Mixture of Peanut Skin Extract, Geniposide, and Isoquercitrin Improves the Hepatic Lipid Accumulation of Mice via Modification of Gut Microbiota Homeostasis and the TLR4 and AMPK Signaling Pathways.

Metabolic-dysfunction-associated steatotic liver disease (MASLD, formerly known as NAFLD) is a global chronic liver disease, and no licensed drugs are currently available for its treatment. The incidence of MASLD is increasing, which could lead to a huge clinical and economic burden. As a multifactorial disease, MASLD involves a complex set of metabolic changes, and many monotherapies for it are not clinically effective. Therefore, combination therapies using multiple drugs are emerging, with the advantages of improving drug efficacy and reducing side effects. Peanut skin extract (PSE), geniposide (GEN), and isoquercitrin (IQ) are three natural antiaging components or compounds. In this study, the preventive effects of individual PSE, GEN, and IQ in comparison with the effects of their mixture (MPGI) were examined in a mouse model of high-fat-feed-induced MASLD. The results showed that MPGI could significantly reduce the body and liver weights of mice and improve hepatic steatosis and liver function indicators. Further mechanistic studies showed that PSE, GEN, and IQ worked together by reducing inflammation, modulating the intestinal flora, and regulating the TLR4/NF-κB, AMPK/ACC/CPT1, and AMPK/UKL1/LC3B signaling pathways. It is a promising therapeutic method for preventing MASLD.

Involvement of the Sch9/Rim15/Msn2 signaling pathway in the anti-aging activity of dendrobine from Dendrobium nobile Lindl. via modification of oxidative stress and autophagy.

BACKGROUND: Aging is an important pathogenic factor of age-related diseases and has brought huge health threat and economic burden to the society. Dendrobium nobile Lindl., a valuable herb in China, promotes longevity according to the record of ancient Chinese materia medica. This study aimed to discover the material basis of D. nobile as an anti-aging herb and elucidate its action mechanism. METHODS: K6001 yeast replicative lifespan assay was used to guide the isolation of D. nobile. The chronological lifespan assay of YOM36 yeast was further conducted to confirm the anti-aging activity of dendrobine. The mechanism in which dendrobine exerts anti-aging effect was determined by conducting anti-oxidative stress assay, quantitative real-time PCR, Western blot, measurements of anti-oxidant enzymes activities, determination of nuclear translocation of Rim15 and Msn2, and replicative lifespan assays of Δsod1, Δsod2, Δcat, Δgpx, Δatg2, Δatg32, and Δrim15 yeasts. RESULTS: Under the guidance of K6001 yeast replicative lifespan system, dendrobine with anti-aging effect was isolated from D. nobile. The replicative and chronological lifespans of yeast were extended upon dendrobine treatment. In the study of action mechanism, dendrobine improved the survival rate of yeast under oxidative stress, decreased the levels of reactive oxygen species and malondialdehyde, and enhanced the enzyme activities and gene expression of superoxide dismutase and catalase, but it failed to elongate the replicative lifespans of Δsod1, Δsod2, Δcat, and Δgpx yeast mutants. Meanwhile, dendrobine enhanced autophagy occurrence in yeast but had no effect on the replicative lifespans of Δatg2 and Δatg32 yeast mutants. Moreover, the inhibition of Sch9 phosphorylation and the promotion of nuclear translocation of Rim15 and Msn2 were observed after treatment with denrobine. However, the effect of dendrobine disappeared from the Δrim15 yeast mutant after lifespan extension, oxidative stress reduction, and autophagy enhancement. CONCLUSIONS: Dendrobine exerts anti-aging activity in yeast via the modification of oxidative stress and autophagy through the Sch9/Rim15/Msn2 signaling pathway. Our work provides a scientific basis for the exploitation of D. nobile as an anti-aging herb.

A new gentiopicroside derivative improves cognitive deficits of AD mice via activation of Wnt signaling pathway and regulation of gut microbiota homeostasis.

