Eugenol derivatives as potential anti-oxidants: is phenolic hydroxyl necessary to obtain an effect?

Structural modification of naturally occurring phenolics as a strategy for developing cytotoxic molecules towards cancer cells

Natural products belonging to different chemical classes have been established as a promising source of novel anticancer drugs. Several low-molecular-weight compounds from the classes of monoterpenes, phenylpropanoids, and flavonoids were shown to possess anticancer activities in previous studies. In this work, over 20 semisynthetic derivatives of molecules belonging to these classes, namely thymol, eugenol, and 6-hydroxyflavanone were synthesized and tested for their cytotoxicity against two human cancer cell lines, namely AGS cells (gastric adenocarcinoma) and A549 cells (human lung carcinoma). An initial screening based on viability assessment was performed to identify the most cytotoxic compounds at 100 μM. The results evidenced that two 6-hydroxyflavanone derivatives were the most cytotoxic among the compounds tested, being selected for further studies. These derivatives displayed enhanced toxicity when compared with their natural counterparts. Moreover, the lactate dehydrogenase (LDH) assay showed that the loss of cell viability was not accompanied by a loss of membrane integrity, thus ruling out a necrotic process. Morphological studies with AGS cells demonstrated chromatin condensation compatible with apoptosis, confirmed by the activation of caspase 3/7. Furthermore, a viability assay on a noncancer human embryonic lung fibroblast cell line (MRC-5) confirmed that these two derivatives possess selective anticancer activity.

Research progress of quercetin in cardiovascular disease

Quercetin is one of the most common flavonoids. More and more studies have found that quercetin has great potential utilization value in cardiovascular diseases (CVD), such as antioxidant, antiplatelet aggregation, antibacterial, cholesterol lowering, endothelial cell protection, etc. However, the medicinal value of quercetin is mostly limited to animal models and preclinical studies. Due to the complexity of the human body and functional structure compared to animals, more research is needed to explore whether quercetin has the same mechanism of action and pharmacological value as animal experiments. In order to systematically understand the clinical application value of quercetin, this article reviews the research progress of quercetin in CVD, including preclinical and clinical studies. We will focus on the relationship between quercetin and common CVD, such as atherosclerosis, myocardial infarction, ischemia reperfusion injury, heart failure, hypertension and arrhythmia, etc. By elaborating on the pathophysiological mechanism and clinical application research progress of quercetin's protective effect on CVD, data support is provided for the transformation of quercetin from laboratory to clinical application.

Research progress of VEGFR small molecule inhibitors in ocular neovascular diseases

Angiogenesis is the biological process in which existing blood vessels generate new ones and it is essential for body growth and development, wound healing, and granulation tissue formation. Vascular endothelial growth factor receptor (VEGFR) is a crucial cell membrane receptor that binds to VEGF to regulate angiogenesis and maintenance. Dysregulation of VEGFR signaling can lead to several diseases, such as cancer and ocular neovascular disease, making it a crucial research area for disease treatment. Currently, anti-VEGF drugs commonly used in ophthalmology are mainly four macromolecular drugs, Bevacizumab, Ranibizumab, Conbercept and Aflibercept. Although these drugs are relatively effective in treating ocular neovascular diseases, their macromolecular properties, strong hydrophilicity, and poor blood-eye barrier penetration limit their efficacy. However, VEGFR small molecule inhibitors possess high cell permeability and selectivity, allowing them to traverse and bind to VEGF-A specifically. Consequently, they have a shorter duration of action on the target, and they offer significant therapeutic benefits to patients in the short term. Consequently, there is a need to develop small molecule inhibitors of VEGFR to target ocular neovascularization diseases. This review summarizes the recent developments in potential VEGFR small molecule inhibitors for the targeted treatment of ocular neovascularization diseases, with the aim of providing insights for future studies on VEGFR small molecule inhibitors.

