Exploring the Therapeutic Potential of Medicinal Herbs Against Coronavirus Infections


The coronavirus (CoV) family has been a focal point of global health concerns, particularly due to its capacity to infect the respiratory and intestinal systems of both animals and humans. A historical perspective reveals that while CoVs have traditionally resulted in mild colds among the human population, they have been the culprits behind severe outbreaks such as the severe acute respiratory syndrome (SARS) in 2002-2003, the Middle-East respiratory syndrome (MERS) in 2012, and the more recent SARS-CoV-2 at the end of 2019. These viruses, especially SARS-CoV-2, have demonstrated significant transmissibility and infectivity, albeit with a relatively lower mortality rate compared to SARS and MERS, raising urgent questions about effective countermeasures and treatments (Andersen et al., 2020; Malik et al., 2020; Liu et al., 2020).

In parallel, the use of medicinal herbs has been a cornerstone in the treatment of various diseases globally, with approximately 64% of the world’s population relying on such remedies. The intersection between traditional medicine and modern pharmacology has been particularly evident in the derivation of nearly half of all synthetic drugs from herbal sources. This integrative approach highlights the efficacy of phytochemicals, including flavonoids and hydroxylated phenols, as anti-infective agents that bolster the body’s defense mechanisms against pathogens. The antimicrobial and larvicidal properties of alkaloids and flavonoids further underscore the potential of herbal compounds in medical applications (Newman & Cragg, 2016; Dixon et al., 1983; Naghibi et al., 2005).

Specific interest has been directed towards the potential benefits of Nigella sativa and its constituent, thymoquinone, among other natural products and flavonoids, in combating SARS-CoV-2. This focus on herbal remedies is rooted in their anti-inflammatory and immune-regulatory effects, historically recognized within folk medicine and substantiated by modern research (Khazdair, 2021; Khazdair, Anaeigoudari, et al., 2021).

The Lamiaceae family, renowned for its rich content of diterpenoids and essential oils, includes species such as Thymus vulgaris (TV) and Zataria multiflora Boiss (ZM), which are traditionally utilized not only in culinary contexts but also in medicinal practices to treat respiratory and oral cavity disorders. The chemical diversity within TV, including its phenolic compounds, terpenoids, flavonoids, steroids, tannins, alkaloids, and saponins, offers a broad spectrum of therapeutic effects ranging from anti-inflammatory and analgesic to antioxidant and anticancer activities (Patil et al., 2021; Mozaffarian, 1996; Namsa et al., 2009; Heidari et al., 2018; Bahri et al., 2022).

Similarly, Z. multiflora has been acknowledged for its analgesic, antiseptic, anthelmintic, and antidiarrheal properties in traditional medicine, supported by studies highlighting its antimicrobial activities against a variety of pathogens. The chemical composition of ZM, with components such as thymol, carvacrol, and β-caryophyllene, underscores its potential in the development of herbal-based therapeutic agents (Ebrahimzadeh et al., 2003; Ahmad et al., 1999; Ghasemi Dehkordi et al., 2002; Zomorodian et al., 2011).

Exploring the Pharmacological Effects of Thyme Vulgaris (TV) and its Components

Thyme Vulgaris (TV) is a flowering plant indigenous to western Mediterranean and southern Europe. Renowned for its culinary uses, TV also possesses a rich pharmacological profile with diverse therapeutic effects ranging from antiseptic and analgesic properties to antiviral and anti-inflammatory effects. Research into the pharmacological effects of TV and its components has elucidated its potential in various medical applications.

Antiviral Effects of TV

Studies have highlighted the antiviral properties of TV, attributing its efficacy to phenolic compounds such as thymol and carvacrol. Thyme extracts have demonstrated significant inhibition of herpes simplex virus 1 (HSV-1) infectivity, with T. zygis extract exhibiting superior efficacy. Furthermore, TV essential oils have shown promise in combating viral infections, notably inhibiting the replication of feline infectious peritonitis (FIP), a disease caused by Coronavirus. Monoterpene compounds found in TV, including α-terpinene, p-cymen, and thymol, have exhibited potent antiviral activity against HSV-1 by directly inactivating virus particles. Essential oils derived from TV, along with other plants like camomile and ginger, have demonstrated efficacy against HSV type 2 (HSV-2), highlighting their potential as natural antiviral agents.

