Pentosidine Formation Research Articles

Inhibitory Effects of Aqueous Ethanol Extracts of Poplar-Type Propolis on Advanced Glycation End Products and Protein Oxidation

(1) Background: The non-enzymatic glycation of proteins is a significant contributor to the formation of advanced glycation end products (AGEs) and intermediates that are responsible for diabetic complications. It is imperative to explore effective inhibitors to prevent protein glycation. (2) Methods: This study aimed to investigate the inhibitory potential of various aqueous ethanol extracts of poplar-type propolis on AGEs and oxidative modifications in bovine serum albumin (BSA)-glucose and BSA-methylglyoxal models. (3) Results: The results revealed that these propolis extracts exhibited significant effectiveness in inhibiting the formation of total AGEs, pentosidine, and Nε-carboxymethyllysine (CML). Furthermore, the investigation discovered that these propolis extracts can effectively inhibit oxidative modification, based on measuring the levels of carbonyl and thiol groups and analyzing tryptophan fluorescence quenching. Notably, 75% ethanol extracts of propolis (EEP) exhibited the highest inhibitory activity, surpassing the chemical inhibitor aminoguanidine (AG). (4) Conclusions: The remarkable anti-glycation potency of aqueous ethanol extracts of poplar-type propolis can be attributed to their elevated contents of phenolic compounds, especially abundant flavonoids, which inhibit the formation of AGEs by scavenging free radicals, decreasing the levels of reactive oxygen species (ROS), and capturing reactive carbonyl species (RCS) in the protein glycation process. Our results indicate that poplar-type propolis may be a potential AGE inhibitor and could be used to develop functional foods and nutraceuticals to prevent diabetic complications.

Protective effect of colchicine on albumin glycation and cellular oxidative stress: Insights into diabetic cardiomyopathy.

The present work elucidates the role of colchicine (COL) on albumin glycation and cellular oxidative stress in diabetic cardiomyopathy (DCM). Human serum albumin (HSA) was glycated with methylglyoxalin the presence of COL (2.5, 3.75, and 5 µM), whereas positive and negative control samples were maintained separately. The effects of COL on HSA glycation, structural and functional modifications in glycated HSA were analyzed using different spectroscopical andfluorescence techniques. Increased fructosamine, carbonyl, and pentosidine formation in glycated HSA samples were inhibited in the presence of COL. Structural conformation of HSA and glycated HSA samples was examined by field emission scanning electron microscopy, circular dichroism, Fourier transform infrared, and proton nuclear magnetic resonance analyses, where COL maintained both secondary and tertiary structures of HSA against glycation. Functional marker assays included ABTS•+ radical scavenging and total antioxidant activities, advanced oxidative protein product formation, and turbidimetry, which showed preserved functional properties of glycated HSA in COL-containing samples. Afterward, rat cardiomyoblast (H9c2 cell line) was treated with glycated HSA-COL complex (400 μg/mL) for examining various cellular antioxidants (nitric oxide, catalase, superoxide dismutase, and glutathione) and detoxification enzymes (aldose reductase, glyoxalase I, andII) levels. All three concentrations of COL exhibited effective anti-glycation properties, enhanced cellular antioxidant levels, and detoxification enzyme activities. The report comprehensively analyzes the potential anti-glycation and properties of COL during its initial assessment.

Pyrogallol experimentally and theoretically suppressed advanced glycation end products (AGEs) formation, as one of the mechanisms involved in the chronic complications of the diabetes

This study aimed to explore the inhibitory effect of pyrogallol on AGE formation in the bovine serum albumin (BSA)/glucose system for 21 days at 37 °C. The AGEs formation was measured in terms of Amadori products, total AGEs, argpyrimidine, and pentosidine. Molecular docking was used to investigate the interaction between pyrogallol and BSA. According to the results, in the presence of pyrogallol, the formation of pentosidine and argpyrimidine AGEs decreased. The molecular interaction studies demonstrated that pyrogallol has a high affinity towards arginine residues of albumin. Finally, results proved pyrogallol is a vigorous antiglycation compound and fruitful for AGE inhibition.

