Increased intestinal permeability and lipopolysaccharide contribute to swainsonine-induced systemic inflammation.

Long-term consumption of swainsonine could be poisonous to livestock, including facilitating apoptosis by impairing lysosomal function and inhibiting autophagic degradation, leading to liver inflammation and even death in livestock. However, the mechanism by swainsonine induced systemic inflammatory responses remained unclear, especially the effects of swainsonine on intestinal permeability, lipopolysaccharide (LPS) level and oxidative stress response were unknown. In this study, swainsonine increased intestinal permeability as evidenced by the significant down-regulation of colonic goblet cells, Akkermansia muciniphila and intestinal tight junction protein Occludin, Claudin 1 and ZO-1, and the significant up-regulation of mRNA expression level of the intestinal permeability indicator protein tyrosine phosphatase receptor type H (Ptprh) in the ileum of mice. Simultaneously, the elevated LPS biosynthetic genes in intestinal microbiota and increased intestinal permeability facilitated more bacterial endotoxin LPS to enter the blood. High concentration of free-form LPS induced high levels of proinflammatory cytokines and oxidative stress response, thereby causing the systemic inflammation. These findings provided a new perspective on swainsonine-induced systemic inflammation, suggesting that intestinal permeability and free-form LPS level may be the potential trigger factors.

Autophagic-lysosomal damage induced by swainsonine is protected by trehalose through activation of TFEB-regulated pathway in renal tubular epithelial cells.

Swainsonine (SW) is the main toxic component of locoweed. Previous studies have shown that kidney damage is an early pathologic change in locoweed poisoning in animals. Trehalose induces autophagy and alleviates lysosomal damage, while its protective effect and mechanism against the toxic injury induced by SW is not clear. Based on the published literature, we hypothesize that transcription factor EB(TFEB) -regulated is targeted by SW and activating TFEB by trehalose would reverse the toxic effects. In this study, we investigate the mechanism of protective effects of trehalose using renal tubular epithelial cells. The results showed that SW induced an increase in the expression level of microtubule-associated protein light chain 3-II and p62 proteins and a decrease in the expression level of ATPase H+ transporting V1 Subunit A, Cathepsin B, Cathepsin D, lysosome-associated membrane protein 2 and TFEB proteins in renal tubular epithelial cells in a time and dose-dependent manner suggesting TFEB-regulated lysosomal pathway is adversely affected by SW. Conversely, treatment with trehalose, a known activator of TFEB promote TFEB nuclear translocation suggesting that TFEB plays an important role in protection against SW toxicity. We demonstrated in lysosome staining that SW reduced the number of lysosomes and increased the luminal pH, while trehalose could counteract these SW-induced effects. In summary, our results demonstrated for the first time that trehalose could alleviate the autophagy degradation disorder and lysosomal damage induced by SW. Our results provide an interesting method for reversion of SW-induced toxicity in farm animals and furthermore, activation of TFEB by trehalose suggesting novel mechanism of treating lysosomal storage diseases.

Ipomoea carnea alkaloid extract vs swainsonine: A comparative study on cytotoxic activity against glial cells.

The consumption of Ipomoea carnea produces a neurological syndrome in animals. The toxic principles of I. carnea are the alkaloids swainsonine (SW) and calystegines B1, B2, B3 and C1. In this study, we investigated the cytotoxicity of an alkaloid extract of Ipomoea carnea (AEE) and natural swainsonine (SW) isolated from Astragalus lentiginosus (25-1000 µM of SW) for 48 h in a glioma cell line. Although the natural SW did not induce any changes in cell viability, the AEE exhibited a dose dependent cytotoxic effect and release of lactate dehydrogenase (LDH) indicative of cytolysis. In order to evaluate the morphological changes involved, cells were examined using phase contrast and fluorescence microscopy with acridine orange-ethidium bromide staining. The AEE caused a cell death compatible with necrosis, whereas exposure to 1000 µM of SW resulted in cytoplasmic vacuolation. Immunocytochemical studies revealed that astrocytes treated with 150 µM of AEE from I. carnea or 1000 µM of SW exhibited morphological characteristics of cell activation. These findings suggest that swainsonine would not be the only component present in the AEE of I. carnea responsible for in vitro cytotoxicity. Calystegines might also play a role in acting synergistically and triggering cell death through necrosis.

Swainsonine inhibits autophagic degradation and causes cytotoxicity by reducing CTSD O-GlcNAcylation.

