Guaranteeing Global Stability for Neuro-Adaptive Control of Unknown Pure-Feedback Nonaffine Systems via Barrier Functions.

Most existing approximation-based adaptive control (AAC) approaches for unknown pure-feedback nonaffine systems retain a dilemma that all closed-loop signals are semiglobally uniformly bounded (SGUB) rather than globally uniformly bounded (GUB). To achieve the GUB stability result, this article presents a neuro-adaptive backstepping control approach by blending the mean value theorem (MVT), the barrier Lyapunov functions (BLFs), and the technique of neural approximation. Specifically, we first resort the MVT to acquire the intermediate and actual control inputs from the nonaffine structures directly. Then, neural networks (NNs) are adopted to approximate the unknown nonlinear functions, in which the compact sets for maintaining the approximation capabilities of NNs are predetermined actively through the BLFs. It is shown that, with the developed neuro-adaptive control scheme, global stability of the resulting closed-loop system is ensured. Simulations are conducted to verify and clarify the developed approach.

Synthesis and bioactivity evaluation of novel nuciferine derivatives with antihyperuricemia and nephroprotective effects.

Hyperuricemia is a common metabolic disease with a series of complications. Nuciferine, a typical aporphine alkaloid natural compound extracted from the leaves of Nelumbo nucifera Gaertn., was confirmed to have an antihyperuricemia effect. In the present study, 30 novel nuciferine derivatives were designed and synthesized. The effects of all derivatives on the regulation of URAT1 were studied in a uric acid-induced HK-2 cell model with benzbromarone as a positive control. The results indicated that Compound 1j showed the optimal URAT1 inhibitory activity through repressing PI3K/Akt pathway in HK-2 cells and the inhibitory effect was similar to that of benzbromarone. In addition, in vivo experiments demonstrated that Compound 1j could reduce uric acid levels and ameliorate kidney damage in hyperuricemic mice. On the one hand, Compound 1j could inhibit the expression of URAT1 and GLUT9 to increase the uric acid excretion index. On the other hand, Compound 1j could regulate the TLR4/IκBα/NF-κB signaling pathway to reduce the levels of inflammatory cytokines, thereby alleviating kidney damage. Meanwhile, a molecular docking assay revealed the potential molecular binding power (-9.79 kcal/mol) between Compound 1j and URAT1, which was more tightly bound than the lead compound nuciferine (-7.44 kcal/mol). Based on these results, Compound 1j may be a future drug for the development of new potential antihyperuricemia and nephroprotective drug candidates.

Synthesis and biological evaluation of geniposide derivatives as inhibitors of hyperuricemia, inflammatory and fibrosis.

Hyperuricemia is a metabolic disease caused by abnormal purine metabolism in the body. Long-term high levels of uric acid in the body will lead to gout and kidney disease. Xanthine oxidase (XOD) is a key enzyme in the pathogenesis of hyperuricemia. In this context, a series of geniposide derivatives were designed, synthesized and evaluated as xanthine oxidase inhibitors. Most of these compounds exhibited potent XOD inhibitory activities in vitro, and representatives 6a, 6c, 6g and 6j were found to be the most potent inhibitors against the enzyme with IC50 values of 2.15 ± 1.03, 1.37± 0.26, 4.14± 0.79 and 1.86± 0.13 µM, which were 33.03-158.37 fold more active than geniposide, respectively. Compounds 6a, 6c, 6g and 6j were evaluated in hyperuricemia mice, and the results demonstrated that compound 6c showed the strongest anti-hyperuricemia and renal protective activity in vivo. Subsequently, the molecular mechanism of compound 6c was studied in this investigation. In vitro cell experiments showed that compound 6c inhibited the inflammation of HK-2 cells under high uric acid conditions by inhibiting the expressions of TGF-ß, TNF-α and IL-1ß, and reduced the cell fibrosis by decreasing the expressions of α-SMA and Collagen I. The results of the mice experiments indicated that compound 6c efficiently decreased the level of serum uric acid (SUA) in hyperuricemia mice by inhibiting the XOD activity. Moreover, compound 6c effectively reduced the urate accumulation in the kidney and simultaneously decreased inflammation by regulating the expression of the TLR4/IκBα/NF-κB signaling pathway. In addition, consistent with cell experiments, compound 6c also reduced renal fibrosis in hyperuricemia mice, which may be due to compound 6c inhibiting the expression of inflammatory factor TGF-ß. Furthermore, a molecular docking study was performed to gain insight into the binding mode of compound 6c with XOD. These results suggest that compound 6c has the potential to be developed into a novel medicine to reduce blood uric acid and treat renal diseases caused by hyperuricemia.

