(+)- and (-)-Ecarlottones, Uncommon Chalconoids from Fissistigma latifolium with Pro-Apoptotic Activity

New sesquiterpene and flavone arabinofuranoside derivative from the leaves of Fissistigma bicolor

A new muurolane-type sesquiterpene, a new flavone arabinofuranoside derivative, and other five known flavone arabinofuranoside derivatives were isolated from the leaves of Fissistigma bicolor (Annonaceae family). Their chemical structures were determined to be (1S,6R,7S)-muurola-4,10(14)-diene-15-ol (1), quercetin 3-O-β-D-apiofuranosyl-(1→2)-α-L-arabinofuranoside (2), quercetin 3-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinofuranoside (3), quercetin 3-O-α-L-arabinofuranoside (4), kaempferol 3-O-β-D-apiofuranosyl-(1→2)-α-L-arabinofuranoside (5), kaempferol 3-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinofuranoside (6), and kaempferol 3-O-α-L-arabinofuranoside (7) by analyses of HR-ESI-MS and NMR spectral data. Compounds 4 and 7 containing monosaccharide, arabinofuranoside, potentially inhibited NO productions in LPS activated RAW264.7 cells (IC₅₀ 13.4 ± 0.5 and 12.6 ± 0.4 µM) in compared to disaccharide derivatives (IC₅₀ ranging from 58.9 ± 3.3 to 65.6 ± 3.8 µM).

Novel Bisamide Alkaloids Enantiomers from Pepper Roots (Piper nigrum L.) with Acetylcholinesterase Inhibitory and Anti-Neuroinflammatory Effects

The roots of Piper nigrum L., a seasoning for cooking various types of broths, are renowned for their high nutritional content and potential medicinal benefits. In this study, nine pairs of novel cyclohexene-type bisamide alkaloids (1a/1b-9a/9b) were isolated from the pepper roots using molecular network analysis strategies. Their structures were determined by extensive spectroscopic data, electronic circular dichroism (ECD) calculations, and X-ray diffraction analyses. Using an intermolecular Diels-Alder reaction, a strategy for the synthesis of bisamide alkaloids from different monomeric amide alkaloids was developed. Furthermore, these compounds were chirally separated for the first time, and compounds 3a and 5a/5b showed significant anti-neuroinflammation effects in the models of lipopolysaccharide(LPS)-induced BV2 microglial cells. Meanwhile, compounds 6b and 7a displayed concentration-dependent inhibitory activities against acetylcholinesterase with IC₅₀ values of 6.05 ± 1.10 and 3.81 ± 0.10 μM, respectively. These findings confirmed that these bisamide alkaloids could be applied in functional food formulations and pharmaceutical products as well as facilitate the further development and usage of pepper roots.

Fissisternoids A and B, two 2′,5′-quinodihydrochalcone-based meroterpenoid enantiomers with unusual carbon skeletons from Fissistigma bracteolatum

Compound 1 represents an unprecedented meroterpenoid featuring a unique tricyclo [3,3,1,01′,5′] decane central framework and 2 possesses a rare 6/6/5/4 tetracyclic carbon skeleton were isolated from Fissistigma bracteolatum.

Two novel aporphine-derived alkaloids from the stems of Fissistigma glaucescens

Two novel aporphine-derived alkaloids, aporaloids A and B (1 and 2), together with eight known biogenetically related alkaloids (3-10), two known isoquinoline alkaloids (3 and 4), and six known aporphinoid alkaloids (5-10) were isolated from the stems of Fissistigma glaucescens. Their structures were elucidated using comprehensive spectroscopic methods. Compounds 1 and 2 represent the rare example of a six-membered lactone ring aporphine-derived alkaloids from natural products. The inhibitory activities of all compounds against four cancer cell lines were evaluated. Aporaloids A and B (1 and 2) showed broad spectrum cytotoxic activities.

Myeloid cell leukemia 1 (MCL-1): Structural characteristics and application in cancer therapy

Apoptosis, a major hallmark of cancer cells, regulates cellular fate and homeostasis. BCL-2 (B-cell CLL/Lymphoma 2) protein family is popularly known to mediate the intrinsic mode of apoptosis, of which MCL-1 is a crucial member. Myeloid cell leukemia 1 (MCL-1) is an anti-apoptotic oncoprotein and one of the most investigated members of the BCL-2 family. It is commonly known to be genetically altered, aberrantly overexpressed, and primarily associated with drug resistance in various human cancers. Recent advancements in the development of selective MCL-1 inhibitors and evaluating their effectiveness in cancer treatment establish its popularity as a molecular target. The overall aim is the selective induction of apoptosis in cancer cells by using a single or combination of BCL-2 family inhibitors. Delineating the precise molecular mechanisms associated with MCL-1-mediated cancer progression will certainly improve the efficacy of clinical interventions aimed at MCL-1 and hence patient survival. This review is structured to highlight the structural characteristics of MCL-1, its specific interactions with NOXA, MCL-1-regulatory microRNAs, and at the same time focus on the emerging therapeutic strategies targeting our protein of interest (MCL-1), alone or in combination with other treatments.

