Aporphines: A privileged scaffold in CNS drug discovery

Targeting glioma with heteroaromatic alkaloids: A review of potential therapeutics

Glioblastoma multiforme (GBM), classified as a grade IV astrocytoma, is the most aggressive and deadly form of glioma, characterized by rapid progression, extensive genetic heterogeneity, and resistance to conventional therapies. Despite advancements in surgical techniques, radiation therapy, and the frontline chemotherapeutic agent temozolomide, the prognosis for GBM patients remains poor, with a median survival of 15 months and a 5-year survival rate of approximately 7 %. The absence of effective long-term treatments underscores the urgent, unmet clinical need for novel therapeutic strategies to improve patient outcomes. Natural products, particularly alkaloids, have garnered attention as a rich source of bioactive compounds with diverse pharmacological properties. Alkaloids, a structurally diverse group of natural products, are renowned for their chemotherapeutic properties and ability to cross the blood-brain barrier (BBB), making them promising candidates for glioma therapy. This review systematically examines all reported heteroaromatic alkaloids with documented anti-glioma activities, highlighting their mechanisms of action where available. By providing a comprehensive resource, it aims to facilitate the identification and optimisation of alkaloid-based compounds for glioma-targeted drug discovery. Additionally, this review emphasizes the importance of incorporating natural products into the drug development pipeline to address the pressing challenges associated with glioma, particularly GBM treatment.

Unlocking the biological potential of crebanine, oxocrebanine and dehydrocrebanine: Pharmacological activity and related molecular mechanisms

The aim of this review is to highlight the biological potential of the aporphine class of alkaloids, crebanine, oxocrebanine and dehydrocrebanine and their molecular mechanisms, in order to understand their therapeutic potential in medicine. Using the phrases herbal medicine, aporphine, crebanine, oxocrebanine, dehydrocrebanine, and phytochemical, all of the scientific data on crebanine, oxocrebanine, and dehydrocrebanine used in this review was gathered from Google, Google Scholar, PubMed, Scopus, and Science Direct. Nevertheless, analytical techniques for the isolation, separation, and identification of crebanine, oxocrebanine, and dehydrocrebanine are also covered in this study. Present review describes the biological potential of crebanine against cerebral ischemia, human cancer, hepatocellular carcinoma, human lung adenocarcinoma, memory and cognition, and cardiac tissues with their anti-inflammatory, anti-bacterial, cytotoxic potential and anti-invasion effect. Additionally, oxocrebanine biological potential against breast cancer, inflammatory disorders, and acute lung injury is explained by scientific research. Nonetheless, the biological effects of dehydrocrebanine on malaria, cancer, and ulcerative colitis are also discussed in this article. In order to understand the potential for health promotion in human illnesses, this review also discussed the molecular mechanisms behind the pharmacological effects of crebanine, oxocrebanine, and dehydrocrebanine. For the isolation, separation, and identification of crebanine, oxocrebanine, and dehydrocrebanine in biological and non-biological substances, the analytical data showed the significance of various analytical techniques. The biological potential of crebanine, oxocrebanine, and dehydrocrebanine is discussed in the current review along with its various molecular mechanisms, pharmacokinetics, and analytical features. To claim their therapeutic applicability in human illnesses, however, the scientific community needs clinical data.

Biological Potential of Oxoglaucine in Medicine for the Treatment of Human Disorders: An Update on Pharmacological Activities and Related Molecular Mechanism

Medicinal plants are an integral part of the medical system in many countries around the world. Natural products have been used as important biological sources for drug discovery over the past half-century. Alkaloids are a group of natural compounds that contain a basic nitrogen atom. Oxoglaucine is a phytochemical of the oxoaporphines class phytochemical isolated from Aquilegia ecalcarata Maxim, Corydalis yanhusuo, Chasmanthera dependens, and Xylopia aethiopica. The purpose of this study is to analyze all the scientific information about oxoglaucine in order to know the health-beneficial potential of oxoglaucine in medicine. The detailed pharmacological activities of oxoglaucine are analyzed and discussed in this review. The scientific data of the present review about oxoglaucine were collected from PubMed, Scopus, Science Direct, and Google using the terms oxoglaucine, oxoaporphines, alkaloid, phytochemical, pharmacological, and herbal medicine. The scientific findings of the present review article describe the biological importance and therapeutic effectiveness of oxoglaucine in medicine. The present article scientific data signified the biological potential of oxoglaucine against inflammatory diseases, arthritis, osteoarthritis, immune response, enterovirus, and poliovirus. Furthermore, its anticancer, antiaggregation, antifungal, antiprotozoal, and cytotoxic potential are also described in this review article. The scientific information in this article will be helpful to all the scientific peoples of biological science to understand the therapeutic potential of oxoglaucine in medicine.

