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Temporal stability of net primary productivity (NPP) is important for predicting the reliable provisioning of ecosystem services under global changes. Although nitrogen (N) addition is known to affect the temporal stability of aboveground net primary productivity (ANPP), it is unclear how it impacts that of belowground net primary productivity (BNPP) and NPP, and whether such effects are scale dependent. Here, using experimental N addition in a grassland, we found different responses of ANPP and BNPP stability to N addition at the local scale and that these responses propagated to the larger spatial scale. That is, N addition significantly decreased the stability of ANPP but did not affect the stability of BNPP and NPP at the two scales investigated. Additionally, spatial asynchrony of both ANPP and BNPP among communities provided greater stability at the larger scale and was not affected by N addition. Our findings challenge the traditional view that N addition would reduce ecosystem stability based on results from aboveground dynamics, thus highlighting the importance of viewing ecosystem stability from a whole system perspective.

The aim of this study was to evaluate the effect and mechanism of hesperidin (HES) on insulin resistance (IR) in the human hepatocellular carcinoma cell line (HepG2 cells). HepG2 cells were induced with lipopolysaccharide (LPS) as a model of IR and treated with HES at three dosages. Next, the levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), the glucose content, and glucose uptake were evaluated by enzyme-linked immunosorbent assay, glucose oxidase-peroxidase method (GOD-POD), or (2-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-2-deoxyglucose) (2-NBDG). Moreover, the protein expression of toll-like receptors 4 (TLR4), insulin receptor substrate 1 (IRS1), nuclear factor kappa B (NF-κB), and glucose transporter 2 (GLUT2) in HepG2 cells treated with HES were assessed via western blotting analysis. In addition, GLUT2 protein expression exposed to HES was detected following treatment with TLR4 inhibitor (HTA125). Our results demonstrated that HES decreased the levels of TNF-α and IL-6, attenuated the glucose content in culture medium and increased glucose uptake in insulin-resistant HepG2 cells in vitro. Moreover, HES upregulated the expression of IRS1 and GLUT2 protein and downregulated the protein expression of TLR4 and NF-κB in insulin-resistant HepG2 cells. The expression of GLUT2 protein had no significant changes when treated with HES after blockade of TLR4. HES attenuated IR in LPS-inducedinsulin-resistant HepG2 cells. Therefore, regulating the IRS1-GLUT2 pathway via TLR4 represents a potential mechanism of HES on IR in HepG2 cells.

A new eudesmanolide, 1-oxo-11αH-eudesma-2,4(14)-dien-12,8β-olide (1), and four new guaianolides, 9β,10β-epoxy-4α-hydroxy-1βH,11αH-guaian-12,8α-olide (2), 9β,10β-epoxy-4α-hydroxy-1βH,11βH-guaian-12,8α-olide (3), 4α,9α-dihydroxy-1βH,11αH-guai-10(14)-en-12,8α-olide (4), and 4α,9α-dihydroxy-1βH,11βH-guai-10(14)-en-12,8α-olide (5), together with one known eudesmanolide and two known germacranolides, were isolated from the whole plants of Carpesium triste. Their structures and relative configurations were elucidated on the basis of spectroscopic methods, including 2D-NMR techniques.

From the whole plants of Ligularia duciformis, four new sesquiterpenoids, 3β-acetoxy-6β-methoxyeremophila-7(11),9(10)-dien-12,8β-olide (1), 3β-acetoxy-8α-hydroxy-6β-methoxyeremophila-7(11),9(10)-dien-12,8β-olide (2), 3β-acetoxy-10β-hydroxy-6β,8β-dimethoxyeremophil-7(11)-en-12,8α-olide (3), and 3β-acetoxy-6β,8β,10β-trihydroxyeremophil-7(11)-en-12,8α-olide (4) were isolated. Their structures were established by high-field NMR techniques (1H,1H-COSY, 13C-APT, HMQC, HMBC, and NOESY) and HR-ESI-MS analysis, together with comparison of the spectroscopic data with those of structurally related compounds. In addition, the cytotoxicity of the new compounds against human hepatic cancer cells Bel-7402, human pneumonic cancer cells A-549, and human colonic cancer cells HCT-8 were evaluated, the new compounds showed no cytotoxicity against the three tumor cells (all IC50 values >200 μM).

A new eudesmanolide, 1-oxo-11αH-eudesma-2,4(14)-dien-12,8β-olide (1), and four new guaianolides, 9β,10β-epoxy-4α-hydroxy-1βH,11αH-guaian-12,8α-olide (2), 9β,10β-epoxy-4α-hydroxy-1βH,11βH-guaian-12,8α-olide (3), 4α,9α-dihydroxy-1βH,11αH-guai-10(14)-en-12,8α-olide (4), and 4α,9α-dihydroxy-1βH,11βH-guai-10(14)-en-12,8α-olide (5), together with one known eudesmanolide and two known germacranolides, were isolated from the whole plants of Carpesium triste. Their structures and relative configurations were elucidated on the basis of spectroscopic methods, including 2D-NMR techniques.