Biological interaction of newly synthesized astaxanthin-s-allyl cysteine biconjugate with Saccharomyces cerevisiae and mammalian α-glucosidase: In vitro kinetics and in silico docking analysis

Biochemical and In Silico Aspects of Active Compounds From Nyctanthes arbor-tristis Flower As Antidiabetic Agent

Targeting alpha-glucosidase (maltase-glucoamylase [MGAM] and sucrase-isomaltase [SI]) under diabetes conditions is important to overcome hyperglycemia. Moreover, it is necessary to mitigate hyperglycemia-mediated oxidative stress to evade the progression of diabetes-associated secondary complications. Hence, in the present study, under-explored Nyctanthes arbor-tristis flowers (NAFs) were studied for inhibition of alpha-glucosidase activities. The NAF methanolic extract (NAFME) was prepared. Through liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) analysis, various phytocompounds belonging to different classes-flavonoids, iridoid glycosides, proanthocyanidin, anthocyanin, polyphenol, phenolic acid, fatty acid ester, and carotenoid-were identified. NAFME showed in vitro antioxidant activity. NAFME inhibited maltase, sucrase, glucoamylase, and isomaltase in mixed mode with Ki values of 179.93, 176.38, 126.03, and 201.56 µg/mL, respectively. In silico screening of phytocompounds identified in NAFME indicated that hinokiflavone (HKF), pelargonidin-3-O-glucoside (PG), isorhamnetin-3-glucoside-7-rhamnoside (IGR), and petunidin-3-rutinoside (PR) showed better interactions with different subunits of human alpha-glucosidase, namely, N-terminal (Nt-MGAM and Nt-SI) and C-terminal (Ct-MGAM and Ct-SI). Molecular dynamics (MD) simulation, binding free energy study (molecular mechanics-generalized Born surface area [MM/GBSA]), and post-MD simulation studies (principal component analysis [PCA] and dynamic cross-correlation matrix [DCCM]) provided an in-depth understanding of these ligands' interactions with proteins. The overall efficacy of NAFME against oxidative stress and alpha-glucosidase in vitro is understood. Moreover, in silico analysis has shown the possible potential of HKF, PG, IGR, and PR to act as alpha-glucosidase inhibitors. Further studies on the antidiabetic potential of NAFME, HKF, PG, IGR, and PR in in vivo conditions are required to fully unveil the applicability of NAFME in the management of T2DM as a complementary medicine.

Astaxanthin-S-Allyl Cysteine Ester Protects Pancreatic β-Cell From Glucolipotoxicity by Suppressing Oxidative Stress, Endoplasmic Reticulum Stress and mTOR Pathway Dysregulation

Glucolipotoxicity (GLT) has emerged as established mechanism in the progression of diabetes. Identifying compounds that mitigate GLT-induced deleterious effect on β-cells are considered important strategy to overcome diabetes. Hence, in the present study, astaxanthin-s-allyl cysteine (AST-SAC) diester was studied against GLT in β-cells. Mus musculus pancreatic β-cell line (βTC-tet) was treated with high glucose (25 mM; HG) and 95 μM palmitate (PA) for 24 h to induce GLT. AST-SAC at various concentrations (5, 10, and 15 μg/ml) were treated to understand the protective effect against HG + PA exposure in β-cells. Under HG + PA exposure conditions oxidative stress, deregulation of mTOR pathway and endoplasmic reticulum (ER) stress are witnessed. AST-SAC treatment eased oxidative stress, mitochondrial depolarization, DNA damage, calcium overload and accumulation of autophagosome against HG + PA exposure conditions thereby protected the cell viability of β-cells. AST-SAC maintained the level of proteins involved in mTOR pathway under HG + PA exposure conditions. Also, AST-SAC treatment has mitigated the increased expression of genes and proteins such as IRE1 and PERK involved in ER stress-mediated unfolded protein response (UPR) signaling pathways. In correspondence to it, the expression of genes involved in insulin secretion was preserved by AST-SAC. Due to these protective effects of AST-SAC the insulin secretion was well-maintained in β-cells under HG + PA exposure conditions. AST-SAC through normalizing antioxidant status and mTOR axis as well as preventing the harmful effect of ER-stress mediated UPR pathway has promoted the β-cell survival and insulin secretion against GLT. Simultaneously targeting oxidative stress/mTOR axis/ER stress is required to efficiently overcome GLT in β-cells.

