identification together with in vitro, ex vivo and in vivo validations, we show that highly purified or synthetic ginsentides promote vasorelaxation by producing nitric oxide through endothelial cells via intracellular PI3K/Akt signaling pathway, alleviate α1-adrenergic receptor overactivity by reversing phenylephrine-induced constriction of aorta, decrease monocyte adhesion to endothelial cells via CD166/ESAM/CD40 and inhibit P2Y12 receptors to reduce platelet aggregation. Orally administered ginsentides were effective in animal models to reduce ADP-induced platelet aggregation, to prevent collagen and adrenaline-induced pulmonary thrombosis as well as anti-stress behavior of tail suspension and forced swimming tests in mice. Together, these results strongly suggest that ginsentides are the principal panacea compounds of ginsengs because of their ability to target multiple extra- and intra-cellular proteins to reverse stress-induced damages.

13.
Phytother Res ; 27(11): 1614-20, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23280757

ABSTRACT

Pomegranate has been documented for the management of diabetes in Unani and Chinese medicine. This study compared the effects of the extracts of different pomegranate parts, including juice, peels, seeds and flowers, on carbohydrate digestive enzymes (α-amylase and α-glucosidase) in vitro. The methanolic flower extract inhibited α-amylase and α-glucosidase, while the methanolic peel extract inhibited α-glucosidase selectively. The most active flower extract was subjected to water-ethyl acetate partition. The ethyl acetate fraction was more potent than the water fraction in inhibiting both enzymes. Gallic acid and ellagic acid also showed selective inhibition against α-glucosidase, and their presence in the ethyl acetate fraction was confirmed by HPLC-DAD and HPLC-HESI-MS. Our findings suggest that the inhibition of carbohydrate digestive enzymes and their phenolic content may contribute to the anti-hyperglycaemic effects of pomegranate flower and peel, and support their claims in diabetes.


Subject(s)
Enzyme Inhibitors/pharmacology , Glycoside Hydrolase Inhibitors , Lythraceae/chemistry , Plant Extracts/pharmacology , alpha-Amylases/antagonists & inhibitors , Animals , Ellagic Acid/pharmacology , Enzyme Inhibitors/chemistry , Flowers/chemistry , Fruit/chemistry , Gallic Acid/pharmacology , Hypoglycemic Agents/chemistry , Hypoglycemic Agents/pharmacology , Plant Extracts/chemistry , Rats , Seeds/chemistry , Swine
14.
Cells ; 12(10)2023 05 16.
Article in English | MEDLINE | ID: mdl-37408235

ABSTRACT

Hypoxia-induced vascular endothelial dysfunction (VED) is a significant contributor to several severe human diseases, including heart disease, stroke, dementia, and cancer. However, current treatment options for VED are limited due to the lack of understanding of the underlying disease mechanisms and therapeutic leads. We recently discovered a heat-stable microprotein in ginseng, called ginsentide TP1, that has been shown to reduce vascular dysfunction in cardiovascular disease models. In this study, we use a combination of functional assays and quantitative pulsed SILAC proteomics to identify new proteins synthesized in hypoxia and to show that ginsentide TP1 provides protection for human endothelial cells against hypoxia and ER stress. Consistent with the reported findings, we also found that hypoxia activates various pathways related to endothelium activation and monocyte adhesion, which in turn, impairs nitric oxide (NO) synthase activity, reduces the bioavailability of NO, and increases the production of reactive oxygen species that contribute to VED. Additionally, hypoxia triggers endoplasmic reticulum stress and initiates apoptotic signaling pathways associated with cardiovascular pathology. Treatment with ginsentide TP1 reduced surface adhesion molecule expression, prevented activation of the endothelium and leukocyte adhesion, restored protein hemostasis, and reduced ER stress to protect against hypoxia-induced cell death. Ginsentide TP1 also restored NO signaling and bioavailability, reduced oxidative stress, and protected endothelial cells from endothelium dysfunction. In conclusion, this study shows that the molecular pathogenesis of VED induced by hypoxia can be mitigated by treatment with ginsentide TP1, which could be one of the key bioactive compounds responsible for the "cure-all" effect of ginseng. This research may lead to the development of new therapies for cardiovascular disorders.


