Storage conditions：Short-term storage at 2~8℃, long-term storage at -20 ~ -80℃

Introduction/Overview

Guanosine, CAS number 118-00-3, is an important natural nucleoside compound formed by the β - N9 glycosidic bond between guanine and ribose in purine bases. As one of the basic building blocks of nucleic acids, guanosine plays a crucial role in nucleic acid metabolism, energy conversion, and signal transduction within cells. In recent years, with the deepening development of natural product pharmacology, guanosine has become an important candidate molecule for antiviral drug development due to its significant antiviral activity, especially its inhibitory effect on herpes simplex virus (HSV). In addition, the potential role of guanine nucleoside in regulating immune response, neuroprotection, and cellular metabolism has also attracted widespread attention.

This article aims to systematically review the chemical structure and physicochemical properties, plant sources and extraction methods, pharmacological activity and mechanism of action, pharmacological evaluation and pharmacokinetic characteristics of guanine nucleoside, and explore its clinical application prospects and future research directions, providing comprehensive and in-depth reference materials for researchers in the field of natural product pharmacology.

Chemical structure and physicochemical properties

The chemical structure of guanine nucleoside consists of the purine base guanine and ribose, which are connected by a β - N9 glycosidic bond to form a typical nucleoside structure. Its molecular formula is C10H13N5O5, with a molecular weight of 283.2440. The guanine moiety in the structure contains multiple nitrogen atoms, endowing it with strong polarity and hydrogen bond donor/acceptor ability; The hydroxyl group of the ribose ring enhances its water solubility.

In terms of physical and chemical properties, the LogP value of guanine nucleoside is -1.8247, indicating its strong hydrophilicity and easy solubility in water (solubility of approximately 4.1618 mg/mL). Its polar surface area (TPSA) is 159.5100 Å ², indicating a high molecular polarity that may limit its passive diffusion ability through lipid membranes. The low permeability of the blood-brain barrier indicates limited distribution in the central nervous system. The hERG channel inhibition experiment showed a negative result, indicating a low risk of cardiac toxicity. The Ames mutagenicity test result is 1.2, indicating that its genotoxicity risk is relatively low and has a good safety basis.

Plant sources and extraction methods

Guanosine is widely present in various organisms, especially in higher plants, microorganisms, and animal tissues. It mainly exists as an intermediate product of nucleic acid metabolism in plants, with relatively low levels. Common plant sources include the nuclei and cytoplasm of certain medicinal plants, such as ginkgo leaves, goji berries, astragalus, etc., but purity and content are greatly affected by plant species, growth environment, and harvesting period.

In terms of extraction methods, traditional guanine nucleoside extraction often uses water extraction or buffer extraction combined with organic solvent separation. The specific steps include:

1. Sample Pretreatment Dry and crush plant tissues to increase surface area.
2. Water extraction Use hot water or buffer to extract and promote nucleoside dissolution.
3. Organic solvent extraction Using ethanol, methanol, etc. to remove lipid soluble impurities.
4. Column chromatography separation Purification of guanine nucleoside using techniques such as ion exchange and reverse phase high performance liquid chromatography (RP-HPLC).
5. Crystallization Obtaining high-purity crystalline products through cooling or solvent evaporation.

In recent years, the application of modern technologies such as ultrasound assisted extraction, microwave-assisted extraction, and enzymatic assisted extraction has improved extraction efficiency and purity, providing technical support for industrial production.

Pharmacological activity research

Antiviral activity

The most well-known pharmacological activity of guanine nucleoside is its antiviral effect, especially its inhibitory effect on herpes simplex virus (HSV). Multiple in vitro experiments have shown that guanosine can effectively reduce the replication of HSV-1 and HSV-2, inhibit viral DNA synthesis, and slow down the process of viral infection. Its antiviral activity is not limited to HSV, but also involves various viruses such as human immunodeficiency virus (HIV) and cytomegalovirus (CMV).

Immune regulatory effect

Guanosine exerts certain immunomodulatory effects by regulating the function of immune cells. Research has shown that guanosine can affect macrophage peroxidase (MPO) activity, regulate inflammatory responses, and reduce oxidative stress levels. In addition, its regulation of chemokine receptors CCR5 and CXCR4 helps to inhibit the cellular invasion of HIV virus.

Neuroprotective effect

In recent years, research on guanine nucleoside in the field of neuroprotection has gradually increased. It exhibits potential neuroprotective functions by regulating neuronal energy metabolism, resisting oxidative stress, and promoting nerve regeneration. In animal models, guanosine has a certain alleviating effect on cerebral ischemia, neurodegenerative diseases, etc.

