Influence of kavain on hepatic ultrastructure

Protective efficacy of luteolin against aflatoxinB1-induced toxicity, oxidative damage, and apoptosis in the rat liver

One particularly harmful mycotoxin, aflatoxin B1 (AFB₁), usually triggers liver toxicity and oxidative stress in both humans and other mammals. Luteolin (LUTN), a popular active phytochemical molecule, exhibits a strong antioxidant potential. The purpose of this investigation was to explore the potential molecular mechanism in rats and determine if LUTN exhibits protective benefits against AFB₁-induced hepatotoxicity. Random selection was used to determine the four treatment groups, each consisting of 24 rats (n = 6). Physiological saline was administered to group 1 (CONT); group 2 received LUTN for a dosage of 50-mg/kg BW. AFB₁ was administered to group 3 for a dosage of 0.75-mg/kg BW, and AFB₁ with LUTN was given to group 4 at the same dosages mentioned in the previous groups. Rats intoxicated with AFB₁ alterations of hepatic transaminases, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), displayed periportal mononuclear cell infiltrations, disorganized lobular architecture, and dispersed necrotic cells in their liver tissues. By reducing serum biochemical levels of the hepatic transaminases ALT and AST brought on by AFB₁ exposure, our results demonstrated that LUTN treatment considerably restored liver injury. Through lowering the production of malondialdehyde (MDA) and reactive oxygen species (ROS), as well as by boosting the activity of the antioxidant enzyme catalase (CAT) and superoxide dismutase (SOD), LUTN mitigated the oxidative stress brought on by AFB₁. Our findings showed that LUTN significantly reversed the liver damage caused by AFB₁. When considered as a whole, LUTN may protect the liver from damage brought on by AFB₁ by acting as a potential mitigator and may aid in the creation of cutting-edge therapies to treat liver illnesses in humans and/or animals.

Descriptive Histopathological and Ultrastructural Study of Hepatocellular Alterations Induced by Aflatoxin B1 in Rats

Simple Summary

Aflatoxins can affect hepatocytes, which results in a series of histological and ultrastructural changes to the cells. We investigated the hepatocellular alterations induced by aflatoxin B1 in rats. Interestingly, we observed several histopathological and ultrastructural alterations in hepatocytes, including necrotic changes and massive vacuolar degeneration. Ultrastructural examinations of treated groups revealed damage to the sinusoidal endothelium, as well as aggregations of hyperactive Kupffer cells in the space of Disse and damaged telocytes. Our findings provide novel insights into the induction of a series of irreversible adverse effects on hepatocytes by aflatoxin B1. Based on our results, we suggest future investigations for the exploration of mechanistic pathways related to these induced hepatocellular alterations.

Abstract

Liver sinusoids are lined by fenestrated endothelial cells surrounded by perisinusoidal cells, Kupffer cells, and pit cells, as well as large granular lymphocytes. The functional ability of the liver cells can be substantially modified by exposure to toxins. In the current work, we assessed the histopathological and ultrastructural effects of a time-course exposure to aflatoxin B1 (AFB1) on the hepatic structures of rats. A total of 30 adult female Wistar rats were randomly divided into three groups: a control group, a group orally administered 250 µg/kg body weight/day of AFB1 for 5 days/week over 4 weeks, and a group that received the same AFB1 treatment but over 8 weeks. Histopathological and ultrastructural examinations of hepatocytes revealed massive vacuolar degeneration and signs of necrosis. Furthermore, the rat liver of the treated group exhibited damage to the sinusoidal endothelium, invasion of the space of Disse with hyperactive Kupffer cells, and some immune cells, as well as Ito cells overloaded with lipids. In addition, damaged telocytes were observed. Taken together, our results indicate that AFB1 induces irreversible adverse effects on the livers of rats.

Hepatotoxicity evaluation of traditional Chinese medicines using a computational molecular model

BACKGROUND

Liver injury caused by traditional Chinese medicines (TCMs) is reported from many countries around the world. TCM hepatotoxicity has attracted worldwide concerns.