Protection of pancreatic beta cells against high glucose-induced toxicity by astaxanthin-s-allyl cysteine diester: alteration of oxidative stress and apoptotic-related protein expression

Purpose: High glucose (HG)-induced oxidative stress is associated with apoptosis in pancreatic β-cells. The protective effect of astaxanthin-s-allyl cysteine diester (AST-SAC) against HG-induced oxidative stress in pancreatic β-cells (βTC-tet cell line) in in vitro was studied.Materials and Methods: βTC-tet cell line was exposed to HG in the presence and absence of AST-SAC. Various parameters such as cell viability, reactive oxygen species generation, mitochondrial membrane potential, DNA fragmentation and expression of proteins involved in apoptosis [p53, B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X (Bax), cytochrome c and caspase 3] were studied.Results: Pre-treatment of βTC-tet cells with AST-SAC (4, 8 and 12 μg/ml) in the presence of HG (25 mM) protected the viability of the cells in a dose-dependent manner. AST-SAC treatment mitigated the oxidative stress thereby preventing the mitochondrial dysfunction, DNA damage and apoptosis in βTC-tet cells against HG toxicity. Treatment with AST-SAC prevented the increased expression of p53 under HG conditions. Further, AST-SAC treatment maintained the level of pro-apoptotic (Bax, cleaved caspase-3 and cytochrome c) and anti-apoptotic (Bcl-2) proteins to that of the control level under HG exposed conditions in βTC-tet cells.Conclusion: Altogether, AST-SAC alleviated HG-induced oxidative damage and apoptosis in pancreatic β-cells by enhancing the antioxidant status and altering apoptotic-related protein expression.

Mammalian maltase-glucoamylase and sucrase-isomaltase inhibitory effects of Artocarpus heterophyllus: An in vitro and in silico approach

Alpha-glucosidase (maltase, sucrase, isomaltase and glucoamylase) activities which are involved in carbohydrate metabolism are present in human intestinal maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI). Hence, these proteins are important targets to identify drugs against postprandial hyperglycemia thereby for diabetes. To find natural-based drugs against MGAM and SI, Artocarpus heterophyllus leaf was explored for MGAM and SI inhibition in in vitro and in silico. A. heterophyllus leaf aqueous active fraction (AHL-AAF) was prepared using Soxhlet extraction followed by silica column chromatography. The phytoconstituents of AHL-AAF were determined using LC-ESI-MS/MS. AHL-AAF showed dose-dependent and mixed inhibition against maltase (IC50 = 460 µg/ml; Ki = 300 µg/ml), glucoamylase (IC50 = 780 µg/ml; Ki = 480 µg/ml), sucrase (IC50 = 900 µg/ml, Ki = 504 µg/ml) and isomaltase (IC50 = 860 µg/ml, Ki = 400 µg/ml). AHL-AAF phytoconstituents interaction with N-terminal (Nt) and C-terminal (Ct) subunits of human MGAM and SI was analyzed using induced-fit docking, molecular dynamics (MD), and binding free energy calculation. In docking studies, rhamnosyl hexosyl methyl quercetin (RHMQ), P-coumaryl-O-16-hydroxy palmitic acid (PCHP), and spirostanol interacted with active site amino acids of human MGAM and SI. Among these RHMQ stably interacted with all the subunits (Nt-MGAM, Ct-MGAM, Nt-SI and Ct-SI) whereas PCHP with Ct-MGAM and Nt-SI during MD analysis. In molecular docking, the docking score of RHMQ with NtMGAM, CtMGAM, NtSI and CtSI was -8.48, -12.88, -11.98 and -11.37 kcal/mol. The docking score of PCHP for CtMGAM and NtSI was -8.59 and -8.4 kcal/mol, respectively. After MD simulation, the root mean square deviation (RMSD) and root mean square fluctuation (RMSF) values further confirmed the stable protein-ligand interaction. The RMSD value of all the complexes were around 2.5 Å and the corresponding RMSF values were also quite low. In MM/GBSA analysis, the involvement of Van der Waals and lipophilic energy in the protein/ligand interactions are understood. Further binding free energy for Nt-MGAM-PCHP, Nt-MGAM-RHMQ, Nt-SI-PCHP, Nt-SI-RHMQ, Ct-MGAM-PCHP, Ct-MGAM-RHMQ and Ct-SI-RHMQ complexes was found to be -24.94, -46.60, -46.56, -44.48, -40.3, -41.86 and -19.39 kcal/mol, respectively. Altogether, AHL-AAF showed inhibition of α-glucosidase activities of MGAM and SI. AHL-AAF could be further studied for its effect on diabetes in in vivo.

