The review provides a detailed discussion of recent advances in the medicinal chemistry of camptothecin, a potent antitumor agent that targets topoisomerase I. Thousands of CPT derivatives have been synthesized. Two of them, Topotecan and Irinotecan, are commercially approved for use in clinic as antitumor agents while more are still in clinic trials. This review summarizes the current status of the modern synthetic approaches to CPT, the mechanism of action of CPT, the structure-activity relationship(SAR), a number of novel CPT analogs and their biologic activity. There is a systematic evaluation of A-, B- and E-ring- modified camptothecins reported recently.

In this study, walnut meal hydrolysates (WMH) and dephenolized walnut meal hydrolysates (DWMH) were found to effectively decrease the serum uric acid level and protect the renal function in potassium oxonate-induced hyperuricemic rats in vivo as well as inhibit xanthine oxidase in vitro. Two novel antihyperuricemic peptides including WPPKN (640.8 Da) and ADIYTE (710.7 Da) were purified from DWMH via Sephadex G-15 gel filtration and reverse-phase high-performance liquid chromatography and identified by LC-ESI-MS/MS. These peptides displayed high in vitro xanthine oxidase inhibition (XOI) activity with IC values of 17.75 ± 0.12 mg mL (WPPKN) and 19.01 ± 0.23 mg mL (ADIYTE). Based on the results of molecular simulation, WPPKN entered into the hydrophobic channel and even obstructed the interaction between xanthine and xanthine oxidase (XO), while ADIYTE was positioned on the surface of the B-chain and blocked the entrance of the substrate to the hydrophobic channel. Therefore, the two peptides are partially responsible for the antihyperuricemic properties of DWMH.

Discrete surface defects are the most common anomalies of rails and they should be carefully inspected. However, it is a challenge to detect such defects in a vision system because of illumination inequality and the variation of reflection property of rail surfaces. This paper presents an intelligent vision detection system (VDS) for discrete surface defects and focuses on two key issues of VDS: image enhancement and automatic thresholding. We propose the local Michelson-like contrast (MLC) measure to enhance rail images. MLC-based method is nonlinear and illumination independent; therefore, it notably improves the distinction between defects and background. In addition, we put forward the new automatic thresholding method-proportion emphasized maximum entropy (PEME) thresholding algorithm. PEME selects a threshold that maximizes the object entropy and meanwhile keeps the defect proportion in a low level. Our experimental results demonstrate that VDS detects the Type-II defects with a recall of 91.61% and Type-I defects with a recall of 88.53%, and the proposed MLC-based image enhancement method and PEME thresholding algorithm outperform the related well-established approaches.Index Terms-Automatic thresholding, contrast measure, image enhancement, maximum entropy (ME), rail surface defects.

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