OBJECTIVE

This study aims to develop a more applicable and optimal tool to evaluate TCM hepatotoxicity.

METHODS

A quantitative structure-activity relationship (QSAR) analysis was performed based on published data and U.S. Food and Drug Administration's Liver Toxicity Knowledge Base (LTKB).

RESULTS

Eleven herbal ingredients with proven liver toxicity in the literature were added into the dataset besides chemicals from LTKB. The finally generated QSAR model yielded a sensitivity of 83.8%, a specificity of 70.1%, and an accuracy of 80.2%. Among the externally tested 20 ingredients from TCMs, 14 hepatotoxic ingredients were all accurately identified by the QSAR model derived from the dataset containing natural hepatotoxins.

CONCLUSIONS

Adding natural hepatotoxins into the dataset makes the QSAR model more applicable for TCM hepatotoxicity assessment, which provides a right direction in the methodology study for TCM safety evaluation. The generated QSAR model has the practical value to prioritize the hepatotoxicity risk of TCM compounds. Furthermore, an open-access international specialized database on TCM hepatotoxicity should be quickly established.

Macrophage depletion ameliorates kavalactone damage in the isolated perfused rat liver

Liver toxicity is a side effect observed with some herbal treatments, including Piper methysticum. The possible mechanisms responsible include inflammation subsequent to activation of liver macrophages and oxidative damage. Hepatotoxicity of the pharmacologically active component of Piper methysticum (kavalactones) was tested in isolated, perfused livers from rats which were pretreated with the macrophage intoxicant gadolinium chloride. Perfusions without kavalactones in gadolinium chloride pretreated and untreated livers were included as negative controls. Serial liver lobe biopsies were collected to measure temporal changes in available (reduced) hepatic glutathione. There were no statistically significant changes in reduced glutathione over the course of perfusion in any experimental group. Liver damage was observed using electron microscopy. Hepatic sinusoids displayed extensive damage to the endothelium in kavalactone-perfused, rat livers. This damage was significantly reduced by pre-treatment with gadolinium chloride. Hence liver macrophages may be a factor in liver injury induced by Piper methysticum. Characterisation and modulation of the liver macrophage response may enable the development of strategies to avoid these hepatic side effects.

Are mould hepatotoxins responsible for kava hepatotoxicity?

Previous studies with kava components such as kavalactones, pipermethystine and flavokavain B have demonstrated hepatotoxicity from these constituents. Regardless, there has recently been speculation that adulterants or impurities such as the mould hepatotoxin aflatoxin are a more likely cause of kava hepatotoxicity, despite a paucity of supporting evidence. Although there is limited similarity between acute kava hepatotoxicity and acute aflatoxicosis, and background levels of aflatoxin have been detected in kava samples, unless epidemiological investigations can uncover direct evidence implicating mould hepatotoxins, it remains more likely that chemical constituents of kava are the cause of the hepatotoxicity from kava.

Liver toxicity and carcinogenicity in F344/N rats and B6C3F1 mice exposed to Kava Kava

Kava Kava is an herbal supplement used as an alternative to antianxiety drugs. Although some reports suggest an association of Kava Kava with hepatotoxicity , it continues to be used in the United States due to lack of toxicity characterization. In these studies F344/N rats and B6C3F1 mice were administered Kava Kava extract orally by gavage in corn oil for two weeks, thirteen weeks or two years. Results from prechronic studies administered Kava Kava at 0.125 to 2g/kg body weight revealed dose-related increases in liver weights and incidences of hepatocellular hypertrophy. In the chronic studies, there were dose-related increases in the incidences of hepatocellular hypertrophy in rats and mice administered Kava Kava for up to 1g/kg body weight. This was accompanied by significant increases in incidences of centrilobular fatty change. There was no treatment- related increase in carcinogenic activity in the livers of male or female rats in the chronic studies. Male mice showed a significant dose-related increase in the incidence of hepatoblastomas. In female mice, there was a significant increase in the combined incidence of hepatocellular adenoma and carcinoma in the low and mid dose groups but not in the high dose group. These findings were accompanied by several nonneoplastic hepatic lesions.

