Schiff base functionalized dialdehyde starch for enhanced removal of Cu (II): Preparation, performances, DFT calculations.

Dialdehyde starch modified by 2-hydrazinopyridine (HYD-DAS) based on the reaction of dialdehyde starch (DAS) and 2-hydrazinopyridine was synthesized and characterized by FT-IR spectra, element analysis and SEM. HYD-DAS can efficiently adsorb Cu (II) ion to demonstrate visual color changes from yellow to dark brown in aqueous solutions. The influence on HYD-DAS to Cu (II) adsorption including pH value of solution, isotherm, kinetics, thermodynamics and possible mechanism had also been examined. Batch experiments indicate that HYD-DAS's to Cu (II) adsorption reaches equilibrium within 250 min, and its adsorption capacity and rate are 195.75 mg/g and 98.63 %, respectively. Moreover, HYD-DAS to Cu (II) adsorption remains robust and underscoring after five cycles to exhibit good selectivity and reusability. Kinetics studies suggest the absorption process follows a quasi-second-order with isotherms aligning to the Langmuir monolayer model, and thermodynamics reveals that it is a spontaneous endothermic nature of adsorption. Based on the analyses of XPS and DFT calculations, a possible mechanism for HYD-DAS to Cu (II) adsorption is that Cu (II) combined with nitrogen atoms from Schiff base and hydrazine pyridine ring in HYD-DAS.

Matrine-Family Alkaloids: Versatile Precursors for Bioactive Modifications.

Matrine-family alkaloids as tetracycloquinolizindine analogues from Traditional Chinese Medicine Sophora flavescens Ait, Sophora subprostrata and Sophora alopecuroides L possess various pharmacological activities and have aroused great interests over the past decades. Especially, a lot of matrine derivatives have been designed and synthesized and their biological activities investigated, and encouraging results have continuously been achieved in recent several years. These studies are helpful to develop more potent candidates or therapeutic agents and disclose their molecular targets and mechanisms. This paper reviews recent advances in the bioactive modifications of matrine-family alkaloids from derivatization of the C-13, C-14 or C-15 position, opening D ring, fusing D ring and structural simplification.

Structural Modifications of Matrine-Type Alkaloids.

Matrine-type alkaloids belong to quinolizidine analogues from Sophora flavescens Ait, Sophora subprostrata and Sophora alopecuroides L. possess numerous therapeutic properties and have attracted continuous attention over the past few decades. In order to improve the activities and amplify their applicants, many matrine-type derivatives have synthesized and evaluated for their biological activities in recent years. These structural modifications have resulted in stronger activities and improvement of the pharmacokinetic properties. The structure and activity relation studies based on matrine- type semi-synthetic derivatives have immensely contributed to the understanding of their mechanism of actions and molecular targets. This review mainly summarizes recent progress in the structural modifications of matrine-type alkaloids based on the alteration of C-13 or C-14 position, opening D ring, fusing D ring and structural simplification.

Progress in the total synthesis of rocaglamide.

The first cyclopenta[b]benzofuran derivative, rocaglamide, from Aglaia elliptifolia, was found to exhibit considerable insecticidal activities and excellent potential as a therapeutic agent candidate in cancer chemotherapy; the genus Aglaia has been subjected to further investigation. Both the structural complexity of rocaglamide and its significant activity make it an attractive synthetic target. Stereoselective synthesis of the dense substitution pattern of these targets is a formidable synthetic challenge: the molecules bear five contiguous stereocenters and cis aryl groups on adjacent carbons. In past years of effort, only a handful of completed total syntheses have been reported, evidence of the difficulties associated with the synthesis of rocaglate natural products. The advance on total synthesis of rocaglamide was mainly reviewed from intramolecular cyclization and biomimetic cycloaddition approach.

Chiral decalins: preparation from oleanolic acid and application in the synthesis of (-)-9-epi-ambrox.

A novel and versatile process was developed to prepare the trans-decalins Delta9(11)-3beta-acetoxysclareolide (2) and Delta9(11)-3beta-acetoxy-8-epi-sclareolide (3), respectively, with 4a-methoxycarbonyl-2,7,7-trimethyl-1-oxo-cis-decalin-2-ene (4) and its C-3 hydroxyl derivative 5 from oleanolic acid (3beta-hydroxyolean-12-en-28-oic acid, 1). Three key steps were (a) introduction of the AcO-12 group and the C-9,C-11 double bond at ring C of methyl 3beta-acetoxyolean-12-en-28-oate (8) to afford the diene, methyl 3,12-diacetoxyolean-9(11),12-dien-28-oate (11); (b) photolytic cleavage of the C-8,C-14 bond in the diene to give an acetoxy-substituted triene 14; and (c) oxidative cleavage of the triene or its hydrolyzed alpha,beta-unsaturated ketone product with m-CPBA/TsOH to give the cis- and trans-decalins 2-5. Delata9(11)-3beta-Acetoxysclareolide (2) was stereospecifically reduced to give 3beta-acetoxy-9-epi-sclareolide (23), from which (-)-9-epi-ambrox (7) was synthesized.