Ornithine: Definition, Structure, Benefits, Sources and Uses

Ornithine is a basic amino acid with the chemical formula C₅H₁₂N₂O₂. It cannot be found in the proteins of living organisms and was discovered in 1877 by the scientist Jaffé in a hydrolysate of bird urine that had been fed benzoic acid, hence the name ornithine. It was later recognized as an important biological substance with many remarkable functions. With the rise and rapid development of the amino acid industry, scientists have developed a strong interest in ornithine. Due to its role in the urea cycle, it is associated with conditions such as hyperornithinemia, hyperammonemia, cyclical vomiting syndrome (a type of eye disease), and tumors.

What is Ornithine?

Ornithine is a non-proteinogenic amino acid derived from the breakdown of arginine during the citric acid cycle, playing a crucial role in the urea cycle. Although ornithine cannot be found in common proteins, it is present in antimicrobial peptides such as casein from Lactobacillus and peptide S from Lactobacillus. Additionally, δ-N-acetylornithine has been found in the roots of certain plants. Fish, meats, dairy products, and eggs are ideal sources of this nutrient. Research has also indicated that ornithine is found in legumes, mushrooms, tobacco leaves, and tobacco smoke. Ornithine can be generated from arginine through basic hydrolysis or via arginase. As part of the urea cycle, it is related to urea production, where carbamoyl phosphate combines with ornithine to form citrulline and phosphate; citrulline is then converted back to arginine, which is subsequently cleaved into urea and ornithine, playing a significant metabolic role. Ornithine is a precursor for various metabolites, including arginine, proline, citrulline, and polyamines. Thus, it can interconvert with arginine, glutamate, and proline within the body, facilitating amino transfer with α-keto acids and glyoxylic acid. Under the action of ornithine decarboxylase, it can be decarboxylated to form putrescine, which can further synthesize polyamines.

Ornithine Amino Acid

Ornithine can be categorized into two primary forms: L-ornithine and D-ornithine. L-ornithine is the predominant form found in biological systems and plays a crucial role in the urea cycle. In contrast, D-ornithine is not commonly found in proteins but has garnered interest in industrial applications.

• L-Ornithine

L-Ornithine is primarily recognized for its pivotal role in the urea cycle, where it assists in the detoxification of ammonia in the body. Its applications span various fields, particularly in sports nutrition and health supplements. Athletes often use L-ornithine to enhance performance and reduce fatigue during intense physical activities. Research indicates that it may improve exercise efficiency by facilitating better energy utilization and reducing muscle soreness post-exercise. Furthermore, L-ornithine has been utilized in medical settings, particularly in managing liver disorders such as hepatic encephalopathy. It is incorporated into formulations like L-ornithine L-aspartate (LOLA), which helps regulate ammonia levels and support liver function.

• D-Ornithine

D-Ornithine, while less common than its L-isomer, also presents unique applications, particularly in research and biotechnology. It is often utilized as a chiral building block in the synthesis of pharmaceuticals and agrochemicals. Its role in the production of polyamines, which are crucial for cell growth and differentiation, highlights its importance in developmental biology and cancer research. D-Ornithine is also being investigated for its potential to enhance the efficacy of certain medications, given its ability to modulate specific biochemical pathways. In terms of non-natural derivatives, D-ornithine can be employed in the development of various peptide-based therapies, expanding its utility in targeted drug delivery systems.

Ornithine Structure

Ornithine is characterized by its unique structural features as a non-proteinogenic α-amino acid, with the chemical formula C₅H₁₂N₂O₂. It contains a primary amino group (-NH₂), a carboxyl group (-COOH), and a side chain that contributes to its basicity and reactivity. The molecular weight of ornithine is 132.19 g/mol, and it has a melting point of 140 °C, softening at 120 °C. Ornithine is highly soluble in water and ethanol, with limited solubility in ether, and it exhibits a density of 1.165 g/cm³. These physical and chemical properties are vital for its reactivity in various biochemical pathways, particularly in amino group transfer and metabolism.

Fig. 1. L-ornithine structure.

Ornithine Benefits

Ornithine offers a multitude of benefits that are crucial for various physiological and metabolic processes. As a key player in the urea cycle, it facilitates the detoxification of ammonia, thus playing an essential role in nitrogen metabolism. Beyond its fundamental metabolic functions, ornithine has garnered attention for its potential effects on exercise performance, fatigue reduction, and muscle recovery. Additionally, it has been linked to immune system support and potential anti-aging properties, making it a valuable compound in both nutritional supplements and therapeutic applications.

• Liver Detoxification: In the body, ornithine primarily participates in the urea cycle, playing an important role in the excretion of ammonia nitrogen. Ornithine helps the liver eliminate toxic ammonia and can alleviate the effects of cirrhosis related to liver dysfunction. Clinical studies report that daily administration of 10 grams of ornithine α-ketoglutarate can shorten the recovery time for hospitalized patients with postoperative infections, tumors, trauma, and burns. It has shown good efficacy in treating brain abnormalities caused by cirrhosis (hepatic encephalopathy).
• Anti-Fatigue and Immune Enhancement: Research has found that additional supplementation of ornithine can enhance strength and endurance. Ornithine promotes cells' more efficient use of energy and is often used as an anti-fatigue health supplement. Furthermore, ornithine increases the synthesis of polyamines, promoting cell proliferation and playing a role in enhancing immune function and anti-cancer properties.
• Muscle Gain and Weight Loss: Recent studies have found that ornithine can stimulate the pituitary gland to secrete growth hormone, promoting protein synthesis and the metabolism of sugars and fats. When consumed in conjunction with exercise, ornithine can reduce body fat accumulation, enhance muscle and strength, and contribute to weight loss. L-ornithine is often combined with arginine and marketed as a muscle-building supplement for bodybuilders. One study reported that 2 grams per day of L-ornithine did indeed increase body weight.
• Anti-Aging: In bodybuilding and muscle nutrition supplements, ornithine and arginine are primary components. Ornithine is responsible for elevating hormone levels, making it essential for anti-aging. It helps maintain the nutritional needs of muscles and body tissues, aiding in the prevention of muscle loss associated with the normal aging process. As people age, the efficiency of protein synthesis declines, and the regenerative capacity of muscle tissue begins to decrease. By increasing growth hormone levels, ornithine can accelerate muscle tissue growth and counteract the effects of aging.

