Inhibitory effect of N,N-didesmethylgrossularine-1 on inflammatory cytokine production in lipopolysaccharide-stimulated RAW 264.7 cells

Indonesian marine and its medicinal contribution

The archipelagic country of Indonesia is populated by the densest marine biodiversity in the world which has created strong global interest and is valued by both Indigenous and European settlements for different purposes. Nearly 1000 chemicals have been extracted and identified. In this review, a systematic data curation was employed to collate bioprospecting related manuscripts providing a comprehensive directory based on publications from 1988 to 2022. Findings with significant pharmacological activities are further discussed through a scoping data collection. This review discusses macroorganisms (Sponges, Ascidian, Gorgonians, Algae, Mangrove) and microorganism (Bacteria and Fungi) and highlights significant discoveries, including a potent microtubule stabilizer laulimalide from Hyattella sp., a prospective doxorubicin complement papuamine alkaloid from Neopetrosia cf exigua, potent antiplasmodial manzamine A from Acanthostrongylophora ingens, the highly potent anti trypanosomal manadoperoxide B from Plakortis cfr. Simplex, mRNA translation disrupter hippuristanol from Briareum sp, and the anti-HIV-1 (+)-8-hydroxymanzamine A isolated from Acanthostrongylophora sp. Further, some potent antibacterial extracts were also found from a limited biomass of bacteria cultures. Although there are currently no examples of commercial drugs from the Indonesian marine environment, this review shows the molecular diversity present and with the known understudied biodiversity, reveals great promise for future studies and outcomes.

Comprehensive review of α-carboline alkaloids: Natural products, updated synthesis, and biological activities

α-carboline (9H-pyrido[2,3-b]indole), contains a pyridine ring fused with an indole backbone, is a promising scaffold for medicinal chemistry. In recent decades, accumulating evidence shows that α-carboline natural products and their derivatives possess diverse bioactivities. However, hitherto, there is no comprehensive review to systematically summarize this important class of alkaloids. In this perspective, this paper represents the first review to provide a comprehensive description of α-carbolines including natural products, updated literature of synthesis, and their diverse biological activities. Their biological activities including antitumor, anti-microbial, anti-Alzheimer’s disease, anti-atherosclerosis, and antioxidant activities were hilighted. And the targets and the main structure activity relationships (SARs) will be presented. Finally, challenges and future directions of this class of compounds will be discussed. This review will be helpful in understanding and encouraging further exploration for this group of alkaloids.

Design and Efficient Synthesis of RalA Inhibitors Containing the Dihydro-α-carboline Scaffold

Ras-related protein RalA is a member of the Ras small GTPases superfamily. Its activation plays an important role in regulating tumor initiation, invasion, migration, and metastasis. In this study, we designed a new type of RalA inhibitor containing a dihydro-α-carboline scaffold. The structurally new dihydro-α-carboline derivatives could be efficiently synthesized in good yields through a newly developed three-component [3+2+1] cyclization reaction. Evaluation of the biological activity showed that some of the dihydro-α-carboline derivatives can inhibit RalA/B and proliferative activities of NSCLC cell lines. The 4-(pyridin-3-yl)-dihydro-α-carboline compound (3 o) was found to be the most potent derivative, with IC₅₀ values of 0.43±0.03, 0.64±0.07, 0.93±0.10, and 1.54±0.15 μM against A549, H1299, H460, and H1975 cells, respectively. Mechanism investigation suggested that 3 o inhibits the RalA/B activation of A549, down-regulates Bcl-2, stimulates cytochrome c and PARP cleavage, and induces cell apoptosis. A molecular docking study revealed that 3 o can form stable hydrogen bonds with residues of RalA. Moreover, amide-π and alkyl-π interactions also contributed to the affinity between 3 o and RalA.

Synthesis of Trifluoromethyl- and Ester Group-Substituted α-Carbolines via Iron-Catalyzed Tandem Cyclization Reaction

An efficient approach to prepare trifluoromethyl-α-carbolines and ester group-substituted α-carbolines via the tandem cyclization reaction of 2-(2-aminophenyl)acetonitriles and trifluoromethyl 1,3-diones or β,γ-unsaturated α-ketoesters was reported. The transformation proceeded smoothly in the presence of catalytic environmental-benign iron salts, which are used to prepare the desired products in moderate to good yields.

