Autoinducer-2 promotes the colonization of Lactobacillus rhamnosus GG to improve the intestinal barrier function in a neonatal mouse model of antibiotic-induced intestinal dysbiosis.

BACKGROUND: Human health is seriously threatened by antibiotic-induced intestinal disorders. Herein, we aimed to determine the effects of Autoinducer-2 (AI-2) combined with Lactobacillus rhamnosus GG (LGG) on the intestinal barrier function of antibiotic-induced intestinal dysbiosis neonatal mice. METHODS: An antibiotic-induced intestinal dysbiosis neonatal mouse model was created using antibiotic cocktails, and the model mice were randomized into the control, AI-2, LGG, and LGG + AI-2 groups. Intestinal short-chain fatty acids and AI-2 concentrations were detected by mass spectrometry and chemiluminescence, respectively. The community composition of the gut microbiota was analyzed using 16S rDNA sequencing, and biofilm thickness and bacterial adhesion in the colon were assessed using scanning electron microscopy. Transcriptome RNA sequencing of intestinal tissues was performed, and the mRNA and protein levels of HCAR2 (hydroxycarboxylic acid receptor 2), claudin3, and claudin4 in intestinal tissues were determined using quantitative real-time reverse transcription PCR and western blotting. The levels of inflammatory factors in intestinal tissues were evaluated using enzyme-linked immunosorbent assays (ELISAs). D-ribose, an inhibitor of AI-2, was used to treat Caco-2 cells in vitro. RESULTS: Compared with the control, AI-2, and LGG groups, the LGG + AI-2 group showed increased levels of intestinal AI-2 and proportions of Firmicutes and Lacticaseibacillus, but a reduced fraction of Proteobacteria. Specifically, the LGG + AI-2 group had considerably more biofilms and LGG on the colon surface than those of other three groups. Meanwhile, the combination of AI-2 and LGG markedly increased the concentration of butyric acid and promoted Hcar2, claudin3 and claudin4 expression levels compared with supplementation with LGG or AI-2 alone. The ELISAs revealed a significantly higher tumor necrosis factor alpha (TNF-α) level in the control group than in the LGG and LGG + AI-2 groups, whereas the interleukin 10 (IL-10) level was significantly higher in the LGG + AI-2 group than in the other three groups. In vitro, D-ribose treatment dramatically suppressed the increased levels of Hcar2, claudin3, and claudin4 in Caco-2 cells induced by AI-2 + LGG. CONCLUSIONS: AI-2 promotes the colonization of LGG and biofilm formation to improve intestinal barrier function in an antibiotic-induced intestinal dysbiosis neonatal mouse model.

S373P Mutation Stabilizes the Receptor-Binding Domain of the Spike Protein in Omicron and Promotes Binding.

A cluster of several newly occurring mutations on Omicron is found at the ß-core region of the spike protein's receptor-binding domain (RBD), where mutation rarely happened before. Notably, the binding of SARS-CoV-2 to human receptor ACE2 via RBD happens in a dynamic airway environment, where mechanical force caused by coughing or sneezing occurs. Thus, we used atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS) to measure the stability of RBDs and found that the mechanical stability of Omicron RBD increased by ∼20% compared with the wild type. Molecular dynamics (MD) simulations revealed that Omicron RBD showed more hydrogen bonds in the ß-core region due to the closing of the α-helical motif caused primarily by the S373P mutation. In addition to a higher unfolding force, we showed a higher dissociation force between Omicron RBD and ACE2. This work reveals the mechanically stabilizing effect of the conserved mutation S373P for Omicron and the possible evolution trend of the ß-core region of RBD.

POGZ suppresses 2C transcriptional program and retrotransposable elements.

The POGZ gene has been found frequently mutated in neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and intellectual disability (ID). We have recently shown that POGZ maintains mouse embryonic stem cells (ESCs). However, the exact mechanisms remain unclear. Here, we show that POGZ plays an important role in the maintenance of ESCs by silencing Dux and endogenous retroviruses (ERVs). POGZ maintains a silent chromatin state at Dux and ERVs by associating with and recruiting TRIM28 and SETDB1, and its loss leads to decreased levels of H3K9me3/H4K20me3, resulting in up-regulation of 2C transcripts and ESC transition to a 2C-like state. POGZ suppresses different classes of ERVs through direct (IAPEy, the intracisternal A-type particle elements) and indirect regulation (MERVL). Activation of POGZ-bound ERVs is associated with up-regulation of nearby neural disease genes such as Serpina3m. Our findings provide important insights into understanding the disease mechanism caused by POGZ dysfunction.