Ornithine Sources

Beyond its biological significance, ornithine and its non-natural derivatives have garnered attention in various industrial applications, particularly in the fields of pharmaceuticals, cosmetics, and nutritional supplements. Ornithine can be sourced from a variety of dietary and biochemical avenues, highlighting its accessibility and importance in nutrition and metabolism. In addition, more and more derivatives are also being developed and synthesized for research and production needs.

• Dietary Sources

Ornithine is not typically found in significant amounts in dietary sources as a free amino acid; however, it can be indirectly obtained through the consumption of protein-rich foods. When proteins are metabolized, they are broken down into various amino acids, including arginine, which can then be converted into ornithine. Foods high in arginine, such as nuts, seeds, meat, and dairy products, contribute to the body's ornithine levels.

• Ornithine Biosynthesis

Ornithine is biosynthesized in the body primarily from arginine through the action of the enzyme arginase, which catalyzes the hydrolysis of arginine to ornithine and urea. This process occurs mainly in the liver, where ornithine subsequently enters the urea cycle, facilitating the detoxification of ammonia produced during amino acid metabolism. In addition to being derived from arginine, ornithine can also be synthesized from proline via a series of enzymatic reactions. The body's ability to produce ornithine endogenously is vital, especially in conditions where the demand for this amino acid may increase, such as during periods of growth, stress, or injury.

• Ornithine Chemical Synthesis

The industrial production of non-natural ornithine derivatives utilizes various chemical and biotechnological methods. Chemical synthesis includes alkylation, which enhances solubility and bioactivity; acylation, which modifies ornithine for improved stability and drug formulation; and esterification, creating esters that alter pharmacokinetic properties. Biotechnological methods involve enzymatic reactions that use specific enzymes to catalyze conversions of ornithine through transamination or amidation, yielding modified amino acids, and microbial fermentation, which employs genetically engineered or naturally selected microorganisms to sustainably produce ornithine derivatives. Additionally, ornithine serves as a building block for non-natural peptides synthesized via solid-phase or liquid-phase techniques.

What Does Ornithine Do?

Ornithine plays a vital role in the urea cycle, facilitating the removal of ammonia from the body. Ornithine and its derivatives demonstrate versatile applications across various industries, including nutritional supplements, pharmaceuticals, and cosmetics. Their unique properties not only enhance product efficacy but also address specific consumer needs, making them valuable components in modern formulations.

• Ornithine Supplement

In the realm of nutritional supplements, ornithine is often utilized for its potential to enhance athletic performance and recovery. Ornithine supplementation may help reduce fatigue and promote muscle recovery after intense exercise by decreasing ammonia accumulation in the body. A notable example is Ornithine Alpha-Ketoglutarate (OKG), a popular supplement among athletes and bodybuilders, which has been shown to improve muscle recovery and increase strength post-exercise, also promoting muscle protein synthesis.

• Ornithine Pharmaceutical Preparations

In the pharmaceutical sector, ornithine and its derivatives are explored for their therapeutic potentials. For instance, L-ornithine is being investigated for its efficacy in treating liver disorders, particularly in reducing ammonia levels in patients with hepatic encephalopathy, where clinical studies suggest that supplementation can improve liver function and enhance overall health.

• Ornithine in Cosmetic Industry

The cosmetic industry has also recognized the benefits of ornithine, particularly for its moisturizing and anti-aging properties. Ornithine can enhance skin hydration and elasticity, making it an attractive ingredient in skincare formulations. Some high-end skincare brands incorporate ornithine in their anti-aging creams and serums, promoting collagen synthesis and improving skin barrier function, helping combat visible signs of aging and aligning with consumer demand for effective skincare solutions.

Arginine and Ornithine

Arginine and ornithine are both key amino acids involved in the urea cycle, playing crucial roles in metabolism and physiological functions. Arginine is recognized for its diverse biological functions, including being a precursor for nitric oxide, which promotes vasodilation and enhances blood flow. In contrast, ornithine serves primarily as an intermediate in the urea cycle, facilitating the detoxification of ammonia. Understanding the similarities and differences between these two amino acids not only highlights their unique contributions to human health but also their potential applications in various therapeutic and nutritional contexts.

In Conclusion

Ornithine is a multifaceted compound with significant implications in biochemistry, nutrition, and health. Its role in the urea cycle, coupled with its benefits in athletic performance and muscle growth, underscores its importance in both physiological processes and industrial applications. As research continues to unveil the potential of ornithine and its derivatives, their applications are likely to expand further, highlighting the ongoing relevance of this unique amino acid in various fields.

** Recommended Products **

Online Inquiry

Name *

Email *

Phone *

Services & Products of Interest * Ornithine: Definition, Structure, Benefits, Sources and Uses

Project Description

Quantity *

- mg g kg ton

Verification Code *

SUBMIT