Formation of advanced glycation end products of chicken breast meat induced by freeze–thaw cycles and subsequent cooking

The impacts of freeze–thaw (F–T) cycles and cooking on the basic composition, protein and lipid oxidation, and advanced glycation end products (AGEs) of chicken breasts were studied. During F–T cycles, the moisture and protein contents of raw and cooked chicken breasts decreased, and protein and lipid oxidation occurred, increasing carbonyl and TBARS contents. Meanwhile, the contents of methylglyoxal, glyoxal, and hydroxymethylfurfural in raw meat increased by 2.27, 2.27, and 5 times, respectively, whereas glyoxal and hydroxymethylfurfural contents increased by 2.73 and 3 times, respectively, after cooking as F–T cycles increased. The formation of carboxymethyl lysine, pentosidine, and fluorescent AGEs in cooked samples was confirmed using an ELISA kit and fluorescent intensity. The study also revealed that AGEs contents of chicken meat were negatively correlated with moisture contents and positively correlated with carbonyl and TBARS levels. Therefore, F–T cycles and subsequent cooking promoted AGEs formation in cooked meat.

Structural role of osteocalcin and its modification in bone fracture.

Osteocalcin (OC), an abundant non-collagenous protein in bone extracellular matrix, plays a vital role in both its biological and mechanical function. OC undergoes post-translational modification, such as glycation; however, it remains unknown whether glycation of OC affects bone's resistance to fracture. Here, for the first time, we demonstrate the formation of pentosidine, an advanced glycation end-product (AGE) cross-link on mouse OC analyzed by ultra-performance liquid chromatography. Next, we establish that the presence of OC in mouse bone matrix is associated with lower interlamellar separation (distance) and thicker bridges spanning the lamellae, both of which are critical for maintaining bone's structural integrity. Furthermore, to determine the impact of modification of OC by glycation on bone toughness, we glycated bone samples in vitro from wild-type (WT) and osteocalcin deficient (Oc-/-) mice, and compared the differences in total fluorescent AGEs and fracture toughness between the Oc -/- glycated and control mouse bones and the WT glycated and control mouse bones. We determined that glycation resulted in significantly higher AGEs in WT compared to Oc-/- mouse bones (delta-WT > delta-OC, p = 0.025). This observed change corresponded to a significant decrease in fracture toughness between WT and Oc-/- mice (delta-WT vs delta-OC, p = 0.018). Thus, we propose a molecular deformation and fracture mechanics model that corroborates our experimental findings and provides evidence to support a 37%-90% loss in energy dissipation of OC due to formation of pentosidine cross-link by glycation. We anticipate that our study will aid in elucidating the effects of a major non-collagenous bone matrix protein, osteocalcin, and its modifications on bone fragility and help identify potential therapeutic targets for maintaining skeletal health.

Formation of Pentosidine Cross-Linking in Myoglobin by Glyoxal: Detection of Fluorescent Advanced Glycation End Product.

Glyoxal, a reactive α-oxoaldehyde, increases in diabetic condition and reacts with proteins to form advanced glycation end products (AGEs) following Maillard-like reaction. Considering the significance of protein modification by glyoxal-derived AGEs, we investigated the in vitro effect of glyoxal (200μM) on the monomeric heme protein myoglobin (Mb) (100μM) after incubation for one week at 25°C. Glyoxal-treated Mb exhibited increased absorbance around the Soret region, decreased α-helicity and thermal stability compared to control Mb. Intrinsic fluorescence spectrum of the treated Mb showed an additional signal in the 400-500nm region on excitation at 280nm that was absent in control Mb. When excited at 335nm, the glyoxal-treated sample gave a strong fluorescence indicating AGE formation. Mass spectrometric studies revealed formation of glyoxal-derived fluorescent AGE adduct pentosidine between Lys-145 and Arg-139 residues of Mb. Other than pentosidine, additional AGE adducts, namely, carboxymethyllysine at Lys-133, hydroimidazolone at Arg-31 and pyrrolidone-carboxymethyllysine at Lys-145 were also detected. Lys-145 was thus found to contain two different types of AGE adducts, indicating the heterogeneous nature of in vitro glycation reaction. AGE-induced protein modifications might be associated with complications in disease conditions.

Effective inhibition of protein glycation by combinatorial usage of limonene and aminoguanidine through differential and synergistic mechanisms

Protein glycation is a major mechanism for establishing secondary complication in diabetes mellitus. Effective inhibition of this process can prevent progression of the disorder into secondary complications. Aminoguanidine (AMG) and limonene (LM) are known protein glycation inhibitors. The aim of the present study was to demonstrate their differential mechanisms of action and to study whether combinatorial therapy can act synergistically and lower dosage, and thereby lower toxicity in treatment of secondary complications in diabetes. Glycation in the presence of 2M urea was inhibited by 23% with AMG and by 66% with LM. AMG is more effective than LM in reducing protein carbonyl formation. SPR studies revealed binding of LM reduces affinity of BSA for glucose. LM demonstrated an increase by 2°C in thermal transition in DSC studies as against reduction by 0.4°C by AMG proving that LM can effectively stabilize the protein structure. Combinatorial treatment of AMG and LM prevented α-helix to β-sheet transitions in BSA at 100μM and inhibited AGE related fluorescence and pentosidine formation by 80 and 90% respectively. The combination can reduce dosage of AMG by almost twenty times, paving the way for effective protein glycation inhibition without toxicity.