Other pharmacological effects

Guanosine nucleoside is involved in various biological processes such as cell proliferation, apoptosis regulation, and metabolic regulation, demonstrating a wide range of biological activities. Its potential in the fields of tumors, metabolic diseases, and others is worth further exploration in the future.

Mechanism of action and molecular targets

The antiviral mechanism of guanine nucleoside is mainly achieved by interfering with key enzymes and proteins in the viral replication cycle. Specific targets include:

• UL42 and UL54 The cofactor and catalytic subunit of HSV DNA polymerase, guanine nucleoside, inhibits viral DNA synthesis through competitive binding or structural mimicry.
• ICP27 HSV transcriptional regulatory proteins affect viral gene expression, and guanosine may block viral transcription by regulating ICP27 activity.
• TK (thymidine kinase)Virus specific enzymes, guanine nucleoside as a nucleoside analogue, interfere with its phosphorylation and activation, preventing virus DNA synthesis.
• GD (glycoprotein D)The key protein for virus invasion into host cells, guanine nucleoside, regulates its binding or expression, hindering virus entry.
• CCR5 and CXCR4 The main cellular receptor of HIV virus, guanosine, inhibits viral infection by regulating its expression or function.
• HIV1-PR (HIV protease) and INT (integrase)Guanosine may bind to these enzymes through molecular simulation, inhibiting viral protein processing and genome integration.

In addition, guanosine also enhances antiviral defense by regulating the host immune system. Its inhibition of macrophage MPO activity reduces the release of inflammatory mediators and minimizes tissue damage.

Evaluation of drug properties and pharmacokinetics

The pharmacological evaluation of guanine nucleoside shows that it has certain advantages and challenges:

• Molecular weight and polarity The molecular weight of 283.2440 and high polarity (TPSA 159.51 Å ²) make it water-soluble, but limit its oral absorption and cell membrane penetration ability.
• LogP value-1.8247 indicates that it has strong hydrophilicity and is difficult to pass through lipid bilayer membranes, which affects its bioavailability.
• Low permeability of blood-brain barrier Restricting its application in central nervous system diseases but reducing the risk of central side effects.
• safety HERG channel inhibition negative and low mutagenicity in Ames test, demonstrating a good safety basis.
• Pharmacokinetic characteristics Guanosine nucleoside has limited absorption after oral administration, and its metabolism in the body is mainly through nucleosidase hydrolysis and liver metabolism. Its half-life is short, and the administration method needs to be optimized to improve efficacy.

Based on the above characteristics, developing derivatives of guanine nucleoside or using nanocarrier systems to improve its pharmacokinetic properties is a key direction to enhance its clinical application value.

Clinical application prospects and prospects

Although guanosine has shown good antiviral and immunomodulatory activity in basic research, its clinical application is still in its infancy. The future development directions include:

1. Development of antiviral drugs Based on the structural optimization of guanine nucleoside, design efficient and low toxicity nucleoside analogues to develop novel antiviral drugs for HSV, HIV, and other viral infections.
2. Combination therapy strategy Combined use with existing antiviral drugs to achieve synergistic effects, reduce the risk of drug resistance, and enhance treatment efficacy.
3. Neuroprotection and Immune Regulation Explore its potential applications in neurodegenerative diseases, multiple sclerosis, and autoimmune diseases, and expand the scope of indications.
4. Innovation in drug delivery systems By utilizing nanotechnology, liposomes, and targeted delivery systems, the bioavailability and tissue specificity can be improved, overcoming drug limitations.
5. Clinical trial design Strengthen preclinical safety and efficacy evaluation, promote clinical trials, and verify its therapeutic potential and safety.

With the advancement of molecular biology and medicinal chemistry, guanine nucleosides and their derivatives are expected to become important components of future antiviral and multifunctional therapeutic drugs.

Conclusion

Guanosine nucleoside, as a natural nucleoside compound, exhibits broad pharmacological potential due to its unique chemical structure and diverse biological activities. Its research achievements in the fields of antiviral, immune regulation, and neuroprotection provide valuable theoretical and practical foundations for natural product pharmacology. Despite challenges in terms of drug efficacy and pharmacokinetics, the application of structural modifications and advanced drug delivery technologies holds promise for breaking through existing limitations and achieving clinical translation. In the future, in-depth mechanism research and application development around guanine nucleoside will promote its important position in new drug development and contribute new therapeutic strategies to human health.