Rachid Chahboun

Background/Objectives: Metal-based coordination compounds are attracting attention in medicinal inorganic chemistry because changes in the metal centre can influence their physicochemical properties and biological responses. This study aimed to evaluate two isostructural ammonium-M(II) hydrogenophosphite hydrates, (NH₄)₂[Mg(H₂O)₆]₃(HPO₃)₄ (complex 1) and (NH₄)₂[Co(H₂O)₆]₃(HPO₃)₄ (complex 2), as bioactive systems with potential anticancer and anti-inflammatory properties. Methods: The complexes were synthesized and characterized by X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), density functional theory (DFT) calculations, and Hirshfeld surface analysis. Their cytotoxic activity was evaluated against B16-F10, HT29, HepG2, and HL-60 tumour cell lines. For complex 2, apoptosis, cell-cycle distribution, and mitochondrial membrane potential were analysed by flow cytometry. Nitric oxide production was measured in LPS-stimulated RAW 264.7 macrophages. Results: Complex 2 showed the highest cytotoxic activity, particularly against HL-60 leukaemia cells (IC₅₀ = 36.98 μg/mL), whereas complex 1 displayed weaker activity. Complex 2 increased apoptotic cell populations, altered cell-cycle distribution, and induced mitochondrial membrane depolarization in HL-60 cells. Both complexes reduced nitric oxide production, with complex 2 showing the strongest effect (IC₅₀ NO = 22.46 μg/mL), exceeding that of diclofenac under the experimental conditions, while complex 1 showed comparable activity to the reference drug. DFT descriptors indicated higher electronic reactivity for complex 2. Conclusions: Replacement of Mg(II) by Co(II) enhances the biological activity of this hydrogenophosphite framework. Complex 2 combines cytotoxic activity against HL-60 cells with apoptosis-associated mitochondrial dysfunction and NO-inhibitory activity in activated macrophages, supporting hydrogenophosphite-based metal complexes as bioactive coordination compounds with potential as multifunctional agents.

The development of efficient C-C bond-forming reactions remains an important objective in organic chemistry. These reactions are fundamental tools for building complex molecules for diverse applications. Among the various strategies available, radical processes promoted by group IV metals—particularly Ti and its titanocene-type complexes—have shown remarkable versatility and utility in organic synthesis. However, closely related zirconium analogues have historically received less attention and have shown a more limited reactivity profile. Thus, zirconium and its zirconocene-type derivatives have often been regarded as the “ugly duckling” of group IV metal-promoted radical chemistry. Yet recent advances indicate that this “ugly duckling” is beginning to reveal its synthetic potential. In this review, we highlight the main synthetic applications of zirconocene(III) complexes and compare them with those of titanocene(III). Special attention is placed on the generation of reactive zirconocene(III) species and their impact on reactivity. Overall, these developments show how zirconocene(III) chemistry is emerging as a valuable complement to titanocene(III)-based radical transformations, turning our ugly duckling into a beautiful swan.

Forsyshiyanine A (8), a trinorditerpene alkaloid isolated from Forsythia suspensa exhibiting in vitro anti-inflammatory and antiviral activities, has been synthesized for the first time from trans-communic acid (12a) and labdane cupressic acid (13). Furthermore, a series of derivatives were efficiently prepared and screened for cytotoxic activities against five human tumoral cell lines. Derivative 25 showed cytotoxicity (IC₅₀ = 6.5 μM) against the Mia PaCa-2 pancreatic cancer cell line, making it an interesting candidate for future structure-activity relationship (SAR) investigations.