Effects of suppressed bone remodeling by minodronic acid and alendronate on bone mass, microdamage accumulation, collagen crosslinks and bone mechanical properties in the lumbar vertebra of ovariectomized cynomolgus monkeys

Collagen crosslinking is an important determinant of the quality of bone material. We have previously shown that suppressed bone turnover by high doses of minodronic acid and alendronate increases compressive strength of vertebra, but also increases microdamage accumulation, in monkey bone. The aim of this study is to examine the effects of these bisphosphonates on collagen crosslinks and intrinsic material properties, in addition to microdamage accumulation, in vertebral cancellous bone in ovariectomized cynomolgus monkeys. Sixty female monkeys aged 9–17years were divided into five groups: sham and ovariectomized groups were treated daily for 17months with lactose vehicle, and the other three groups were given minodronic acid daily at 0.015 or 0.15mg/kg or alendronate daily at 0.5mg/kg orally. After sacrifice, lumbar vertebrae were subjected to histomorphometry, microdamage measurement, analysis of collagen crosslinking and compressive mechanical tests. Minodronic acid caused dose-dependent suppression of increased bone remodeling due to ovariectomy, and low-dose minodronic acid suppressed remodeling same level as alendronate. However, low-dose minodronic acid did not change microdamage accumulation, collagen maturity and the pentosidine level, whereas high-dose minodronic acid and alendronate increased these parameters. Compressive ultimate load was increased following high-dose minodronic acid and alendronate, but no treatment altered the reduction in intrinsic material properties caused by ovariectomy. These findings suggest that deterioration of bone material and formation of pentosidine and microdamage induced by minodronic acid is less than that expected based on the extent of remodeling suppression, in comparison with alendronate, but this was not reflected in any significant change of mechanical properties.

Beneficial Effects of Lemon Balm Leaf Extract on In Vitro Glycation of Proteins, Arterial Stiffness, and Skin Elasticity in Healthy Adults.

Glycation, a non-enzymatic glycosylation of proteins, induces tissue damage in association with various diseases and aging phenomena. Pentosidine, an advanced glycation end product, is involved in aging phenomena such as tissue stiffness. In this study, we aimed to find a potent anti-glycation food material and to verify its health benefits by clinical trial. From among 681 hot water plant extracts, lemon balm (Melissa officinalis; LB) leaf extract was selected and revealed to have more potent inhibitory activity for pentosidine formation than a representative anti-glycation agent, aminoguanidine. Rosmarinic acid (RA), a typical polyphenol in Lamiaceae plants, was identified as a major active component in LB extract (LBE). Furthermore, LBE or RA dose-dependently suppressed glycation-associated reactions such as increased fluorescence, yellowing of collagen fiber sheets, and degeneration of the fibrous structure of elastin fiber sheets. An open-label, parallel-group comparative trial was conducted in 28 healthy Japanese subjects aged 31-65 y who consumed LB tea (LB group) or barley tea (Control group) for 6 wk. The LB group showed significant reductions in brachial-ankle pulse wave velocity, reflecting arterial stiffness, and b* (yellow) color values in forearm skin compared with the Control group. A gender-stratified analysis revealed that cheek skin elasticity was significantly improved in the LB group compared with the Control group only in female subjects. It is concluded that the hot water extract of LB leaf has the potential to provide health benefits with regard to glycation-associated tissue damage in blood vessels and skin of healthy adults.