Rapid synthesis and immunogenicity of mycobacterial (1→5)-α-d-arabinofuranan

A rapid synthesis of the α(1→5) arabinofuranan polysaccharides, found on the outer surface of Mycobacterium tuberculosis (Mtb), is achieved by a regio- and stereocontrolled ring opening polymerization of β-d-arabinofuranose-1,2,5-orthobenzoate. The robust polymerization reaction allows the incorporation of an amine linker, which was used to conjugate with protein tetanus toxoid (TT) to further investigate its adjuvant activities. The synthetic arabinan, which is the glycan on the non-reducing end of Mtb lipoarabinomannan (LAM), was evaluated for its immunological properties in vitro and in vivo. Systemic inflammation and the promotion of innate immune response were observed in macrophages treated with the synthetic arabinan as an adjuvant through an increase in the production of TNF-α and IL-12. In vivo evaluation of IFN-γ, IL-2, and TNF-α productions in mice pre-immunized with the synthetic arabinan conjugated TT indicated great enhancements of the immunological responses when compared to that of TT alone.

α-Carboline derivative TJY-16 inhibits tumor growth by inducing G2/M cell cycle arrest in glioma cells

Background

Glioblastoma multiforme (GBM) is the most lethal primary brain tumors which remains difficult to cure despite advances in surgery, radiotherapy and chemotherapy. Therefore, the development of new drug is urgently needed. α-carboline derivatives were usually isolated from marine animals such as Britannia marine tunicate Dendrodoa grossularia and Indonesian ascidian Polycarpa aurata. In this study, we have synthesized several α-carboline compounds and examined their anti-glioma activities.

Results

We report that among α-carboline derivatives TJY-16 (6-acetyl-9-(3,4,5-trimethoxybenzyl)-9H-pyrido[2,3-b] indole) is the most potent α-carboline analog to induce glioma cell death with IC₅₀ value of around 50 nM. TJY-16 decreased cell viability of glioma cells in a concentration- and time-dependent manner. Trypan blue exclusion assay showed that the reduction of cell viability was due to both cell growth inhibition and cell death. Flow cytometric analysis showed that TJY-16 induced G2/M cell cycle arrest followed by induction of sub-G1 phase. Hoechst staining detected the apoptotic features such as nuclear shrinkage and DNA condensation. Western blot analysis showed the increased level of cleaved caspase-3. The activation of caspase-8 and depolarization of mitochondrial membrane potential (ΔΨm) indicated that both extrinsic and intrinsic apoptotic pathways were involved in TJY-16-induced apoptosis. TJY-16 effectively inhibited tumor growth and induced caspase-3 activation in the xenograft tumor model of U87 glioma cells.

Conclusions

Our results suggest that TJY-16 may kill glioma cells by inducing G2/M cell cycle arrest followed by apoptosis. Thus, TJY-16 is a promising agent for the treatment of malignant gliomas.

Photochemical Synthesis of Complex Carbazoles: Evaluation of Electronic Effects in Both UV- and Visible-Light Methods in Continuous Flow

An evaluation of both a visible-light- and UV-light-mediated synthesis of carbazoles from various triarylamines with differing electronic properties under continuous-flow conditions has been conducted. In general, triarylamines bearing electron-rich groups tend to produce higher yields than triarylamines possessing electron-withdrawing groups. The incorporation of nitrogen-based heterocycles, as well as halogen-containing arenes in carbazole skeletons, was well tolerated, and often synthetically useful complementarity was observed between the UV-light and visible-light (photoredox) methods.

New cytotoxic 1,2,4-thiadiazole alkaloids from the ascidian Polycarpa aurata

Two new alkaloids, polycarpathiamines A and B (1 and 2), were isolated from the ascidian Polycarpa aurata. Their structures were unambiguously determined by 1D, 2D NMR, and HRESIMS measurements and further confirmed by comparison with a closely related analogue, 3-dimethylamino-5-benzoyl-1,2,4-thiadiazole (4), that was prepared by chemical synthesis. Compounds 1 and 2 both feature an uncommon 1,2,4-thiadiazole ring whose biosynthetic origin is proposed. Compound 1 showed significant cytotoxic activity against L5178Y murine lymphoma cells (IC50 0.41 μM).