Xiaobin Zeng

Promoting osteoblast differentiation by the flavanes from Huangshan Maofeng tea is linked to a reduction of oxidative stress

Epidemiological evidence has shown an association between tea consumption and the prevention of bone loss in the elderly. Previous studies indicated that green tea exerted osteoprotective effect in vivo. This study aims to investigate the constituents in Huangshan Maofeng tea and systemically evaluate their antioxidative and osteogenic effects in vitro. Five flavanes, isolated from Huangshan Maofeng tea, showed effects on proliferation of osteoblastic cells and ameliorated H2O2-induced C2C12 mouse myoblast cell apoptosis at 3.125-50 μg/ml. (-)-Epicatechin observably increased alkaline phosphatase (ALP) activity and hydroxyproline content. (-)-Epiafzelechin at 25 μg/ml significantly increased the area of mineralized bone nodules. The activities of flavanes in promoting osteblastic proliferation and differentiation are positively correlated with activities in protecting against apoptosis in C2C12 cells. It indicates that anti-osteoporosis effect of these flavanes may be linked to their antioxidative activity. The observed effects of these flavanes suggest that these flavanes may have beneficial effects on bone health.

Cytotoxic ceramides and glycerides from the roots of Livistona chinensis

A 70% ethanol extract of the roots of Livistona chinensis has been investigated, led to the isolation of 13 compounds, including a new ceramide, (2S,3S,4R,9Z)-2-[(2R)-2-hydroxytricosanoylamino]-9-octadecene-1,3,4-triol (2), a new glycosyl ceramide, 1-O-β-D-glucopyranosyl-(2S,3S,4R,9Z)-2-[(2R)-2-hydroxydocosanoylamino]-9-octadecene-1,3,4-triol (3), three new monoacylglycerols, 1-(34-hydroxytetratriacontanoyl)-sn-glycerol (9), 1-[nonadeca-(9Z,12Z)-dienoyl]-sn-glycerol (10), and 1-[12-hydroxypentatriaconta-(13E,15Z)-dienoyl]-sn-glycerol (11), a new diacylglycerol, 1-(heptadeca-6Z,9Z-dienoyl)-3-(octadeca-6Z,9Z,12Z-trienoyl)-sn-glycerol (12), as well as a new diacylglycerol aminoglycoside, 1-octadecanoyl-2-nonadecanoyl-3-O-(6-amino-6-deoxy)-β-D-glucopyranosyl-sn-glycerol (13). The structures of new compounds were elucidated, based on spectroscopic, zymologic and chemical methods. Among the compounds tested, compounds 3, 4 and 13 showed significantly antiproliferative effects against the human tumor cell lines (K562, HL-60, HepG2, and CNE-1) with the IC₅₀ of 10-65 μM. To our knowledge, this is first report of the occurrence of ceramides and acylglycerols in the genus Livistona.

Antimicrobial and cytotoxic phenolics and phenolic glycosides from Sargentodoxa cuneata.

Five new phenolic glycosides, Sargentodosides A-E, and two new dihydronaphthalene lignans, Sargentodognans F-G, together with thirty-two known phenolic compounds were isolated from the 60% ethanol extracts of Sargentodoxa cuneata. Their structures including absolute configurations were determined by spectroscopic analysis and electronic circular dichroism experiments. In bioscreening experiments, twelve compounds (22-26, 29, 33-34, 36, 38) exhibited antibacterial activities against S. aureus ATCC 29213 with minimum inhibitory concentration (MIC) values of 2-516μg/mL. And compound 29 showed the highest antibacterial activity against S. aureus ATCC 29213 with MIC values of 2μg/mL, while the MIC values of levofloxacin was 8μg/mL. Three compounds (29, 33, 36) exhibited antibacterial activities against S. aureus ATCC 25923 with MIC values of 256-516μg/mL. Two compounds (29, 33) exhibited antibacterial activities against A. baumanii ATCC 19606 with MIC values of 128-516μg/mL. However, no compound exhibited antimicrobial activities against C. albicans ATCC 10231. Moreover, three compounds (10, 25, 36) exhibited significant inhibition of proliferation in the two cell lines Hela and Siha, and showed stronger inhibitive activity of these two selected cell lines than cisplatin in the cytotoxic assay. Thus, S. cuneata is a potential plant source for further research targeting bacteria and cancer diseases.

