Bioactivity and molecular docking of lactones isolated from Centaurea pseudosinaica Czerep.

Two cytotoxic sesquiterpene lactones, 17-epichlorohyssopifolin A (1) and chlorjanerin (2), and a monoterpene lactone, loliolide (3) were isolated from Centaurea pseudosinaica. The cytotoxicity of the total extract and terpenoids 1-3 were evaluated against three human cancer cells (HepG2, PC-3, and HT-29), along with the human normal primary epidermal keratinocytes (HEKa) cells. With IC50 values ranging between 0.6 ± 0.04 and 5.0 ± 0.61 µg/mL against HepG2; 0.2 ± 0.01 and 11.9 ± 1.31 µg/mL against PC-3, and 0.04 ± 0.013 and 8.9 ± 0.97 µg/mL against HT-29, the total extract, and lactones 1-3 demonstrated cytotoxic effects. Compound 1 displayed the strongest impact on all cancer cells and a slightly safe effect on the normal cells HEKa. Compound 1 caused accumulation of HepG2 and HT-29 cells in G1 phase as displayed cell cycle analysis. On the other hand, the cell distributions were increased in the S phase in PC-3 cells. Furthermore, 1 caused apoptosis in PC-3 and HePG2 cells with 91.50%, and 79.72 %, respectively. A higher fraction of necrotic cells was observed in HT-29 cells amounting to 23.60%. These results suggested that the promising cytotoxicity exhibited by 1 is brought by the apoptosis induction in the cancer cells, which were evaluated. As the compounds showed antiproliferative effect against the HT-29 cells, the docking simulation was performed aiming at determining how they would interact with the EGFR enzyme, whose PDB: 4I23 is considered one of the two distinct wild types of EGFR enzymes. The antibacterial activity results revealed that 3 showed the most remarkable antibacterial effects, especially against the examined Gram-positive bacteria. The total extract exhibited potent activity against all examined bacteria. The total extract showed a potent antifungal effect against two Candida and two Aspergillus pathogens. The antioxidant activity revealed the potency of the total extract and 3 as antioxidant candidates. The obtained results refer to the importance of Centaurea pseudosinaica as a source of potent antiproliferative agents and the whole plant as an antipathogenic and antioxidant agent.

Antiproliferative Isoprenoid Derivatives from the Red Sea Alcyonacean Xenia umbellata.

From the soft coral Xenia umbellata, seven isoprenoid derivatives were isolated, including a new xenicane diterpene, xeniolide O (5) and a new gorgostane derivative gorgst-3ß,5α,6ß,11α,20(S)-pentol-3-monoacetate (7), along with three known sesquiterpenes (1-3), a known diterpene (4), and a known steroid (6). The extensive analyses of the NMR, IR, and MS spectral data led to determination of their chemical structures. Compounds 1-7 displayed a cytotoxic effect against breast adenocarcinoma (MCF-7), hepatocellular carcinoma (HepG2), and cervix adenocarcinoma (HeLa), with IC50 values ranging between 1.5 ± 0.1-23.2 ± 1.5; 1.8 ± 0.1-30.6 ± 1.1 and 0.9 ± 0.05-12.8 ± 0.5 µg/mL, respectively. Compound 3 showed potent cytotoxic effects against MCF-7, HepG2, and HeLa with IC50 values = 2.4 ± 0.20, 3.1 ± 0.10 and 0.9 ± 0.05 µg/mL, respectively. Compounds 2, 5, and 7 displayed cytotoxic effect against Hela cells with IC50 values = 12.8 ± 0.50, 6.7 ± 1.00 and 11.5 ± 2.20 µg/mL, respectively. Two DNA binding dyes, acridine orange (AO) and ethidium bromide (EtBr) were used for the detection of viable, apoptotic, and necrotic cells. The early apoptotic cell death was observed in all types of treated cells. The late apoptotic cells were highly present in HepG2 cells. Compounds 5 and 7 induced a high percentage of necrosis towards HepG2 and HeLa cells. The late apoptosis was recorded as a high rate after treatment with 7 on all cancer cells.

Marine-Derived Macrocyclic Alkaloids (MDMAs): Chemical and Biological Diversity.

The curiosity and attention that researchers have devoted to alkaloids are due to their bioactivities, structural diversity, and intriguing chemistry. Marine-derived macrocyclic alkaloids (MDMAs) are considered to be a potential source of drugs. Trabectedin, a tetrahydroisoquinoline derivative, has been approved for the treatment of metastatic soft tissue sarcoma and ovarian cancers. MDMAs displayed potent activities that enabled them to be used as anticancer, anti-invasion, antimalarial, antiplasmodial, and antimicrobial. This review presents the reported chemical structures, biological activities, and structure-activity relationships of macrocyclic alkaloids from marine organisms that have been published since their discovery until May 2020. This includes 204 compounds that are categorized under eight subclasses: pyrroles, quinolines, bis-quinolizidines, bis-1-oxaquinolizidines, 3-alkylpiperidines, manzamines, 3-alkyl pyridinium salts, and motuporamines.