Effect of saffron supplementation on liver enzymes: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND AND AIMS: Possible protective effects of saffron (Crocus sativus L) have been reported in several randomized clinical trials (RCTs). Current systematic review was performed to summarize the efficacy of saffron intake on liver enzymes. METHODS: An electronic database search was conducted on PubMed/Medline, Scopus, Web of Science, and Cochrane for RCTs comparing effect of saffron and placebo on liver enzymes from inception to July 2021. There was no restriction in language of included studies and we calculated the standardized mean difference (SMD) and 95% Confidence Intervals (CI) for each variable. Random-effect model was used to calculate effect size. RESULTS: Eight studies (n = 463 participants) were included in the systematic review. The saffron intake was associated with a statistically significant decrease in aspartate aminotransferase (AST) (SMD: -0.18; 95% CI: -0.34, -0.02; I2 = 0%) in comparison to placebo intake. Our results also indicated that saffron consumption did not have a significant effect on alanine aminotransferase (ALT) (SMD: -0.14; 95% CI: -0.36, 0.09; I2 = 47.0%) and alkaline phosphatase (ALP) levels (SMD: 0.14; 95% CI: -0.18, 0.46; I2 = 42.9%) compared to placebo. CONCLUSIONS: Saffron intake showed beneficial impacts on circulating AST levels. However, larger well-designed RCTs are still needed to clarify the effect of saffron intake on these and other liver enzymes.

The mitochondrial pyruvate carrier (MPC) complex mediates one of three pyruvate-supplying pathways that sustain Arabidopsis respiratory metabolism.

Malate oxidation by plant mitochondria enables the generation of both oxaloacetate and pyruvate for tricarboxylic acid (TCA) cycle function, potentially eliminating the need for pyruvate transport into mitochondria in plants. Here, we show that the absence of the mitochondrial pyruvate carrier 1 (MPC1) causes the co-commitment loss of its putative orthologs, MPC3/MPC4, and eliminates pyruvate transport into Arabidopsis thaliana mitochondria, proving it is essential for MPC complex function. While the loss of either MPC or mitochondrial pyruvate-generating NAD-malic enzyme (NAD-ME) did not cause vegetative phenotypes, the lack of both reduced plant growth and caused an increase in cellular pyruvate levels, indicating a block in respiratory metabolism, and elevated the levels of branched-chain amino acids at night, a sign of alterative substrate provision for respiration. 13C-pyruvate feeding of leaves lacking MPC showed metabolic homeostasis was largely maintained except for alanine and glutamate, indicating that transamination contributes to the restoration of the metabolic network to an operating equilibrium by delivering pyruvate independently of MPC into the matrix. Inhibition of alanine aminotransferases when MPC1 is absent resulted in extremely retarded phenotypes in Arabidopsis, suggesting all pyruvate-supplying enzymes work synergistically to support the TCA cycle for sustained plant growth.

The Effect of Switching from Tenofovir Disoproxil Fumarate (TDF) to Tenofovir Alafenamide (TAF) on Liver Enzymes, Glucose, and Lipid Profile.

OBJECTIVE: We aimed to investigate the effect of switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) on the hepatic safety and metabolic profile. METHODS: Consecutive HIV patients, enrolled in the Surveillance Cohort Long-term Toxicity Antiretrovirals/Antivirals (SCOLTA) project, switching from TDF to TAF were included. Changes from baseline (T0) to 6-month follow-up (T1) were evaluated using paired t-test and signed rank test. RESULTS: A total of 190 patients switched from TDF to TAF and had one 6-month follow-up visit. They were 80% male, 74.2% at CDC stage A-B, 93.7% with undetectable HIV-viral load. Mean age was 46.7±10.7 years, body mass index was 25.0±3.9 kg/m2, median CD4 cell count was 634 cell/µL (interquartile range [IQR]=439-900), aspartate aminotransferase (AST) was 23 (IQR=19-30) IU/L, and alanine aminotransferase (ALT) was 24 (IQR=17-34) IU/L. At T1, both AST (median=-1, IQR=-5-2 IU/L, P=0.004) and ALT (median=-2, IQR=-7-3 IU/L, P=0.0004) showed a significant decrease. Among 28 patients with ALT >40 at baseline, reduction was significant both clinically (-17, IQR=-32--1) and statistically (P=0.0003). Total cholesterol levels (TC) increased (+13.4±3.8 mg/dL, P=0.0006), as well as HDL-cholesterol (HDL-C) (+3.8±1.2 mg/dL, P=0.02), LDL Cholesterol (LDL-C) (+7.6±3.4, P=0.03) and glucose (+4.0±1.8 mg/dL, P=0.02). D:A:D: and Framingham risk score did not change at 6 months after switch. CONCLUSION: A significant reduction of liver enzymes was observed after switching from TDF to TAF, especially in subjects with initial level of ALT >40 IU/L. Glucose, TC, HDL-C, and LDL-C increased, with no effect on cardiovascular risk scores.