BACKGROUND: In our previous study, we found that gentiopicroside (GPS) isolated from Gentiana rigescens Franch has a significant antiaging activity via regulation of mitophagy and oxidative stress. In order to increase the anti-aging activity of GPS, several compounds based on the chemical structure of GPS were synthesized and evaluated for bioactivity with yeast replicative lifespan assay, and 2H-gentiopicroside (2H-GPS) as leading compound was selected for AD treatment. PURPOSE AND METHODS: To investigate whether 2H-GPS has anti- Alzheimer's disease effects, we used D-galactose (Dgal)-induced model mice to evaluate the effect of 2H-GPS on AD mice. Furthermore, we explored the action mechanism of this compound with RT-PCR, Western Blot, ELISA and 16S rRNA gene sequence analysis. RESULTS: Memory dysfunction and reduction in the number of neurons in the brain of mice were observed in Dgal treated group. These symptoms of AD mice were significantly relieved by administering 2H-GPS and donepezil (Done), respectively. In the Dgal only treated group, the protein levels of ß-catenin, REST and phosphorylated GSK-3ß, involved in the Wnt signaling pathway were significantly decreased, whereas the protein levels of GSK-3ß, Tau, phosphorylated Tau, P35 and PEN-2 were significantly increased. Importantly, treatment with 2H-GPS resulted in restoration of memory dysfunction and levels of these proteins. Furthermore, the composition of the gut microbiota after 2H-GPS administration was explored through 16S rRNA gene sequence analysis. Moreover, the mice, in which depleted gut microbiota with antibiotic cocktail (ABX), were used for evaluation of whether the gut microbiota is involved to the effect of 2H-GPS. Significant changes in gut microbiota composition were observed between AD and 2H-GPS-treated AD mice, and ABX partially eliminated the AD-restoring effect of 2H-GPS. CONCLUSION: 2H-GPS improves the symptoms of AD mice through combination of the regulation of Wnt signaling pathway and the microbiota-gut-brain axis, and the mechanism of action of 2H-GPS is distinct from that of Done.

First report of jujube anthracnose caused by Colletotrichum siamense in China.

Jujube (Zizyphus jujuba Mill.), a native small deciduous tree of China, is widely cultivated in China, Korea, India, Japan, Europe, and the United States (Chen et al. 2020). The fruit have been commonly consumed as healthy food supplements and traditional Chinese medicine for over 2000 years (Li et al. 2007). In August 2019, anthracnose-like leaf spot symptoms were observed on jujube plants in Xiaomenya Village, Jinan City, Shandong Province, China (36°27'39″N, 117°3'13″E), with over 30% leaf disease incidence. The spots were circular, sunken, brown in the center and with dark brown edges. As the spots enlarged and coalesced, it resulted in leaf perforation and early defoliation. Sometimes acervuli were observed on the lesions (Fig. S1a, b). To identify the causal agent, 20 diseased leaves were sampled, the margins of the lesions were cut into pieces (5 × 5 mm), sterilized and cultured following the protocol described previously (Wan et al. 2020) at 25 ℃ for 5 days. Twelve monospore isolates showing identical colony morphology were obtained. Three representative isolates, JNZG11, JNZG311, JNZG313, were used for further study. When grown on PDA the colony color was initially white and then turned pale-gray to gray in 5-day-old cultures. On the reverse, colonies were brown-black with an orange pigmentation near the center. Aerial mycelium was cottony, dense, white to pale-gray. Conidia were hyaline, 1-celled, smooth-walled, subcylindrical, oblong, attenuated with slightly rounded ends, (11.1-) 12.7-13.3 (-17.8) ×(-4.4) 5.2-5.5 (-6.3) µm (n=50). Appressoria were dark-brown, oval or irregular, (7.3-) 8.6-9.2 (-9.8) ×(-5.1) 5.8-6.9 (-7.0) µm (n=50) (Fig. S1c-g). The morphology resembled those of Colletotrichum gloeosporioides species complex (Cannon et al. 2012). For accurate identification, the sequences of the ribosomal internal transcribed spacer (ITS), actin (ACT), ß-tub2 (TUB2), calmodulin (CAL), chitin synthase (CHS-1), and glyceraldehyde-3phosphate dehydrogenase (GAPDH) of the 3 isolates were sequenced (Weir et al. 2012), and deposited into GenBank (Accession Nos. see Table 1). The six loci (ITS, GAPDH, ACT, CHS-1, CAL, and TUB2) were concatenated and the aligned sequences (1904 bp) were 99.7% homologous to ex-type C. siamense ICMP18578. The sequences of 38 Colletotrichum species (44 isolates) were downloaded from GenBank for phylogenetic analyses. In the maximum likelihood phylogenetic tree generated, the highest log likelihood was -8798.90 and the three isolates were all in the C. siamense clade (bootstrap support 94 %) (Fig. S2). To complete Koch's postulates, 60 healthy, mature jujube leaves on 12 branches (5 leaves per branch) (variety 'Zhongqiuhong') were inoculated with 20 µL of spore suspension (106 conidia/mL) or sterile water as a control. The branches were placed in sterile beakers containing a small amount of sterile water sealed with plastic wrap and maintained at 28 °C, 12 h light/dark. Five days after inoculation, all treated leaves showed the typical anthracnose symptom, similar to that observed in the field (Fig. S1h). The same fungus was re-isolated from the margins of the lesions using the aforementioned methods. Whereas no fungus were isolated from the controls. Previously, C. siamense has been reported to infect Z. mauritiana in China (Shu et al. 2020). To our knowledge, this is the first report of C. siamense causing anthracnose on Z. jujuba in China. This finding provides crucial information for the effective management of this disease.