In the context of recent viral outbreaks such as COVID-19, TV has garnered attention for its therapeutic potential. Clinical studies have indicated that TV extracts and essential oils can alleviate symptoms associated with COVID-19, including cough, fever, and respiratory distress. Moreover, molecular docking studies have suggested that compounds present in TV, such as thymol and carvacrol, exhibit inhibitory effects against key viral entry proteins, offering a potential avenue for antiviral therapy.

Anti-inflammatory Effects of TV

TV has demonstrated significant anti-inflammatory properties, modulating various inflammatory mediators and pathways. Studies have shown that TV extracts can suppress the secretion of proinflammatory cytokines such as IL-6, IL-1β, and TNF-α, while increasing the levels of anti-inflammatory mediator IL-10. Furthermore, TV extracts have been effective in reducing lung injury induced by lipopolysaccharide (LPS), attenuating inflammatory responses and mucus secretion in epithelial cells.

Animal studies have further elucidated the anti-inflammatory effects of TV, with supplementation attenuating airway inflammation and oxidative stress in rodent models. Thymol, a key component of TV, has shown promise in mitigating lung inflammation by inhibiting inflammatory cell influx and cytokine release. Additionally, thymol has been found to modulate key signaling pathways involved in inflammation, including MAPKs and NF-κB.

The Therapeutic Potential of ZM and Carvacrol: A Comprehensive Analysis of Pharmacological Properties

ZM, scientifically known as Zataria multiflora, has a rich history of traditional use for various medicinal purposes. Its diverse pharmacological properties have garnered significant attention from researchers worldwide. This article delves into the extensive array of studies elucidating the pharmacological properties of ZM and its major constituent, carvacrol, shedding light on their potential therapeutic applications.

Antiviral Properties of ZM and Carvacrol

Research has highlighted the antiviral potential of ZM and its active component, carvacrol. Studies have demonstrated the efficacy of ZM in reducing viral replication in poultry infected with H9N2 influenza and inhibiting plaque formation in HSV-1-infected cells. Carvacrol, a key component of ZM, exhibits potent antiviral activity against various viruses, including human respiratory syncytial virus (HRSV), herpes simplex virus (HSV), and human noroviruses (NoVs). Furthermore, carvacrol has shown promise in inhibiting viral gene expression and protease activity, making it a potential candidate for combating viral infections, including COVID-19.

Anti-Inflammatory Effects of ZM and Carvacrol

ZM extracts have demonstrated anti-inflammatory properties by modulating cytokine expression and immune responses. Studies have shown that ZM extracts suppress pro-inflammatory cytokines while enhancing the production of anti-inflammatory mediators. Moreover, ZM exhibits immunomodulatory effects, stimulating the immune response against pathogens and allergens. Carvacrol, the bioactive compound in ZM, exerts anti-inflammatory effects by reducing cytokine levels, inhibiting leukocyte chemotaxis, and modulating immune cell function. Clinical trials have further corroborated the anti-inflammatory efficacy of ZM and carvacrol, indicating their potential in managing inflammatory and allergic disorders.

Therapeutic Applications

The pharmacological properties of ZM and carvacrol hold promising therapeutic implications across various health conditions. From respiratory ailments like asthma and chronic obstructive pulmonary disease (COPD) to viral infections and inflammatory disorders, ZM and carvacrol offer multifaceted therapeutic benefits. Clinical studies have demonstrated their efficacy in improving pulmonary function, reducing respiratory symptoms, and attenuating inflammatory responses in patients with respiratory disorders and chemical exposures.

Exploring the Antioxidant Effects of Herbs and Their Constituents: A Comprehensive Analysis

In recent years, there has been growing interest in the antioxidant properties of herbs and their constituents, driven by the increasing awareness of oxidative stress-related diseases and the potential of natural remedies in combating them. Among the herbs gaining attention for their antioxidant effects are Thymus vulgaris (TV) and Zataria multiflora (ZM), along with their active constituents such as carvacrol and thymol. This article delves into a detailed examination of the research findings regarding the antioxidant capabilities of these herbs and compounds.