Effect of hydroxytyrosol and olive leaf extract on 1,2-dicarbonyl compounds, hydroxymethylfurfural and advanced glycation endproducts in a biscuit model

The antiglycative activity of hydroxytyrosol (HT) and olive leaf extract (OLE) was investigated in wheat-flour biscuits. Quercetin (QE) and gallic acid (GA) were used as reference of antiglycative activity of phenolic compounds. HT, OLE, QE and GA were added in the range of 0.25–0.75% (w/w). Samples were compared against a control recipe baked at 180°C/20min. HT biscuit was able to inhibit efficiently the formation of hydroxymethylfurfural (HMF) and 3-deoxyglucosone (3-DG), as well as reduced the formation of overall free fluorescent AGEs and pentosidine. The inhibition of the 3-DG and HMF formation was directly and significantly correlated under controlled baking conditions. However, samples formulated with OLE exerted similar antiglycative capacity against pentosidine and Nε-carboxyethyl-lysine, although the amount of HT in the biscuit was 100-fold lower than the biscuit formulated with HT. Methylglyoxal, 3-DG, and glyoxal were the predominant 1,2-dicarbonyl compounds after baking but only 3-DG was significantly reduced by HT.

Osteolytic and mixed cancer metastasis modulates collagen and mineral parameters within rat vertebral bone matrix.

Metastatic involvement in vertebral bone diminishes the mechanical integrity of the spine; however minimal data exist on the potential impact of metastases on the intrinsic material characteristics of the bone matrix. Thirty-four (34) female athymic rats were inoculated with HeLa (N = 17) or Ace-1 (N = 17) cancer cells lines producing osteolytic or mixed (osteolytic and osteoblastic) metastases, respectively. A maximum of 21 days was allowed between inoculation and rat sacrifice for vertebrae extraction. High performance liquid chromatography (HPLC) was utilized to determine modifications in collagen-I parameters such as proline hydroxylation and the formation of specific enzymatic and non-enzymatic (pentosidine) cross-links. Raman spectroscopy was used to determine relative changes in mineral crystallinity, mineral carbonation, mineral/collagen matrix ratio, collagen quality ratio, and proline hydroxylation. HPLC results showed significant increase in the formation of pentosidine and decrease in the formation of the enzymatic cross-link deoxy-pryridinoline within osteolytic bone compared to mixed bone. Raman results showed decreased crystallinity, increased carbonation, and collagen quality (aka 1660/1690 sub-band) ratio with osteolytic bone compared to mixed bone and healthy controls along with an observed increase in proline hydroxylation with metastatic involvement. The mineral/matrix ratio decreased in both osteolytic and mixed bone compared to healthy controls. Quantifying modifications within the intrinsic characteristics of bone tissue will provide a foundation to assess the impact of current therapies on the material behavior of bone tissue in the metastatic spine and highlight targets for the development of new therapeutics and approaches for treatment. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2126-2136, 2016.

ChemInform Abstract: Polycyclic N‐Heterocyclic Compounds. Part 84. Reaction of N‐(Pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4‐yl)amidines or N‐(Pyrido[2′,3′:4,5]furo[3,2‐d]pyrimidin‐4‐yl)amidines with Hydroxylamine Hydrochloride.

AbstractSome of the newly synthesized N‐substituted formamide oxime derivatives show inhibitory activity against pentosidine formation [cf.

Glycation of human cortical and cancellous bone captures differences in the formation of Maillard reaction products between glucose and ribose.

To better understand some aspects of bone matrix glycation, we used an in vitro glycation approach. Within two weeks, our glycation procedures led to the formation of advanced glycation end products (AGEs) at the levels that corresponded to approx. 25–30 years of the natural in vivo glycation. Cortical and cancellous bones from human tibias were glycated in vitro using either glucose (glucosylation) or ribose (ribosylation). Both glucosylation and ribosylation led to the formation of higher levels of AGEs and pentosidine (PEN) in cancellous than cortical bone dissected from all tested donors (young, middle-age and elderly men and women). More efficient glycation of bone matrix proteins in cancellous bone most likely depended on the higher porosity of this tissue, which facilitated better accessibility of the sugars to the matrix proteins. Notably, glycation of cortical bone from older donors led to much higher AGEs levels as compared to young donors. Such efficient in vitro glycation of older cortical bone could result from aging-related increase in porosity caused by the loss of mineral content. In addition, more pronounced glycation in vivo would be driven by elevated oxidation processes. Interestingly, the levels of PEN formation differed pronouncedly between glucosylation and ribosylation. Ribosylation generated very high levels of PEN (approx. 6- vs. 2.5-fold higher PEN level than in glucosylated samples). Kinetic studies of AGEs and PEN formation in human cortical and cancellous bone matrix confirmed higher accumulation of fluorescent crosslinks for ribosylation. Our results suggest that in vitro glycation of bone using glucose leads to the formation of lower levels of AGEs including PEN, whereas ribosylation appears to support a pathway toward PEN formation. Our studies may help to understand differences in the progression of bone pathologies related to protein glycation by different sugars, and raise awareness for excessive sugar supplementation in food and drinks.