Gentirigeoside B from Gentiana rigescens Franch Prolongs Yeast Lifespan via Inhibition of TORC1/Sch9/Rim15/Msn Signaling Pathway and Modification of Oxidative Stress and Autophagy.

Gentirigeoside B (GTS B) is a dammaren-type triterpenoid glycoside isolated from G. rigescens Franch, a traditional Chinese medicinal plant. In the present study, the evaluation of the anti-aging effect and action mechanism analysis for this compound were conducted. GTS B significantly extended the replicative lifespan and chronological lifespan of yeast at doses of 1, 3 and 10 µM. Furthermore, the inhibition of Sch9 and activity increase of Rim15, Msn2 proteins which located downstream of TORC1 signaling pathway were observed after treatment with GTS B. Additionally, autophagy of yeast was increased. In addition, GTS B significantly improved survival rate of yeast under oxidative stress conditions as well as reduced the levels of ROS and MDA. It also increased the gene expression and enzymatic activities of key anti-oxidative enzymes such as Sod1, Sod2, Cat and Gpx. However, this molecule failed to extend the lifespan of yeast mutants such as ∆cat, ∆gpx, ∆sod1, ∆sod2, ∆skn7 and ∆uth1. These results suggested that GTS B exerts an anti-aging effect via inhibition of the TORC1/Sch9/Rim15/Msn signaling pathway and enhancement of autophagy. Therefore, GTS B may be a promising candidate molecule to develop leading compounds for the treatment of aging and age-related disorders.

The Insulin Receptor: A Potential Target of Amarogentin Isolated from Gentiana rigescens Franch That Induces Neurogenesis in PC12 Cells.

Amarogentin (AMA) is a secoiridoid glycoside isolated from the traditional Chinese medicine, Gentiana rigescens Franch. AMA exhibits nerve growth factor (NGF)-mimicking and NGF-enhancing activities in PC12 cells and in primary cortical neuron cells. In this study, a possible mechanism was found showing the remarkable induction of phosphorylation of the insulin receptor (INSR) and protein kinase B (AKT). The potential target of AMA was predicted by using a small-interfering RNA (siRNA) and the cellular thermal shift assay (CETSA). The AMA-induced neurite outgrowth was reduced by the siRNA against the INSR and the results of the CETSA suggested that the INSR showed a significant thermal stability-shifted effect upon AMA treatment. Other neurotrophic signaling pathways in PC12 cells were investigated using specific inhibitors, Western blotting and PC12(rasN17) and PC12(mtGAP) mutants. The inhibitors of the glucocorticoid receptor (GR), phospholipase C (PLC) and protein kinase C (PKC), Ras, Raf and mitogen-activated protein kinase (MEK) significantly reduced the neurite outgrowth induced by AMA in PC12 cells. Furthermore, the phosphorylation reactions of GR, PLC, PKC and an extracellular signal-regulated kinase (ERK) were significantly increased after inducing AMA and markedly decreased after treatment with the corresponding inhibitors. Collectively, these results suggested that AMA-induced neuritogenic activity in PC12 cells potentially depended on targeting the INSR and activating the downstream Ras/Raf/ERK and PI3K/AKT signaling pathways. In addition, the GR/PLC/PKC signaling pathway was found to be involved in the neurogenesis effect of AMA.