Targeting USP10 induces degradation of oncogenic ANLN in esophageal squamous cell carcinoma.

Anillin (ANLN) is a mitosis-related protein that promotes contractile ring formation and cytokinesis, but its cell cycle-dependent degradation mechanisms in cancer cells remain unclear. Here, we show that high expression of ANLN promotes cytokinesis and proliferation in esophageal squamous cell carcinoma (ESCC) cells and is associated with poor prognosis in ESCC patients. Furthermore, the findings of the study showed that the deubiquitinating enzyme USP10 interacts with ANLN and positively regulates ANLN protein levels. USP10 removes the K11- and K63-linked ubiquitin chains of ANLN through its deubiquitinase activity and prevents ANLN ubiquitin-mediated degradation. Importantly, USP10 promotes contractile ring assembly at the cytokinetic furrow as well as cytokinesis by stabilizing ANLN. Interestingly, USP10 and the E3 ubiquitin ligase APC/C co-activator Cdh1 formed a functional complex with ANLN in a non-competitive manner to balance ANLN protein levels. In addition, the macrolide compound FW-04-806 (F806), a natural compound with potential for treating ESCC, inhibited the mitosis of ESCC cells by targeting USP10 and promoting ANLN degradation. F806 selectively targeted USP10 and inhibited its catalytic activity but did not affect the binding of Cdh1 to ANLN and alters the balance of the USP10-Cdh1-ANLN complex. Additionally, USP10 expression was positively correlated with ANLN level and poor prognosis of ESCC patients. Overall, targeting the USP10-ANLN axis can effectively inhibit ESCC cell-cycle progression.

Activation of Young LINE-1 Elements by CRISPRa.

Long interspersed element-1 (LINE-1; L1s) are mobile genetic elements that comprise nearly 20% of the human genome. L1s have been shown to have important functions in various biological processes, and their dysfunction is thought to be linked with diseases and cancers. However, the roles of the repetitive elements are largely not understood. While the CRISPR activation (CRISPRa) system based on catalytically deadCas9 (dCas9) is widely used for genome-wide interrogation of gene function and genetic interaction, few studies have been conducted on L1s. Here, we report using the CRISPRa method to efficiently activate L1s in human L02 cells, a derivative of the HeLa cancer cell line. After CRISPRa, the young L1 subfamilies such as L1HS/L1PA1 and L1PA2 are found to be expressed at higher levels than the older L1s. The L1s with high levels of transcription are closer to full-length and are more densely occupied by the YY1 transcription factor. The activated L1s can either be mis-spliced to form chimeric transcripts or act as alternative promoters or enhancers to facilitate the expression of neighboring genes. The method described here can be used for studying the functional roles of young L1s in cultured cells of interest.

Total Sesquiterpenoids of Loquat Leaves Alleviated High-Fat Diet-Induced Obesity by Targeting Fecal Metabolic Profiling and Gut Microbiota Composition.

In the present study, we demonstrated that whether the gut microbiota and related metabolites contribute to the therapeutic effect of total sesquiterpenoids (TSs) from loquat leaves on obesity. A 4-week high fat diet was used to induce obesity which was then treated with TSs for another 4 weeks. TSs remarkedly reduced the weight of body and white adipose and the levels of total cholesterol (TC) and triglyceride (TG) in serum. We also found that TSs restored the diversity and richness of gut microbiota. In addition, TSs administration affected the relative abundance of seven key genera. Meanwhile, TSs were determined to affect the metabolism of the host through detecting the metabolites in feces. By applying KEGG and the correlation analysis with gut microbiota, 10 differential metabolites were identified to be the key. The results in this work proved that TSs inhibited obesity by remodeling gut microbiota and related metabolites.

Interdomain Linker Effect on the Mechanical Stability of Ig Domains in Titin.

Titin is the largest protein in humans, composed of more than one hundred immunoglobulin (Ig) domains, and plays a critical role in muscle's passive elasticity. Thus, the molecular design of this giant polyprotein is responsible for its mechanical function. Interestingly, most of these Ig domains are connected directly with very few interdomain residues/linker, which suggests such a design is necessary for its mechanical stability. To understand this design, we chose six representative Ig domains in titin and added nine glycine residues (9G) as an artificial interdomain linker between these Ig domains. We measured their mechanical stabilities using atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS) and compared them to the natural sequence. The AFM results showed that the linker affected the mechanical stability of Ig domains. The linker mostly reduces its mechanical stability to a moderate extent, but the opposite situation can happen. Thus, this effect is very complex and may depend on each particular domain's property.