Swainsonine (SW) is the primary toxin in locoweed, a poisonous plant. SW can cause animal poisoning, affect the quality and safety of meat products and threaten human health, but the mechanism of its toxicity is little defined. Here, we identified 159 differentially expressed proteins, many of which are involved in autophagy and glycosylation modification processes, using proteomics sequencing analysis. O-linked-N-acetylglucosamylation (O-GlcNAcylation) is a glycosylation modification widely involved in various biological processes. Our results show that SW toxicity is related to O-GlcNAcylation. In addition, increased O-GlcNAcylation with the O-GlcNAcase (OGA) inhibitor TMG promoted autophagy, while decreased O-GlcNAcylation with the O-GlcNAc transferase (OGT) inhibitor OSMI inhibited autophagy. Further analysis by Immunoprecipitation (IP) showed that SW could change the O-GlcNAcylation of Cathepsin D (CTSD), reducing the expression of mature CTSD (m-CTSD). In summary, these findings suggest that SW inhibits the O-GlcNAcylation of CTSD, affecting its maturation and leading to the impairment of lysosome function. Consequently, it inhibits autophagy degradation, and causes cytotoxicity, providing a new theoretical basis for SW toxicological mechanism.

Swainsonine-induced vacuolar degeneration is regulated by mTOR-mediated autophagy in HT22 cells.

The indolizidine alkaloid, swainsonine (SW), is the main toxic component of locoweed, which can cause locoism in animals with characteristic neurological dysfunction. Pathological manifestations at cellular level include extensive vacuolar degeneration. Studies have shown that SW can induces autophagy, but the role and mechanism of autophagy in SW-induced vacuolar degeneration is unclear. In this study, we analyzed the role of autophagy in SW-induced cell injury in mouse hippocampal neurons cell line (HT22) using western blotting, qRT-PCR, transmission electron microscopy and immunofluorescence microscopy. The results showed that the expressions of LC3-II, ATG5, Beclin1 and p62 proteins and their mRNAs in HT22 cells were induced by SW treatment. The SW treatment increased the number of autophagosomes with enhanced fluorescence intensity of monodansylcadaverine (MDC) and LC3-II in a time-dose dependent manner. The results of lysosome staining showed that SW could increase the number of lysosomes, increase the intraluminal pH. Transmission electron microscopy results indicate that SW induced autophagosomes, and Baf A1 could effectively alleviate SW-induced vacuolar degeneration. At the molecular level, SW treatment inhibited the expression of p-PI3K, p-AKT, p-ERK, p-AMPK, p-mTOR, p-p70S6K and p-4EBP1 and promoted the expression of p53. Our results collectively suggest, PI3K/AKT/mTOR, ERK/mTOR and p53/mTOR signaling pathways are involved in the regulation of SW-induced autophagy in HT22 cells, while the AMPK/mTOR signaling pathway is not involved in this regulation. Inhibition of autophagic degradation can effectively alleviate SW-induced vacuolar degeneration.

Evaluation of the context of downstream N- and free N-glycomic alterations induced by swainsonine in HepG2 cells.

Swainsonine (SWA), a potent inhibitor of class II α-mannosidases, is present in a number of plant species worldwide and causes severe toxicosis in livestock grazing these plants. The mechanisms underlying SWA-induced animal poisoning are not fully understood. In this study, we analyzed the alterations that occur in N- and free N-glycomic upon addition of SWA to HepG2 cells to understand better SWA-induced glycomic alterations. After SWA addition, we observed the appearance of SWA-specific glycomic alterations, such as unique fucosylated hybrid-type and fucosylated M5 (M5F) N-glycans, and a remarkable increase in all classes of Gn1 FNGs. Further analysis of the context of these glycomic alterations showed that (fucosylated) hybrid type N-glycans were not the precursors of these Gn1 FNGs and vice versa. Time course analysis revealed the dynamic nature of glycomic alterations upon exposure of SWA and suggested that accumulation of free N-glycans occurred earlier than that of hybrid-type N-glycans. Hybrid-type N-glycans, of which most were uniquely core fucosylated, tended to increase slowly over time, as was observed for M5F N-glycans. Inhibition of swainsonine-induced unique fucosylation of hybrid N-glycans and M5 by coaddition of 2-fluorofucose caused significant increases in paucimannose- and fucosylated paucimannose-type N-glycans, as well as paucimannose-type free N-glycans. The results not only revealed the gross glycomic alterations in HepG2 cells induced by swainsonine, but also provide information on the global interrelationships between glycomic alterations.

