New insights into the chemistry and anticancer activity of Ophiocordyceps xuefengensis.

Ophiocordyceps xuefengensis (O. xuefengensis), the sister taxon of Ophiocordyceps sinensis (O. sinensis), is consumed as a "tonic food" due to its health benefits. However, little is known regarding the chemistry and bioactivity of O. xuefengensis. In this study, we characterized 80 indole-based alkaloids in the ethyl acetate fraction of O. xuefengensis by high performance liquid chromatography-quadrupole time of flight mass spectrometry (HPLC-Q-TOF-MS/MS), of which 54 indole-based alkaloids were identified as possibly new compounds. Furthermore, 29 of these compounds were established as potential anti-cancer compounds by ligand fishing combined with HPLC-Q-TOF-MS/MS. Moreover, molecular docking identified the NH- and OH- groups of these compounds as the key active groups. The present study has expanded the knowledge on the characteristic indole-based alkaloids and anti-cancer activity of O. xuefengensis.

Molecular and Biological Investigation of Isolated Marine Fungal Metabolites as Anticancer Agents: A Multi-Target Approach.

Cancer is the leading cause of death globally, with an increasing number of cases being annually reported. Nature-derived metabolites have been widely studied for their potential programmed necrosis, cytotoxicity, and anti-proliferation leading to enrichment for the modern medicine, particularly within the last couple of decades. At a more rapid pace, the concept of multi-target agents has evolved from being an innovative approach into a regular drug development procedure for hampering the multi-fashioned pathophysiology and high-resistance nature of cancer cells. With the advent of the Red Sea Penicillium chrysogenum strain S003-isolated indole-based alkaloids, we thoroughly investigated the molecular aspects for three major metabolites: meleagrin (MEL), roquefortine C (ROC), and isoroquefortine C (ISO) against three cancer-associated biological targets Cdc-25A, PTP-1B, and c-Met kinase. The study presented, for the first time, the detailed molecular insights and near-physiological affinity for these marine indole alkaloids against the assign targets through molecular docking-coupled all-atom dynamic simulation analysis. Findings highlighted the superiority of MEL's binding affinity/stability being quite in concordance with the in vitro anticancer activity profile conducted via sulforhodamine B bioassay on different cancerous cell lines reaching down to low micromolar or even nanomolar potencies. The advent of lengthy structural topologies via the metabolites' extended tetracyclic cores and aromatic imidazole arm permitted multi-pocket accommodation addressing the selectivity concerns. Additionally, the presence decorating polar functionalities on the core hydrophobic tetracyclic ring contributed compound's pharmacodynamic preferentiality. Introducing ionizable functionality with more lipophilic characters was highlighted to improve binding affinities which was also in concordance with the conducted drug-likeness/pharmacokinetic profiling for obtaining a balanced pharmacokinetic/dynamic profile. Our study adds to the knowledge regarding drug development and optimization of marine-isolated indole-based alkaloids for future iterative synthesis and pre-clinical investigations as multi-target anticancer agents.

Combinations of indole based alkaloids from Mitragyna speciosa (Kratom) and cisplatin inhibit cell proliferation and migration of nasopharyngeal carcinoma cell lines.

ETHNOPHARMACOLOGICAL RELEVANCE: Mitragyna speciosa (Korth.) or kratom is a medicinal plant indigenous to Southeast Asia. The leaf of M. speciosa is used as a remedy in pain management including cancer related pain, in a similar way as opioids and cannabis. Despite its well-known analgesic effect, there is a scarce of information on the cancer-suppressing potential of M. speciosa and its active constituents. AIM OF THE STUDY: To assess the potential applicability of M. speciosa alkaloids (mitragynine, speciociliatine or paynantheine) as chemosensitizers for cisplatin in Nasopharyngeal carcinoma (NPC) cell lines. MATERIALS AND METHODS: The cytotoxic effects of the extracts, fractions and compounds were determined by conducting in vitro cytotoxicity assays. Based on the cytotoxic screening, the alkaloid extract of M. speciosa exhibited potent inhibitory effect on the NPC cell line NPC/HK1, and therefore, was chosen for further fractionation and purification. NPC cell lines NPC/HK1 and C666-1 were treated with combinations of cisplatin and M. speciosa alkaloids combinations in 2D monolayer culture. The effect of cisplatin and mitragynine as a combination on cell migration was tested using in vitro wound healing and spheroid invasion assays. RESULTS: In our bioassay guided isolation, both methanolic and alkaloid extracts showed mild to moderate cytotoxic effect against the NPC/HK1 cell line. Both NPC cell lines (NPC/HK1 and C666-1) were insensitive to single agent and combination treatments of the M. speciosa alkaloids. However, mitragynine and speciociliatine sensitized the NPC/HK1 and C666-1 cells to cisplatin at ~4- and >5-fold, respectively in 2D monolayer culture. The combination of mitragynine and cisplatin also significantly inhibited cell migration of the NPC cell lines. Similarly, the combination also of mitragynine and cisplatin inhibited growth and invasion of NPC/HK1 spheroids in a dose-dependent manner. In addition, the spheroids did not rapidly develop resistance to the drug combinations at higher concentrations over 10 days. CONCLUSION: Our data indicate that both mitragynine and speciociliatine could be potential chemosensitizers for cisplatin. Further elucidation focusing on the drug mechanistic studies and in vivo studies are necessary to support delineate the therapeutic applicability of M. speciosa alkaloids for NPC treatment.

Indole-based alkaloids from Ophiocordyceps xuefengensis.

Seven undescribed indole-based alkaloids, xuefengins A-D and xuefenglasins A-C, were isolated from natural Ophiocordyceps xuefengensis, along with six known alkaloids. Their structures were elucidated by comprehensive spectroscopy, with absolute configurations confirmed by comparison with calculated electronic circular dichroism spectra. Eleven of the isolates were tested for cytotoxicity against the U937, NB4, MCF-7, Hep G2, and A549 cancer cell lines. Two compounds exhibited moderate activities, with IC50 values of 2.83-25.68 µM and 1.54-12.16 µM. Further pharmacological studies showed that these two compounds inhibit cell proliferation by inducing apoptosis, and decreasing p38 and caspase-3 levels in A549 cells.

Application of Pictet-Spengler Reaction to Indole-Based Alkaloids Containing Tetrahydro-ß-carboline Scaffold in Combinatorial Chemistry.

Indole-based alkaloids are well-known in the literature for their diverse biological properties. Polysubstituted optically active tetrahydro-ß-carboline derivatives functionalized on C-1 position are the common structural motif in most of the indole-based alkaloids, as well as highly marketed drugs. The stereoselective Pictet-Spengler reaction is one of the currently most important synthetic techniques used for the preparation of these privileged tetrahydro-ß-carboline scaffolds. To date, there are numerous research reports that have been published on the synthesis of the tetrahydro-ß-carboline scaffold both on solid phase, as well as in solution phase. Moreover rapid growth has been observed for the enantioselective synthesis of tetrahydro-ß-carboline scaffold using chiral organocatalysts. In this Review, efforts have been taken to shed light on the latest information available on different strategies to synthesize tetrahydro-ß-carboline both on solid phase and in solution phase during the last 20 years. Furthermore, we believe that the present synthetic methodologies covered in this Review will help to improve the status of this privileged tetrahydro-ß-carboline scaffold in its use for drug discovery.