Organic synthesis, the art and science of constructing complex organic compounds from simpler ones, is one of the most important fields of research in organic chemistry

Two natural ent-kaurene diterpenoids, ent-15α-angeloyloxykaur-16-en-3β-ol (7) and ent-15α-angeloyloxykaur-16-en-3β,9-diol (8), were extracted from the aerial parts of Distichoselinum tenuifolium, and six new derivatives were synthesised from compound (7). The antitumour properties of these natural and derivative ent-kaurenes (2, 7, 9–13) were evaluated in three cancer cell lines: HT29 (colon cancer), HepG2 (hepatocellular carcinoma), and B16-F10 (murine melanoma). Among them, the synthesised ent-kaurene (13) containing an exomethylene–cyclopentanone moiety showed the strongest antiproliferative effects in all cell lines tested, with significantly lower IC50 values around 2.5 μM. Compounds 13 and 12, together with their precursor (7), were selected for further comparative cytometric and microscopic analyses. Cell cycle studies revealed that derivatives 12 and 13 exhibited promising cytostatic activity by inducing selective G2/M phase arrest, particularly effective in HT29 and HepG2 cells. Conversely, precursor (7) showed no significant effect on B16-F10 cell cycle distribution. The Annexin V-FITC/PI double staining assay confirmed the robust apoptotic effects of compounds (7), 12 and 13, with compound 13 inducing up to 99% total apoptosis and exhibiting significant apoptotic activity in all cell lines tested. These apoptotic effects were closely linked to mitochondrial dysfunction, as evidenced by a marked loss of mitochondrial membrane potential and reduced Rh123 fluorescence in treated cells, thereby activating the intrinsic apoptotic pathway. These findings highlight the critical role of mitochondrial disruption in the cytotoxic mechanisms of these ent-kaurenes and underscore their potential as promising anticancer agents.

Synthesis of the natural product prattinin A and some new derivatives has been achieved using abietic acid. The final products and a selection of intermediates were evaluated for their antibacterial activity against three human pathogenic bacteria: E. coli, P. aeruginosa, and S. aureus. The results showed that the antibacterial activity varies depending on the chemical structure of the compounds. Notably, compound 27 exhibited the most potent activity against E. coli and P. aeruginosa, with a minimal inhibitory concentration (MIC) of 11.7 µg/mL, comparable to that of the standard antibiotic ciprofloxacin, and strong activity against S. aureus, with an MIC of 23.4 µg/mL. Furthermore, we assessed the stability of these derivative compounds as potential antimicrobial agents and determined their interactions with the crystal structure of the protein receptor mutant TEM-12 from E. coli (pdb:1ESU) using molecular docking via UCSF Chimera software 1.17.3. The results suggest that 27 has potential as a natural antibiotic agent.

A mild and highly selective reduction of alkenes and alkynes using Mn/water is described. The highly controlled generation of H₂ allows the selective reduction of these compounds in the presence of labile functional groups under mild and environmentally acceptable conditions.

Synthesis of the rearranged abietane diterpenes pygmaeocins C and D, viridoquinone, saprorthoquinone, and 1-deoxyviroxocine has been successfully achieved. The anticancer and anti-inflammatory activities of selected orthoquinonic compounds 5, 7, 13, and 19, as well as pygmaeocin C (17), were evaluated for the first time. The antitumor properties were assessed using three cancer cell lines: HT29 colon cancer cells, Hep G2 hepatocellular carcinoma cells, and B16-F10 murine melanoma cells. Compounds 5 and 13 showed the highest cytotoxicity in HT29 cells (IC₅₀ = 6.69 ± 1.2 µg/mL and IC₅₀ = 2.7 ± 0.8 µg/mL, respectively). Cytometric studies showed that this growth inhibition involved phase S cell cycle arrest and apoptosis induction, possibly through the activation of the intrinsic apoptotic pathway. Morphological apoptotic changes, including nuclear fragmentation and chromatin condensation, were also observed. Furthermore, the anti-inflammatory activity of these compounds was evaluated on the basis of their ability to inhibit nitric oxide production on the lipopolysaccharide activated RAW 264.7 macrophage cell line. Although all compounds showed high anti-inflammatory activity, with percentages between 40 and 100%, the highest anti-inflammatory potential was obtained by pygmaeocin B (5) (IC_50NO = 33.0 ± 0.8 ng/mL). Our results suggest that due to their dual roles, this type of compound could represent a new strategy, contributing to the development of novel anticancer agents.