Structural diversity, evolutionary origin, and metabolic engineering of plant specialized benzylisoquinoline alkaloids

Covering: up to June 2024Benzylisoquinoline alkaloids (BIAs) represent a diverse class of plant specialized metabolites derived from L-tyrosine, exhibiting significant pharmacological properties such as anti-microbial, anti-spasmodic, anti-cancer, cardiovascular protection, and analgesic effects. The industrial production of valuable BIAs relies on extraction from plants; however, challenges concerning their low concentration and efficiency hinder drug development. Hence, alternative approaches, including biosynthesis and chemoenzymatic synthesis, have been explored. Model species like Papaver somniferum and Coptis japonica have played a key role in unraveling the biosynthetic pathways of BIAs; however, many aspects, particularly modified steps like oxidation and methylation, remain unclear. Critical enzymes, e.g., CYP450s and methyltransferases, play a substantial role in BIA backbone formation and modification, which is essential for understanding the origin and adaptive evolution of these plant specialized metabolites. This review comprehensively analyzes the structural diversity of reported BIAs and their distribution in plant lineages. In addition, the progress in understanding biosynthesis, evolution, and catalytic mechanisms underlying BIA biosynthesis is summarized. Finally, we discuss the progress and challenges in metabolic engineering, providing valuable insights into BIA drug development and the sustainable utilization of BIA-producing plants.

Nuciferine inhibits TLR4/NF-κB/MAPK signaling axis and alleviates adjuvant-induced arthritis in rats

Rheumatoid arthritis is an inflammatory condition primarily affecting the joints. Nuciferine (NCF), a key bioactive aporphine alkaloid biosynthesized in lotus leaves, exhibits promising anti-inflammatory and antioxidant properties. In this study, we investigated whether NCF could alleviate inflammatory arthritis conditions in a complete Freund's adjuvant (CFA)-mediated arthritis model in rats. The arthritis model was established through intradermal injection of CFA (100 μL) in the sub-plantar region of the right hind paw. The arthritic animals were treated orally with NCF at 5 and 10 mg/kg and indomethacin (Indo) at 5 mg/kg body weight as reference control. NCF treatment remarkably alleviated inflammatory joint swelling and arthritic index. The radiological and histological analysis revealed evidence of the beneficial effects of NCF. NCF treatment decreased the content of pro-inflammatory cytokines (TNF-α and IL-1β) and myeloperoxidase (MPO) activity and restored the anti-inflammatory cytokine (IL-10) in the paw joints. The serum levels of pro-inflammatory cytokines were also markedly reduced in the NCF (10 mg/kg) treatment group. Moreover, the arthritis-induced inflammatory mediators, including cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) and the toll-like receptor (TLR)-4, mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) signaling proteins were substantially decreased in the NCF treatment groups. NCF treatment also restored the antioxidant defense enzymes and abrogated lipid peroxidation in the paw tissue. Our findings strongly suggest that NCF is a promising therapeutic molecule for rheumatoid arthritis, inspiring further research, and development in this area.

Seven-membered N-heterocycles as approved drugs and promising leads in medicinal chemistry as well as the metal-free domino access to their scaffolds

Azepanes or azepines are structural motifs of many drugs, drug candidates and evaluated lead compounds. Even though compounds having N-heterocyclic 7-membered rings are often found in nature (e.g. alkaloids), the natural compounds of this group are rather rare as approved therapeutics. Thus, recently studied and approved azepane or azepine-congeners predominantly consist of semi-synthetically or synthetically-obtained scaffolds. In this review a comparison of approved drugs and recently investigated leads was proposed taking into regard their structural aspects (stereochemistry), biological activities, pharmacokinetic properties and confirmed molecular targets. The 7-membered N-heterocycles reveal a wide range of biological activities, not only against CNS diseases, but also as e.g. antibacterial, anticancer, antiviral, antiparasitic and against allergy agents. As most of the approved or investigated potential drugs or lead structures, belonging to 7-membered N-heterocycles, are synthetic scaffolds, this report also reveals different and efficient metal-free cascade approaches useful to synthesize both simple azepane or azepine-containing congeners and those of oligocyclic structures. Stereochemistry of azepane/azepine fused systems, in view of biological data and binding with the targets, is discussed. Apart from the approved drugs, we compare advances in SAR studies of 7-membered N-heterocycles (mainly from 2018 to 2023), whereas the related synthetic part concerning various domino strategies is focused on the last ten years.

