Click Reactions in Chemistry of Triterpenes - Advances Towards Development of Potential Therapeutics

2018 ◽  
Vol 25 (5) ◽  
pp. 636-658 ◽  
Author(s):  
Jan Pokorny ◽  
Lucie Borkova ◽  
Milan Urban
Keyword(s):  
Biological Activities ◽  
Synthetic Approach ◽  
Clinical Use ◽  
New Approach ◽  
Click Reactions ◽  
Drug Candidates ◽  
The Past ◽  
Low Toxicity ◽  
New Compounds ◽  
Potential Therapeutics

Triterpenoids are natural compounds with a large variety of biological activities such as anticancer, antiviral, antibacterial, antifungal, antiparazitic, antiinflammatory and others. Despite their low toxicity and simple availability from the natural resources, their clinical use is still severely limited by their higher IC50 and worse pharmacological properties than in the currently used therapeutics. This fact encouraged a number of researchers to develop new terpenic derivatives more suitable for the potential clinical use. This review summarizes a new approach to improve both, the activity and ADME-Tox properties by connecting active terpenes to another modifying molecules using click reactions. Within the past few years, this synthetic approach was well explored yielding a lot of great improvements of the parent compounds along with some less successful attempts. A large quantity of the new compounds presented here are superior in both activity and ADME-Tox properties to their parents. This review should serve the researchers who need to promote their hit triterpenic structures towards their clinical use and it is intended as a guide for the chemical synthesis of better drug candidates.

scholarly journals Modern Synthetic Methods for the Stereoselective Construction of 1,3-Dienes

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 249
Author(s):  
Raquel G. Soengas ◽  
Humberto Rodríguez-Solla
Keyword(s):  
Organic Chemistry ◽  
Natural Products ◽  
Functional Group ◽  
Biological Activities ◽  
Synthetic Methods ◽  
Bond Forming ◽  
Drug Candidates ◽  
The Past ◽  
Wide Range

The 1,3-butadiene motif is widely found in many natural products and drug candidates with relevant biological activities. Moreover, dienes are important targets for synthetic chemists, due to their ability to give access to a wide range of functional group transformations, including a broad range of C-C bond-forming processes. Therefore, the stereoselective preparation of dienes have attracted much attention over the past decades, and the search for new synthetic protocols continues unabated. The aim of this review is to give an overview of the diverse methodologies that have emerged in the last decade, with a focus on the synthetic processes that meet the requirements of efficiency and sustainability of modern organic chemistry.

scholarly journals New Scabimycins A-C Isolated from Streptomyces acidiscabies (Lu19992)

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5922
Author(s):  
Constanze Paulus ◽  
Josef Zapp ◽  
Andriy Luzhetskyy
Keyword(s):  
Natural Products ◽  
Bioactive Peptides ◽  
Biological Activities ◽  
Powerful Source ◽  
Drug Candidates ◽  
Chemical Structures ◽  
Wide Range ◽  
Streptomyces Acidiscabies ◽  
New Compounds ◽  
Important Drug

Peptide natural products displaying a wide range of biological activities have become important drug candidates over the years. Microorganisms have been a powerful source of such bioactive peptides, and Streptomyces have yielded many novel natural products thus far. In an effort to uncover such new, meaningful compounds, the metabolome of Streptomyces acidiscabies was analyzed thoroughly. Three new compounds, scabimycins A–C (1–3), were discovered, and their chemical structures were elucidated by NMR spectroscopy. The relative and absolute configurations were determined using ROESY NMR experiments and advanced Marfey’s method.

Derivatives and Analogues of Resveratrol: Recent Advances in Structural Modification

2019 ◽  
Vol 19 (10) ◽  
pp. 809-825 ◽  
Author(s):  
Qing-Shan Li ◽  
Yao Li ◽  
Girdhar Singh Deora ◽  
Ban-Feng Ruan
Keyword(s):  
Structural Modification ◽  
Biological Activities ◽  
Biological Properties ◽  
Synthetic Analogues ◽  
Pharmacological Activities ◽  
The Past ◽  
Structure Activity ◽  
Clinical Drugs ◽  
New Compounds ◽  
Reliable Basis

Resveratrol is a non-flavonoid polyphenol containing a terpenoid backbone. It has been intensively studied because of its various promising biological properties, such as anticancer, antioxidant, antibacterial, neuroprotective and anti-inflammatory activities. However, the medicinal application of resveratrol is constrained by its poor bioavailability and stability. In the past decade, more attention has been focused on making resveratrol derivatives to improve its pharmacological activities and pharmacokinetics. This review covers the literature published over the past 15 years on synthetic analogues of resveratrol. The emphasis is on the chemistry of new compounds and relevant biological activities along with structure-activity relationship. This review aims to provide a scientific and reliable basis for the development of resveratrol-based clinical drugs.