Versatility of copper-iron bimetallic nanoparticles fabricated using Hibiscus rosa-sinensis flower phytochemicals: various enzymes inhibition, antibiofilm effect, chromium reduction and dyes removal

Bimetallic nanoparticles (NPs) are considered superior in terms of stability and function with respect to its monometallic counterparts. Hence, in the present study Hibiscus rosa-sinensis flower extract was used to synthesis copper-iron bimetallic nanoparticles (HF-FCNPs). HF-FCNPs was characterized and its applications (biological and environmental) were determined. HF-FCNPs were spherical in shape with high percentage of copper inducted into the NPs. HF-FCNPs inhibited mammalian glucosidases [maltase (IC50: 548.71 ± 61.01 µg/mL), sucrase (IC50: 441.34 ± 36.03 µg/mL), isomaltase (IC50: 466.37 ± 27.09 µg/mL) and glucoamylase (IC50: 403.12 ± 14.03 µg/mL)], alpha-amylase (IC50: 16.27 ± 1.73 µg/mL) and acetylcholinesterase [AChE (IC50: 0.032 ± 0.004 µg/mL)] activities. HF-FCNPs showed competitive inhibition against AChE, maltase and sucrase activities; mixed inhibition against isomaltase and glucoamylase activities; whereas non-competitive inhibition against α-amylase activity. HF-FCNPs showed zone of inhibition of 16 ± 2 mm against S. mutans at 100 µg/mL concentration. HF-FCNPs inhibited biofilm formation of dental pathogen, S. mutans. SEM and confocal microscopy analysis revealed the disruption of network formation and bacterial cell death induced by HF-FCNPs treatment on tooth model of S. mutans biofilm. HF-FCNPs efficiently removed hexavalent chromium in pH-independent manner and followed first order kinetics. Through Langmuir isotherm fit the qmax (maximum adsorption capacity) was determined to be 62.5 mg/g. Further, HF-FCNPs removed both anionic and cationic dyes. Altogether, facile synthesis of HF-FCNPs was accomplished and its biological (enzyme inhibition and antibiofilm activity) and environmental (catalyst to remove pollutants) applications have been understood.

Exploring the interaction of phytochemicals from Hibiscus rosa-sinensis flowers with glucosidase and acetylcholinesterase: An integrated in vitro and in silico approach

Targeting multiple factors such as oxidative stress, alpha glucosidase and acetylcholinesterase (AChE) are considered advantageous for the treatment of diabetes and diabetes associated-cognitive dysfunction. In the present study, Hibiscus rosa-sinensis flowers anthocyanin-rich extract (HRA) was prepared. Phytochemical analysis of HRA using LC-ESI/MS/MS revealed the presence of various phenolic acids, flavonoids and anthocyanins. HRA showed in vitro antioxidant activity at low concentrations. HRA inhibited all the activities of mammalian glucosidases and AChE activity. The IC50 value of HRA for the inhibition of maltase, sucrase, isomaltase, glucoamylase and AChE was found to be 308.02 ± 34.25 µg/ml, 287.8 ± 19.49 µg/ml, 424.58 ± 34.75 µg/ml, 408.94 ± 64.82 µg/ml and 264.13 ± 30.84 µg/ml, respectively. Kinetic analysis revealed mixed-type inhibition against all the activities except for glucoamylase (competitive) activity. In silico analysis confirmed the interaction of two active constituents cyanidin 3-sophoroside (CS) and quercetin 3-O-sophoroside (QS) with four subunits, n-terminal and c-terminal subunits of human maltase-glucoamylase and sucrase-isomaltase as well as with AChE. Molecular dynamics simulation, binding free energy calculation, DCCM, PCA, PCA-based free energy surface analysis ascertained the stable binding of CS and QS with target proteins studied. HRA could be used as complementary therapy for diabetes and cognitive improvement.

