Induction of Mkp-1 and Nuclear Translocation of Nrf2 by Limonoids from Khaya grandifoliola C.DC Protect L-02 Hepatocytes against Acetaminophen-Induced Hepatotoxicity

Piceatannol Alleviates Deoxynivalenol-Induced Damage in Intestinal Epithelial Cells via Inhibition of the NF-κB Pathway

Deoxynivalenol (DON) is a common mycotoxin that is widely found in various foods and feeds, posing a potential threat to human and animal health. This study aimed to investigate the protective effect of the natural polyphenol piceatannol (PIC) against DON-induced damage in porcine intestinal epithelial cells (IPEC-J2 cells) and the underlying mechanism. The results showed that PIC promotes IPEC-J2 cell proliferation in a dose-dependent manner. Moreover, it not only significantly relieved DON-induced decreases in cell viability and proliferation but also reduced intracellular reactive oxygen species (ROS) production. Further studies demonstrated that PIC alleviated DON-induced oxidative stress damage by increasing the protein expression levels of the antioxidant factors NAD(P)H quinone oxidoreductase-1 (NQO1) and glutamate-cysteine ligase modifier subunit (GCLM), and the mRNA expression of catalase (CAT), Superoxide Dismutase 1 (SOD1), peroxiredoxin 3 (PRX3), and glutathione S-transferase alpha 4 (GSTα4). In addition, PIC inhibited the activation of the nuclear factor-B (NF-κB) pathway, downregulated the mRNA expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) to attenuate DON-induced inflammatory responses, and further mitigated DON-induced cellular intestinal barrier injury by regulating the protein expression of Occludin. These findings indicated that PIC had a significant protective effect against DON-induced damage. This study provides more understanding to support PIC as a feed additive for pig production.

Comparative assessment of hepatoprotective properties of Artesunate and flavonoids from Artemisia annua on acetaminophen and carbon tetrachloride-induced cytotoxicity in primary mice hepatocytes

Background

Artesunate (ART) is a semi-synthetized molecule from Artemisinin, an active compound isolated from the medicinal plant Artemisia annua, widely used for the treatment of malaria. Previous studies reported that ART may exert a dual effect on the liver. Accordingly, this study investigated the potential protective action of ART against Acetaminophen (APAP) and Carbon tetrachloride (CCl₄)-induced hepatotoxicity in primary mice hepatocytes, in comparison to that of flavonoid extracted from A. annua (FAA). In addition, the antioxidant properties of FAA were also assessed.

Methods

The antioxidant activities of FAA and Ascorbic acid (ASC) (0.01-100 μg/mL) were assessed through inhibition of lipid peroxidation, reduction of ferric and phosphomolydenum, and hydroxyl and DPPH radicals scavenging assays. The hepatoprotective effects of FAA and ART (0.1-100 μg/mL) were evaluated against APAP (11 mM) or CCl4 (4 mM) induced oxidative damage in primary mouse hepatocytes. Biochemical parameters associated with hepatotoxicity assessed include cell viability, cell membrane integrity, cellular glutathione, and antioxidant enzyme activities.

Results

The obtained finding revealed FAA displayed a remarkable antioxidant activities as evidenced by the low IC₅₀/EC₅₀ values (3.85-19.32 μg/mL), comparable to that of ASC (3.26-18.04 μg/mL). When tested at 10 μg/mL, both FAA and ART significantly (p˂0.05) preserved cell viability, inhibited alanine aminotransferase leakage and lipid membrane peroxidation, and restored superoxide dismutase and catalase activities and glutathione content induced by APAP or CCl₄ in a similar way as Silymarin. However, ART showed a significant (p˂0.05) cytotoxic effect on hepatocytes at 100 and 1000 μg/mL and did not confer obvious protection at 100 μg/mL.

Conclusion

Overall, our data demonstrated that ART harms mice hepatocytes at high concentration while conferring relative protection against APAP and CCl₄-hepatotoxicity at low concentration. In contrast, FAA effectively protects liver cells without cytotoxicity effect, event at 100 μg/mL. Accordingly, ART should be given to the patient only under a medical prescription.