Pimpinella anisum Essential Oil Nanoemulsion Toxicity against Tribolium castaneum? Shedding Light on Its Interactions with Aspartate Aminotransferase and Alanine Aminotransferase by Molecular Docking.

The insecticidal activity is the result of a series of complex interactions between toxic substances as ligands and insect's enzymes as targets. Actually, synthetic insecticides used in pest control programs are harmful to the environment and may affect non-target organisms; thus, the use of natural products as pest control agents can be very attractive. In the present work, the toxic effect of aniseed (Pimpinella anisum L.) essential oil (EO) and its nanoemulsion (NE) against the red flour beetle Tribolium castaneum, has been evaluated. To assess the EO mode of action, the impact of sub-lethal concentrations of aniseed EO and NE was evaluated on enzymatic and macromolecular parameters of the beetles, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein, total lipids and glucose. Finally, a molecular docking study was conducted to predict the mode of action of the major EO and NE components namely E-anethole, Limonene, alpha-himalachalene, trans-Verbenol and Linalool at binding site of the enzymes AST and ALT. Herein, the binding location of the main compounds in both proteins are discussed suggesting the possible interactions between the considered enzymes and ligands. The obtained results open new horizons to understand the evolution and response of insect-plant compounds interactions and their effect predicted at the molecular levels and side effects of both animal and human.

Characterizations and hepatoprotective effect of polysaccharides from Mesona blumes against tetrachloride-induced acute liver injury in mice.

Mesona blumes polysaccharide (MBP), a primary active component extracted from Mesona blumes, has a number of bioactivities. Nevertheless, hepatoprotective activity of MBP has been rarely reported. The purpose of this study is to investigate hepatoprotective effects of MBP on acute liver injury in mice. Results indicated that the MBP could remarkably decrease the increased levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum caused by tetrachloride (CCl4) treatment (P < 0.05). Medium and high dose of MBP treatment (200 mg/kg body weight, 300 mg/kg body weight) not only prominently enhanced the levels of antioxidant enzymes (superoxide dismutase, SOD) and non-enzyme antioxidants (glutathione, GSH) compared with CCl4-induced, but also dramatically decreased lipid peroxidation levels of liver tissues (P < 0.05). In addition, medium and high doses of MBP significantly enhanced the serum levels of IL-1ß and TNF-α (P < 0.05). This study showed that MBP had hepatoprotective activity against acute liver injury caused by CCl4.

Effect of chlorpyrifos and enrofloxacin on selected enzymes in rats.

This study examined the effect of chlorpyrifos and/or enrofloxacin on the activity of acetylcholinesterase (AChE) in the blood and brain, and the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum. The experiment was conducted on Wistar strain rats. Chlorpyrifos was administered with a stomach tube at a dose of 0.04 LD50 for 28 days and enrofloxacin at a dose of 5 mg/kg bw for 5 consecutive days. The experiment found that enrofloxacin changed the activity of the enzymes under study only to a small extent. At the dose applied in the experiment, chlorpyrifos decreased the activity of AChE significantly, both in blood and in the brain, and increased the activity of ALT and AST in rat serum. The administration of chlorpyrifos in combination with enrofloxacin changed the activity of the enzymes under study only slightly. A weaker, but longer, inhibition of AChE activity in both blood and the brain was observed in this group compared to the animals exposed only to chlorpyrifos. However, although enrofloxacin, like chlorpyrifos, increases the activity of ALT and AST in serum, their combined administration did not increase the hepatotoxic effect.

Development of alanine aminotransferase reactor based on polymer@Fe3O4 nanoparticles for enzyme inhibitors screening by chiral ligand exchange capillary electrophoresis.

