High-Throughput Chemical Screen Identifies a Novel Potent Modulator of Cellular Circadian Rhythms and Reveals CKIα as a Clock Regulatory Kinase

A novel compound “longdaysin” was found to dramatically slow down the speed of the circadian clock through simultaneous inhibition of protein kinases CKIδ, CKIα, and ERK2

Indirubin derivatives: A patent review (2010-present)

Introduction: Indirubins are bisindole alkaloids naturally occurring in indigo-bearing plants or in mollusks from the Muricidae family. They belong to the rather small family of indigoids, which has nevertheless found an extreme importance in the fields of dyes and medicinal chemistry. Indirubin has been found to be the active ingredient of a traditional Chinese Medicine used to treat the symptoms of leukemia. Further biological explorations revealed the ability of indirubin to bind cyclin-dependent kinases and 6-bromoindirubin, extracted from mollusks, to bind glycogen synthase kinase-3. The high affinity displayed by the two natural products has opened a vast field of research and triggered the development of hundred of derivatives with biological activities.Areas covered: The traditional use of indirubin for the treatment of leukemia has prompted different research groups to study the cytotoxic effect of indirubin derivatives on both solid tumors and leukemia. Moreover, the affinity of indirubins for kinases also allowed the exploration of their activity towards stem cells.Expert opinion: The derivatives presented are in accordance with first discoveries and establish the close relation between activity and kinase inhibition. New derivatives have been patented and new interferences in signaling pathways are described. However, few in vivo studies have been performed and more efficient solutions are needed to unravel the major issue of solubility. © 2015 Informa UK, Ltd

Recent advances and new strategies in the NMR-based identification of natural products

Nature comprises an untapped pool of unique compounds with high structural uniqueness and exceptional properties. At the core of natural products (NPs) discovery is the identification procedure and NMR remains the most efficient method. Technical improvements such as miniaturized and crycogenic NMR probes along with hyphenation capabilities and computational support are at the center of evolution. Concepts such as dereplication and metabolomics are increasingly adopted in NPs using the power of databases, currently fragmented. The introduction and utilization of these technical and computational implements could lead NPs research to more comprehensive structure identification and new holistic perspectives. © 2013 Elsevier Ltd

Natural and nature-derived products targeting human coronaviruses

The ongoing pandemic of severe acute respiratory syndrome (SARS), caused by the SARS-CoV-2 human coronavirus (HCoV), has brought the international scientific community before a state of emergency that needs to be addressed with intensive research for the discovery of pharmacological agents with antiviral activity. Potential antiviral natural products (NPs) have been discovered from plants of the global biodiversity, including extracts, compounds and categories of compounds with activity against several viruses of the respiratory tract such as HCoVs. However, the scarcity of natural products (NPs) and small-molecules (SMs) used as antiviral agents, especially for HCoVs, is notable. This is a review of 203 publications, which were selected using PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar, evaluates the available literature since the discovery of the first human coronavirus in the 1960s; it summarizes important aspects of structure, function, and therapeutic targeting of HCoVs as well as NPs (19 total plant extracts and 204 isolated or semi-synthesized pure compounds) with anti-HCoV activity targeting viral and non-viral proteins, while focusing on the advances on the discovery of NPs with anti-SARS-CoV-2 activity, and providing a critical perspective. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Simple indole alkaloids from the neotropical rutaceous tree raputia simulans

The genus Raputia Aubl. comprises 10 neotropical species of the family Rutaceae belonging to the subtribe Cuspariinae. We report herein the investigation of the dichloromethane extract of the stem bark of R.simulans, which has led to the isolation of indole type alkaloids. The isolation procedure was performed by fast centrifugal partition chromatography (FCPC) and adsorption chromatography and afforded 11 isolates: indole-5-carbaldehyde (1), 7-prenylindole (2), 5-prenylindole (3), verticillatine B (4), 5-(but-3-en-2-one)indole (5), 5-(2-methylbut-3-en-1-ol)indole (6), 5-[methyl-4-(2-methyl-4-oxobutanoate)]indole (7), 5-[4-(methyl)furan-2-yl]indole (8), 5-[4-(methoxymethyl)furan-2-yl]indole (9), 5-[5-(3-methylfuran-2(5H)-one)] indole (10), and 5-(4-methyl-2,5-dihydrofuran-2-yl)indole (11). Metabolites 511 were isolated for the first time and bear uncommon substituents on position 5 of the indole moiety. © Georg Thieme Verlag KG Stuttgart - New York

