COVID-19 and Senotherapeutics: Any Role for the Naturally-occurring Dipeptide Carnosine?

The Possible Roles of β-alanine and L-carnosine in Anti-aging

β-alanine (BA), being a non-proteinogenic amino acid, is an important constituent of L-carnosine (LC), which is necessary for maintaining the muscle buffering capacity and preventing a loss of muscle mass associated with aging effects. BA is also very important for normal human metabolism due to the formation of a part of pantothenate, which is incorporated into coenzyme A. BA is synthesized in the liver, and its combination with histidine results in the formation of LC, which accumulates in the muscles and brain tissues and has a well-defined physiological role as a good buffer for the pH range of muscles that caused its rapidly increased popularity as ergogenic support to sports performance. The main antioxidant mechanisms of LC include reactive oxygen species (ROS) scavenging and chelation of metal ions. With age, the buffering capacity of muscles also declines due to reduced concentration of LC and sarcopenia. Moreover, LC acts as an antiglycation agent, ultimately reducing the development of degenerative diseases. LC has an anti-inflammatory effect in autoimmune diseases such as osteoarthritis. As histidine is always present in the human body in higher concentrations than BA, humans have to get BA from dietary sources to support the required amount of this critical constituent to supply the necessary amount of LC synthesis. Also, BA has other beneficial effects, such as preventing skin aging and intestinal damage, improving the stress-- fighting capability of the muscle cells, and managing an age-related decline in memory and learning. In this review, the results of a detailed analysis of the role and various beneficial properties of BA and LC from the anti-aging perspective are presented.

The Potential Use of Carnosine in Diabetes and Other Afflictions Reported in Long COVID Patients

Carnosine is a dipeptide expressed in both the central nervous system and periphery. Several biological functions have been attributed to carnosine, including as an anti-inflammatory and antioxidant agent, and as a modulator of mitochondrial metabolism. Some of these mechanisms have been implicated in the pathophysiology of coronavirus disease-2019 (COVID-19). COVID-19 is caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). The clinical manifestation and recovery time for COVID-19 are variable. Some patients are severely affected by SARS-CoV-2 infection and may experience respiratory failure, thromboembolic disease, neurological symptoms, kidney damage, acute pancreatitis, and even death. COVID-19 patients with comorbidities, including diabetes, are at higher risk of death. Mechanisms underlying the dysfunction of the afflicted organs in COVID-19 patients have been discussed, the most common being the so-called cytokine storm. Given the biological effects attributed to carnosine, adjuvant therapy with this dipeptide could be considered as supportive treatment in patients with either COVID-19 or long COVID.

Small-molecule metabolome identifies potential therapeutic targets against COVID-19

Respiratory viruses are transmitted and acquired via the nasal mucosa, and thereby may influence the nasal metabolome composed of biochemical products produced by both host cells and microbes. Studies of the nasal metabolome demonstrate virus-specific changes that sometimes correlate with viral load and disease severity. Here, we evaluate the nasopharyngeal metabolome of COVID-19 infected individuals and report several small molecules that may be used as potential therapeutic targets. Specimens were tested by qRT-PCR with target primers for three viruses: Influenza A (INFA), respiratory syncytial virus (RSV), and SARS-CoV-2, along with unaffected controls. The nasopharyngeal metabolome was characterized using an LC–MS/MS-based screening kit capable of quantifying 141 analytes. A machine learning model identified 28 discriminating analytes and correctly categorized patients with a viral infection with an accuracy of 96% (R² = 0.771, Q² = 0.72). A second model identified 5 analytes to differentiate COVID19-infected patients from those with INFA or RSV with an accuracy of 85% (R² = 0.442, Q² = 0.301). Specifically, Lysophosphatidylcholines-a-C18:2 (LysoPCaC18:2) concentration was significantly increased in COVID19 patients (P < 0.0001), whereas beta-hydroxybutyric acid, Methionine sulfoxide, succinic acid, and carnosine concentrations were significantly decreased (P < 0.0001). This study demonstrates that COVID19 infection results in a unique nasopharyngeal metabolomic signature with carnosine and LysoPCaC18:2 as potential therapeutic targets.

Unveiling the Hidden Therapeutic Potential of Carnosine, a Molecule with a Multimodal Mechanism of Action: A Position Paper

Carnosine (β-alanyl-L-histidine) is a naturally occurring endogenous dipeptide and an over-the-counter food supplement with a well-demonstrated multimodal mechanism of action that includes the detoxification of reactive oxygen and nitrogen species, the down-regulation of the production of pro-inflammatory mediators, the inhibition of aberrant protein formation, and the modulation of cells in the peripheral (macrophages) and brain (microglia) immune systems. Since its discovery more than 100 years ago, a plethora of in vivo preclinical studies have been carried out; however, there is still substantial heterogeneity regarding the route of administration, the dosage, the duration of the treatment, and the animal model selected, underlining the urgent need for "coordinated/aligned" preclinical studies laying the foundations for well-defined future clinical trials. The main aim of the present position paper is to critically and concisely consider these key points and open a discussion on the possible "alignment" for future studies, with the goal of validating the full therapeutic potential of this intriguing molecule.

Carnosine to Combat Novel Coronavirus (nCoV): Molecular Docking and Modeling to Cocrystallized Host Angiotensin-Converting Enzyme 2 (ACE2) and Viral Spike Protein

Aims: Angiotensin-converting enzyme 2 (ACE2) plays an important role in the entry of coronaviruses into host cells. The current paper described how carnosine, a naturally occurring supplement, can be an effective drug candidate for coronavirus disease (COVID-19) on the basis of molecular docking and modeling to host ACE2 cocrystallized with nCoV spike protein. Methods: First, the starting point was ACE2 inhibitors and their structure–activity relationship (SAR). Next, chemical similarity (or diversity) and PubMed searches made it possible to repurpose and assess approved or experimental drugs for COVID-19. Parallel, at all stages, the authors performed bioactivity scoring to assess potential repurposed inhibitors at ACE2. Finally, investigators performed molecular docking and modeling of the identified drug candidate to host ACE2 with nCoV spike protein. Results: Carnosine emerged as the best-known drug candidate to match ACE2 inhibitor structure. Preliminary docking was more optimal to ACE2 than the known typical angiotensin-converting enzyme 1 (ACE1) inhibitor (enalapril) and quite comparable to known or presumed ACE2 inhibitors. Viral spike protein elements binding to ACE2 were retained in the best carnosine pose in SwissDock at 1.75 Angstroms. Out of the three main areas of attachment expected to the protein–protein structure, carnosine bound with higher affinity to two compared to the known ACE2 active site. LibDock score was 92.40 for site 3, 90.88 for site 1, and inside the active site 85.49. Conclusion: Carnosine has promising inhibitory interactions with host ACE2 and nCoV spike protein and hence could offer a potential mitigating effect against the current COVID-19 pandemic.