Intoxication of llamas by Astragalus punae in Argentina.

Several plants that contain indolizidine alkaloids, including swainsonine, are toxic to livestock, causing dysfunctional lysosomes and storage disease. Swainsonine induces a neurovisceral disease, known as locoism, in sheep, goats, and cattle, which occurs in several parts of the world, including, but not limited to, the western United States, China, and parts of Australia. In South America, locoism has been described in the Andean region of Argentina affecting sheep, cattle, and llamas. Intoxication by consumption of Astragalus punae was suspected in 4 llamas in Jujuy Province, northwestern Argentina. The grazing area contained abundant specimens of A. punae. The clinical course was ~15 d, and included moderate ataxia, incoordination of hindlimbs, and progressive loss of body condition. Microscopically, fine cytoplasmic microvacuolation was observed in the proximal convoluted renal tubules. Ultrastructurally, these changes consisted of severely dilated lysosomes. Swainsonine was detected in stem and leaf samples of A. punae at a concentration of 0.06%. Based on clinical history and signs, histologic and ultrastructural changes, and plant analysis, a diagnosis of swainsonine toxicosis caused by consumption of A. punae was made, which has not been reported previously, to our knowledge.

Toxicity of the swainsonine-containing plant Ipomoea carnea subsp. fistulosa for goats and sheep.

In order to determine the toxicity of swainsonine present in Ipomoea carnea for goats and sheep, 12 goats and 12 sheep were divided into 3 groups of 4 goats (G1, G2 and G3) and 3 groups of 4 sheep (S4, S5 and S6) each. Groups G1 and S4 were used as controls; G2 and S5 received 1 mg/kg body weight of swainsonine from plant material and G3 and S6 received 3 mg/kg. Groups G2 and G3 presented the first clinical signs, on average, after the 54th and 39th days of ingestion of the plant, respectively. Groups S5 and S6 presented the first clinical signs, on average, on the 64th and 42nd days of the experiment, respectively. In sheep, in addition to having a longer period of ingestion until the onset of clinical signs, these signs were less severe, being evident only after the animals were forced to move. These results demonstrated that goats are more susceptible to swainsonine poisoning than sheep. Complete regression of clinical signs was observed in 5 goats and 6 sheep. However, three goats and one sheep remained with clinical signs until 120 days of the experiment, suggesting that to control the poisoning the animals should be removed from the pastures immediately after the first clinical signs. There were no significant differences in weight between the different groups, suggesting that for goats ingesting the plant, toxic Ipomoea species can be used as forage for intermittent periods of 15-30 days.

The effect of Ipomoea carnea on maternal reproductive outcomes and fetal and postnatal development in rats.

Ipomoea carnea is a toxic plant found in Brazil and other tropical countries. The plant contains the alkaloids calystegines and swainsonine, which inhibit key cellular enzymes and cause systematic cell death. It is known that swainsonine is excreted in the amniotic fluid of dams exposed to the plant. Thus, the aim of this study was to verify whether the toxic effect of I. carnea on fetuses is due to exclusively the passage of the active principle of the plant through the placenta, or if the placentotoxic effect of swainsonine could collaborate in the adverse effects observed in the fetus. The teratogenic effects of exposure to the toxic principles of I. carnea were evaluated not only using the conventional protocol but also at later stages in the postnatal developmental period. Females were treated, from gestation day (GD) 6 until GD19, with 0.0, 1.0, 3.0 or 7.0 g/kg body weight of I. carnea dry leaves. The plant did not induce changes in reproductive performance or biochemical profile of the dams. Dams that received the highest dose of I. carnea showed cytoplasmic vacuolization in the liver, kidney and placental tissue. I. carnea promoted different lectin binding patterns in different areas of placental tissue. No fetal skeletal or visceral malformations was observed. The postnatal evaluation revealed a lower litter weight and a lower pup body weight one day after birth in the group that received the highest dose of I. carnea. Physical milestones were unaffected by the treatments. Female pups from all experimental groups exhibited a delay in achieving a negative geotaxis response. The results show that the toxic principle of I. carnea produces injury in utero in mothers and fetuses, but these deleterious effects were better demonstrated using postnatal evaluation.

Maternal exposure to swainsonine impaired the early postnatal development of mouse dentate gyrus of offspring.