Hydro-ethanolic extract of Khaya grandifoliola attenuates heavy metals-induced hepato-renal injury in rats by reducing oxidative stress and metals-bioaccumulation

People living in developing countries are exposed to hepato-renal injuries induced by heavy metals like lead (Pb), cadmium (Cd), and mercury (Hg) since drinking water supplied is often polluted with a high concentration of those metals. Accordingly, it is necessary to search for antidotes against heavy metals poisoning. Hence, medicinal plants bearing anti-hepatotoxic properties represent a credible option; and such plant is Khaya grandifoliola. However, there is a paucity of knowledge regarding its protective effect on heavy metals-induced hepato-renal toxicity. Thus, this study was designed to assess the protective effect of the hydro-ethanolic stem bark extract of K. grandifoliola (HKG) against hepato-renal injuries induced by chronic consumption of drinking water containing high contents of Pb, Cd, and Hg; in addition to the investigation of the chemical antioxidant properties of HKG. For the antioxidant assays, HKG was tested as a potential inhibitor of lipid peroxidation, reducer of ferric and phosphomolybdenum, and scavenger of hydroxyl and 2,2-Diphenyl-Picryl-Hydrazyl radicals. Its protective effects were evaluated by daily co-treating rats with heavy metals solution (10 mL/kg b.w) containing 0.9, 0.58, and 1.13 ppm respectively for Pb, Cd and Hg and HKG (25 or 100 mg/kg b.w) for five consecutive months; and biochemical parameters associated to liver and kidneys functions, oxidative stress and metals bioaccumulation were assessed. HKG displayed a strong antioxidant capacity (IC50/EC50 range 3.95–17.17 μg/mL) correlated to its polyphenols content and comparable to that of Ascorbic acid. Serum levels of alkaline phosphatase, alanine/aspartate aminotransferase, and creatinine; renal and hepatic content of Cd and Pb, malondialdehyde and glutathione, activities of superoxide dismutase and catalase showed the protective effect of HKG, further evidenced by histopathological analysis. Taking together, these results demonstrated that HKG alleviates heavy metals-induced hepato-renal injuries in rats by reducing oxidative stress and metals-bioaccumulation.

Research progress of meliaceous limonoids from 2011 to 2021

Covering: July 2010 to December 2021Limonoids, a kind of natural tetranortriterpenoids with diverse skeletons and valuable insecticidal and medicinal bioactivities, are the characteristic metabolites of most plants of the Meliaceae family. The chemistry and bioactivities of meliaceous limonoids are a continuing hot area of natural products research; to date, about 2700 meliaceous limonoids have been identified. In particular, more than 1600, including thirty kinds of novel rearranged skeletons, have been isolated and identified in the past decade due to their wide distribution and abundant content in Meliaceae plants and active biosynthetic pathways. In addition to the discovery of new structures, many positive medicinal bioactivities of meliaceous limonoids have been investigated, and extensive achievements regarding the chemical and biological synthesis have been made. This review summarizes the recent research progress in the discovery of new structures, medicinal and agricultural bioactivities, and chem/biosynthesis of limonoids from the plants of the Meliaceae family during the past decade, with an emphasis on the discovery of limonoids with novel skeletons, the medicinal bioactivities and mechanisms, and chemical synthesis. The structures, origins, and bioactivities of other new limonoids were provided as ESI. Studies published from July 2010 to December 2021 are reviewed, and 482 references are cited.

Application of 3D Hepatic Plate-Like Liver Model for Statin-Induced Hepatotoxicity Evaluation

Background: Drug-induced liver injury is one of the main reasons of withdrawals of drugs in postmarketing stages. However, an experimental model(s) which can accurately recapitulates liver functions and reflects the level of drug hepatotoxicity is lack. In this study, we assessed drug hepatotoxicity using a novel three-dimensional hepatic plate-like hydrogel fiber (3D-P) co-culture system.

Methods: During the 28-days culture period, the liver-specific functions, hepatocyte polarity, sensitivity of drug-induced toxicity of 3D-P co-culture system were evaluated with 2D co-culture, collagen sandwich co-culture, 3D hybrid hydrogel fiber co-culture and human primary hepatocytes as controls. High-content imaging and analysis (HCA) methods were used to explore the hepatotoxicity mechanism of five statins.

Results: The 3D-P co-culture system showed enhancing liver-specific functions, cytochrome P450 enzymes (CYPs) metabolic activity and bile excretion, which were considered to result from improved hepatocyte polarity. Three of the statins may cause acute or chronic hepatotoxicity by via different mechanisms, such as cholestatic liver injury.

Conclusion: Our 3D-P co-culture system is characterized by its biomimetic hepatic plate-like structure, long-term stable liver specificity, and prominent bile secretion function, making it applicable for acute/chronic drug hepatotoxicity assessments.