Assessment and histological analysis of the IPRL technique for sequential in situ liver biopsy

BACKGROUND

The isolated perfused rat liver (IPRL) is a technique used in a wide range of liver studies. Typically livers are assessed at treatment end point. Techniques have been described to biopsy liver in the live rat and post-hepatectomy.

RESULTS

This paper describes a technique for obtaining two full and one partial lobe biopsies from the liver in situ during an IPRL experiment. Our approach of retaining the liver in situ assists in minimising liver capsule damage, and consequent leakage of perfusate, maintains the normal anatomical position of the liver during perfusion and helps to keep the liver warm and moist. Histological results from sequential lobe biopsies in control perfusions show that cytoplasmic vacuolation of hepatocytes is a sign of liver deterioration, and when it occurs it commences as a diffuse pattern which tends to develop a circumscribed, centrilobular pattern as perfusion progresses.

CONCLUSIONS

Liver lobe biopsies obtained using this method can be used to study temporal effects of drug treatments and are suitable for light and electron microscopy, and biochemical analyses.

Toxicokinetics of kava

Kava is traditionally consumed by South Pacific islanders as a drink and became popular in Western society as a supplement for anxiety and insomnia. Kava extracts are generally well tolerated, but reports of hepatotoxicity necessitated an international reappraisal of its safety. Hepatotoxicity can occur as an acute, severe form or a chronic, mild form. Inflammation appears to be involved in both forms and may result from activation of liver macrophages (Kupffer cells), either directly or via kava metabolites. Pharmacogenomics may influence the severity of this inflammatory response.

Does inflammation play a role in kava hepatotoxicity?

The pathophysiology of kava hepatotoxicity remains inconclusive. There is circumstantial evidence for the roles of toxic metabolites, inhibition of cyclooxygenase (COX) enzymes and depletion of liver glutathione. Pharmacogenomic effects are likely, particularly for Cytochrome P450 genes. Experimental and clinical cases of hepatotoxicity show evidence of hepatitis. The question remains whether this inflammation is caused by components of kava directly, or indirectly due to the downstream effects.

Kavalactones Yangonin and Methysticin induce apoptosis in human hepatocytes (HepG2) in vitro

While cases of severe kava hepatotoxicity have been reported, studies examining the toxicity of individual kavalactones are limited. The present study examined the in vitro hepatotoxicity of kavain, methysticin and yangonin on human hepatocytes (HepG2) and the possible mechanism(s) involved. Cytotoxicity was assessed using lactate dehydrogenase (LDH) and ethidium bromide (EB) assays. The mode of cell death was analysed with acridine orange/ethidium bromide dual staining with fluorescence microscopy. Glutathione oxidation was measured using the ortho-phthalaldehyde (OPT) fluorescence assay. Kavain had minimal cytotoxicity, methysticin showed moderate concentration-dependent toxicity and yangonin displayed marked toxicity with ~ 40% reduction in viability in the EB assay. Acridine orange/ethidium bromide staining showed the predominant mode of cell death was apoptosis rather than necrosis. No significant changes were observed in glutathione levels, excluding this as the primary mechanism of cell death in this model. Further studies may elucidate the precise apoptotic pathways responsible and whether toxic kavalactone metabolites are involved.

Role of ethanol in kava hepatotoxicity

Kava is known for its recreational, ceremonial and medicinal use in the Pacific. The aqueous non-alcoholic drink of kava rhizome produces intoxicating, relaxing and soothing effects. While kava's medicinal effects receive worldwide recognition, kava-containing products came under scrutiny after over 100 reports of spontaneous adverse hepatic effects. Many mechanisms have been postulated to explain the unexpected toxicity, one being pharmacokinetic interactions between kavalactones and co-administered drugs involving cytochrome P450 enzyme system. Alcohol is often co-injested in kava hepatotoxicity cases. This review evaluates the possible hepatotoxicity mechanisms involving alcohol and kava.