Adaptive Approximation-Based Tracking Control for a Class of Unknown High-Order Nonlinear Systems With Unknown Powers.

In this article, the problem of adaptive tracking control is tackled for a class of high-order nonlinear systems. In contrast to existing results, the considered system contains not only unknown nonlinear functions but also unknown rational powers. By utilizing the fuzzy approximation approach together with the barrier Lyapunov functions (BLFs), we present a new adaptive tracking control strategy. Remarkably, the BLFs are employed to determine a priori the compact set for maintaining the validity of fuzzy approximation. The primary advantage of this article is that the developed controller is independent of the powers and can be capable of ensuring global stability. Finally, two illustrative examples are given to verify the effectiveness of the theoretical findings.

Design, synthesis and in vitro anticancer research of novel tetrandrine and fangchinoline derivatives.

Cancer treatment is one of the major public health issues in the world. Tetrandrine (Tet) and fangchinoline (d-Tet) are two bis-benzyl isoquinoline alkaloids extracted from Stephania tetrandra S. Moore, and their antitumor activities have been confirmed. However, the effective dose of Tet and d-Tet were much higher than that of the positive control and failed to meet clinical standards. Therefore, in this study, as a continuation of our previous work to study and develop high-efficiency and low-toxic anti-tumor lead compounds, twenty new Tet and d-Tet derivatives were designed, synthesized and evaluated as antitumor agents against six cancer cell lines (H460, H520, HeLa, HepG-2, MCF-7, SW480 cell lines) and BEAS-2B normal cells by CCK-8 analysis. Ten derivatives showed better cytotoxic effects than the parent fangchinoline, of which 4g showed the strongest cell growth inhibitory activity with an IC50 value of 0.59 µM against A549 cells. Subsequently, the antitumor mechanism of 4g was studied by flow cytometry, Hoechst 33258, JC-1 staining, cell scratch, transwell migration, and Western blotting assays. These results showed that compound 4g could inhibit A549 cell proliferation by arresting the G2/M cell cycle and inhibiting cell migration and invasion by reducing MMP-2 and MMP-9 expression. Meanwhile, 4g could induce apoptosis of A549 cells through the intrinsic pathway regulated by mitochondria. In addition, compound 4g inhibited the phosphorylation of PI3K, Akt and mTOR, suggesting a correlation between blocking the PI3K/Akt/mTOR pathway and the above antitumor activities. These results suggest that compound 4g may be a future drug for the development of new potential drug candidates against lung cancer.

Design, synthesis and in vitro evaluation of fangchinoline derivatives as potential anticancer agents.

The isolation and modification of natural products play an important role in the synthesis of anti-tumor drugs for the treatment of cancer. The present study was designed to evaluate the effects of fangchinoline derivatives against cancer cells. In vitro cytotoxicity of all derivatives against five cancer cell lines (A549, Hela, HepG-2, MCF-7 and MDA-MB-231 cell lines) and HL-7702 normal cells was assessed using the CCK-8 assay, and the results showed that most of the synthesized compounds displayed better cytotoxic effects on all the tested cells compared to that of the parent fangchinoline. In particular, compound 3i had the strongest inhibitory effect on cell proliferation, with an IC50 value of 0.61 µM against A549 cells. Compared with fangchinoline and HCPT (hydroxycamptothecine), the anti-proliferative activity of compound 3i was significantly increased. More interestingly, compound 3i had slight toxic side effects on normal cells, with an IC50 value of 27.53 µM. Moreover, the cell viability and cell cycle assays revealed that compound 3i inhibited A549 cell proliferation and arrested A549 cells at the G2/M-phase. The apoptosis-inducing effects of compound 3i and the associated molecular mechanisms were assessed using flow cytometry, cell staining, reactive oxygen species assays, RT-qPCR and Western blot analysis. These results suggested that compound 3i induces apoptosis through a mitochondria-mediated intrinsic pathway. This study revealed that compound 3i is a promising candidate for future development as an anti-tumor drug.

[ITS sequence identification of Radix Bupleuri].

OBJECTIVE: To provide the basis of molecular authentication of Radix Bupleuri by the comparison of the internal transcribed spacer (ITS) sequences of five kinds of Radix Bupleuri in common use. METHOD: Firstly, total DNA of five kinds of Radix Bupleuri was extracted. Secondly, the ITS sequence was amplified by PCR with universal primer of ITS and PCR product was directly sequenced after purification. RESULT: The length of ITS1 and ITS2 sequence was 214-220 bp and 230-231 bp respectively. There were distinct variation sites between the ITS sequences of the five kinds of Radix Bupleuri. CONCLUSION: ITS sequence may be the evidence for the molecular authentication of Radix Bupleuri.