Active endogenous retroviral elements in human pluripotent stem cells play a role in regulating host gene expression.

Human endogenous retroviruses, also called LTR elements, can be bound by transcription factors and marked by different histone modifications in different biological contexts. Recently, individual LTR or certain subclasses of LTRs such as LTR7/HERVH and LTR5_Hs/HERVK families have been identified as cis-regulatory elements. However, there are still many LTR elements with unknown functions. Here, we dissected the landscape of histone modifications and regulatory map of LTRs by integrating 98 ChIP-seq data in human embryonic stem cells (ESCs), and annotated the active LTRs enriching enhancer/promoter-related histone marks. Notably, we found that MER57E3 functionally acted as proximal regulatory element to activate respective ZNF gene. Additionally, HERVK transcript could mainly function in nucleus to activate the adjacent genes. Since LTR5_Hs/LTR5 was bound by many early embryo-specific transcription factors, we further investigated the expression dynamics in different pluripotent states. LTR5_Hs/LTR5/HERVK exhibited higher expression level in naïve ESCs and extended pluripotent stem cells (EPSCs). Functionally, the LTR5_Hs/LTR5 with high activity could serve as a distal enhancer to regulate the host genes. Ultimately, our study not only provides a comprehensive regulatory map of LTRs in human ESCs, but also explores the regulatory models of MER57E3 and LTR5_Hs/LTR5 in host genome.

Sesquiterpene glycoside isolated from loquat leaf targets gut microbiota to prevent type 2 diabetes mellitus in db/db mice.

According to ancient records, loquat leaf has been used as both a food and medicine in China for thousands of years. Sesquiterpene glycosides from loquat leaf have achieved remarkable effects on hyperglycemia. However, their specific activities and underlying mechanisms on type 2 diabetes mellitus (T2DM) are not fully understood. In the present study, we found that SG1, a unique sesquiterpene glycoside isolated from loquat leaf, had the capability to prevent insulin resistance and inflammation. In db/db mice, SG1 administration (25 and 50 mg kg-1 day-1) inhibited hyperglycemia and the release of inflammatory cytokines. To further explore the possible role of gut microbiota in SG1 for treating T2DM, we applied 16S rRNA pyrosequencing based on the V3-V4 region to analyze the fecal samples of different groups. Alpha diversity analysis showed that SG1 administration could obviously increase diversity and richness in db/db mice. At the phylum level, due to SG1 treatment, the relative abundance of Firmicutes and Actinobacteria was lowered while that of Bacteroidetes was raised. Additionally, 7 key genera in the db/db mice with SG1 supplementation were enriched: Lactobacillus, Lachnospiraceae_NK4A136_group, and Ruminococcus, Bacteroides, Prevotellaceae_UCG-001, Alistipes, and Roseburia. These findings proved that SG1 could prevent T2DM by relieving insulin resistance and inflammation and by remodeling the gut microbiota in db/db mice.

Novel Sesquiterpene Glycoside from Loquat Leaf Alleviates Type 2 Diabetes Mellitus Combined with Nonalcoholic Fatty Liver Disease by Improving Insulin Resistance, Oxidative Stress, Inflammation, and Gut Microbiota Composition.

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with type 2 diabetes mellitus (T2DM). Sesquiterpene glycosides from loquat leaf achieved beneficial effects on metabolic syndromes such as NAFLD and diabetes; however, their specific activity and underlying mechanism on T2DM-associated NAFLD have not yet been fully understood. In the present study, we found that sesquiterpene glycoside 3 (SG3), a novel sesquiterpene glycoside isolated from loquat leaf, was able to prevent insulin resistance (IR), oxidative stress, and inflammation. In db/db mice, SG3 administration (25 and 50 mg/kg/day) inhibited obesity, hyperglycemia, and the release of inflammatory cytokines. SG3 (5 and 10 µM) also significantly alleviated hepatic lipid accumulation, oxidative stress, and inflammatory response induced by high glucose combined with oleic acid in HepG2 cells. Western blotting analysis showed that these effects were related to repair the abnormal insulin signaling and inhibit the cytochrome P450 2E1 (CYP2E1) and NOD-like receptor family pyrin domain-containing 3 (NLRP3), both in vivo and in vitro. In addition, SG3 treatment could decrease the ratio of Firmicutes/Bacteroidetes and increase the relative abundance of Lachnospiraceae, Muribaculaceae, and Lactobacillaceae after a high-throughput pyrosequencing of 16S rRNA to observe the changes of related gut microbial composition in db/db mice. These findings proved that SG3 could protect against NAFLD in T2DM by improving IR, oxidative stress, inflammation through regulating insulin signaling and inhibiting CYP2E1/NLRP3 pathways, and remodeling the mouse gut microbiome. It is suggested that SG3 could be considered as a new functional additive for a healthy diet.