Subject(s)
Cardiovascular Diseases , Vascular Diseases , Humans , Endothelial Cells/metabolism , Endoplasmic Reticulum Stress , Vascular Diseases/metabolism , Hypoxia/metabolism , Apoptosis , Cardiovascular Diseases/metabolism , Micropeptides
15.
Cell Physiol Biochem ; 30(3): 805-14, 2012.
Article in English | MEDLINE | ID: mdl-22868254

ABSTRACT

Disruption to the vascular homoeostasis is detrimental in vascular diseases. This study examined how the combination of homocysteine, adenosine and tumor necrosis factor-alpha (TNF-α) influenced endothelial cell survival. In cultured human-derived cardiovascular (EA.hy926) and cerebrovascular (HBEC-5i) endothelial cells, cell death events were initiated by TNF-α (0.1-10 ng/mL) only when both homocysteine (0.5 mM) and adenosine (0.5 mM) were present. The accelerated cell death events induced by the combination were triggered through excessive apoptosis. This was evident by membrane phospholipid phosphatidylserine externalisation, cell shrinkage and DNA fragmentation, as well as an increase in the expressions and occurrence of active caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP) positive cells. Collectively, homocysteine, adenosine and TNF-α are interrelated in the survival of endothelial cells, and this co-existence should be considered in future drug development for cardiovascular and cerebrovascular diseases.


Subject(s)
Adenosine/toxicity , Apoptosis/drug effects , Homocysteine/toxicity , Tumor Necrosis Factor-alpha/toxicity , Caspase 3/metabolism , Cell Line , Cell Survival/radiation effects , Endothelial Cells/cytology , Endothelial Cells/drug effects , Endothelial Cells/metabolism , Endothelium, Vascular/cytology , Humans , Poly(ADP-ribose) Polymerases/metabolism
16.
Adv Exp Med Biol ; 771: 396-413, 2012.
Article in English | MEDLINE | ID: mdl-23393692

ABSTRACT

Herbal medicines have been used in the management of diabetes in traditional medicine. This chapter reviews recent findings of the most popular herbs reported to treat diabetes through their relevant mechanistic pathways. These include increased insulin secretion, improvement in insulin sensitivity, enhanced glucose uptake by adipose and muscle tissues, inhibition of glucose absorption from intestine, inhibition of glucose production from hepatocytes and anti-inflammatory activities. The pharmacological activities have highlighted the potential efficacy of these herbal medicines in the management of diabetes.


Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Drugs, Chinese Herbal/therapeutic use , Herbal Medicine/methods , Medicine, Ayurvedic , Humans
17.
Front Pharmacol ; 13: 942168, 2022.
Article in English | MEDLINE | ID: mdl-36052138

ABSTRACT

Corneal scarring reduces corneal transparency, compromises vision, and is a major cause of vision loss worldwide. Epidermal growth factor (EGF), which is the prototypic member of the EGF receptor (EGFR) agonists, is present in tears to provide repair and regeneration. Recently, we discovered bleogen pB1 in the cactus plant Pereskia bleo and showed that it is a non-canonical and hyperstable EGFR agonist with EGF-like wound healing properties for diabetic rats. Here, we apply bleogen pB1 to accelerate corneal wound healing in rats. To assess the corneal healing effects of bleogen pB1, we induced an acute alkali burn to the right eye of male Wistar rats. After five consecutive ophthalmic applications, fluorescein staining and opacity scores of the bleogen pB1-treated, and the positive control EGF-treated groups improved significantly compared to the saline control group. Immunohistochemical analyses revealed that infiltrated CD68+ macrophages and the expression of the myofibroblast marker alpha smooth muscle actin (α-SMA) were significantly decreased in the bleogen pB1- and the EGF-treated groups. By employing a differential gene expression analysis of bleogen pB1- and EGF-treated keratinocytes through RNA-seq, we demonstrated that bleogen pB1 or EGF treatments can affect the expression of genes associated with inflammatory responses and extracellular matrix remodeling. Taken together, our results indicate that the plant-derived EGFR agonist bleogen pB1 can produce similar effects to those of EGF in accelerating corneal wound healing as well as in reducing persistent inflammation and myofibroblast accumulation in the cornea.

18.
Front Plant Sci ; 13: 899740, 2022.
Article in English | MEDLINE | ID: mdl-35620686

ABSTRACT

Heveins and hevein-containing (hev-) lectins play important roles in stress and pathogenic responses in plants but cause health concerns in humans. Hev-hololectins contain multiple modular hev-peptide domains and are abundantly present in cereals and pseudocereals. However, it is unclear why some cereal hev-hololectins are presented as different forms of proteolytically processed proteoforms. Here we show the precursor architectures of hev-hololectins lead to different processing mechanisms to give either hololectins or hevein-like peptides. We used mass spectrometry and datamining to screen hev-peptides from common cereals, and identified from the oat plant Avena sativa nine novel hevein-like peptides, avenatide aV1-aV9. Bioinformatic analysis revealed that asparaginyl endopeptidase (AEP) can be responsible for the maturation of the highly homologous avenatides from five oat hev-hololectin precursors, each containing four tandemly repeating, hev-like avenatide domains connected by AEP-susceptible linkers with 13-16 residues in length. Further analysis of cereal hev-hololectins showed that the linker lengths provide a distinguishing feature between their cleavable and non-cleavable precursors, with the cleavables having considerably longer linkers (>13 amino acids) than the non-cleavables (<6 amino acids). A detailed study of avenatide aV1 revealed that it contains eight cysteine residues which form a structurally compact, metabolic-resistant cystine-knotted framework with a well-defined chitin-binding site. Antimicrobial assays showed that avenatide aV1 is anti-fungal and inhibits the growth of phyto-pathogenic fungi. Together, our findings of cleavable and non-cleavable hololectins found in cereals expand our knowledge to their biosynthesis and provide insights for hololectin-related health concerns in human.