Ehretiquinone from Onosma bracteatum Wall Exhibits Antiaging Effect on Yeasts and Mammals through Antioxidative Stress and Autophagy Induction.

The antiaging benzoquinone-type molecule ehretiquinone was isolated in a previous study as a leading compound from the herbal medicine Onosma bracteatum wall. This paper reports the antiaging effect and mechanism of ehretiquinone by using yeasts, mammal cells, and mice. Ehretiquinone extends not only the replicative lifespan but also the chronological lifespan of yeast and the yeast-like chronological lifespan of mammal cells. Moreover, ehretiquinone increases glutathione peroxidase, catalase, and superoxide dismutase activity and reduces reactive oxygen species and malondialdehyde (MDA) levels, contributing to the lifespan extension of the yeasts. Furthermore, ehretiquinone does not extend the replicative lifespan of Δsod1, Δsod2, Δuth1, Δskn7, Δgpx, Δcat, Δatg2, and Δatg32 mutants of yeast. Crucially, ehretiquinone induces autophagy in yeasts and mice, thereby providing significant evidence on the antiaging effects of the molecule in the mammalian level. Concomitantly, the silent information regulator 2 gene, which is known for its contributions in prolonging replicative lifespan, was confirmed to be involved in the chronological lifespan of yeasts and participates in the antiaging activity of ehretiquinone. These findings suggest that ehretiquinone shows an antiaging effect through antioxidative stress, autophagy, and histone deacetylase Sir2 regulation. Therefore, ehretiquinone is a promising molecule that could be developed as an antiaging drug or healthcare product.

Amarogentin from Gentiana rigescens Franch Exhibits Antiaging and Neuroprotective Effects through Antioxidative Stress.

In the present study, the replicative lifespan assay of yeast was used to guide the isolation of antiaging substance from Gentiana rigescens Franch, a traditional Chinese medicine. A compound with antiaging effect was isolated, and the chemical structure of this molecule as amarogentin was identified by spectral analysis and compared with the reported data. It significantly extended the replicative lifespan of K6001 yeast at doses of 1, 3, and 10 µM. Furthermore, amarogentin improved the survival rate of yeast under oxidative stress by increasing the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), and these enzymes' gene expression. In addition, this compound did not extend the replicative lifespan of sod1, sod2, uth1, and skn7 mutants with K6001 background. These results suggested that amarogentin exhibited antiaging effect on yeast via increase of SOD2, CAT, GPx gene expression, enzyme activity, and antioxidative stress. Moreover, we evaluated antioxidant activity of this natural products using PC12 cell system, a useful model for studying the nervous system at the cellular level. Amarogentin significantly improved the survival rate of PC12 cells under H2O2-induced oxidative stress and increased the activities of SOD and SOD2, and gene expression of SOD2, CAT, GPx, Nrf2, and Bcl-x1. Meanwhile, the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) of PC12 cells were significantly reduced after treatment of the amarogentin. These results indicated that antioxidative stress play an important role for antiaging and neuroprotection of amarogentin. Interestingly, amarogentin exhibited neuritogenic activity in PC12 cells. Therefore, the natural products, amarogentin from G. rigescens with antioxidant activity could be a good candidate molecule to develop drug for treating neurodegenerative diseases.

Gentiopicroside, a Secoiridoid Glycoside from Gentiana rigescens Franch, Extends the Lifespan of Yeast via Inducing Mitophagy and Antioxidative Stress.