Neurogenesis in the dentate gyrus (DG) plays a key role in the normal of structure and function of the hippocampus-learning and memory. After eating the locoweeds, animals develop a chronic neurological disease called "locoism". Swainsonine (SW) is the main toxin in locoweeds. Studies have shown that SW induces neuronal apoptosis in vitro and impairs learning and memory in adult mouse. The present study explored effects of SW exposure to dams on the postnatal neurogenesis of DG of offspring. Pregnant ICR mice were orally gavaged with SW at a dose of 0, 5.6 or 8.4 mg/kg/day from gestation day 10 to postnatal day (PND) 21, respectively. We found that SW impaired the proliferation capacity of neural progenitor cells in the DG so that the number of newborn cells was reduced at PND 8. Using the postnatal in vivo electroporation, we showed that the dendritic branching and total length of granule cells were significantly decreased due to SW exposure. In addition, on PND 21, the density of NeuN-positive and Reelin-positive interneurons increased in the hilus, implying the disorder of neuronal migration. These results suggest that maternal exposure to SW, the neurogenesis of DG on offspring was disrupted, finally leading to the functional disorder of DG.

Swainsonine induces autophagy via PI3K/AKT/mTOR signaling pathway to injure the renal tubular epithelial cells.

Swainsonine is a major toxic ingredients of locoweed plants, ingestion of these plants may cause locoism in livestock characterized by extensive cellular vacuolar degeneration of multiple tissues. However, so far, the mechanisms responsible for vacuolar degeneration induced by SW are not known. In this study, we investigated the role of autophagy in SW-induced TCMK-1 cells using Western blotting, transmission electron microscopy, immunofluorescent microscopy and qRT-PCR. The results showed that SW treatment increased the levels of LC3-II. The co-localization of LC3-II and lysosomal protein LAMP-2 results suggested that SW treatment does not interfere with fusion between autophagosome and lysosome. TEM results indicated that SW induced aggregation of the lysosome around the autophagosome. In addition, SW treatment suppressed p-PI3K, p-Akt, p-mTOR, p-p70S6K and p-4EBP1 level. In conclusion, SW induced autophagy via pI3K/AKT/mTOR signaling pathway and revealed the role of autophagy in causing the SW toxicity characterized by the vacuolar degeneration.

A Screen for Swainsonine in Select North American Astragalus Species.

Swainsonine is found in several plant species worldwide, and causes severe toxicosis in livestock grazing these plants, leading to a chronic condition characterized by weight loss, altered behavior, depression, decreased libido, infertility, and death. Swainsonine has been detected in 13 North American Astragalus species of which eight belong to taxa in four taxonomic sections, the Densifolii, Diphysi, Inflati, and Trichopodi. These sections belong to two larger groups representing several morphologically related species, the Pacific Piptolobi and the small-flowered Piptolobi. The objective of this study was to screen the other 31 species for swainsonine in sections Densifolii, Diphysi, Inflati, and Trichopodi previously not known to contain swainsonine. Furthermore, to broaden the scope further, 21 species within the 8 sections of the Pacific Piptolobi and the small flowered Piptolobi were screened for swainsonine. Swainsonine was detected for the first time in 36 Astragalus taxa representing 29 species using liquid and gas chromatography coupled with mass spectrometry. Several taxonomic sections were highly enriched in species that contain swainsonine while others were not. A systematic examination for swainsonine in these species will provide important information on the toxic risk of these species and may be a valuable reference for diagnosticians and land managers.

Swainsonine-induced lysosomal storage disease in goats caused by the ingestion of Sida rodrigoi Monteiro in North-western Argentina.

There are numerous poisonous plants that can induce intralysosomal accumulation of glycoproteins and neurologic syndromes. Here we describe for the first time, a disease caused by ingesting Sida rodrigoi Monteiro in goats in North-western Argentina. The animals showed weight loss, indifference to the environment, unsteady gait and ataxia. Histopathologic studies showed vacuolization in cells of various organs, mainly in the CNS. The material deposited in the cells was positive for LCA (Lens culinaris agglutinin), WGA (Triticum vulgaris agglutinin), sWGA (succinyl-Triticum vulgaris agglutinin) and Con-A (Concanavalia ensiformis agglutinin) lectins. Finally, toxic levels of swansonine were identified in the plant. The present investigation allowed to recognize S. rodrigoi Monteiro poisoning as a plant induced α-mannosidosis.

Reproductive Toxicities Caused by Swainsonine from Locoweed in Mice.