Uvarmicranones A and B, two new benzoquinones and cytotoxic constituents from the stems of Uvaria micrantha (A. DC.) Hook. f. & Thomson

Two novel benzoquinones, uvarmicranones A (1) and B (2), along with 15 known compounds (3 - 17) were isolated from the stems of Uvaria micrantha (Annonaceae). Their structures were elucidated by analyses of NMR and high-resolution mass data. A plausible biosynthetic pathway of uvarmicranone A (1) via Diels-Alder cycloaddition reaction was also proposed. Some isolated compounds were evaluated for their cytotoxic activities. Compounds 1, 14, and 15 showed moderate cytotoxic effects against T-cell acute lymphoblastic cells (MOLT-3), with IC₅₀ values of 7.83 ± 0.83, 6.53 ± 1.01, and 4.20 ± 0.29 μM, respectively. Additionally, compound 15 exhibited moderate cytotoxicity against cervical carcinoma cells (HeLa) with an IC₅₀ value of 7.00 ± 3.15 μM.

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.

Pro-apoptotic carboxamide analogues of natural fislatifolic acid targeting Mcl-1 and Bcl-2

A library of 26 novel carboxamides deriving from natural fislatifolic acid has been prepared. The synthetic strategy involved a bio-inspired Diels-Alder cycloaddition, followed by functionalisations of the carbonyl moiety. All the compounds were evaluated on Bcl-xL, Mcl-1 and Bcl-2 proteins. In this series of cyclohexenyl chalcone analogues, six compounds behaved as dual Bcl-xL/Mcl-1 inhibitors in micromolar range and one exhibited sub-micromolar affinities toward Mcl-1 and Bcl-2. The most potent compounds evaluated on A549 and MCF7 cancer cell lines showed moderate cytotoxicities.

Terpenoids from the Stems of Fissistigma polyanthoides and Their Anti-Inflammatory Activity

Twelve new terpenoids (1-12) were isolated from the stems of Fissistigma polyanthoides, an anti-inflammatory medicinal plant traditionally used in Vietnam. Most of them (1-9) possess a sesquiterpenoid backbone (e.g., guaiane, germacrane, and cadinane) connected to a 2'-O-trans-cinnamoyl)-β-d-glucopyranose moiety, which is rare in Nature. Among them, compounds 4 (5/8-fused ring) and 6 (spiran [4,5] ring) represent uncommonly rearranged sesquiterpenoids. Compounds 10-12 are a novel monoterpene and two megastigmane derivatives, respectively. The individual structures were elucidated by combining NMR and MS data, and their configuration was established in NOESY and ECD experiments. Compounds 1-9 were also examined for their potential to interact with nuclear factor-kappa B activator protein 1 (NF-κB/AP-1) signaling by using the myelomonocytic reporter cell line THP-1Blue-CD14. Compounds 1-5 showed dose-dependent inhibitory effects [IC₅₀ 13.7 μM (1) to 49.0 μM (5)] on lipopolysaccharide-stimulated cells. However, compounds 1 to 4 also negatively affected cell viability in the same concentration range, while compound 5 was less potently cytotoxic.

Ni-catalyzed cross-electrophile coupling between vinyl/aryl and alkyl sulfonates: synthesis of cycloalkenes and modification of peptides

We report here the coupling reactions between vinyl/aryl and alkyl C-O electrophiles that can be derived from chemical feedstocks and naturally occurring functional groups. This method provides an efficient approach to the synthesis of a wide range of functionalized, and/or secondary alkyl substituted cycloalkenes. These compounds are difficult to produce by conventional methods. The reaction proceeds with broad substrate scope, and tolerates various functional groups such as alcohol, aldehyde, ketone, ester, amide, alkene, alkyne, heterocycles, organotin and organosilicon compounds. The synthetic utility of this method has been demonstrated by providing facile access to important building blocks. We also demonstrated the possibility to apply this method for late-stage modification of peptides. A broad range of functionalized alkyl groups could be selectively introduced into tyrosine in peptides via C-C bond formation, which has been a challenge to the existing procedures.