Gentiopicroside (GPS), an antiaging secoiridoid glycoside, was isolated from Gentiana rigescens Franch, a traditional Chinese medicine. It prolonged the replicative and chronological lifespans of yeast. Autophagy, especially mitophagy, and antioxidative stress were examined to clarify the mechanism of action of this compound. The free green fluorescent protein (GFP) signal from the cleavage of GFP-Atg8 and the colocation signal of MitoTracker Red CMXRos and GFP were increased upon the treatment of GPS. The free GFP in the cytoplasm and free GFP and ubiquitin of mitochondria were significantly increased at the protein levels in the GPS-treated group. GPS increased the expression of an essential autophagy gene, ATG32 gene, but failed to extend the replicative and chronological lifespans of ATG32 yeast mutants. GPS increased the survival rate of yeast under oxidative stress condition; enhanced the activities of catalase, superoxide dismutase, and glutathione peroxidase; and decreased the levels of reactive oxygen species and malondialdehyde. The replicative lifespans of Δsod1, Δsod2, Δuth1, and Δskn7 were not affected by GPS. These results indicated that autophagy, especially mitophagy, and antioxidative stress are involved in the antiaging effect of GPS.

Peanut skin extract ameliorates the symptoms of type 2 diabetes mellitus in mice by alleviating inflammation and maintaining gut microbiota homeostasis.

In this study, mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet were used to investigate the antidiabetic effect and mechanism of action of peanut skin extract (PSE). Results revealed that the fasting blood glucose, body weight, and food intake of mice with T2DM significantly decreased after they were given PSE. The effects of 80 mg/kg PSE were similar to those of 140 mg/kg metformin (MET). The glucose tolerance and insulin sensitivity of the mice also improved. The composition of intestinal microflora in the mice significantly changed after PSE administration. In particular, no Actinobacteria was detected in the PSE-treated group, and the ratio of Firmicutes to Bacteroidetes was remarkably reduced. PSE also increased the abundance of gut microbiota involved in fatty acid biosynthesis, lipid biosynthesis, and sucrose metabolism. The abundance of gut microbiota related to aminoacyl-tRNA biosynthesis also decreased. Lipopolysaccharide, interleukin (IL)-6, IL-1ß and tumor necrosis factor-α in the blood, liver and adipose tissue were reduced by PSE. Similarly, the mRNA expression levels of IkappaB kinase and nuclear factor kappaB in the hypothalamus were reduced by PSE. These results suggested that PSE and MET elicited significant antidiabetic effects by maintaining gut microbiota and inhibiting inflammation.

Pleiocarpumlignan A, a new dineolignan from Piper pleiocarpum Chang ex Tseng.

The investigation of chemical constituents from the whole plants Piper pleiocarpum Chang ex Tseng resulted in the isolation of one new dineolignan, pleiocarpumlignan A (1), along with one known benzoate derivative, trans-2,3-diacetoxy-1-[(benzoy1oxy)methyl]-cyclohexa-4,6-diene (2), and two known neolignans (3-4) as (±)-trans-dehydrodiisoeugenol (3), (7R,8R,3'S)-△8'-3',6'-dihydro-3'-methoxy-3,4-methylenedioxy-6'-oxo-8,3',7,O,4'-lignan (4). Their structures were elucidated through extensive spectroscopic analyses including 1D, 2D NMR, HR-ESI-MS, and by comparison with the literature. All compounds (1-4) were firstly isolated from Piper pleiocarpum Chang ex Tseng. The 13C NMR spectra of 2 were completely assigned for the first time. Cytotoxic activities of these isolated compounds against five human cancer cell lines (including A-549, SMMC-7721, HL-60, MCF-7, and SW-480) were evaluated.

Leptin and Adiponectin Signaling Pathways Are Involved in the Antiobesity Effects of Peanut Skin Extract.