In Vitro Antiviral Potential, Antioxidant, and Chemical Composition of Clove (Syzygium aromaticum) Essential Oil

Viral infections are spread all around the world. Although there are available therapies, their safety and effectiveness are constrained by their adverse effects and drug resistance. Therefore, new natural antivirals have been used such as essential oils, which are natural products with promising biological activity. Accordingly, the present study aimed to identify the components of clove (Syzygium aromaticum) essential oil (EOCa) and verify its antioxidant and antiviral activity. The oil was analyzed using GC/MS, and the antioxidant capacity was evaluated as a function of the radical scavenging activity. A plaque reduction test was used to measure the antiviral activity against herpes simplex virus (HSV-1), hepatitis A virus (HAV), and an adenovirus. GC/MS analysis confirmed the presence of eugenol as the main component (76.78%). Moreover, EOCa had powerful antioxidant activity with an IC50 of 50 µg/mL. The highest antiviral potential was found against HAV, with a selectivity index (SI) of 14.46, while showing poor selectivity toward HSV-1 with an SI value of 1.44. However, no relevant effect was detected against the adenovirus. The antiviral activity against HAV revealed that its effect was not related to host cytotoxicity. The findings imply that EOCa can be utilized to treat diseases caused by infections and free radicals.

Effect of chemical modifications of tannins on their antimicrobial and antibiofilm effect against Gram-negative and Gram-positive bacteria

Background

Tannins have demonstrated antibacterial and antibiofilm activity, but there are still unknown aspects on how the chemical properties of tannins affect their biological properties. We are interested in understanding how to modulate the antibiofilm activity of tannins and in delineating the relationship between chemical determinants and antibiofilm activity.

Materials and methods

The effect of five different naturally acquired tannins and their chemical derivatives on biofilm formation and planktonic growth of Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was determined in the Calgary biofilm device.

Results

Most of the unmodified tannins exhibited specific antibiofilm activity against the assayed bacteria. The chemical modifications were found to alter the antibiofilm activity level and spectrum of the tannins. A positive charge introduced by derivatization with higher amounts of ammonium groups shifted the anti-biofilm spectrum toward Gram-negative bacteria, and derivatization with lower amounts of ammonium groups and acidifying derivatization shifted the spectrum toward Gram-positive bacteria. Furthermore, the quantity of phenolic OH-groups per molecule was found to have a weak impact on the anti-biofilm activity of the tannins.

Conclusion

We were able to modulate the antibiofilm activity of several tannins by specific chemical modifications, providing a first approach for fine tuning of their activity and antibacterial spectrum.

Humic acid enhanced pyrene degradation by Mycobacterium sp. NJS-1

The search for nature-based tools to enhance bioremediation is essential for the sustainable restoration of contaminated ecosystems. Humic acid (HA) is an important component of organic matter in soil and water, but its effect on the microbial degradation of organic pollutants remains unclear. In this study, the biodegradation of pyrene by Mycobacterium sp. NJS-1 with and without HA was investigated. Only around 10.5% of pyrene was biodegraded in the pyrene treatment alone, whereas the addition of HA significantly enhanced biodegradation to the point where over 90% of pyrene was biodegraded. The production of 4,5-dihydropyrene-4,5-diol and phenanthrene-3,4-diol indicated the metabolic pathway via attacking of 4,5-positions of pyrene. Interestingly, 1,2-dimethoxypyrene was detected with the addition of HA, suggesting that HA induced a new ring-opening pathway involving the attack on the 1,2-positions of pyrene. The addition of HA first induced protein self-cleavage behavior with a significant increase in phenylalanine, tyrosine, and tryptophan containing large numbers of COO^- groups. Furthermore, it altered the intracellular and extracellular ultrastructure of bacterial cells, promoting their growth in size and number as well as reducing the space between them. Overall, HA increased the ring-opening positions of pyrene and facilitated its interaction with bacterial cells, thus improving its biodegradability. Building upon the findings of this study to further research is conducive to the sustainable solution of environmental pollution.

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols' anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

Lipidic Matrixes Containing Clove Essential Oil: Biological Activity, Microstructural and Textural Studies

Clove essential oil (CEO) is known for having excellent antioxidant and antimicrobial properties, but the poor stability of its components to light and temperature compromise this activity. The aim of this study is to evaluate the textural, antioxidant, antimicrobial and microstructural properties of matrixes produced with representative natural waxes and CEO. Thus, waxy emulsifiers, such as beeswax, candelilla wax, carnauba wax, and ozokerite wax, were employed to create such matrixes. The thermal, microstructural, textural, wetting, antioxidant, antimicrobial and infrared characteristics of the matrixes were then studied. The diverse chemical composition (long-chain wax esters in carnauba wax and short-chain fatty acids and hydrocarbons in beeswax and ozokerite wax, respectively) explained the differences in wetting, texture, melting, and crystallization characteristics. Crystal forms of these matrix systems varied from grainy, oval, to needle-like shape, but keeping an orthorhombic allomorph. The alignment and reorganization of beeswax and ozokerite wax into needle-like crystals increased the matrix strength and adhesion force compared to those of carnauba and candelilla matrixes, which showed weak strength and grainy morphology. The former two waxes and their matrixes also showed the largest plasticity. These lipidic matrixes show potential use for topical applications having acceptable antioxidant and textural properties.