Natural Product-Inspired Dopamine Receptor Ligands

Due to their evolutionary bias as ligands for biologically relevant drug targets, natural products offer a unique opportunity as lead compounds in drug discovery. Given the involvement of dopamine receptors in various physiological and behavioral functions, they are linked to numerous diseases and disorders such as Parkinson's disease, schizophrenia, and substance use disorders. Consequently, ligands targeting dopamine receptors hold considerable therapeutic and investigative promise. As this perspective will highlight, dopamine receptor targeting natural products play a pivotal role as scaffolds with unique and beneficial pharmacological properties, allowing for natural product-inspired drug design and lead optimization. As such, dopamine receptor targeting natural products still have untapped potential to aid in the treatment of disorders and diseases related to central nervous system (CNS) and peripheral nervous system (PNS) dysfunction.

Identification of the cytochrome P450s responsible for the biosynthesis of two types of aporphine alkaloids and their de novo biosynthesis in yeast

Aporphine alkaloids have diverse pharmacological activities; however, our understanding of their biosynthesis is relatively limited. Previous studies have classified aporphine alkaloids into two categories based on the configuration and number of substituents of the D-ring and have proposed preliminary biosynthetic pathways for each category. In this study, we identified two specific cytochrome P450 enzymes (CYP80G6 and CYP80Q5) with distinct activities toward (S)-configured and (R)-configured substrates from the herbaceous perennial vine Stephania tetrandra, shedding light on the biosynthetic mechanisms and stereochemical features of these two aporphine alkaloid categories. Additionally, we characterized two CYP719C enzymes (CYP719C3 and CYP719C4) that catalyzed the formation of the methylenedioxy bridge, an essential pharmacophoric group, on the A- and D-rings, respectively, of aporphine alkaloids. Leveraging the functional characterization of these crucial cytochrome P450 enzymes, we reconstructed the biosynthetic pathways for the two types of aporphine alkaloids in budding yeast (Saccharomyces cerevisiae) for the de novo production of compounds such as (R)-glaziovine, (S)-glaziovine, and magnoflorine. This study provides key insight into the biosynthesis of aporphine alkaloids and lays a foundation for producing these valuable compounds through synthetic biology.

Synthetic aporphine alkaloids are potential therapeutics for Leigh syndrome

Mitochondrial diseases are mainly caused by dysfunction of mitochondrial respiratory chain complexes and have a variety of genetic variants or phenotypes. There are only a few approved treatments, and fundamental therapies are yet to be developed. Leigh syndrome (LS) is the most severe type of progressive encephalopathy. We previously reported that apomorphine, an anti- "off" agent for Parkinson's disease, has cell-protective activity in patient-derived skin fibroblasts in addition to strong dopamine agonist effect. We obtained 26 apomorphine analogs, synthesized 20 apomorphine derivatives, and determined their anti-cell death effect, dopamine agonist activity, and effects on the mitochondrial function. We found three novel apomorphine derivatives with an active hydroxy group at position 11 of the aporphine framework, with a high anti-cell death effect without emetic dopamine agonist activity. These synthetic aporphine alkaloids are potent therapeutics for mitochondrial diseases without emetic side effects and have the potential to overcome the low bioavailability of apomorphine. Moreover, they have high anti-ferroptotic activity and therefore have potential as a therapeutic agent for diseases related to ferroptosis.

2-Phenylcyclopropylmethylamine (PCPMA) as a privileged scaffold for central nervous system drug design

The use of privileged scaffolds in medicinal chemistry is an effective way to accelerate the drug discovery process, especially at the hit/lead optimization stage. 2-Phenylcyclopropylmethylamine (PCPMA) is a less commonly used chemical scaffold in medicinal chemistry, but many PCPMA-containing compounds exert therapeutic effects for various diseases, in particular central nervous system (CNS) diseases such as depression, schizophrenia, sleep disorder, and Parkinson's disease. The backbone of the PCPMA scaffold enables a unique structure of an amino group linked to a benzene ring through an alkyl linker, making it a useful template for the design of bioactive compounds especially for CNS drug targets including aminergic GPCRs and transporters. This review summarizes the medicinal chemistry studies of PCPMA-containing drugs and drug-like molecules, their mechanisms of action, and biological activities. We conclude that PCPMA is a unique and useful privileged scaffold for CNS drug design.