Excessive food intake and metabolic disorder promote obesity and diabetes. In China, peanut skin is used as a herbal medicine to treat hemophilia, thrombocytopenic purpura, and hepatic hemorrhage. In the present study, we demonstrated that peanut skin extract (PSE) safely reduced appetite, body weight, fat tissue, plasma TG and TC, and blood glucose level in mice with diet-induced obesity (DIO). Moreover, the leptin/leptin receptor/neuropeptide Y (NPY) and adiponectin signaling pathways involved in the antiobesity effects of PSE are confirmed through leptin and adiponectin overexpression and leptin receptor silencing in mice. PSE consisted of oligosaccharide and polyphenol in a mass ratio of 45 : 55, and both parts were important for the antiobesity function of PSE. Our results suggested that PSE can be developed as functional medical food to treat metabolic disorders and obesity.

Structure Characterization and Action Mechanism of an Antiaging New Compound from Gastrodia elata Blume.

A new compound, bis(4-hydroxybenzyl)ether mono-ß-L-galactopyranoside (1), was isolated from the rhizome of Gastrodia elata Blume. Its structure was elucidated using extensive spectroscopic analysis, including 1D and 2D NMR, HR-ESI-TOF-MS, and chemical derivatization. Compound 1 extended the replicative lifespan of K6001 and the chronological lifespan of YOM36 yeast strains. To understand the mechanism of action, oxidative stress assessment, reactive oxygen species (ROS) and malondialdehyde (MDA) levels, catalase (CAT) and total glutathione peroxidase (GPx) activity assays, and replicative lifespan assay of sod1, sod2, uth1, and skn7 yeast mutant strains were performed. Results indicated the significant increase in the survival rate of yeast under oxidative stress after treatment with 1. ROS and MDA levels were reduced significantly. Meanwhile, the activity of CAT and GPx was significantly increased. The lifespan of sod1, sod2, uth1, and skn7 mutants of K6001 was not affected by 1. Furthermore, we investigated the gene expression related to longevity after administrating 1. The significant increase of Sir2 and reduction of Uth1 gene expression in the 1-treated group were observed. These results indicated that antioxidative stress played an important role in the antiaging effect of 1; Sir2 and Uth1 genes were involved in antiaging effects of 1.

Novel Anti-Aging Benzoquinone Derivatives from Onosma bracteatum Wall.

The aim of this study was to investigate anti-aging molecules from Onosma bracteatum Wall, a traditional medicinal plant used in the Unani and Ayurvedic systems of medicine. During bioassay-guided isolation, two known benzoquinones, allomicrophyllone (1) and ehretiquinone (2) along with three novel benzoquinones designated as ehretiquinones B-D (3-5) were isolated from O. bracteatum. Their structures were characterized by spectroscopic analysis through 1D and 2D NMR, by MS spectroscopic analysis and comparing with those reported in the literatures. The anti-aging potential of the isolated benzoquinones was evaluated through a yeast lifespan assay, and the results indicated that 1, 2, 4 and 5 significantly extended the replicative lifespan of K6001 yeast, indicating that these benzoquinones obtained from O. brateatum have the ability to be employed as a potential therapeutic agent against age-related diseases.

3ß,23,28-Trihydroxy-12-oleanene 3ß-Caffeate from Desmodium sambuense-Induced Neurogenesis in PC12 Cells Mediated by ER Stress and BDNF-TrkB Signaling Pathways.

3ß,23,28-Trihydroxy-12-oleanene 3ß-caffeate (compound 1) is a neuritogenic pentacyclic triterpenoid, which was isolated from Desmodium sambuense based on a PC12 cell bioassay system. Compound 1 induced neurite outgrowth dose-dependently in PC12 cells and primary cortical neurons at doses of 0.1, 0.3, and 1 µM. The potential target of compound 1 was predicted by ChemProteoBase profiling, and the mechanism of action was investigated using specific inhibitors, Western blot analysis, and PC12 [rasN17] and PC12 [mtGAP] mutants. Compound 1 activates endoplasmic reticulum (ER) as an ER stress inducer, and the maker of ER stress GRP78 protein significantly increased after treatment with compound 1. The inhibitors of tyrosine kinase B (TrkB), insulin-like growth factor 1 receptor (IGF-1R), mitogen-activated protein kinase (MEK), and phosphatidylinositol 3 kinase (PI3K) significantly decreased the neurite outgrowth induced by compound 1. Furthermore, the increases of phosphorylation of TrkB, IGF-1R, extracellular signal-regulated kinase (ERK), and protein kinase B (AKT) were observed in the compound 1-treated group, and the phosphorylation of these proteins was diminished by corresponding inhibitors. Thus, the compound-1-induced neuritogenic activity depended on the activation of slight ER stress and associated BDNF-TrkB/Ras/Raf/ERK and IGF-1R/PI3K/AKT signaling pathways in PC12 cells.