The therapeutic use of quercetin in ophthalmology: recent applications

Quercetin is a natural flavonol antioxidant found in various plant sources and food samples. It is well known for its notable curative effects on the treatment of ophthalmic diseases due to various biological activities, such as antioxidant, anti-inflammatory, and anti-fibrosis activities. This review will discuss the latest developments in therapeutic quercetin for the treatment of keratoconus, Graves' orbitopathy, ocular surface, cataracts, glaucoma, retinoblastoma, and other retinal diseases.

Use of medicinal plants for headache, and their potential implication in medication-overuse headache: Evidence from a population-based study in Nepal

Background

In Nepal, traditional treatment using medicinal plants is popular. Whereas medication-overuse headache is, by definition, caused by excessive use of acute headache medication, we hypothesized that medicinal plants, being pharmacologically active, were as likely a cause.

Methods

We used data from a cross-sectional, nationwide population-based study, which enquired into headache and use of medicinal plants and allopathic medications. We searched the literature for pharmacodynamic actions of the medicinal plants.

Results

Of 2100 participants, 1794 (85.4%) reported headache in the preceding year; 161 (7.7%) reported headache on ≥15 days/month, of whom 28 (17.4%) had used medicinal plants and 117 (72.7%) allopathic medication(s). Of 46 with probable medication-overuse headache, 87.0% (40/46) were using allopathic medication(s) and 13.0% (6/46) medicinal plants, a ratio of 6.7:1, higher than the overall ratio among those with headache of 4.9:1 (912/185). Of 60 plant species identified, 49 were pharmacodynamically active on the central nervous system, with various effects of likely relevance in medication-overuse headache causation.

Conclusions

MPs are potentially a cause of medication-overuse headache, and not to be seen as innocent in this regard. Numbers presumptively affected in Nepal are low but not negligible. This pioneering project provides a starting point for further research to provide needed guidance on use of medicinal plants for headache.

Eugenol protects against citrinin-induced cytotoxicity and oxidative damages in cultured human colorectal HCT116 cells

This study aimed to investigate the protective effects of Eugenol (EUG), an effective antioxidant phenolic compound with a radical scavenging activity against citrinin (CTN)-induced toxicity in vitro using HCT116 cells. CTN is a well-known mycotoxin found in different constituents of the food chain. This environmental contaminant produces free radicals which interacts with cellular macromolecules and produces oxidation of protein, lipid, and DNA. The cytotoxic effects were monitored by measuring cell viability, reactive oxygen species (ROS) generation, antioxidant enzyme activities, malondialdehyde (MDA) production, protein oxidation, and DNA fragmentation. Our results have shown that the pretreatment of HCT116 cells with EUG, 2 h prior to citrinin (CTN) exposure, significantly decreased CTN-induced cell death, inhibited ROS generation, modulated activities of both catalase (CAT) and superoxide dismutase (SOD), and reduced MDA production. Level of protein-bound sulfhydryls and DNA fragmentation were also declined as compared with CTN-treated cells. These findings suggest that EUG would be an effective protective agent against CTN-induced oxidative stress, and thereby, it may complement and add to the functions of antioxidant vitamins and enzymes as a protection against the cytotoxicity of this mycotoxin.

Design, synthesis, and in silico studies of novel eugenyloxy propanol azole derivatives having potent antinociceptive activity and evaluation of their β-adrenoceptor blocking property