Swainsonine is the primary toxin in locoweeds. It causes intention tremors, reproductive dysfunction, emaciation, and death. The objective of the present study was to evaluate the potential reproductive and developmental toxicities caused by swainsonine in mice. The treatment groups consisting of three generations of mice were given a range of concentrations of swainsonine by intraperitoneal injection (2.50 mg/kg body weight (BW), 1.20 mg/kg BW, 0.60 mg/kg BW, and 0 mg/kg BW). The 0 mg/kg BW group exhibited significantly fewer estrous cycles and an increased number of estrous ones compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups (P < 0.05). All three generations of mice treated with swainsonine had significantly higher spleen, liver, and kidney indices and significantly lower body weights compared to the 0 mg/kg BW group (P < 0.05). For the first and second generations of treatment group, the copulation indices and the numbers of live pups on postnatal days (PND) 0, 4, and 15 were significantly decreased compared to those of the 0 mg/kg BW group (P < 0.05). The fertility and gestation indices of the treatment group of the first generation were significantly increased compared to the 2.50 mg/kg BW, 1.20 mg/kg BW, and 0.60 mg/kg BW groups of the second generation (P < 0.05). Cumulatively, these results indicate that swainsonine may cause reproductive and developmental toxicities in mice in both parents and offspring.

POISONING BY THE SWAINSONINE-CONTAINING PLANT SIDA CARPINIFOLIA IN CAPTIVE SAMBAR DEER (CERVUS UNICOLOR).

Plant intoxications in wildlife are difficult to diagnose, are overlooked, or are sometimes even neglected. Hence, factors that induce wild animals to ingest poisonous plants have not been sufficiently documented. An outbreak of glycoprotein storage disease in sambar deer ( Cervus unicolor ), induced by ingestion of the swainsonine-containing plant, common wireweed (Sida carpinifolia), is reported. Nine out of 55 deer held by a zoo in Brazil were affected. The poisoning was characterized by emaciation and neurologic signs followed by unexpected death in some of the animals. Animals presented abnormal consciousness, posterior paresis, and musculoskeletal weakness; less evident were vestibulo-cerebellar signs. Histologically, there was vacuolation of neurons and epithelial cells of the pancreatic acines, thyroid follicules, and renal tubules. Furthermore, in the central nervous system were axonal degeneration, necrosis, and loss of neurons. Three factors may lead to the ingestion of S. carpinifolia by sambar deer: 1) A grazing field with only S. carpinifolia as a source of forage; 2) a large number of animals kept in this field; and 3) a hierarchy within a cervid group in which dominant males isolated and displaced juvenile and weaker adult males, leaving them with access to only S. carpinifolia.

The toxicology mechanism of endophytic fungus and swainsonine in locoweed.

Locoweed is a perennial herbaceous plant included in Astragalus spp. and Oxytropis spp. that contains the toxic indolizidine alkaloid swainsonine. The livestock that consume locoweed can suffer from a type of toxicity called locoism. There are aliphaticnitro compounds, selenium, selenium compounds, and alkaloids in locoweed. The toxic component in locoweed has been identified as swainsonine, an indolizidine alkaloid. Swainsonine inhibits lysosomal a-mannosidase and mannosidase II, resulting in altered oligosaccharide degradation and incomplete glycoprotein processing. Corresponding studies on endophytic fungi producing swainsonine have been isolated from a variety of locoweed, and these endophytic fungi and locoweed have a close relationship. Endophytic fungi can promote the growth of locoweed and increase swainsonine production. As a result, livestock that consume locoweed exhibit several symptoms, including dispirited behavior, staggering gait, chromatopsia, trembling, ataxia, and cellular vacuolar degeneration of most tissues by pathological observation. Locoism results in significant annual economic losses. Therefore, in this paper, we review the current research on locoweed, including that on locoweed species distribution in China, endophyte fungus in locoweed, the toxicology mechanism of locoweed, and the swainsonine effect on reproduction.

Analysis of Swainsonine and Swainsonine N-Oxide as Trimethylsilyl Derivatives by Liquid Chromatography-Mass Spectrometry and Their Relative Occurrence in Plants Toxic to Livestock.