Aqueous Solutions as Potential Ultrasonic Contrast Agents

1979 ◽  
Vol 1 (3) ◽  
pp. 265-279 ◽  
Author(s):  
J. Ophir ◽  
R. E. McWhirt ◽  
N. F. Maklad
Keyword(s):  
Aqueous Solutions ◽  
Thermal Effects ◽  
New Approach ◽  
Ultrasonic Properties ◽  
The Past ◽  
Low Toxicity ◽  
Ultrasonic Backscatter ◽  
Sound Density

Enhancement of ultrasonic backscatter and reflectivity from tissues has been demonstrated in the past using gas bubbles and thermal effects. This paper presents a new approach, whereby such enhancement can be achieved by the introduction of suitable aqueous solutions into tissue. Ideally, such solutions should exhibit low toxicity and ultrasonic properties markedly different from those of tissue. Twenty-two potential materials were identified and the speed of sound, density and acoustic impedance in their solutions were determined as a function of concentration. Some of these solutions were used in preliminary in vitro and in vivo canine experiments and echo enhancement was demonstrated.

scholarly journals A Review on Phytochemicals of the Genus Maytenus and Their Bioactive Studies

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4563
Author(s):  
Yuan-Yuan Huang ◽  
Lu Chen ◽  
Guo-Xu Ma ◽  
Xu-Dong Xu ◽  
Xue-Gong Jia ◽  
...  
Keyword(s):  
Theoretical Basis ◽  
Biological Activities ◽  
Current Status ◽  
Synthesis Methods ◽  
Chemical Research ◽  
Structural Classification ◽  
The Past ◽  
Development And Utilization ◽  
Hiv Inhibition ◽  
New Compounds

The genus Maytenus is a member of the Celastraceae family, of which several species have long been used in traditional medicine. Between 1976 and 2021, nearly 270 new compounds have been isolated and elucidated from the genus Maytenus. Among these, maytansine and its homologues are extremely rare in nature. Owing to its unique skeleton and remarkable bioactivities, maytansine has attracted many synthetic endeavors in order to construct its core structure. In this paper, the current status of the past 45 years of research on Maytenus, with respect to its chemical and biological activities are discussed. The chemical research includes its structural classification into triterpenoids, sesquiterpenes and alkaloids, along with several chemical synthesis methods of maytansine or maytansine fragments. The biological activity research includes activities, such as anti-tumor, anti-bacterial and anti-inflammatory activities, as well as HIV inhibition, which can provide a theoretical basis for the better development and utilization of the Maytenus.

scholarly journals Green Synthetic Approach: An Efficient Eco-Friendly Tool for Synthesis of Biologically Active Oxadiazole Derivatives

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1163
Author(s):  
Bimal Krishna Banik ◽  
Biswa Mohan Sahoo ◽  
Bera Venkata Varaha Ravi Kumar ◽  
Krishna Chandra Panda ◽  
Jasma Jena ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Biological Activities ◽  
Product Yield ◽  
Biologically Active ◽  
Synthetic Approach ◽  
Green Protocol ◽  
Drug Candidates ◽  
New Drug ◽  
Drug Molecules ◽  
Oxadiazole Derivatives

Green synthetic protocol refers to the development of processes for the sustainable production of chemicals and materials. For the synthesis of various biologically active compounds, energy-efficient and environmentally benign processes are applied, such as microwave irradiation technology, ultrasound-mediated synthesis, photo-catalysis (ultraviolet, visible and infrared irradiation), molecular sieving, grinding and milling techniques, etc. Thesemethods are considered sustainable technology and become valuable green protocol to synthesize new drug molecules as theyprovidenumerous benefits over conventional synthetic methods.Based on this concept, oxadiazole derivatives are synthesized under microwave irradiation technique to reduce the formation of byproduct so that the product yield can be increased quantitatively in less reaction time. Hence, the synthesis of drug molecules under microwave irradiation follows a green chemistry approach that employs a set of principles to minimize or remove the utilization and production of hazardous toxic materials during the design, manufacture and application of chemical substances.This approach plays a major role in controlling environmental pollution by utilizing safer solvents, catalysts, suitable reaction conditions and thereby increases the atom economy and energy efficiency. Oxadiazole is a five-membered heterocyclic compound that possesses one oxygen and two nitrogen atoms in the ring system.Oxadiazole moiety is drawing considerable interest for the development of new drug candidates with potential therapeutic activities including antibacterial, antifungal, antiviral, anticonvulsant, anticancer, antimalarial, antitubercular, anti-asthmatic, antidepressant, antidiabetic, antioxidant, antiparkinsonian, analgesic and antiinflammatory, etc. This review focuses on different synthetic approaches of oxadiazole derivatives under microwave heating method and study of their various biological activities.