Khaya grandifoliola C. DC. (Meliaceae: Sapindales): Ethnobotany, phytochemistry, pharmacological properties, and toxicology

ETHNOPHARMACOLOGICAL RELEVANCE

Khaya grandifoliola is a well-known tree species in Africa with a conservation status of 'vulnerable' due to its overexploitation by the wood industry. Several studies have recorded numerous ethnobotanical uses of this plant, as well as the scientific validation of the efficacy of extracts from different plant parts used for the treatment of various ailments. However, this useful information is scattered throughout the literature and thus there is no opportunity to identify the existing knowledge gaps.

AIM OF THE STUDY

This review aims to highlight the medicinal importance of Khaya grandifoliola including its known phytochemistry, biological activities and toxicology, to encourage a refocused conservation strategy since all current efforts are geared towards maintaining its continuous supply to the wood industry.

MATERIALS AND METHODS

Articles on K. grandifoliola were sourced from online databases such as Google Scholar, Medicine, PubMed, Science Direct, Scopus, SciFinder and other science journal websites up to May 2020. The search was conducted using various combinations of keywords such as biotechnological uses, biological activity, ethnobotany, ethnomedicine, indigenous uses, pharmacological activity, phytochemistry, proximate composition, toxicity, and traditional uses of K. grandifoliola. All downloaded articles were screened to determine their relevance to the scope of the review and the selected papers were included.

RESULTS

The review revealed a host of ethnomedicinal uses such as anticancer, antidiabetic, antimicrobial, anti-sickling, anti-ulcerogenic, and hepatoprotective, many of which are supported by scientific data. More importantly, toxicity tests revealed that many of the extracts are safe at various therapeutic doses. Important knowledge gaps that should be explored include phytochemical characterization and validation of some ethnobotanical claims on the folkloric usage of the plant.

CONCLUSIONS

Notwithstanding the importance of K. grandifoliola in the wood industry, this review reveals that its use as a medicine is equally important. Its medicinal uses are also well supported with scientific studies as well as favourable toxicological studies though some scientific knowledge gaps require further studies.

Advanced preclinical models for evaluation of drug-induced liver injury - consensus statement by the European Drug-Induced Liver Injury Network [PRO-EURO-DILI-NET]

Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF) and one of the leading indications for liver transplantation in Western societies. Given the wide use of both prescribed and over the counter drugs, DILI has become a major health issue for which there is a pressing need to find novel and effective therapies. Although significant progress has been made in understanding the molecular mechanisms underlying DILI, our incomplete knowledge of its pathogenesis and inability to predict DILI is largely due to both discordance between human and animal DILI in preclinical drug development and a lack of models that faithfully recapitulate complex pathophysiological features of human DILI. This is exemplified by the hepatotoxicity of acetaminophen (APAP) overdose, a major cause of ALF because of its extensive worldwide use as an analgesic. Despite intensive efforts utilising current animal and in vitro models, the mechanisms involved in the hepatotoxicity of APAP are still not fully understood. In this expert Consensus Statement, which is endorsed by the European Drug-Induced Liver Injury Network, we aim to facilitate and outline clinically impactful discoveries by detailing the requirements for more realistic human-based systems to assess hepatotoxicity and guide future drug safety testing. We present novel insights and discuss major players in APAP pathophysiology, and describe emerging in vitro and in vivo pre-clinical models, as well as advanced imaging and in silico technologies, which may improve prediction of clinical outcomes of DILI.

Biological activities of limonoids in the Genus Khaya (Meliaceae): a review

Background

Limonoids are a class of highly oxygenated modified triterpenoids with a diverse range of biological activities. Although with restricted occurrence in the plant kingdom, these compounds are found extensively in the Meliaceae and Rutaceae families. Limonoids are of great interest in science given that the small number of plant families where they occur exhibit a broad range of medicinal properties that promote health and prevent disease.

Main text

The Meliaceae family includes the genus Khaya and comprises tree species that have been used in traditional medicine to treat several ailments. In recent years, the genus Khaya has attracted much research interest owing to the presence of limonoids in different plant parts of a few species that can serve as therapeutic molecules in the pharmaceutical industry. In this study, a literature search over the past two decades (2000–2020) was conducted on the biological activities of limonoids in the genus Khaya using different databases such as Google Scholar, PubMed, Scopus and ISI Web of Science. The taxonomy, geographical distribution and the various traditional uses of the genus are presented in detail. This study reveals that the currently documented biological activities of limonoids both in vivo and in vitro are limited to four species (K. anthotheca, K. grandifoliola, K. ivorensis and K. senegalensis) in the genus Khaya, and include anticancer, antimalarial, hepatoprotection, anti-inflammatory, neuroprotection, antimicrobial, antifungal and antifeedant. The most well-researched species, K. senegalensis, has the most notable biological activities and traditional uses in the genus Khaya.