Alanine aminotransferase (ALT) plays significant role in biological and clinical research. In this study, a unique ALT enzyme reactor based on multifunctional polymer@magnetic nanoparticles has been constructed for the first time and the enzymolysis efficiency has been evaluated by chiral ligand exchange capillary electrophoresis technique. Poly(N-acryloxysuccinimide) has been synthesized by reversible addition-fragmentation chain transfer polymerization method and immobilized on the magnetic nanoparticles via the succinimide group in the polymer. Interestingly, the enzyme also could easily react with the succinimide group, which enables of ALT covalent bonding onto the polymer. The enzyme amount immobilized and the immobilization time have been investigated. Comparing with free ALT in solution (Vmax of free enzyme = 0.6 mM min-1), the resultant enzyme reactor has exhibited good reusability and stability, and displayed about five times enhanced enzymolysis efficiency with L-alanine as the substrate (Vmax of enzyme reactor = 3.4 mM min-1). Furthermore, the prepared enzyme reactor has been applied in ALT inhibitors screening. The enzyme reactors based on the multifunctional polymer@magnetic nanoparticles have depicted great potential in anti-liver drugs development, liver diseases study and ALT related biological process inspect.

Exploration of the Inhibitory Potential of Varespladib for Snakebite Envenomation.

Phospholipase A2s (PLA2) is a major component of snake venom with diverse pathologic toxicities and, therefore, a potential target for antivenom therapy. Varespladib was initially designed as an inhibitor of mammal PLA2s, and was recently repurposed to a broad-spectrum inhibitor of PLA2 in snake venom. To evaluate the protective abilities of varespladib to hemorrhage, myonecrosis, and systemic toxicities that are inflicted by different crude snake venoms, subcutaneous ecchymosis, muscle damage, and biochemical variation in serum enzymes derived from the envenomed mice were determined, respectively. Varespladib treatment showed a significant inhibitory effect to snake venom PLA2, which was estimated by IC50 in vitro and ED50 in vivo. In animal models, the severely hemorrhagic toxicity of D. acutus and A. halys venom was almost fully inhibited after administration of varespladib. Moreover, signs of edema in gastrocnemius muscle were remarkably attenuated by administration of varespladib, with a reduced loss of myonecrosis and desmin. Serum levels of creatine kinase, lactate dehydrogenase isoenzyme 1, aspartate transaminase, and alanine transaminase were down-regulated after treatment with varespladib, which indicated the protection to viscera injury. In conclusion, varespladib may be a potential first-line drug candidate in snakebite envenomation first aid or clinical therapy.

The synergy of diammonium glycyrrhizinate remarkably reduces the toxicity of oxymatrine in ICR mice.

Most traditional Chinese medicine prescription dosages are imprecise. This study analyzes the toxicities and adverse effects of a combination the active ingredients of licorice and Kushen medicine: oxymatrine (OMT) and diammonium glycyrrhizinate (DG). The median lethal dose (LD50) and mortality were analyzed in single-dose OMT (or DG) intraperitoneally injected mice with or without combination DG (or OMT). Body weight changes as well as levels of serum sodium and potassium, alanine transaminase (ALT), aspartate transaminase (AST), creatinine, and urea were measured in mice treated with a daily dose of OMT and/or DG for 14days. This study showed that the LD50 of OMT for males and females were 347.44 and 429.15mg/kg, respectively. The LD50 of DG were 525.10 and 997.26mg/kg for males and females, respectively. DG significantly decreased the mice LD50-induced mortality of the OMT, however OMT did not succeed in reducing the LD50-induced mortality rate of DG. The combination of OMT and DG obviously attenuated the changes of the body weight, serum sodium, and potassium induced by DG or OMT alone. These results suggested that toxicity and adverse effects of the OMT was significantly attenuated by DG. The OMT neutralized the adverse effects of the DG, but not the toxicity.

Low Dose Acetaminophen Induces Reversible Mitochondrial Dysfunction Associated with Transient c-Jun N-Terminal Kinase Activation in Mouse Liver.