The design, synthesis, antinociceptive and β-adrenoceptor blocking activities of several eugenyloxy propanol azole derivatives have been described. In this synthesis, the reaction of eugenol with epichlorohydrin provided adducts 3 and 4 which were N-alkylated by diverse azoles to obtain the eugenyloxy propanol azole analogues in good yields. Adducts 3 and 4 were also reacted with azide ion to obtain the corresponding azide 6. The 'Click' Huisgen cycloaddition reaction of 6 with diverse alkynes afforded the title compounds in good yields. The synthesized eugenyloxy propanol azole derivatives were in vivo studied for the acute antinociception on male Spargue Dawley rats using tail-flick test. Compounds 5f, 5g, 7b and 11a exhibited potent analgesic properties in comparison with eugenol as a standard drug. In addition, all compounds were ex vivo tested for β-adrenoceptor blocking properties on isolated left atrium of male rats which exhibited partial antagonist or agonist behaviour compared to the standard drugs. The molecular docking study on the binding site of transient receptor potential vanilloid subtype 1 (TRPV1) has indicated that like capsaicin, eugenyloxy propanol azole analogues exhibited the strong affinity to bind at site of TPRV1 in a "tail-up, head-down" conformation and the presence of triazolyl moieties has played undeniable role in durable binding of these ligands to TRPV1. The in silico pharmacokinetic profile, drug likeness and toxicity predictions carried out for all compounds determined that 5g can be considered as potential antinociceptive drug candidate for future research.

Eugenol derivatives: synthesis, characterization, and evaluation of antibacterial and antioxidant activities

Eugenol is the major component of clove essential oil and has demonstrated relevant biological potential with well-known antimicrobial and antioxidant action. Therefore, this work carried out the synthesis, purification, characterization, and evaluation of the antioxidant and antibacterial potential of 19 eugenol derivatives. The derivatives were produced by esterification reactions in the hydroxyl group (−OH) of eugenol with different carboxylic acids and also by addition reactions in the double bond of the allyl group. The derivatives had a promising antibacterial potential, including a lower minimum inhibitory concentration of 500 μg/mL than eugenol (1000 μg/mL). In addition, the derivatives were active against bacterial strains (Escherichia coli, Staphylococcus aureus) that eugenol itself showed no activity, thus increasing the spectrum of antibacterial action. As for the antioxidant activity, it was observed that the derivatives that involved esterification reactions in the hydroxyl group (−OH) of the eugenol molecule’s phenol resulted in a significant reduction of the antioxidant action (IC₅₀ > 100 μg/mL) when compared with the eugenol precursor molecule (IC₅₀ = 4.38 μg/mL). On the other hand, the structural changes located in the double bond affected much more smoothly the capacity of capturing radicals than the starting molecule, also being obtained derivatives with proximal antioxidant capacity (IC₅₀ = 19.30 μg/mL) to commercial standards such as Trolox (IC₅₀ = 16.00 μg/mL).

Molecular interactions of active constituents of essential oils in zwitterionic lipid bilayers

Eugenol and its related compounds are major active constituents of essential oils and have been extensively used as food flavoring agents with significant lipid peroxidation inhibition activity, highlighting the importance of understanding detailed molecular mechanisms behind their interactions with lipid bilayer. For this, we studied antioxidant activity of essential oils rich extract of Cinnamomum tamala leaves and molecular dynamics simulations of eugenol, isoeugenol, methyleugenol, acetyleugenol and eugenol oxide in POPC and PLPC lipid bilayers. All the compounds penetrated into bilayer however, isoeugenol showed highest affinity for the pure POPC and PLPC bilayers with lowest free energy profiles, formed more H-bonds with bilayer oxygen atoms and more pronounced changes in area per lipid and thickness of the bilayer, thus more efficient for scavenging radicals coming from outside as well as centrally located lipid peroxyl radicals. These molecular interactions rationalize the difference in inhibition activities of lipid peroxidation by eugenol and its related compounds.

Perspectives on medicinal properties of natural phenolic monoterpenoids and their hybrids

Carvacrol, thymol and eugenol belong to a class of naturally presenting phenols with a ten-carbon unit, which are present in essential oils of many plants. These versatile molecules are incorporated as useful ingredients in many food products and find applications in agricultural, pharmaceutical, fragrance, cosmetic, flavor and other industries. They are wide ranging of biological and pharmaceutical activities: anti-inflammatory, antimicrobial, analgesic, anticancer and antioxidant. This review summarizes pharmacological and medicinal activities of these phytochemicals and their synthetic hybrids.