Phytochemical profiling, human insulin stability and alpha glucosidase inhibition of Gymnema latifolium leaves aqueous extract: Exploring through experimental and in silico approach

Diabetes mellitus Type 2 (DM2T) is a rapidly expanding metabolic endocrine disorder worldwide. It is caused due to inadequate insulin secretion by pancreatic beta cells as well as development of insulin resistance. This study aimed to investigate the anti-α-glucosidase, insulin stabilization effect, and non-cytotoxic nature of Gymnema latifolium leaf aqueous extract (GLAE). FTIR analysis revealed the functional groups of compounds present in GLAE. Through LC/ESI-MS/MS analysis, about 12 compounds which belongs to different classes, triterpene glycosides, flavonoids, phenolics, stilbene glycosides and chlorophenolic glycosides were identified. GLAE showed in vitro antioxidant activity. GLAE stabilized insulin by increasing its α-helical content. GLAE inhibited the mammalian α-glucosidase (IC50 = 144 μg/mL) activity through competitive mode (Ki = 61.30 µg/mL). GLAE did not affect the viability of normal cell line (Vero cell line) which shows its non-toxic nature. Molecular docking of phytocompounds identified in GLAE was done with human α-glucosidase and insulin. The top 2 compounds [Gymnema saponin V (GSV) and quercetin 3-(2-galloylglucoside) (QGG) with α-glucosidase; GSV and Z)-resveratrol 3,4'-diglucoside (RDG) with human insulin] with low binding free energy were subjected to 100 ns molecular dynamics simulation to ascertain the stable binding of ligand with protein. The MM/GBSA analysis revealed binding free energy of GSV/α-glucosidase and QGG /α-glucosidase to be - 20.9935 and, - 30.9461 kcal/mol, respectively. Altogether GLAE is valuable source of anti-α-glucosidase inhibitors and insulin stabilizing compounds, suggesting potential lead for further exploration as complementary medicine against DM2T.

GC-MS, alpha-amylase, and alpha-glucosidase inhibition and molecular docking analysis of selected phytoconstituents of small wild date palm fruit (Phoenix pusilla)

Phoenix pusilla (Arecaceae), commonly known as "small wild date palm", is regarded as one of the underutilized fruit crops in South India. Methanol extract of P. pusilla ripened fruits (PPRF) was analyzed for in vitro porcine pancreatic alpha-amylase (PPAA) and rat small intestine alpha-glucosidase (RIAG) inhibition activities, and through gas chromatography-mass spectrometry (GC-MS) analysis. The GC-MS analysis showed the presence of 25 phytoconstituents from PPRF which was further assessed on the docking behavior of five targeted enzymes diabetes mellitus (DM) namely (i) human aldose reductase, (ii) protein tyrosine phosphatase 1B, (iii) pancreatic alpha-amylase, (iv) peroxisome proliferator-activated receptor gamma, and (v) dipeptidyl peptidase IV by using the AutoDock Vina method. In addition to this physicochemical, bioactivity score, absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis was performed using the Molinspiration and pkCSM free online servers. Methanolic extract of PPRF showed 50% inhibition concentration (IC50) at 69.86 and 72.60 μg/mL levels against PPAA and RIAG enzymes activities, respectively. Interestingly in the present study, GC-MS analysis showed the presence of 25 phytoconstituents from PPRF. Physicochemical analysis of PPRF has exhibited that 13 ligands have complied well with Lipinski's Rule of Five (RoF). With regard to ADMET analysis, one ligand (9,12-octadecadienoic acid [Z,Z]) has predicated to possess both the hepatotoxicity (HT) and skin sensitization (SS) effect. The docking studies showed that 1-formyl-2,5-dimethoxy-6,9,10-trimethyl-anthracene exhibited the maximum atomic contact energy (ACE) for all the five target enzymes of DM. Thus, the current study suggested that the methanolic extract of PPRF and its phytoconstituents could be considered as potent antidiabetic agents.