Cytotoxic rotenoid glycosides from the seeds of Amorpha fruticosa

Four new rotenoid glycosides, namely amorphaside A-D (1-4), along with four known ones (5-8) were isolated from the seeds of Amorpha fruticosa. Their chemical structures and absolute configurations were elucidated by HRESIMS, NMR and CD spectra, as well as deduction from biosynthesis route. The sugar units were determined by acid hydrolysis, appropriate derivatization and HPLC analysis. The in vitro anti-proliferative activities of all compounds were evaluated against MCF-7 and HCT-116 cell lines. The results showed that compounds 1-3 had no effect on cell proliferation in the two cell lines even with the concentration of 50 μM, and compounds 4, 7 and 8 had selective cytotoxicity against MCF-7 with IC50 values of 3.90, 0.95 and 34.08 μM, respectively, while compounds 5 and 6 both showed significant cytotoxicity to the two cell lines with IC50 values less than 2.00 μM, even better than the positive control cisplatin. These preliminary results indicated that compounds 5 and 6 might be valuable to anticancer drug candidates.

Investigations on the Antifungal Effect of Nerol against Aspergillus flavus Causing Food Spoilage

The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

Urinary metabolites of cinobufagin in rats and their antiproliferative activities

Cinobufagin was one of the important cardenolidal steroids and a major component of Chan’Su, a famous traditional Chinese medicine. The urinary metabolites of cinobufagin after single oral doses of 25 mg kg−1 in rats were investigated. Eleven metabolites were isolated and purified by liquid–liquid extraction, open-column chromatography, medium-pressure liquid chromatography, as well as semi-preparative high-performance liquid chromatography. Their structures were elucidated by chemical and various spectroscopic methods, which were identified as desacetylcinobufagin (M-1), 3-oxo-desacetylcinobufagin (M-2), 3-oxo-cinobufagin (M-3), 3-epi-desacetylcinobufagin (M-4), 3-epi-12β-hydroxyl desacetylcinobufagin (M-5), 5β-hydroxyl cinobufagin (M-6), 5β-hydroxyl desacetylcinobufagin (M-7), 12β-hydroxyl cinobufagin (M-8), 1β,12β-dihydroxyl cinobufagin (M-9), 12β-hydroxyl desacetylcinobufagin (M-10) and 1β,12β-dihydroxyl desacetylcinobufagin (M-11), respectively. Among them, M-1 was the main urinary metabolite of cinobufagin with a yield of 17.7%. Most metabolites were hydroxylated products of cinobufagin at C-1β, 5β and 12β positions, as well as deacetylated products at C-16. Except M-1, M-4 and M-7, the other eight metabolites were novel in vivo metabolites of cinobufagin. Some metabolites showed potential cytotoxicity against human hepatoma cells (HepG2) and human leukaemia (K562, HL-60) cells; however, their cytotoxicities generally decreased after metabolic conversion.

Tetrahydroxystilbene glucoside isolated from Polygonum multiflorum Thunb. demonstrates osteoblast differentiation promoting activity

Polygonum multiflorum Thunb. is a traditional Chinese medicinal herb that has been widely used to treat age-associated diseases. Tetrahydroxystilbene glucoside (TSG), also known as 2,3,5,4-tetrahydroxystilbene-2-O-β-D-glucoside, is a major component of this herb. The present study was designed to investigate the osteogenic differentiation promoting activity of TSG in rat mesenchymal stem cells (MSCs) and in zebrafish. Preliminary experiments using MTT assay and ALP methods indicate that the high potential activity for promoting osteogenic differentiation was observed when 50% ethanol eluate was used. Further isolation and purification of TSG from the 50% ethanol eluate was performed by bioassay-guided fractionation, and its structure was confirmed using nuclear magnetic resonance and mass spectrometry analyses. In addition, the relative content of TSG with the highest potential activity in the promotion of osteogenic differentiation was identified as 14.34% by reversed-phase high performance liquid chromatography. Subsequently, the osteogenic differentiation promoting abilities of TSG in MSCs were examined. The results demonstrated that TSG promoted the alkaline phosphatase activity at concentrations of 1.56–25 µg/ml, while it increased the content of osteocalcin 7 days after treatment with 6.25–25 µg/ml in MSCs. Furthermore, experiments in zebrafish indicated that different concentrations of TSG (3.12–12.5 µg/ml) protected against further bone loss induced by 10 µmol/l dexamethasone (Dex), simulating an osteoporosis (OP) model. TSG treatment (12.5 µg/ml) in Dex-induced zebrafish significantly increased the area of nodules by 50.14% compared with the untreated model group. In conclusion, TSG, as a major component of P. multiflorum Thunb. exhibited an osteogenic promoting activity in MSCs and in zebrafish. The results provided scientific evidence to support the potential use of TSG for protecting the bone in degenerative diseases, such as OP.