Mechanism underlying methyl eugenol attenuation of intestinal ischemia/reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury is associated with a high risk of mortality in the clinical situation. Many factors are involved in I/R, including reactive oxygen species, cytokine release, and apoptosis. We aimed to determine whether a pure methyl eugenol (ME) given before intestinal ischemia, protects against intestinal I/R injury and the possible mechanism involved in this protection. Rat received ME (100 mg/kg) for 30 days then underwent intestinal I/R with 30 min ischemia and 60 min reperfusion. Serum lactate dehydrogenase (LDH) level, tissue malondialdehyde (MDA), as well as some antioxidant biomarkers were assessed, while the serum level of tumor necrosis factor alpha (TNF-α) was determined by ELISA. The change in TNF-α and interleukin 6 (IL-6) gene expressions were evaluated and confirmed by assessing protein level of TNF-α in the intestinal tissue by immunohistochemistry. Apoptosis was evaluated using DNA-laddering assay and by detecting caspase-3 immunohistochemically. Administration of ME prior to I/R injury resulted in a modulation of the production of MDA, LDH, and nitric oxide and restoration of the tested oxidative stress biomarkers. Pretreatment with ME downregulated messenger RNA of TNF-α and IL-6 inflammatory cytokines and their protein expressions in I/R rats. Marked inhibition of the apoptotic DNA and improvement of the architectures of small intestine were observed after pretreatment with ME. ME exhibits a protective effect against intestinal I/R via amelioration of the oxidative stress and inflammatory cytokines gene expression. Therefore, the supplementation of ME prior to intestinal I/R might be helpful in the attenuation of I/R complications.

Effect of Selected Plant Phenolics on Fe2+-EDTA-H₂O₂ System Mediated Deoxyribose Oxidation: Molecular Structure-Derived Relationships of Anti- and Pro-Oxidant Actions

In the presence of transition metal ions and peroxides, polyphenols, well-known dietary antioxidants, can act as pro-oxidants. We investigated the effect of 13 polyphenols and their metabolites on oxidative degradation of deoxyribose by an ^•OH generating Fenton system (Fe²⁺-ethylenediaminetetraacetic acid (EDTA)-H₂O₂). The relationship between phenolics pro-oxidant/anti-oxidant effects and their molecular structure was analyzed using multivariate analysis with multiple linear regression and a backward stepwise technique. Four phenolics revealed a significant inhibitory effect on OH-induced deoxyribose degradation, ranging from 54.4% ± 28.6% (3,4-dihydroxycinnamic acid) to 38.5% ± 10.4% (catechin) (n = 6), correlating with the number of –OH substitutions (r = 0.58). Seven phenolics augmented the oxidative degradation of deoxyribose with the highest enhancement at 95.0% ± 21.3% (quercetin) and 60.6% ± 12.2% (phloridzin). The pro-oxidant effect correlated (p < 0.05) with the number of –OH groups (r = 0.59), and aliphatic substitutes (r = −0.22) and weakly correlated with the occurrence of a catechol structure within the compound molecule (r = 0.17). Selective dietary supplementation with phenolics exhibiting pro-oxidant activity may increase the possibility of systemic oxidative stress in patients treated with medications containing chelating properties or those with high plasma concentrations of H₂O₂ and non-transferrin bound iron.

Synthesis, Antifungal Evaluation and In Silico Study of N-(4-Halobenzyl)amides

A collection of 32 structurally related N-(4-halobenzyl)amides were synthesized from cinnamic and benzoic acids through coupling reactions with 4-halobenzylamines, using (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) as a coupling agent. The compounds were identified by spectroscopic methods such as infrared, ¹H- and ¹³C- Nuclear Magnetic Resonance (NMR) and high-resolution mass spectrometry. The compounds were then submitted to antimicrobial tests by the minimum inhibitory concentration method (MIC) and nystatin was used as a control in the antifungal assays. The purpose of the tests was to evaluate the influence of structural changes in the cinnamic and benzoic acid substructures on the inhibitory activity against strains of Candida albicans, Candida tropicalis, and Candida krusei. A quantitative structure-activity relationship (QSAR) study with KNIME v. 3.1.0 and Volsurf v. 1.0.7 softwares were realized, showing that descriptors DRDRDR, DRDRAC, L4LgS, IW4 and DD2 influence the antifungal activity of the haloamides. In general, 10 benzamides revealed fungal sensitivity, especially a vanillic amide which enjoyed the lowest MIC. The results demonstrate that a hydroxyl group in the para position, and a methoxyl at the meta position enhance antifungal activity for the amide skeletal structure. In addition, the double bond as a spacer group appears to be important for the activity of amide structures.