N501Y mutation of spike protein in SARS-CoV-2 strengthens its binding to receptor ACE2.

SARS-CoV-2 has been spreading around the world for the past year. Recently, several variants such as B.1.1.7 (alpha), B.1.351 (beta), and P.1 (gamma), which share a key mutation N501Y on the receptor-binding domain (RBD), appear to be more infectious to humans. To understand the underlying mechanism, we used a cell surface-binding assay, a kinetics study, a single-molecule technique, and a computational method to investigate the interaction between these RBD (mutations) and ACE2. Remarkably, RBD with the N501Y mutation exhibited a considerably stronger interaction, with a faster association rate and a slower dissociation rate. Atomic force microscopy (AFM)-based single-molecule force microscopy (SMFS) consistently quantified the interaction strength of RBD with the mutation as having increased binding probability and requiring increased unbinding force. Molecular dynamics simulations of RBD-ACE2 complexes indicated that the N501Y mutation introduced additional π-π and π-cation interactions that could explain the changes observed by force microscopy. Taken together, these results suggest that the reinforced RBD-ACE2 interaction that results from the N501Y mutation in the RBD should play an essential role in the higher rate of transmission of SARS-CoV-2 variants, and that future mutations in the RBD of the virus should be under surveillance.

Potent RBD-specific neutralizing rabbit monoclonal antibodies recognize emerging SARS-CoV-2 variants elicited by DNA prime-protein boost vaccination.

Global concerns arose as the emerged and rapidly spreading SARS-CoV-2 variants might escape host immunity induced by vaccination. In this study, a heterologous prime-boost immunization strategy for COVID-19 was designed to prime with a DNA vaccine encoding wild type (WT) spike protein receptor-binding domain (RBD) followed by S1 protein-based vaccine in rabbits. Four vaccine-elicited rabbit monoclonal antibodies (RmAbs), including 1H1, 9H1, 7G5, and 5E1, were isolated for biophysical property, neutralization potency and sequence analysis. All RmAbs recognized RBD or S1 protein with KD in the low nM or sub nM range. 1H1 and 9H1, but neither 7G5 nor 5E1, can bind to all RBD protein variants derived from B.1.351. All four RmAbs were able to neutralize wild type (WT) SARS-CoV-2 strain in pseudovirus assay, and 1H1 and 9H1 could neutralize the SARS-CoV-2 WT authentic virus with IC50 values of 0.136 and 0.026 µg/mL, respectively. Notably, 1H1 was able to neutralize all 6 emerging SARS-CoV-2 variants tested including D614G, B.1.1.7, B.1.429, P.1, B.1.526, and B.1.351 variants, and 5E1 could neutralize against the above 5 variants except P.1. Epitope binning analysis revealed that 9H1, 5E1 and 1H1 recognized distinct epitopes, while 9H1 and 7G5 may have overlapping but not identical epitope. In conclusion, DNA priming protein boost vaccination was an effective strategy to induce RmAbs with potent neutralization capability against not only SARS-CoV-2 WT strain but also emergent variants, which may provide a new avenue for effective therapeutics and point-of-care diagnostic measures.

Chicoric Acid Ameliorates Nonalcoholic Fatty Liver Disease via the AMPK/Nrf2/NFκB Signaling Pathway and Restores Gut Microbiota in High-Fat-Diet-Fed Mice.