Semi-synthesis and Structure-Activity Relationship of Neuritogenic Oleanene Derivatives.

(3S,4R)-23,28-Dihydroxyolean-12-en-3-yl (2E)-3-(3,4-dihydroxyphenyl)acrylate (1 a), which possesses significant neuritogenic activity, was isolated from the traditional Chinese medicine (TCM) plant, Desmodium sambuense. To confirm the structure and to assess biological activity, we semi-synthesized 1 a from commercially available oleanolic acid. A series of novel 1 a derivatives was then designed and synthesized for a structure-activity relationship (SAR) study. All synthetic derivatives were characterized by analysis of spectral data, and their neuritogenic activities were evaluated in assays with PC12 cells. The SAR results indicate that the number and position of the hydroxy groups on the phenyl ring and the triterpene moiety, as well as the length of the (saturated or unsaturated) alkyl chain that links the phenyl ring with the triterpene critically influence neuritogenic activity. Among all the tested compounds, 1 e [(3S,4R)-23,28-dihydroxyolean-12-en-3-yl (2E)-3-(3,4,5-trihydroxyphenyl)acrylate] was found to be the most potent, inducing significant neurite outgrowth at 1 µm.

Antiaging of Cucurbitane Glycosides from Fruits of Momordica charantia L.

Methanol extracts of Momordica charantia L. fruits are extensively studied for their antiaging activities. A new cucurbitane-type triterpenoid (1) and nine other known compounds (2-10) were isolated, and their structures were determined according to their spectroscopic characteristics and chemical derivatization. Biological evaluation was performed on a K6001 yeast bioassay system. The results indicated that all the compounds extended the replicative lifespan of K6001 yeast significantly. Compound 9 was used to investigate the mechanism involved in the increasing of the lifespan. The results indicated that this compound significantly increases the survival rate of yeast under oxidative stress and decreases ROS level. Further study on gene expression analysis showed that compound 9 could reduce the levels of UTH1 and SKN7 and increase SOD1 and SOD2 gene expression. In addition, it could not extend the lifespan of the yeast mutants of Uth1, Skn7, Sod1, and Sod2. These results demonstrate that compound 9 exerts antiaging effects via antioxidative stress and regulation of UTH1, SKN7, SOD1, and SOD2 yeast gene expression.

Leptin Gene Transfer Improves Symptoms of Type 2 Diabetic Mice by Regulating Leptin Signaling Pathway and Insulin Resistance of Peripheral Tissues.

The leptin gene was transferred into the liver of streptozocin- and high fat diet-induced type 2 diabetic (T2D) mice by hydrodynamic-based gene delivery. The food intake, water consumption, glucose concentration, and triglyceride and total cholesterol levels of T2D mice were significantly decreased. Meanwhile, plasma leptin was remarkably increased after gene transfer for 2, 3, 5, and 7 days, while plasma adiponectin was also significantly increased at day 2. To understand the mechanism of action of leptin on T2D mice, gene expressions related to glycometabolism and energy metabolism in the liver, epididymal adipose tissue, hypothalamus, and muscle were measured. The mRNA expression levels of adiponectin receptor 1 (ADR1), glucose transporter 4 (GLUT4), glucose-6-phosphase, and peroxisome proliferator-activated receptor γ in the liver, leptin, adiponectin, and hormone-sensitive lipase in adipose tissue, leptin, leptin-receptor, ADR1 in the hypothalamus, and ADR1, GLUT4, and insulin 1 in the gastrocnemius significantly increased. Moreover, the hepatic glycogen of the leptin-gene-treated group was significantly increased in comparison to the control group. Meanwhile, the significant decrease of forkhead box O1, adiponectin receptor 2, and peroxisome proliferator-activated receptor α in the liver, and agouti-related protein and proopiomelanocortin genes in the hypothalamus were also observed. In fat tissue and hypothalamus, leptin and adiponectin protein levels were also significantly increased, whereas the neuropeptide Y protein level was significantly decreased. These results indicated that the leptin gene transfer could improve the symptoms of T2D mice by regulating the leptin-hypothalamus signaling pathway and improving the insulin resistance of the peripheral tissues of T2D mice.