Evidences of Herbal Medicine-Derived Natural Products Effects in Inflammatory Lung Diseases

Pulmonary inflammation is a hallmark of many respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory syndrome distress (ARDS). Most of these diseases are treated with anti-inflammatory therapy in order to prevent or to reduce the pulmonary inflammation. Herbal medicine-derived natural products have been used in folk medicine and scientific studies to evaluate the value of these compounds have grown in recent years. Many substances derived from plants have the biological effects in vitro and in vivo, such as flavonoids, alkaloids, and terpenoids. Among the biological activities of natural products derived from plants can be pointed out the anti-inflammatory, antiviral, antiplatelet, antitumor anti-allergic activities, and antioxidant. Although many reports have evaluated the effects of these compounds in experimental models, studies evaluating clinical trials are scarce in the literature. This review aims to emphasize the effects of these different natural products in pulmonary diseases in experimental models and in humans and pointing out some possible mechanisms of action.

Antioxidant properties in a non-polar environment of difluoromethyl bioisosteres of methyl hydroxycinnamates

OBJECTIVES

Many natural antioxidants have poor pharmacokinetic properties that impair their therapeutic use. For hydroxycinnamic acids (HCAs) and other phenolic antioxidants, their major drawback is their low lipophilicity and a rapid metabolism. The difluoromethyl group may be considered as a 'lipophilic hydroxyl' due to its hydrogen bond donor and acceptor properties; this prompted us to assess it as a bioisosteric replacement of a phenolic hydroxyl for increasing the lipophilicity of HCAs.

METHODS

Six difluoromethyl-substituted methyl cinnamates (4a-c, 5a-c) related to caffeic acid were synthesized and their antioxidant activity evaluated by chemical (FRAP, DPPH scavenging, inhibition of β-carotene bleaching, at 1-200 μm), electrochemical (differential pulse voltammetry, cyclic voltammetry) and cell-based (inhibition of lipid peroxidation in erythrocytes, at 1 and 50 μm) assays.

KEY FNDINGS

Analogues 4a-c and 5a-c were inactive in FRAP and DPPH assays and only those containing a free phenolic hydroxyl (4a and 5a) exhibited electrochemical activity although with high redox potentials. Compounds 4a,b and 5a,b were active in the inhibition of β-carotene bleaching assay and all analogues inhibited lipid peroxidation in the human erythrocytes assay.

CONCLUSIONS

Lipophilic difluoromethyl-substituted cinnamic esters retain radical scavenging capabilities that prove useful to confer antioxidant properties in a non-polar environment.

Eugenol-rich Fraction of Syzygium aromaticum (Clove) Reverses Biochemical and Histopathological Changes in Liver Cirrhosis and Inhibits Hepatic Cell Proliferation

Background:

Dried flower bud of Syzygium aromaticum (clove) is rich in eugenol, an antioxidant and antiinflammatory compound that can protect liver against injury. Clove, besides eugenol, also contains other pharmacologically active phytochemicals such as β-sitosterol and ascorbic acid. This study reports the effect of eugenol-rich fraction (ERF) of clove on liver cirrhosis induced by thioacetamide.

Methods:

Cirrhosis of the liver, which predisposes to hepatocellular carcinoma, was induced by administering thioacetamide (0.03%) in drinking water for 16 weeks. Cirrhotic animals were divided into two groups; the treated group was administered ERF for 9 weeks, one week after discontinuation of thioacetamide, while the other group received normal saline for a similar duration of time.

Results:

The treatment with ERF, as determined by histopathology and through a battery of biochemical markers of hepatic injury, oxidative stress and drug metabolizing enzymes, significantly ameliorated the signs of liver cirrhosis. It lowered the elevated levels of alkaline phosphatase, γ-glutamyl transferase and other biochemical changes in liver cirrhosis. Histopathology of the liver corroborated the effect of ERF with biochemical findings. ERF treatment further inhibited cell proliferation, as demonstrated by reduced [³H]-thymidine uptake.

Conclusions:

Data provide evidence supporting the protective action of ERF on liver cirrhosis. The study assumes significance because cirrhosis predisposes the liver to cancer, which is characterized by abnormal cell proliferation. ERF in this study is reported to inhibit hepatic cell proliferation and at the same time decrease oxidative stress, which might be the mechanism of protection against liver cirrhosis.