Conclusion

The present detailed and up-to-date review of recent literature on the biological activities in the genus Khaya reveals the potentials of limonoids for drug development in managing several ailments.

Inhibition of CYP2E1 and activation of Nrf2 signaling pathways by a fraction from Entada africana alleviate carbon tetrachloride-induced hepatotoxicity

Entada africana is used in non-conventional medicine for the management of liver ailments. A fraction, designated EaF10 (methylene chloride/methanol 90:10, v/v) with promising hepatoprotective activity has been isolated. Since the mechanisms underlying EaF10 hepatoprotective action remain unknown, this study was undertaken to investigate the anti-hepatotoxic mechanism of the fraction against carbon tetrachloride (CCl₄)-induced hepatotoxicity and its antioxidant properties. Antioxidant activities of EaF10 were assessed through four chemical antioxidant assays and its anti-hepatotoxic effect evaluated in vivo and in vitro by post-treatment (25 or 100 mg/Kg) or co-treatment (6.25–100 μg/mL) in CCl₄-intoxicated mice and normal human liver cells line L-02 hepatocytes respectively; and biochemical and molecular parameters assessed respectively by spectrophotometry, and by quantitative real-time polymerase chain reaction and western blot analysis. EaF10 exhibited strong antioxidant activities correlated with its polyphenol content. Serum levels of alanine/aspartate aminotransferase (AST/ALT) and nitrite oxide, liver contents of glutathione (GSH) protein carbonylation and malondialdehyde (MDA), liver activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) and cell viability showed the anti-hepatotoxic effect of EaF10, supported by histopathological observations. The fraction decreased the protein level of Cytochrome P450 2E1 (CYP2E1) and Kelch-like ECH-associated protein-1 (Keap-1), induced nuclear translocation of Nuclear factor-erythroid 2-related factor-2 (Nrf2) coupled to an increase of the mRNA levels of CAT, SOD1 and GST in CCl₄-intoxicated L-02 hepatocytes. These findings evidenced that the studied plant fraction possesses a strong antioxidant capacity and prevents CCl₄-induced hepatotoxicity, likely through inhibition of CYP2E1 and activation of the Nrf2 signaling pathway.

Acetaminophen-induced apoptosis: Facts versus fiction

An overdose of the widely used analgesic acetaminophen (APAP) is the most common cause of acute liver failure in the western world and hence is a clinically significant problem. Thus, mechanisms of APAP-induced hepatotoxicity have been the focus of extensive investigation for decades and it was established that APAP induces hepatocyte cell death by necrosis. Although APAP-induced necrosis shares some features of apoptosis induced by the intrinsic pathway, apoptotic cell death in this context was ruled out due to the absence of caspase activation and lack of protection by caspase inhibitors and missing morphological characteristics of apoptotic cells. Deeper mechanistic understanding of the cell death process after APAP in recent years has now revealed that cells die by programmed necrosis and apoptosis is not a relevant mode of cell death in this context. Hence, it is alarming to note that an increasing number of studies are being published purporting to indicate that APAP induces apoptotic cell death. These papers broadly measure "apoptotic markers" with questionable specificity such as Bax, Bcl-2 and caspase-3 protein expression, or use the terminal deoxynucleotidyl transferase dUTP nick end labeling assay as basis for the conclusion that there is apoptosis after APAP overdose. The misguided use of these apoptosis parameters in correlative studies without context or scientific rationale confuses the field and threatens to undo decades of careful mechanistic investigation into this topic. This review examines this emerging problem in detail and recommends approaches to correct it.

RELEVANCE FOR PATIENTS

Hepatotoxicity and acute liver failure caused by an acetaminophen overdose is a serious clinical problem in western countries. Understanding the mode of cell death and the signaling pathways involved is critical for developing new therapeutic approaches. Recent trends to claim that apoptosis is a relevant mode of cell death in acetaminophen hepatotoxicity are not justified by sound scientific data and will not lead to effective new drug development.