Acetaminophen (APAP) overdose causes hepatotoxicity involving mitochondrial dysfunction and c-jun N-terminal kinase (JNK) activation. Because the safe limit of APAP dosing is controversial, our aim was to evaluate the role of the mitochondrial permeability transition (MPT) and JNK in mitochondrial dysfunction after APAP dosing considered nontoxic by criteria of serum alanine aminotransferase (ALT) release and histological necrosis in vivo. C57BL/6 mice were given APAP with and without the MPT inhibitor, N-methyl-4-isoleucine cyclosporin (NIM811), or the JNK inhibitor, SP600125. Fat droplet formation, cell viability, and mitochondrial function in vivo were monitored by intravital multiphoton microscopy. Serum ALT, liver histology, total JNK, and activated phospho(p)JNK were also assessed. High APAP (300 mg/kg) caused ALT release, necrosis, irreversible mitochondrial dysfunction, and hepatocellular death. By contrast, lower APAP (150 mg/kg) caused reversible mitochondrial dysfunction and fat droplet formation in hepatocytes without ALT release or necrosis. Mitochondrial protein N-acetyl-p-benzoquinone imine adducts correlated with early JNK activation, but irreversible mitochondrial depolarization and necrosis at high dose were associated with sustained JNK activation and translocation to mitochondria. NIM811 prevented cell death and/or mitochondrial depolarization after both high and low dose APAP. After low dose, SP600125 decreased mitochondrial depolarization. In conclusion, low dose APAP produces reversible MPT-dependent mitochondrial dysfunction and steatosis in hepatocytes without causing ALT release or necrosis, whereas high dose leads to irreversible mitochondrial dysfunction and cell death associated with sustained JNK activation. Thus, nontoxic APAP has the potential to cause transient mitochondrial dysfunction that may synergize with other stresses to promote liver damage and steatosis.

Hepatic ALT isoenzymes are elevated in gluconeogenic conditions including diabetes and suppressed by insulin at the protein level.

BACKGROUND: Alanine transaminase (ALT) plays an important role in gluconeogenesis by converting alanine into pyruvate for glucose production. Early studies have shown that ALT activities are upregulated in gluconeogenic conditions and may be implicated in the development of diabetes. ALT consists of two isoforms, ALT1 and ALT2, with distinctive subcellular and tissue distributions. Whether and how they are regulated are largely unknown. METHODS: By using Western blotting analysis, we measured hepatic ALT isoforms at the protein level in obese and diabetic animals and in Fao hepatoma cells treated with dexamethasone and insulin. In addition, we measured glucose output in Fao cells over-expressing ALT1 and ALT2. RESULTS: Both ALT isoforms in the liver were increased in diabetic Goto-Kakizaki rats and during fasting. However, in ob/ob mice, only ALT2, but not ALT1, protein levels were elevated, and the increase of ALT2 was correlated with that of ALT activity. We further demonstrated that, in vitro, both ALT1 and ALT2 were induced by glucocorticoid dexamethasone, but suppressed by insulin in Fao cells. Finally, we showed that the over-expression of ALT1 and ALT2 in Fao cells directly increased glucose output. CONCLUSIONS: We have shown the similarity and difference in the regulation of ALT isoforms in gluconeogenic conditions at the protein level, supporting that ALT isoenzymes play an important role in glucose metabolism and may be implicated the development of insulin resistance and diabetes.

Inhibition study of alanine aminotransferase enzyme using sequential online capillary electrophoresis analysis.

We report the study of several inhibitors on alanine aminotransferase (ALT) enzyme using sequential online capillary electrophoresis (CE) assay. Using metal ions (Na(+) and Mg(2+)) as example inhibitors, we show that evolution of the ALT inhibition reaction can be achieved by automatically and simultaneously monitoring the substrate consumption and product formation as a function of reaction time. The inhibition mechanism and kinetic constants of ALT inhibition with succinic acid and two traditional Chinese medicines were derived from the sequential online CE assay. Our study could provide valuable information about the inhibition reactions of ALT enzyme.

Effects of dietary supplementation with vitamin C and vitamin E and their combination on growth performance, some biochemical parameters, and oxidative stress induced by copper toxicity in broilers.

This study investigated effects of dietary supplementation with vitamin C, vitamin E on performance, biochemical parameters, and oxidative stress induced by copper toxicity in broilers. A total of 240, 1-day-old, broilers were assigned to eight groups with three replicates of 10 chicks each. The groups were fed on the following diets: control (basal diet), vitamin C (250 mg/kg diet), vitamin E (250 mg/kg diet), vitamin C + vitamin E (250 mg/kg + 250 mg/kg diet), and copper (300 mg/kg diet) alone or in combination with the corresponding vitamins. At the 6th week, the body weights of broilers were decreased in copper, copper + vitamin E, and copper + vitamin C + vitamin E groups compared to control. The feed conversion ratio was poor in copper group. Plasma aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase activities, iron, copper concentrations, and erythrocyte malondialdehyde were increased; plasma vitamin A and C concentrations and erythrocyte superoxide dismutase were decreased in copper group compared to control. Glutathione peroxidase, vitamin C, and iron levels were increased; aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and copper levels were decreased in copper + vitamin C group, while superoxide dismutase, glutathione peroxidase, and vitamin E concentrations were increased; aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase were decreased in copper with vitamin E group compared to copper group. The vitamin C concentrations were increased; copper, uric acid, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and malondialdehyde were decreased in copper + vitamin C + vitamin E group compared to copper group. To conclude, copper caused oxidative stress in broilers. The combination of vitamin C and vitamin E addition might alleviate the harmful effects of copper as demonstrated by decreased lipid peroxidation and hepatic enzymes.