Bioactivity-guided isolation of neuritogenic triterpenoids from the leaves of Ilex latifolia Thunb.

Ilex latifolia Thunb is a traditional Chinese tea and herbal medicine. In this study, one new triterpene saponin (1) and six known triterpenoids (2-7) were isolated from the methanol extract of I. latifolia using a PC12 cell bioassay system. The structures and stereochemistry of these compounds were elucidated using spectroscopic methods and chemical derivatization. This new triterpene saponin (1) was characterized as an ursolic type acid with a 19α-hydroxyl and a trisaccharide moiety at C-3. Compound 1 significantly promoted the neurite outgrowth in PC12 cells by 52% at 10 µM, whereas compounds 2-7 showed less neuritogenic activity. Structure activity relationship studies indicated that introducing a trisaccharide moiety at C-3 is important for the neuritogenic activity, but the sugar group at C-28 decreased this activity. In addition, compound 1 increased the neurite outgrowth length in primary cortical neuron cells of mice and also exhibited a neuronal protection effect on H2O2-damaged PC12 cells at optimum concentrations.

Lindersin B from Lindernia crustacea induces neuritogenesis by activation of tyrosine kinase A/phosphatidylinositol 3 kinase/extracellular signal-regulated kinase signaling pathway.

BACKGROUND: Neurotrophic factors such as nerve growth factor (NGF) play important roles in nervous system. NGF is a potential therapeutic drug for treatment of neurodegenerative diseases. However, because of physicochemical property, NGF cannot pass through the blood-brain barrier (BBB). Hence, small molecules which exhibit NGF-mimic activity and can pass through the BBB are considered to be promising drug candidates for treatment of such diseases. PURPOSE: The present study was designed to isolate NGF-mimic substance from extract of natural products, determine their structures and investigate mechanism of action of the active substance. METHODS: Extract of Lindernia crustacean was partitioned between water and ethyl acetate to obtain water layer and ethyl acetate layer samples, respectively, and then evaluated their neuritogenic activity in PC12 cells. The active sample was separated by open columns, followed by HPLC purification to obtain active compound. Then, specific inhibitors were used to investigate signaling pathway of neurite outgrowth induced by the active compound. Finally, western blot analysis was performed to confirm the pathway proposed by inhibitor experiments. RESULTS: The ethyl acetate layer sample of extract of Lindernia crustacea exhibited significant neuritogenic activity. Two new compounds, named as linderside A and lindersin B, were isolated; their structures were elucidated by spectroscopic and chemical derivatization methods. Linderside A is a cucurbitane glycoside, whereas lindersin B is a cucurbitane triterpenoid. Each compound has an unusual isopentene unit, namely, a double bond bound to an unmodified isopropyl group at the end of cucurbitane triterpenoid side chain. Among them, lindersin B induced significant neurite outgrowth in PC12 cells, while linderside A was inactive against PC12 cells. Western blotting analysis results showed that lindersin B-induced neuritogenic activity depended on the activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK). Moreover, tyrosine kinase A (TrKA) and phosphatidylinositol 3 kinase (PI3K) were also involved in the signaling pathway. CONCLUSIONS: Two new cucurbitane triterpenoids, linderside A and lindersin B, were isolated from Lindernia crustacean. Neurite outgrowth induced by lindersin B in PC12 cells depends on activation of TrkA/PI3K/ERK signaling pathway.