A new meroterpenoid functions as an anti-tumor agent in hepatoma cells by downregulating mTOR activation and inhibiting EMT.

Liver cancer, also known as primary liver cancer, is cancer that starts in the liver. JNU-144, a new meroterpenoid purified from Lithospermum erythrorhizon, has exhibited promising anticancer activity; however, the molecular mechanisms of action of JNU-144 on malignant cells remain unclear. Our studies revealed that JNU-144 suppressed cell viability and proliferation in hepatoma cells by downregulating mTOR activation. Meanwhile, JNU-144 activated the intrinsic apoptosis pathway and subsequently triggered apoptotic cell death in SMMC-7721 cells. We also found that JNU-144 inhibited the epithelial–mesenchymal transition in both SMMC-7721 and HepG2 cells through reprogramming of epithelial–mesenchymal transition (EMT)-related gene expression or regulating protein instability. These findings indicate that JNU-144 exerts potent anticancer activity in hepatoma cells and may be developed as a potential therapeutic drug.

Pteisolic acid G, a novel ent‑kaurane diterpenoid, inhibits viability and induces apoptosis in human colorectal carcinoma cells

Human colorectal cancer (CRC) is a major cause of cancer morbidity and mortality, and its incidence rates are increasing in economical transitioning areas globally. To develop efficient chemotherapy drugs for CRC, the present study isolated and identified a novel ent-kaurane diterpenoid from Pteris semipinnata, termed pterisolic acid G (PAG). This ent-kaurane diterpenoid was demonstrated to significantly inhibit the growth of human CRC HCT116 cells in a time- and dose-dependent manner, determined using the Cell Counting Kit-8 assay. Additionally, western blot analysis, Hoechst 33342 staining and cytometry analysis revealed that PAG not only inhibited the viability of HCT116 cells by suppressing the dishevelled segment polarity protein 2/glycogen synthase kinase 3 β/β-catenin pathway, but also induced the apoptosis of HCT116 cells by downregulating nuclear factor-κB p65 activity, stimulating p53 expression and promoting the generation of intracellular reactive oxygen species. These results suggest that PAG, a novel inhibitor of the Wnt/β-catenin pathway and inducer of apoptosis, should be investigated in more detail using in vivo experiments and comprehensive mechanistic studies in order to examine the potential use of PAG as a novel therapeutic agent for the treatment of CRC.

Apoptosis and surfactant protein-C expression inhibition induced by lipopolysaccharide in AEC II cell may associate with NF-κB pathway

Lipopolysaccharide (LPS), a Gram-negative bacterial outer membrane component, is one of the major causes of septic shock. Herein we investigate LPS-induced apoptosis of rat alveolar epithelial type II cells (AEC II) and the effects of LPS on surfactant protein-C (SP-C) expression in AEC II, along with the possible molecular mechanisms. LPS exposure impaired cell viability and increased apoptosis of AEC II significantly in concentration-dependent manner embodied in increased caspase-3 expression and the activity of caspase-3. Simultaneously, our results also indicated that LPS inhibited surfactant protein-C (SP-C) expression in AEC II. Mechanistic studies revealed that LPS treatment significantly increased the expression of NF-κB p50, NF-κB p65 and IKKβ proteins as well as induced IκB-α phosphorylation. Moreover, pretreatment with IKK inhibitor IKK-16 or NF-κB inhibitor PDTC ameliorated LPS-caused alterations in cleaved caspase-3 expression, the activity of caspase-3 and SP-C expression. Taken together, these results demonstrate that LPS can induce apoptosis of AEC II and decrease SP-C expression partly through activating the NF-κB pathway.