Mangosteen pericarp extract inhibits the formation of pentosidine and ameliorates skin elasticity.

The inhibition of advanced glycation end-products (AGEs) by daily meals is believed to become an effective prevention for lifestyle-related diseases. In the present study, the inhibitory effect of hot water extracts of mangosteen (Garcinia mangostana L.) pericarp (WEM) on the formation of pentosidine, one of AGEs, in vitro and in vivo and the remedial effect on skin conditions were measured. WEM significantly inhibited pentosidine formation during gelatin incubation with ribose. Several compounds purified from WEM, such as garcimangosone D and rhodanthenone B, were identified as inhibitors of pentosidine formation. Oral administration of WEM at 100 mg/day to volunteer subjects for 3 months reduced the serum pentosidine contents. Because obtaining skin biopsies from healthy volunteers is ethically difficult, AGE accumulation in the skin was estimated by a fluorescence detector. The oral administration of WEM significantly reduced the skin autofluorescence intensity, demonstrating that WEM also reduced AGE accumulation in the skin. Furthermore, the elasticity and moisture content of the skin was also improved by WEM. These results demonstrate that intakes of WEM reduces the glycation stress and results in the improvement of skin conditions.

ChemInform Abstract: Polycyclic N‐Heterocyclic Compounds. Part 80. Synthesis and Evaluation of Effects on in vitro Pentosidine Formation of 5,6‐Dihydro[1]benzothieno[3′,2′:2,3]thiepino[4,5‐d]pyrimidine and Related Compounds.

AbstractA series of title compounds are synthesized (< 45 examples).

A central role for intermolecular dityrosine cross-linking of fibrinogen in high molecular weight advanced oxidation protein product (AOPP) formation

BackgroundAdvanced oxidation protein products (AOPPs) are dityrosine cross-linked and carbonyl-containing protein products formed by the reaction of plasma proteins with chlorinated oxidants, such as hypochlorous acid (HOCl). Most studies consider human serum albumin (HSA) as the main protein responsible for AOPP formation, although the molecular composition of AOPPs has not yet been elucidated. Here, we investigated the relative contribution of HSA and fibrinogen to generation of AOPPs. MethodsAOPP formation was explored by SDS-PAGE, under both reducing and non-reducing conditions, as well as by analytical gel filtration HPLC coupled to fluorescence detection to determine dityrosine and pentosidine formation. ResultsFollowing exposure to different concentrations of HOCl, HSA resulted to be carbonylated but did not form dityrosine cross-linked high molecular weight aggregates. Differently, incubation of fibrinogen or HSA/fibrinogen mixtures with HOCl at concentrations higher than 150μM induced the formation of pentosidine and high molecular weight (HMW)-AOPPs (>200kDa), resulting from intermolecular dityrosine cross-linking. Dityrosine fluorescence increased in parallel with increasing HMW-AOPP formation and increasing fibrinogen concentration in HSA/fibrinogen mixtures exposed to HOCl. This conclusion is corroborated by experiments where dityrosine fluorescence was measured in HOCl-treated human plasma samples containing physiological or supra-physiological fibrinogen concentrations or selectively depleted of fibrinogen, which highlighted that fibrinogen is responsible for the highest fluorescence from dityrosine. ConclusionsA central role for intermolecular dityrosine cross-linking of fibrinogen in HMW-AOPP formation is shown. General significanceThese results highlight that oxidized fibrinogen, instead of HSA, is the key protein for intermolecular dityrosine formation in human plasma.

Polycyclic N‐Heterocyclic Compounds. Part 84: Reaction of N‐(pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4‐yl)amidines or N‐(pyrido[2′,3′:4,5]furo[3,2‐d]pyrimidin‐4‐yl)amidines with Hydroxylamine Hydrochloride

The reactions of nine N‐(pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4‐yl)amidines (3) with hydroxylamine hydrochloride produced new cyclization products. These were formed via ring cleavage of the pyrimidine component followed by a 1,2,4‐oxadiazole‐forming ring closure to give N‐[2‐([1,2,4]oxadiazol‐5‐yl)thieno[2,3‐b]pyridin‐3‐yl]formamide oximes (11). Reaction of six N‐(pyrido[2′,3′:4,5]furo[3,2‐d]pyrimidin‐4‐yl)amidines (12) with hydroxylamine hydrochloride gave similar results. Effects of the newly synthesized compounds on pentosidine formation were also evaluated.