Hepatoprotection of pine nut polysaccharide via NRF2/ARE/MKP1/JNK signaling pathways against carbon tetrachloride-induced liver injury in mice

Previously, we obtained a purified polysaccharide (PNP40c-1) from Pinus koraiensis pine nut and reported its protective effect on carbon tetrachloride (CCl₄)-induced liver injury in vitro. The object of this study is to investigate its hepatoprotective activity in vivo and elucidate the mechanism underlying the hepatoprotection. PNP40c-1 effectively prevented the accumulation of serum liver injury biomarkers including alanine aminotransferase, aspartate aminotransferase, alkaline phpsphatase and total bilirubin stimulated by CCl₄. The pathological changes in PNP40c-1-treated mice livers were also markedly ameliorated. Results showed that PNP40c-1 suppressed the production of reactive oxygen species (ROS) and lipid peroxidation, upregulated Nrf2/ARE pathway and enhanced the antioxidant capacity of hepatocytes. Furthermore, the reaction between Nrf2 and ARE promoted the generation of Mkp1, which inhibited the activation of JNK induced by CCl₄, and suppressed hepatocytes apoptosis by regulating the protein expression of Bax, cleaved-Caspase-3 and Bcl2, exerting hepatoprotective activity. Taken together, upregulation of Nrf2/ARE pathway and suppression of JNK activation via Nrf2/ARE/Mkp1/JNK signaling pathways are the main mechanisms underlying the hepatoprotective effect of PNP40c-1 against CCl₄-induced mice liver injury. These results indicated that PNP40c-1 has potential to serve as a hepatoprotective agent against chemical induced hepatotoxicity.

Natural limonoids protect mice from alcohol-induced liver injury

Background Alcoholic liver disease (ALD) is regarded as a global health problem with limited therapeutic options. Previous studies highlighted some anticancer, antiviral, and hepatoprotective activities of limonoids, but the effects of these compounds on ALD remain unknown. The present study aimed to evaluate the effect of some natural limonoids on ethanol-induced liver injury. Methods Thirty-five albino mice (Mus musculus) were administered with 40% ethanol in the presence or absence of the different limonoids [including three havanensin-type limonoids, TS1, TS3, Rubescin D isolated from an African medicinal plant, Trichilia rubescens Oliv. (Meliaceae), and one limonin], or silymarin at 50 mg/kg for 3 days. Thereafter, the effect of the most active compound was evaluated in a chronic model of ALD. For this purpose, 24 mice with each group consisting of six mice were administered orally with 40% ethanol and limonoid at different doses (50, 75, and 100 mg/kg) for 28 days. Finally, biochemical parameters such as alanine aminotransferase (ALT), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), triglyceride (TG), and tumor necrosis factor α (TNF-α) levels were quantified in liver homogenates. Results All tested limonoids significantly (p < 0.01) reduced ALT levels relative to the negative control in the acute model. However, in comparison to other limonoids, limonin at 50 and 75 mg/kg significantly reduced TG, MDA, and TNF-α levels (1.8-fold); alleviated leukocyte infiltration in liver tissue; significantly increased the activity of SOD; and decreased those of CAT better than silymarin used as a positive control at 50 mg/kg. Conclusions These data suggest that limonin possesses protective effects on long-term alcohol poisoning partially due to antioxidant and anti-inflammatory mechanisms.

Hyperoside alleviated N-acetyl-para-amino-phenol-induced acute hepatic injury via Nrf2 activation

N-acetyl-para-amino-phenol (APAP) acute hepatic injury is receiving increasing attention. In the present study, we examined the effects of Hyperoside (Hype) on APAP-induced acute hepatic injury. Oral administration of Hype dose-dependently attenuated the index of hepatic injury, including the production of AST, ALT, and ALP. Increased glutathione (GSH) and decreased ROS production induced by Hype demonstrated its potential antioxidant capacity. In addition, Nrf2 and its downstream genes were markedly activated by Hype. Furthermore, enhanced levels of SOD, GST, and GSH-Px were markedly suppressed by Hype in a dose-dependent manner. At the same time, decreased LPO was also detected in Hype-treated mice. The in vitro study verified a protective effect of Hype on APAP-induced injuries in LO2 cells. Moreover, the regulatory effect was found to be mostly dependent on Nrf2 which decreased LDH and ALT generation and increased cell viability. Nrf2-silenced LOS cells were sensitive to APAP-induced injury, while Hype did not exhibit any further effects on LO2 cells, which demonstrate the critical role of Nrf2 in this process. Taken together, our results demonstrated the ability of Hype to inhibit APAP-induced acute hepatic injury and its potential use in the treatment of Nrf2-associated diseases.

Allyl methyl trisulfide protected against acetaminophen (paracetamol)-induced hepatotoxicity by suppressing CYP2E1 and activating Nrf2 in mouse liver

In order to investigate the protective effects of allyl methyl trisulfide (AMTS) on acetaminophen (APAP)-induced hepatotoxicity, 75 KM mice were randomized into 5 groups, i.e. a control group, an APAP group, and three AMTS/APAP groups.