This study examines the effects of chicoric acid (CA) on nonalcoholic fatty liver disease (NAFLD) in high-fat-diet- (HFD-) fed C57BL/6 mice. CA treatment decreased body weight and white adipose weight, mitigated hyperglycemia and dyslipidemia, and reduced hepatic steatosis in HFD-fed mice. Moreover, CA treatment reversed HFD-induced oxidative stress and inflammation both systemically and locally in the liver, evidenced by the decreased serum malondialdehyde (MDA) abundance, increased serum superoxide dismutase (SOD) activity, lowered in situ reactive oxygen species (ROS) in the liver, decreased serum and hepatic inflammatory cytokine levels, and reduced hepatic inflammatory cell infiltration in HFD-fed mice. In addition, CA significantly reduced lipid accumulation and oxidative stress in palmitic acid- (PA-) treated HepG2 cells. In particular, we identified AMPK as an activator of Nrf2 and an inactivator of NFκB. CA upregulated AMPK phosphorylation, the nuclear protein level of Nrf2, and downregulated NFκB protein level both in HFD mice and PA-treated HepG2 cells. Notably, AMPK inhibitor compound C blocked the regulation of Nrf2 and NFκB, as well as ROS overproduction mediated by CA in PA-treated HepG2 cells, while AMPK activator AICAR mimicked the effects of CA. Similarly, Nrf2 inhibitor ML385 partly blocked the regulation of antioxidative genes and ROS overproduction by CA in PA-treated HepG2 cells. Interestingly, high-throughput pyrosequencing of 16S rRNA suggested that CA could increase Firmicutes-to-Bacteroidetes ratio and modify gut microbial composition towards a healthier microbial profile. In summary, CA plays a preventative role in the amelioration of oxidative stress and inflammation via the AMPK/Nrf2/NFκB signaling pathway and shapes gut microbiota in HFD-induced NAFLD.

Structural basis for transcription inhibition by E. coli SspA.

Stringent starvation protein A (SspA) is an RNA polymerase (RNAP)-associated protein involved in nucleotide metabolism, acid tolerance and virulence of bacteria. Despite extensive biochemical and genetic analyses, the precise regulatory role of SspA in transcription is still unknown, in part, because of a lack of structural information for bacterial RNAP in complex with SspA. Here, we report a 3.68 Å cryo-EM structure of an Escherichia coli RNAP-promoter open complex (RPo) with SspA. Unexpectedly, the structure reveals that SspA binds to the E. coli σ70-RNAP holoenzyme as a homodimer, interacting with σ70 region 4 and the zinc binding domain of EcoRNAP ß' subunit simultaneously. Results from fluorescent polarization assays indicate the specific interactions between SspA and σ70 region 4 confer its σ selectivity, thereby avoiding its interactions with σs or other alternative σ factors. In addition, results from in vitro transcription assays verify that SspA inhibits transcription probably through suppressing promoter escape. Together, the results here provide a foundation for understanding the unique physiological function of SspA in transcription regulation in bacteria.

Flavonoids isolated from loquat (Eriobotrya japonica) leaves inhibit oxidative stress and inflammation induced by cigarette smoke in COPD mice: the role of TRPV1 signaling pathways.

Chronic obstructive pulmonary disease (COPD) is a chronic, progressive lung disease with few successful treatments, and is strongly associated with cigarette smoking (CS). Since the novel coronavirus has spread worldwide seriously, there is growing concern that patients who have chronic respiratory conditions like COPD can easily be infected and are more prone to having severe illness and even mortality because of lung dysfunction. Loquat leaves have long been used as an important material for both pharmaceutical and functional applications in the treatment of lung disease in Asia, especially in China and Japan. Total flavonoids (TF), the main active components derived from loquat leaves, showed remarkable anti-inflammatory and antioxidant activities. However, their protective activity against CS-induced COPD airway inflammation and oxidative stress and its underlying mechanism still remain not well-understood. The present study uses a CS-induced mouse model to estimate the morphological changes in lung tissue. The results demonstrated that TF suppressed the histological changes in the lungs of CS-challenged mice, as evidenced by reduced generation of pro-inflammatory cytokines including interleukin 6 (IL-6), IL-1ß, tumor necrosis factor α (TNF-α), nitric oxide (NO), and inducible nitric oxide synthase (iNOS) and diminished the protein expression of transient receptor potential vanilloid 1 (TRPV1). Moreover, TF also inhibited phosphorylation of IKK, IκB and NFκB and increased p-Akt. Interestingly, TF could inhibit CS-induced oxidative stress in the lungs of COPD mice. TF treatment significantly inhibited the level of malondialdehyde (MDA) and increased the activity of superoxide dismutase (SOD). In addition, TF markedly downregulated TRPV1 and cytochrome P450 2E1 (CYP2E1) and upregulated the expression of SOD-2, while the p-JNK level was observed to be inhibited in COPD mice. Taken together, our findings showed that the protective effect and putative mechanism of the action of TF resulted in the inhibition of inflammation and oxidative stress through the regulation of TRPV1 and the related signal pathway in lung tissues. It suggested that TF derived from loquat leaves could be considered to be an alternative or a new functional material and used for the treatment of CS-induced COPD.