Starting with Thymus vulgaris (TV), studies have demonstrated its efficacy in alleviating oxidative stress-induced damage. El-Nekeety et al. (2011) reported that oral administration of TV essential oil significantly reduced markers of oxidative stress in aflatoxin-treated rats, including decreased levels of aspartate transaminase (AST), alkaline phosphatase (ALP), alanine transaminase (ALT), cholesterol (Cho), triglycerides (TriG), total lipids, and creatinine in serum. Concurrently, there was a notable increase in the total antioxidant capacity (TAC) level in liver tissue, along with reduced malondialdehyde (MDA) levels in the liver and kidneys.

Moreover, TV extract has shown promise in mitigating lead (Pb)-induced toxicity, as evidenced by El-Boshy et al. (2019). Treatment with TV extract improved Pb-induced alterations and modulated cytokine levels, enhancing anti-inflammatory cytokines while suppressing pro-inflammatory ones. Additionally, TV extract boosted antioxidant enzyme activities and reduced MDA levels, indicating its potential in combating oxidative stress.

Similarly, Thyme water extract (TWE) exhibited antioxidant effects in Japanese quails, as indicated by Sengül et al. (2008). TWE supplementation led to an increase in total oxidant status and total antioxidant response while reducing DNA damage, highlighting its protective role against oxidative stress.

Moving on to Zataria multiflora (ZM), the herb and its constituents have shown remarkable antioxidant properties across various studies. Alizadeh & Shaabani (2014) reported that ZM extract is rich in phenolic compounds with potent antioxidant activities. Fatemi et al. (2012) demonstrated strong radical scavenging activity and inhibition of peroxidation products by ZM hydroalcoholic extracts.

Furthermore, both ZM essential oil and methanolic extract exhibited antioxidant properties, as evidenced by studies conducted by Moshafi et al. (2007) and Sharififar et al. (2007). These findings were corroborated by Saei-Dehkordi et al. (2010), who observed significant antioxidant capacity across different ecotypes of ZM.

In cellular studies, ZM demonstrated antioxidant effects by reducing reactive oxygen species (ROS) production and lipid peroxidation, inhibiting nitric oxide (NO) synthase activity, and preventing nitrosative stress, as reported by Kavoosi & Teixeira da Silva (2012). Additionally, ZM extract exhibited protective effects against cyclophosphamide-induced oxidative stress in bone marrow cells and showed potential in improving cognitive function in an Alzheimer’s disease rat model (Hosseinimehr et al., 2010; Majlessi et al., 2012).

Moreover, ZM extract demonstrated protective effects against hyperglycemia and bisphenol A-induced oxidative stress in mice, as well as cyclophosphamide-induced lung injury (Habibi et al., 2014). These effects were attributed to the reduction of MDA levels and enhancement of antioxidant enzymes and glutathione content.

The active constituents of ZM, carvacrol, and thymol, have also shown notable antioxidant effects in various studies. Karimian et al. (2012) demonstrated the antioxidant activity of carvacrol through MDA and NO scavenging mechanisms. Similarly, thymol exhibited antioxidant effects by reducing H2O2 and NO production and modulating NO synthase activities (Kavoosi & Teixeira da Silva, 2012).

Furthermore, both carvacrol and thymol showed anti-inflammatory and antioxidant effects in models of inflammation and oxidative stress-induced conditions (Celik et al., 2013; Hassanshahi et al., 2014). These compounds were found to reduce pro-inflammatory cytokines and oxidative stress markers while enhancing antioxidant enzyme activities.

In cellular studies, thymol demonstrated protective effects against radiation-induced cytotoxicity by enhancing antioxidant enzyme levels and reducing MDA levels (Archana et al., 2009).

In conclusion, the research findings highlight the significant antioxidant effects of herbs such as Thymus vulgaris and Zataria multiflora, along with their active constituents carvacrol and thymol. These natural compounds hold promise as potential therapeutic agents for combating oxidative stress-related diseases. Further research is warranted to elucidate their mechanisms of action and explore their therapeutic potential in clinical settings.

reference link : https://onlinelibrary.wiley.com/doi/10.1002/fsn3.3903


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