Therapeutic Potentials of Microalgae and Their Bioactive Compounds on Diabetes Mellitus

Diabetes mellitus is a metabolic disorder characterized by hyperglycemia due to impaired insulin secretion, insulin resistance, or both. Oxidative stress and chronic low-grade inflammation play crucial roles in the pathophysiology of diabetes mellitus. There has been a growing interest in applying natural products to improve metabolic derangements without the side effects of anti-diabetic drugs. Microalgae biomass or extract and their bioactive compounds have been applied as nutraceuticals or additives in food products and health supplements. Several studies have demonstrated the therapeutic effects of microalgae and their bioactive compounds in improving insulin sensitivity attributed to their antioxidant, anti-inflammatory, and pancreatic β-cell protective properties. However, a review summarizing the progression in this topic is lacking despite the increasing number of studies reporting their anti-diabetic potential. In this review, we gathered the findings from in vitro, in vivo, and human studies to discuss the effects of microalgae and their bioactive compounds on diabetes mellitus and the mechanisms involved. Additionally, we discuss the limitations and future perspectives of developing microalgae-based compounds as a health supplement for diabetes mellitus. In conclusion, microalgae-based supplementation has the potential to improve diabetes mellitus and be applied in more clinical studies in the future.

Lawsonia inermis flower aqueous extract expressed better anti-alpha-glucosidase and anti-acetylcholinesterase activity and their molecular dynamics

Lawsonia inermis (henna) has been used in traditional medicine throughout the world and biological property of its flower has been least explored. In the present study, the phytochemical characterization and biological activity (in vitro radical scavenging activity, anti-alpha glucosidase and anti-acetylcholinesterase) of aqueous extract prepared from henna flower (HFAE) was carried out by both Qualitative and quantitative phytochemical analysis and Fourier-transform infrared spectroscopy revealed the functional group of the phytoconstituents such as phenolics, flavonoids, saponin, tannins and glycosides. The phytochemicals present in HFAE was preliminary identified by liquid chromatography/electrospray ionization tandem mass spectrometry. The HFAE showed potent in vitro antioxidant activity and the HFAE inhibited mammalian α-glucosidase (IC50 = 129.1 ± 5.3 µg/ml; Ki = 38.92 µg/ml) and acetylcholinesterase (AChE; IC50 = 137.77 ± 3.5 µg/ml; Ki = 35.71 µg/ml) activity by competitive manner. In silico molecular docking analysis revealed the interaction of active constituents identified in HFAE with human α-glucosidase and AChE. Molecular dynamics simulation for 100 ns showed the stable binding of top two ligand/enzyme complexes with lowest binding energy such as 1,2,3,6-Tetrakis-O-galloyl-beta-D-glucose (TGBG)/human α-glucosidase, Kaempferol 3-glucoside-7-rhamnoside (KGR)/α-glucosidase, agrimonolide 6-O-β-D-glucopyranoside (AMLG)/human AChE and KGR/AChE. Through MM/GBSA analysis, the binding energy for TGBG/human α-glucosidase, KGR/α-glucosidase, AMLG/human AChE and KGR/AChE was found to be -46.3216, -28.5772, -45.0077 and -47.0956 kcal/mol, respectively. Altogether, HFAE showed an excellent antioxidant, anti-alpha glucosidase and anti-AChE activity under in vitro. This study suggest HFAE with remarkable biological activities could be further explored for therapeutics against type 2 diabetes and diabetes-associated cognitive decline.Communicated by Ramaswamy H. Sarma.

In silico and in vitro investigation of anticancer effect of newly synthesized nonivamide-s-allyl cysteine ester

Nonivamide (NOV), less pungent analogue of capsaicin present in various Capsicum species is known for various biological properties. S-allyl cysteine (SAC) abundantly present in aged garlic extract is gaining importance for anticancer property. NOV was esterified with SAC to increase the biological activity. In silico ADME analysis revealed the drug-likeness of NOV-SAC. Molecular docking and dynamics simulation analysis were done to understand the interaction of NOV-SAC with therapeutic target proteins (human estrogen receptor α, tumo protein negative regulator mouse double minute 2, B-cell lymphoma 2 and cyclin-dependent kinase 2) to treat cancer. NOV-SAC interacted with these proteins stably with favorable binding energy which was calculated through MMGBSA method. In line with in silico results, NOV-SAC showed antiproliferative activity against breast cancer cell line (MCF-7). NOV-SAC treatment increased ROS generation, decreased the antioxidant level, arrested cells at G1/S phase, disrupted mitochondrial membrane potential and initiated DNA fragmentation. The expression of p53 is increased by NOV-SAC treatment, in concordance the ratio of Bcl-2/Bax was decreased. Altogether, NOV-SAC was synthesized for the first time and it induced apoptosis in MCF-7 cells through triggering ROS generation and increasing the expression of p53. The in silico results has been mirrored in in vitro analysis of NOV-SAC against cancer cell line.Communicated by Ramaswamy H. Sarma.