Diving into the world of marine 2,11-cyclized cembranoids: a summary of new compounds and their biological activities

2020 ◽  
Vol 37 (10) ◽  
pp. 1367-1383
Author(s):  
Geng Li ◽  
Jeroen S. Dickschat ◽  
Yue-Wei Guo
Keyword(s):  
Biological Activities ◽  
The Past ◽  
The World ◽  
New Compounds

This review summarises new marine 2,11-cyclized cembranoids from the past decade in a structured presentation according to their hypothetical biosynthesis.

TEM study of a biofilm on copper corrosion

1996 ◽  
Vol 54 ◽  
pp. 220-221
Author(s):  
W. A. Chiou ◽  
N. Kohyama ◽  
B. Little ◽  
P. Wagner ◽  
M. Meshii
Keyword(s):  
Marine Bacterium ◽  
Culture Medium ◽  
Copper Alloys ◽  
Pure Copper ◽  
Localized Corrosion ◽  
Natural Seawater ◽  
Copper Corrosion ◽  
New Approach ◽  
The Past ◽  
Copper Tolerant

The corrosion of copper and copper alloys in a marine environment is of great concern because of their widespread use in heat exchangers and steam condensers in which natural seawater is the coolant. It has become increasingly evident that microorganisms play an important role in the corrosion of a number of metals and alloys under a variety of environments. For the past 15 years the use of SEM has proven to be useful in studying biofilms and spatial relationships between bacteria and localized corrosion of metals. Little information, however, has been obtained using TEM capitalizing on its higher spacial resolution and the transmission observation of interfaces. The research presented herein is the first step of this new approach in studying the corrosion with biological influence in pure copper.Commercially produced copper (Cu, 99%) foils of approximately 120 μm thick exposed to a copper-tolerant marine bacterium, Oceanospirillum, and an abiotic culture medium were subsampled (1 cm × 1 cm) for this study along with unexposed control samples.

On-Surface Radical Oligomerisation: A New Approach to STM Tip-Induced Reactions

2018 ◽  
Author(s):  
Gaolei Zhan ◽  
Younes Makoudi ◽  
Judicael Jeannoutot ◽  
Simon Lamare ◽  
Michel Féron ◽  
...  
Keyword(s):  
Sample Surface ◽  
Scanning Tunnelling Microscope ◽  
Transfer Event ◽  
New Approach ◽  
The Past ◽  
Organic Nanostructures ◽  
Scanning Tunnelling ◽  
New Strategy ◽  
Surface Fabrication ◽  
And Control

Over the past decade, on-surface fabrication of organic nanostructures has been widely investigated for the development of molecular electronic devices, nanomachines, and new materials. Here, we introduce a new strategy to obtain alkyl oligomers in a controlled manner using on-surface radical oligomerisations that are triggered by the electrons/holes between the sample surface and the tip of a scanning tunnelling microscope. The resulting radical-mediated mechanism is substantiated by a detailed theoretical study. This electron transfer event only occurs when <i>V</i><sub>s</sub> < -3 V or <i>V</i><sub>s</sub> > + 3 V and allows access to reactive radical species under exceptionally mild conditions. This transfer can effectively ‘switch on’ a sequence leading to formation of oligomers of defined size distribution due to the on-surface confinement of reactive species. Our approach enables new ways to initiate and control radical oligomerisations with tunnelling electrons, leading to molecularly precise nanofabrication.

A common mechanism links activities of butyrate in the colon

2017 ◽  
Author(s):  
Mohit S. Verma ◽  
Michael J. Fink ◽  
Gabriel L Salmon ◽  
Nadine Fornelos ◽  
Takahiro E. Ohara ◽  
...  
Keyword(s):  
Stem Cells ◽  
Histone Deacetylases ◽  
Biological Activities ◽  
Short Chain Fatty Acids ◽  
Common Mechanism ◽  
Epithelial Stem Cells ◽  
Degree Of Unsaturation ◽  
Structure Activity ◽  
Starting Point ◽  
New Compounds

Two biological activities of butyrate in the colon (suppression of proliferation of colonic epithelial stem cells and inflammation) correlate with inhibition of histone deacetylases. Cellular and biochemical studies of molecules similar in structure to butyrate, but different in molecular details (functional groups, chain-length, deuteration, oxidation level, fluorination, or degree of unsaturation) demonstrated that these activities were sensitive to molecular structure, and were compatible with the hypothesis that butyrate acts by binding to the Zn<sup>2+</sup> in the catalytic site of histone deacetylases. Structure-activity relationships drawn from a set of 36 compounds offer a starting point for the design of new compounds targeting the inhibition of histone deacetylases. The observation that butyrate was more potent than other short-chain fatty acids is compatible with the hypothesis that crypts evolved (at least in part), to separate stem cells at the base of crypts from butyrate produced by commensal bacteria.

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