The p75 neurotrophin receptor enhances HIF-dependent signaling in glioma.

Tumor hypoxia is associated with several features of aggressive glioma growth, including migration, invasion, and stemness. Most of the cellular adaptation to hypoxia is mediated by the hypoxia-inducible factors HIF-1α and HIF-2α, but regulation of these factors by both oxygen-dependent and -independent mechanisms in brain tumors is only partially understood. Here, we show that the p75 neurotrophin receptor (p75NTR) is stabilized at hypoxia in murine glioma in vivo, as well as in primary human glioma cultures in vitro. Expression of p75NTR resulted in increased stabilization of HIF-1α and HIF-2α, and RNAi or pharmacologic targeting of p75NTR diminished HIF stabilization and HIF-dependent signaling at hypoxia. Consequentially, p75NTR inhibition resulted in decreased migration, invasion, and stemness in response to hypoxia, suggesting that p75NTR is a central regulator of hypoxia-induced glioma aggressiveness. Together, our findings support the literature that identifies p75NTR as a potential therapeutic target in brain tumors.

Curcumin attenuates collagen-induced inflammatory response through the "gut-brain axis".

BACKGROUND: Previous studies have demonstrated that oral administration of curcumin exhibited an anti-arthritic effect despite its poor bioavailability. The present study aimed to explore whether the gut-brain axis is involved in the therapeutic effect of curcumin. METHODS: The collagen-induced arthritis (CIA) rat model was induced by immunization with an emulsion of collagen II and complete Freund's adjuvant. Sympathetic and parasympathetic tones were measured by electrocardiographic recordings. Unilateral cervical vagotomy (VGX) was performed before the induction of CIA. The ChAT, AChE activities, and serum cytokine levels were determined by ELISA. The expression of the high-affinity choline transporter 1 (CHT1), ChAT, and vesicular acetylcholine transporter (VAChT) were determined by real-time PCR and immunohistochemical staining. The neuronal excitability of the vagus nerve was determined by whole-cell patch clamp recording. RESULTS: Oral administration of curcumin restored the imbalance between the sympathetic and parasympathetic tones in CIA rats and increased ChAT activity and expression of ChAT and VAChT in the gut, brain, and synovium. Additionally, VGX eliminated the effects of curcumin on arthritis and ACh biosynthesis and transport. Electrophysiological data showed that curcumin markedly increased neuronal excitability of the vagus nerve. Furthermore, selective α7 nAChR antagonists abolished the effects of curcumin on CIA. CONCLUSIONS: Our results demonstrate that curcumin attenuates CIA through the "gut-brain axis" by modulating the function of the cholinergic system. These findings provide a novel approach for mechanistic studies of anti-arthritic compounds with low oral absorption and bioavailability.

A novel sesquiterpene glycoside from Loquat leaf alleviates oleic acid-induced steatosis and oxidative stress in HepG2 cells.

Loquat (Eriobotrya japonica) leaf has displayed beneficial effect on metabolic syndrome. In our previously study, total sesquiterpene glycosides (TSG) isolated from Loquat leaf exhibited therapeutic effect on Non-alcoholic fatty liver disease (NAFLD) in vivo, but the accurate active compound remains unknown. Sesquiterpene glycoside 1 (SG1) is a novel compound, which is exclusively isolated from Loquat leaf, but its biological activity has been rarely reported. The present study was designed to evaluate the pharmacological effect of SG1, the main component of TSG, in oleic acid (OA)-induced HepG2 cell model of NAFLD with its related mechanisms of action. In this study, both SG1 and TSG were found to significantly reduce the lipid deposition in the cell model. They could also decrease total cholesterol (TC), triglyceride (TG) and intracellular free fatty acid (FFA) contents. Compared with OA-treated cells, the superoxide dismutase (SOD) level increased, and the malondialdehyde (MDA) and 4-hydroxynonenal levels respectively decreased after the administration of SG1 or TSG. The high dose of SG1 (140 µg/mL) displayed a similar therapeutic effect as TSG at 200 µg/mL. Both SG1 and TSG were found to suppress the expression of cytochrome P450 2E1 (CYP2E1) and the phosphorylation of c-jun terminal kinase (JNK) and its downstream target c-Jun in OA-treated cell. These results demonstrate again that TSG are probably the main responsible chemical profiles of Loquat leaf for the treatment of NAFLD, for which it can effectively improve OA-induced steatosis and reduce oxidative stress, probably by downregulating of CYP2E1 expression and JNK/c-Jun phosphorylation, while SG1 may be the principle compound.