Oxygen affects the ability of mouse blastocysts to regulate ammonium.

During embryo culture, ammonium is generated by amino acid metabolism and from the spontaneous deamination of amino acids at 37°C. Although ammonium has been shown to be embryo toxic, few studies have investigated the mechanism(s) by which the early embryo can regulate ammonium. Whilst 20% oxygen represents a source of stress to the developing embryo, it is not known how oxygen affects the physiology of the embryo in the presence of other sources of stress. The aim of this study was, therefore, to investigate possible pathways involved in ammonium sequestration in the preimplantation embryo and the effect of oxygen on the regulation of these pathways. Glutamine and alanine were investigated as possible ammonium sequestration pathways. Amino acid utilization by blastocysts was determined after culture from the postcompaction stage with 0, 150, or 300 µM ammonium (in either 5% or 20% oxygen) and with or without 500 µM L-methionine sulfoximine (MSO), an inhibitor of glutamine synthetase. In the presence of MSO, ammonium production was significantly increased and glutamate was no longer consumed. Glutamine synthetase inhibition with MSO significantly decreased glutamine formation. Ammonium and oxygen independently altered overall amino acid turnover. Together, 5% oxygen and ammonium promoted glutamine production, whereas in the presence of 20% oxygen and ammonium, glutamine was consumed. Data reveal that both oxygen and ammonium affect amino acid utilization by the developing embryo, however, 20% oxygen appears to have the greater impact. Mouse blastocysts can alleviate ammonium stress by its transamination to both glutamine and alanine, but only under physiological conditions.

Protective role of Aralia elata polysaccharide on mercury(II)-induced cardiovascular oxidative injury in rats.

Mercury(II) is a highly toxic environmental pollutant leading to oxidative stress in animals and human beings. In this study we aimed to investigate the possible protective effect of a water-soluble polysaccharide (AEP-w1) from the root bark of Aralia elata against experimental mercury(II)-induced cardiovascular oxidative injury in rat model. The results showed that delayed AEP-w1 supplement to HgCl2-treated mice not only decreased serum lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α) levels, but also increased serum nitric oxide (NO) metabolite levels and antioxidant capacity. Moreover, AEP-w1 administration to HgCl2-treated mice significantly decreased malondialdehyde (MDA) level and myeloperoxidase (MPO) activity and increased superoxide dismutase (SOD) and catalase (CAT) activities, along with glutathione (GSH) level in rat cardiac tissue. In addition, elevated serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine (Cr) levels in the saline-treated Hg group were also reversed by AEP-w1 treatment. Therefore, the present study demonstrates that alleviation of HgCl2-induced oxidative injury in rat by AEP-w1 contributes to better understanding of its beneficial effect against cardiovascular diseases.

Rutin and quercetin, bioactive compounds from tartary buckwheat, prevent liver inflammatory injury.

Tartary buckwheat (Fagopyrum tataricum) is a healthy and nutritionally important food item. In this study, we investigated the hepatoprotective effects of 75% ethanol extracts from tartary buckwheat (EEB) against ethanol- and carbon tetrachloride (CCl(4))-induced liver damage. EEB were administered to C57BL/6 mice (ethanol induction) and Sprague-Dawley (SD) rats (CCl(4) induction) for 4 and 8 consecutive weeks, respectively. The major active compounds, rutin and quercetin, were also administered to ethanol- and CCl(4)-induced animals. EEB inhibited increase in serum aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) levels in the ethanol- and CCl(4)-induced animals; similar effects were found after rutin and quercetin administration. Moreover, EEB elevated the antioxidant enzyme activities, including those of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD), and inhibited the levels of hepatic inflammation in the ethanol- and CCl(4)-treated animals. This study suggests that EEB exerts hepatoprotection via promoting anti-oxidative and anti-inflammatory properties against oxidative liver damage.