A flavonoid fraction purified from Rutaceae aurantiae (DaflonR) inhibiting AGE formation, reduces urinary albumin clearance and corrects hypoalbuminemia in normotensive and hypertensive diabetic rats

AimAdvanced glycation endproducts (AGEs) have been shown to contribute to alteration of glomerular permselectivity to proteins in diabetes. Oxidative stress is required for AGE formation. Therefore we studied the effect of an antioxidant micronized purified flavonoid fraction (MPFF, DaflonR 500mg), on urinary albumin clearance in diabetic rats. MethodsHyperglycaemia was induced by streptozotocin 55mg/kg IM at days 0 and 7 in normotensive Wistar rats (NWR, diabetes duration 5 months) or hypertensive Wistar Kyoto rats (SHR, diabetes duration 2 months). MPFF was administered at 300mg/kg/day, from day −2 until sacrifice. ResultsAfter 5 months of diabetes in NWR, MPFF reduced albumin clearance from 729±92 to 392±60nl/min/kg, p<0.01, and restored albuminemia from 20.4±0.9 to 24.0±1g/l, p<0.05; albumin fractional clearance was significantly diminished in the flavonoid-treated diabetic rats (0.360±0.037‰ versus 1.335±0.430‰ in the diabetic controls, p<0.001); MPFF did not significantly modify blood glucose and plasma fructosamine levels. After 2 months of diabetes in SHR, MPFF reduced albumin clearance from 243±121 to 101±47nl/min/kg, p<0.05, and restored albuminemia from 21.1±1.6 to 26.7±2.2g/l (p<0.05); MPFF also decreased plasma fluorescence characteristic of AGEs (p<0.02). Besides hesperetin, a main metabolite of MPFF recovered in plasma, inhibited in vitro the formation of the crosslinking AGE pentosidine in collagen incubated with high glucose (p<0.001). ConclusionOur results confirm the role of glycoxidative stress in diabetic nephropathy. MPFF might be useful as complementary treatment for preventing diabetic microangiopathy.

Polycyclic N‐Heterocyclic Compounds. Part 80: Synthesis and Evaluation of Effects on In Vitro Pentosidine Formation of 5,6‐Dihydro[1]benzothieno[3′,2′:2,3]thiepino[4,5‐d]pyrimidine and Related Compounds

Reaction of 3‐(3‐cyanopropylthio)[1]benzothiophene‐2‐carbonitrile with tert‐BuONa gave 5‐amino‐1,2‐dihydro[1]benzothieno[3,2‐d]thieno[2,3‐b]pyridine and 5‐amino‐2,3‐dihydro[1]benzothieno[3,2‐b]thiepin‐4‐carbonitrile. The latter compound served as a convenient scaffold for the synthesis of the new heterocycles, [1]benzothieno[3′,2′:2,3]thiepino[4,5‐d]pyrimidines. All of our new tetracyclic products were evaluated for in vitro inhibitory activity on the formation of pentosidine, which is one of representative advanced glycation end products.

Aegle marmelos Correa leaf extract prevents secondary complications in streptozotocin-induced diabetic rats and demonstration of limonene as a potent antiglycating agent

To study the antiglycating, antidiabetic and antioxidant properties of Aegle marmelos Correa leaf extract and identify the bioactive constituent. The effect of the chloroform extract of Aegle marmelos Correa was studied in streptozotocin-induced diabetic rats through evaluation of biochemical parameters. Antiglycation activity was assessed in vitro through measurement of total and specific advanced glycation end products, protein carbonyl formation and collagen solubility tests. Antioxidant potential was evaluated using the ferric-reducing antioxidant power assay and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assays. Identification of the bioactive component was attempted through silica gel column chromatography and GC-MS analysis. In-vivo studies for 60 days revealed that the extract prevented kidney damage and other secondary complications. The chloroform extract at 16 μg could inhibit protein glycation by 44.33% and pentosidine formation by 59.31%, and could effectively inhibit protein carbonyl formation. It could scavenge DPPH radicals up to 85.26% (IC50: 26 μg). Bio-guided fractionation revealed limonene as the bioactive component, which could account for the antiglycating activity shown by the chloroform extract. The chloroform extract of Aegle marmelos demonstrated antidiabetic antiglycating and antioxidant activity, effectively preventing kidney damage and establishment of cataracts. Limonene is reported for the first time as possessing potent antiglycating activity and is non-toxic at the concentration used.