19.
J Med Chem ; 64(11): 7746-7759, 2021 06 10.
Article in English | MEDLINE | ID: mdl-34015925

ABSTRACT

Here, we report the discovery of the first plant-derived and noncanonical epidermal growth factor receptor (EGFR) agonist, the 36-residue bleogen pB1 from Pereskia bleo of the Cactaceae family. We show that bleogen pB1 is a low-affinity EGFR agonist using a suite of chemical, biochemical, cellular, and animal experiments which include incisor eruption and wound-healing mouse models. A focused positional scanning pB1 library of Ala- and d-amino acid scans yielded a high-affinity pB1 analog, [K29k]pB1, with a 60-fold-improved EGFR affinity and mitogenicity. We show that the potency of [K29k]pB1 and the epidermal growth factor (EGF) is comparable in a diabetic mouse wound-healing model. We also show that both bleogen pB1 and [K29k]pB1 are hyperstable, being >100-fold more stable than EGF against proteolytic degradation. Overall, our discovery of a noncanonical proteolytic-resistant EGFR agonist scaffold could open new avenues for developing wound healing and skin regeneration therapeutics and biomaterials.


Subject(s)
Cactaceae/chemistry , ErbB Receptors/agonists , Peptides/chemistry , Amino Acid Motifs , Animals , Binding Sites , Cactaceae/metabolism , Cell Movement/drug effects , Cell Proliferation/drug effects , Diabetes Mellitus, Experimental/chemically induced , Diabetes Mellitus, Experimental/pathology , Drug Evaluation, Preclinical , ErbB Receptors/metabolism , Humans , Mice , Mice, Inbred C57BL , Molecular Docking Simulation , Peptides/metabolism , Peptides/pharmacology , Plant Leaves/chemistry , Plant Leaves/metabolism , Plant Proteins/chemistry , Protein Stability , Signal Transduction/drug effects , Structure-Activity Relationship , Wound Healing/drug effects
20.
Saudi J Biol Sci ; 28(1): 813-824, 2021 Jan.
Article in English | MEDLINE | ID: mdl-33424371

ABSTRACT

Current pre-clinical evidences of Centella focus on its pharmacological effects on normal wound healing but there are limited studies on the bioactivity of Centella in cellular dysfunction associated with diabetic wounds. Hence we planned to examine the potential of Centella cordifolia in inhibiting methylglyoxal (MGO)-induced extracellular matrix (ECM) glycation and promoting the related cellular functions. A Cell-ECM adhesion assay examined the ECM glycation induced by MGO. Different cell types that contribute to the healing process (fibroblasts, keratinocytes and endothelial cells) were evaluated for their ability to adhere to the glycated ECM. Methanolic extract of Centella species was prepared and partitioned to yield different solvent fractions which were further analysed by high performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) method. Based on the antioxidant [2,2-diphenyl-1-picrylhydrazyl (DPPH) assay] screening, anti-glycation activity and total phenolic content (TPC) of the different Centella species and fractions, the ethyl acetate fraction of C. cordifolia was selected for further investigating its ability to inhibit MGO-induced ECM glycation and promote cellular distribution and adhesion. Out of the three Centella species (C. asiatica, C. cordifolia and C. erecta), the methanolic extract of C. cordifolia showed maximum inhibition of Advanced glycation end products (AGE) fluorescence (20.20 ± 4.69 %, 25.00 ± 3.58 % and 16.18 ± 1.40 %, respectively). Its ethyl acetate fraction was enriched with phenolic compounds (3.91 ± 0.12 mg CAE/µg fraction) and showed strong antioxidant (59.95 ± 7.18 µM TE/µg fraction) and antiglycation activities. Improvement of cells spreading and adhesion of endothelial cells, fibroblasts and keratinocytes was observed for ethyl acetate treated MGO-glycated extracellular matrix. Significant reduction in attachment capacity of EA.hy926 cells seeded on MGO-glycated fibronectin (41.2%) and attachment reduction of NIH3t3 and HaCaT cells seeded on MGO-glycated collagen (33.7% and 24.1%, respectively) were observed. Our findings demonstrate that ethyl acetate fraction of C. cordifolia was effective in attenuating MGO-induced glycation and cellular dysfunction in the in-vitro wound healing models suggesting that C. cordifolia could be a potential candidate for diabetic wound healing. It could be subjected for further isolation of new phytoconstituents having potential diabetic wound healing properties.

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