Cerium chloride improves protein and carbohydrate metabolism of fifth-instar larvae of Bombyx mori under phoxim toxicity.

The organophosphorus pesticide poisoning of the silkworm Bombyx mori is one of the major events causing serious damage to sericulture. Added low-dose rare earths are demonstrated to increase resistance in animals. However, very little is known about whether or not added CeCl3 can increase resistance of silkworm to phoxim poisoning. The present findings suggested that added CeCl3 to mulberry leaves markedly increased contents of protein, glucose and pyruvate, and carbohydrate metabolism-related enzyme activities, including lactate dehydrogenase, succinate dehydrogenase and malate dehydrogenase, and attenuated free amino acids, urea, uric acid and lactate levels and inhibited the protein metabolism-related enzymes activities, such as protease, alanine aminotransferase and aspartate aminotransferase in the haemolymph of B. mori, under phoxim toxicity. These findings suggest that added CeCl3 may improve protein and carbohydrate metabolisms, thus leading to increases of growth and survival rate of B. mori under phoxim stress.

Effects of alanine aminotransferase inhibition on the intermediary metabolism in Sparus aurata through dietary amino-oxyacetate supplementation.

In liver, through the reaction catalysed by alanine aminotransferase (ALT), alanine becomes an effective precursor for gluconeogenesis. In the present study amino-oxyacetate (AOA) was used to evaluate its effect on liver ALT activity of the carnivorous fish Sparus aurata. Moreover, the derived metabolic effects on metabolites and other key enzymes of glycolysis, gluconeogenesis and the pentose phosphate pathway were also studied. A dose-effect-dependent inhibition of AOA on hepatic cytosolic and mitochondrial ALT activity was observed in vitro. In vivo, AOA behaved as an inhibitor of hepatic cytosolic ALT activity. A long-term exposure to AOA increased pyruvate kinase activity in the liver irrespective of the composition of the diet supplied to fish. 1H NMR studies showed that inclusion of AOA to the diet decreased the hepatic levels of alanine, glutamate and glycogen. Moreover, 2H NMR analysis indicated a higher renewal rate for alanine in the liver of fish fed with a high-carbohydrate/low-protein diet, while AOA decreased alanine 2H-enrichment irrespective of the diet. The present study indicates that AOA-dependent inhibition of the cytosolic ALT activity could help to increase the use of dietary carbohydrate nutrients.

Rapid development of new protein biosensors utilizing peptides obtained via phage display.

There is a consistent demand for new biosensors for the detection of protein targets, and a systematic method for the rapid development of new sensors is needed. Here we present a platform where short unstructured peptides that bind to a desired target are selected using M13 phage display. The selected peptides are then chemically synthesized and immobilized on gold, allowing for detection of the target using electrochemical techniques such as electrochemical impedance spectroscopy (EIS). A quartz crystal microbalance (QCM) is also used as a diagnostic tool during biosensor development. We demonstrate the utility of this approach by creating a novel peptide-based electrochemical biosensor for the enzyme alanine aminotransferase (ALT), a well-known biomarker of hepatotoxicity. Biopanning of the M13 phage display library over immobilized ALT, led to the rapid identification of a new peptide (ALT5-8) with an amino acid sequence of WHWRNPDFWYLK. Phage particles expressing this peptide exhibited nanomolar affinity for immobilized ALT (K(d,app) = 85±20 nM). The newly identified ALT5-8 peptide was then chemically synthesized with a C-terminal cysteine for gold immobilization. The performance of the gold-immobilized peptides was studied with cyclic voltammetry (CV), QCM, and EIS. Using QCM, the sensitivity for ALT detection was 8.9±0.9 Hz/(µg/mL) and the limit of detection (LOD) was 60 ng/mL. Using EIS measurements, the sensitivity was 142±12 impedance percentage change %/(µg/mL) and the LOD was 92 ng/mL. In both cases, the LOD was below the typical concentration of ALT in human blood. Although both QCM and EIS produced similar LODs, EIS is preferable due to a larger linear dynamic range. Using QCM, the immobilized peptide exhibited a nanomolar dissociation constant for ALT (K(d) = 20.1±0.6 nM). These results demonstrate a simple and rapid platform for developing and assessing the performance of sensitive, peptide-based biosensors for new protein targets.