Astaxanthin-s-allyl cysteine diester against high glucose-induced neuronal toxicity in vitro and diabetes-associated cognitive decline in vivo: Effect on p53, oxidative stress and mitochondrial function

Neuroprotective effect of astaxanthin-s-allyl cysteine diester (AST-SAC) against high glucose (HG)-induced oxidative stress in in vitro and cognitive decline under diabetes conditions in in vivo has been explored. Pretreatment of AST-SAC (5, 10 and 15 μM) dose-dependently preserved the neuronal cells (SH-SY5Y) viability against HG toxicity through i) decreasing oxidative stress (decreasing reactive oxygen species generation and increasing endogenous antioxidants level); ii) protecting mitochondrial function [oxidative phosphorylation (OXPHOS) complexes activity and mitochondrial membrane potential (MMP)]; and iii) decreasing p53 level thereby subsequently decreasing the level of apoptotic marker proteins. Male Spraque-Dawley rats were orally administered AST-SAC (1 mg/kg/day) for 45 days in streptozotocin-induced diabetes mellitus (DM) rats. AST-SAC administration prevented the loss of spatial memory in DM rats as determined using the novel object location test. AST-SAC administration alleviated the DM-induced injury in brain such as increased cholinesterases activity, elevated oxidative stress and mitochondrial dysfunction. Altogether, the results from the present study demonstrated that AST-SAC averted the neuronal apoptosis and preserved the cognitive function against HG toxicity under DM conditions.

Inhibitory mechanism of sinensetin on α-glucosidase and non-enzymatic glycation: Insights from spectroscopy and molecular docking analyses

Inhibition of α-glucosidase and non-enzymatic glycation is regarded as an effective method to prevent and treat type 2 diabetes and its complications. In this study, the inhibition of sinensetin on α-glucosidase and non-enzymatic glycation was studied with multi-spectroscopic techniques and molecular docking analysis. The results of fluorescence spectroscopy analysis indicated that sinensetin quenched the endogenous fluorescence of α-glucosidase in static manner. The binding of sinensetin with α-glucosidase was a spontaneous process primarily driven by hydrophobic interaction. At 298 K, the binding constant was (5.70 ± 0.12) × 10⁴ L·mol^-1 and the binding site number was 1. The conformation of α-glucosidase was altered by sinensetin, which was revealed by circular dichroism (CD), FTIR spectra, synchronous fluorescence and three-dimensional (3D) fluorescence spectroscopy methods. Molecular docking analysis demonstrated that sinensetin interacted with the amino acid residues of α-glucosidase, which might prevent the entrance of substrate, leading to the decrease of catalytic efficiency of α-glucosidase. Furthermore, glycation assays showed that sinensetin stabilized the structure of bovine serum albumins (BSA), interacted with BSA, strongly inhibited the formation of dityrosine, N'-formylkynurenine and advanced glycation end products (AGEs). This study provided useful information concerning sinensetin preventing and treating type 2 diabetes and its related complications.

Effects of Hydroxyl Group on the Interaction of Carboxylated Flavonoid Derivatives with S. Cerevisiae α-Glucosidase

Introduction

Carboxyalkyl flavonoids derivatives are considered as effective inhibitors in reducing post-prandial hyperglycaemia.

Methods

Combined with Density Functional Theory (DFT) and the theory of Atoms in Molecules (AIM), molecular docking and charge density analysis are carried out to understand the molecular flexibility, charge density distribution and the electrostatic properties of these carboxyalkyl derivatives.

Results

Results show that the electron density of the chemical bond C14-O17 on B ring of molecule II increases while O17-H18 decreases at the active site, suggesting the existence of weak non-covalent interactions, most prominent of which are H-bonding and electrostatic interaction. When hydroxyl groups are introduced, the highest positive electrostatic potentials are distributed near the B ring hydroxyl hydrogen atom and the carboxyl hydrogen atom on the A ring. It was reported that quercetin has a considerably inhibitory activity to S. cerevisiae α-glucosidase, from the binding affinities, it is suggested that the position and number of hydroxyl groups on the B and C rings are also pivotal to the hypoglycemic activity when the long carboxyalkyl group is introduced into the A ring.