The raputindoles: Novel cyclopentyl bisindole alkaloids from raputia simulans

Figure presented A novel class of bisindole alkaloids is established by the isolation and structural determination of raputindoles A-D (1-4) from the Amazonian plant Raputia simulans Kallunki (Rutaceae). Complete spectroscopic characterization was accomplished by means of NMR spectroscopy and APCI (+) HRMS. Raputindoles A-D possess a cyclopentyl moiety fused on the benzene part of the indole ring, originating from the combination of prenylated indole monomers. © 2010 American Chemical Society

Identification of the coloring constituents of four natural indigoid dyes

A high performance liquid chromatography (HPLC) method combined with spectrophotometric UV-Vis detection is developed for the separation and identification of seven indigoid coloring compounds: indigotin, which is commercially available, and indirubin, 6-bromoindigotin, 6′- bromoindirubin, 6-bromoindirubin, 6,6′-dibromoindigotin, and 6,6′-dibromoindirubin, which are synthesized to be used as reference compounds in the HPLC analysis. The chromatographic method is employed for the identification of the blue/purple coloring compounds in samples extracted from four mollusks, which have been used for the production of Tyrian Purple since antiquity: Hexaplex trunculus, Murex brandaris, Nucella lapillus, and Thais haemastoma. The composition of the analyzed samples, with respect to the reference materials, is compared and discussed. All seven indigoids are identified in Hexaplex trunculus and some of them are identified in the other three purple extracts. Copyright © Taylor & Francis Group, LLC

Sesquiterpene lactones and flavonoids with chemotaxonomic significance from Volutaria lippii (L.) Cass

Phytochemical investigation on the aerial parts of Volutaria lippii (L.) Cass. led to the isolation of previously undescribed sesquiterpene lactone (1), along with other seven known compounds (2–8). Their chemical structures were determined on the basis of MS, IR and NMR spectroscopic data spectra and further supported by comparison with the data descripted in literature. All isolates from the studied plant were mentioned for the first time. This finding could be of chemotaxonomic significance for the genus Volutaria. © 2021 Elsevier Lt

Chemical and Biological Investigation of Olive Mill Waste Water - OMWW Secoiridoid Lactones

Olive mill waste water is the major byproduct of the olive oil industry containing a range of compounds related to Olea europaea and olive oil constituents. Olive mill waste water comprises an important environmental problem in olive oil producing countries, but it is also a valuable material for the isolation of high added value compounds. In this study, an attempt to investigate the secoiridoid content of olive mill waste water is described with the aid of ultrahigh-performance liquid chromatography-electrospray ionization (±)-high-resolution mass spectrometry and centrifugal partition chromatography methods. In total, seven secoiridoid lactones were isolated, four of which are new natural products. This is the first time that a conjugate of hydroxytyrosol and a secoiridoid lactone has been isolated from olive mill waste water and structurally characterized. Furthermore, the range of isolated compounds allowed for the proposal of a hypothesis for the biotransformation of olive secoiridoids during the production of olive mill waste water. Finally, the ability of the representative compounds to reduce the intracellular reactive oxygen species was assessed with the dichlorofluorescein assay in conjunction with the known antioxidant agent hydroxytyrosol. © Georg Thieme Verlag KG Stuttgart, New York

One-step semisynthesis of oleacein and the determination as a 5-lipoxygenase inhibitor

The dialdehydes oleacein (2) and oleocanthal (4) are closely related to oleuropein (1) and ligstroside (3), the two latter compounds being abundant iridoids of Olea europaea. By exploiting oleuropein isolated from the plant leaf extract, an efficient procedure has been developed for a one-step semisynthesis of oleacein under Krapcho decarbomethoxylation conditions. Highlighted is the fact that 5-lipoxygenase is a direct target for oleacein with an inhibitory potential (IC50: 2 μM) more potent than oleocanthal (4) and oleuropein (1). This enzyme catalyzes the initial steps in the biosynthesis of pro-inflammatory leukotrienes. Taken together, the methodology presented here offers an alternative solution to isolation or total synthesis for the procurement of oleacein, thus facilitating the further development as a potential anti-inflammatory agent. © 2014 The American Chemical Society and American Society of Pharmacognosy