There are limited data concerning the occurrence of swainsonine N-oxide in plants known to contain swainsonine and its relative impact on toxicity of the plant material. A liquid chromatography-mass spectrometry method based on a solvent partitioning extraction procedure followed by trimethylsilylation and analysis using reversed phase high-pressure liquid chromatography-mass spectrometry was developed for the analysis of swainsonine and its N-oxide. The concentrations of each were measured in several swainsonine-containing taxa as well as two endophytic isolates that produce swainsonine. In vegetative samples the relative percent of N-oxide to free base ranged from 0.9 to 18%. In seed samples the N-oxide to free base ratio ranged from 0 to 10%. The measured concentrations of swainsonine N-oxide relative to swainsonine only slightly increases the actual toxicity of the various plant samples in a combined assay of both compounds.

A swainsonine survey of North American Astragalus and Oxytropis taxa implicated as locoweeds.

Swainsonine, an indolizidine alkaloid with significant physiological activity, is an α-mannosidase and mannosidase II inhibitor that causes lysosomal storage disease and alters glycoprotein processing. Swainsonine is found in a number of plant species worldwide, and causes severe toxicosis in livestock grazing these plants, leading to a chronic wasting disease characterized by weight loss, depression, altered behavior, decreased libido, infertility, and death. Swainsonine has been detected in 19 Astragalus and 2 Oxytropis species in North America by thin layer chromatography, gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry and a jack bean α-mannosidase inhibition assay. In addition, 5 species in North America are presumed to contain swainsonine based upon reports from field cases. Many of these plant species have not been analyzed for swainsonine using modern instrumentation such as gas or liquid chromatography coupled with mass spectrometry. To provide clarification, 22 Astragalus species representing 93 taxa and 4 Oxytropis species representing 18 taxa were screened for swainsonine using both liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. Swainsonine was detected in 48 Astragalus taxa representing 13 species and 5 Oxytropis taxa representing 4 species. Forty of the fifty-three swainsonine-positive taxa had not been determined to contain swainsonine previously using liquid or gas chromatography coupled with mass spectrometry. The list of swainsonine-containing taxa reported here will serve as a reference for risk assessment and diagnostic purposes.

Alteration of glycan structures by swainsonine affects steroidogenesis in bovine luteal cells.

The indolizidine alkaloid swainsonine (SW), a potent inhibitor of Golgi α-mannosidase II, is considered the primary toxicant in locoweeds causing toxicity syndrome known as locoism in livestock. Locoweed consumption decreases serum progesterone concentration and causes serious disorders in reproductive functions of livestock. However, direct effects of SW on luteal steroidogenic cells (LSCs) remain unclear. In the present study, we investigated the effect of N-glycan processing inhibition by SW on progesterone production and viability in cultured bovine LSCs. Swainsonine (0.1 µg/mL) fully inhibited glycosylation in the LSCs, but it had no effect on viability and progesterone production in the LSCs. Luteinizing hormone is known to promote progesterone production and expressions of steroidogenic acute regulatory protein and scavenger receptor type B class I. Pretreatment of LSCs with SW suppressed each of these effects, possibly by inhibiting LH receptor activity. These results suggest that SW inhibits N-glycan processing, which attenuates LH receptor activity, which, in turn, reduces progesterone production by CL.

The effects of swainsonine on the activity and expression of α-mannosidase in BRL-3A cells.

Swainsonine (SW) is the principal toxic ingredient of locoweeds, which can cause intensive vacuolar degeneration because of α-mannosidase inhibition after animal ingestion. While SW can lead to obvious liver damage in vivo, the mechanism of hepatotoxic damage caused by SW is not clear. Therefore, BRL-3A cells were treated for 24, 48, and 72 h with SW at various concentrations (0, 700, 900, 1100 µg/mL). The α-mannosidase (AMAN) activity was determined in BRL-3A cells using an enzyme substrate technique. The expression of mRNA and proteins of GM II (MAN2A1) and LAM (MAN2B1) in BRL-3A cells was detected by qPCR and Western-blot. The results showed that SW could significantly reduce the activity of AMAN in a time-dose effect relationship. Compared with the control group, the activity of AMAN significantly decreased only in the group treated with 1100 µg/mL SW for 24 h (P < 0.01), but the activity decreased significantly (P < 0.05 or P < 0.01) in all experimental groups treated for 48 or 72 h. SW also significantly reduced the expression of MAN2A1 and MAN2B1 mRNA and proteins in a time-dose effect relationship (P < 0.05 or P < 0.01), while the inhibition of SW was stronger for MAN2B1 than for MAN2A1. These results suggest that SW can significantly reduce the activity and expression of α-mannosidase thus causing SW-induced hepatotoxic damage.