Conclusion

It is concluded that the presence of three well-defined zones in the structure, both hydrophobicity alkyl, hydrophilicity carboxyl and hydroxyl groups are necessary.

Purification of fucoxanthin from Sargassum wightii Greville and understanding the inhibition of angiotensin 1-converting enzyme: An in vitro and in silico studies

The isolation and purification of active components from the brown algae Sargassum.wightii is highly limited. In the present study, fucoxanthin was purified from S. wightii using simple methods. Ethyl acetate fraction obtained by Soxhlet extraction contained high concentration of fucoxanthin. Fucoxanthin-rich fraction was further subjected to open silica column chromatography and thin layer chromatography to obtain purified fucoxanthin. Purified fucoxanthin showed in vitro antioxidant activity. Fucoxanthin showed inhibition of angiotensin I-converting enzyme (ACE) with half maximal inhibitory value of 822.64 ± 17.69 μM. Kinetic analysis revealed mixed non-competitive inhibition with inhibitory constant of 600 μM for fucoxanthin against ACE. Molecular docking analysis showed the interaction of fucoxanthin with amino acids and zinc ion present in the active site of the human ACE. Molecular dynamics analysis demonstrated the stability of the fucoxanthin and ACE complex in in silico. These results show that S. wightii may be used as food ingredient to overcome hypertension.

Tackling Achilles' Heel in Synthetic Biology: Pairing Intracellular Synthesis of Noncanonical Amino Acids with Genetic-Code Expansion to Foster Biotechnological Applications

For the last two decades, synthetic biologists have been able to unlock and expand the genetic code, generating proteins with unique properties through the incorporation of noncanonical amino acids (ncAAs). These evolved biomaterials have shown great potential for applications in industrial biocatalysis, therapeutics, bioremediation, bioconjugation, and other areas. Our ability to continue developing such technologies depends on having relatively easy access to ncAAs. However, the synthesis of enantiomerically pure ncAAs in practical quantitates for large-scale processes remains a challenge. Biocatalytic ncAA production has emerged as an excellent alternative to traditional organic synthesis in terms of cost, enantioselectivity, and sustainability. Moreover, biocatalytic synthesis offers the opportunity of coupling the intracellular generation of ncAAs with genetic-code expansion to overcome the limitations of an external supply of amino acid. In this minireview, we examine some of the most relevant achievements of this approach and its implications for improving technological applications derived from synthetic biology.

Novel antioxidant astaxanthin-s-allyl cysteine biconjugate diminished oxidative stress and mitochondrial dysfunction to triumph diabetes in rat model

AIMS

The present study determines the effect of administration of novel antioxidant astaxanthin-s-allyl cysteine biconjugate (AST-SAC) against streptozotocin-induced diabetes mellitus (DM) in rats.

MAIN METHODS

AST-SAC (1 mg/kg/day) was treated against DM in rats for 45 days. The oxidative stress, antioxidants level, insulin secretion, activities of various carbohydrate metabolizing enzymes were studied. The glucose uptake in L6 myotubes was studied. In addition, in silico analysis of interaction of AST-SAC with proteins such as insulin receptor (IR) and 5'-adenosine monophosphate-activated protein kinase (AMPK) were carried out.

KEY FINDINGS

Administration of AST-SAC in DM rats has protected the mitochondrial function (decreased oxidative stress and normalized oxidative phosphorylation activities) and antioxidant capacity of the pancreas which has resulted in beta cells rejuvenation and insulin secretion restoration. AST-SAC decreased the alpha-glucosidases activities to bring glycemic control in DM rats. Due to these effects the glycoprotein components and lipids were restored to near normalcy in DM rats. AST-SAC protected the antioxidant status of liver, kidney and plasma; and curbed the progression of secondary complications of DM. AST-SAC treatment stimulated glucose uptake in L6 myotubes in in vitro. To support this observation, AST-SAC interacted with proteins such as IR and AMPK in silico.

SIGNIFICANCE

AST-SAC can be considered as "multi-target-directed ligand", that is, through these manifold effects, AST-SAC has been able to prevail over DM in rats.