Bulbispermine: a crinine-type Amaryllidaceae alkaloid exhibiting cytostatic activity toward apoptosis-resistant glioma cells

Incredible use of plant-derived bioactives as anticancer agents

Cancer is a major global concern. Despite considerable advancements in cancer therapy and control, there are still large gaps and requirements for development. In recent years, various naturally occurring anticancer drugs have been derived from natural resources, such as alkaloids, glycosides, terpenes, terpenoids, flavones, and polyphenols. Plant-derived substances exhibit their anticancer potential through antiproliferative activity, cytotoxicity, apoptosis, angiogenesis and cell cycle arrest. Natural compounds can affect the molecular activity of cells through various signaling pathways, like the cell cycle pathway, STAT-3 pathway, PI3K/Akt, and Ras/MAP-kinase pathways. Capsaicin, ouabain, and lycopene show their anticancer potential through the STAT-3 pathway in breast, colorectal, pancreatic, lung, cervical, ovarian and colon cancers. Epigallocatechin gallate and emodin target the JNK protein in skin, breast, and lung cancers, while berberine, evodiamine, lycorine, and astragalin exhibit anticancer activity against breast, liver, prostate, pancreatic and skin cancers and leukemia through the PI3K/Akt and Ras/MAP-kinase pathways. In vitro/in vivo investigations revealed that secondary metabolites suppress cancer cells by causing DNA damage and activating apoptosis-inducing enzymes. After a meticulous literature review, the anti-cancer potential, mode of action, and clinical trials of 144 bioactive compounds and their synthetic analogues are included in the present work, which could pave the way for using plant-derived bioactives as anticancer agents.

Undescribed Amaryllidaceae Alkaloids from Zephyranthes citrina and Their Cytotoxicity

This phytochemical study presents the isolation of eight alkaloids from Zephyranthes citrina Baker. The structures of the new alkaloids, zephycitrine (1) and 6-oxonarcissidine (2), were established by analysis of spectroscopic and spectrometric data. Processing the EtOH extract under acid-base conditions yielded the unreported isolation artifacts 3 and 4. This work also provides analytical data for alkaloids not properly described in the literature (5 and 6). The hippeastidine/zephyranine scaffolds in derivatives 3, 4, and 8-10 are also thoroughly discussed. Furthermore, a cytotoxicity screening of 25 Amaryllidaceae alkaloids isolated from Z. citrina was performed. Only the known alkaloids haemanthamine (12), haemanthidine (13), and lycorine (27) showed significant cell growth inhibition.

A review of natural products and small-molecule therapeutics acting on central nervous system malignancies: Approaches for drug development, targeting pathways, clinical trials, and challenges

In 2021, the World Health Organization released the fifth edition of the central nervous system (CNS) tumor classification. This classification uses histopathology and molecular pathogenesis to group tumors into more biologically and molecularly defined entities. The prognosis of brain cancer, particularly malignant tumors, has remained poor worldwide, approximately 308,102 new cases of brain and other CNS tumors were diagnosed in the year 2020, with an estimated 251,329 deaths. The cost and time-consuming nature of studies to find new anticancer agents makes it necessary to have well-designed studies. In the present study, the pathways that can be targeted for drug development are discussed in detail. Some of the important cellular origins, signaling, and pathways involved in the efficacy of bioactive molecules against CNS tumorigenesis or progression, as well as prognosis and common approaches for treatment of different types of brain tumors, are reviewed. Moreover, different study tools, including cell lines, in vitro, in vivo, and clinical trial challenges, are discussed. In addition, in this article, natural products as one of the most important sources for finding new chemotherapeutics were reviewed and over 700 reported molecules with efficacy against CNS cancer cells are gathered and classified according to their structure. Based on the clinical trials that have been registered, very few of these natural or semi-synthetic derivatives have been studied in humans. The review can help researchers understand the involved mechanisms and design new goal-oriented studies for drug development against CNS malignancies.

Advances in glioblastoma multiforme: Integrating therapy and pathology perspectives

Glioblastoma, a highly lethal form of brain cancer, is characterized by its aggressive growth and resistance to conventional treatments, often resulting in limited survival. The response to therapy is notably influenced by various patient-specific genetic factors, underscoring the disease's complexity. Despite the utilization of diverse treatment modalities such as surgery, radiation, and chemotherapy, many patients experience local relapse, emphasizing the critical need for improved therapeutic strategies to effectively target these formidable tumors. Recent years have witnessed a surge in interest in natural products derived from plants, particularly alkaloids, for their potential anticancer effects. Alkaloids have shown promise in cancer chemotherapy by selectively targeting crucial signaling pathways implicated in tumor progression and survival. Specifically, they modulate the NF-κB and MAPK pathways, resulting in reduced tumor growth and altered gene expression across various cancer types. Additionally, alkaloids exhibit the capacity to induce cell cycle arrest, further impeding tumor proliferation in several malignancies. This review aims to delineate recent advances in understanding the pathology of glioblastoma multiforme (GBM) and to explore the potential therapeutic implications of alkaloids in managing this deadly disease. By segregating discussions on GBM pathology from those on alkaloid-based therapies, we provide a structured overview of the current challenges in GBM treatment and the promising opportunities presented by alkaloid-based interventions. Furthermore, we briefly discuss potential future directions in GBM research and therapy beyond alkaloids, including emerging treatment modalities or areas of investigation that hold promise for improving patient outcomes. In conclusion, our efforts offer hope for enhanced outcomes and improved quality of life for GBM patients through alkaloid-based therapies. By integrating insights from pathology and therapeutic perspectives, we underscore the significance of a comprehensive approach in addressing this devastating disease.

Design of semisynthetic derivatives of the Amaryllidaceae alkaloid ambelline and exploration of their in vitro cytotoxic activities

Ambelline, an alkaloid from the Amaryllidaceae family with a crinane-type skeleton, has not yet demonstrated any outstanding biological activity. However, its analogues prepared by derivatization of the C-11 hydroxyl group show different interesting effects. Continuing our earlier work, twelve novel aromatic esters were developed (10, 14, 16, 17, 22-25, 30-33) and studied, together with previously synthesized derivatives (2-9, 11-13, 15, 18-21, 26-29) in terms of their cytotoxic activity. The cytotoxic potential was determined on a panel of nine human cancer cell lines and one noncancerous cell line to characterize their biological activity spectrum. To describe and foresee the structure-activity relationship for further research, substances synthesized and described in our previous work were also included in this cytotoxicity study. The most significant activity was associated with analogues having methyl (10), methoxy (14-17), or ethoxy (18) substitution on the phenyl condensed to ambelline. However, the 4-chloro-3-nitrobenzoyl derivative (32) showed the most promising IC₅₀ values, ranging from 0.6 ± 0.1 µM to 9.9 ± 0.2 µM. In vitro cytotoxicity studies indicated the most potent antiproliferative activity of 32 in a dose-dependent and time-dependent manner. Besides, 32 was found to be effective in decreasing viability and triggering apoptosis of MOLT-4 T-lymphoblastic leukemia cells.

Cytotoxicity and Antiviral Properties of Alkaloids Isolated from Pancratium maritimum

Ten Amaryllidaceae alkaloids (AAs) were isolated for the first time from Pancratium maritimum collected in Calabria region, Italy. They belong to different subgroups of this family and were identified as lycorine, which is the main alkaloid, 9-O-demethyllycorine, haemanthidine, haemanthamine, 11-hydroxyvittatine, homolycorine, pancracine, obliquine, tazettine and vittatine. Haemanthidine was isolated as a scalar mixture of two 6-epimers, as already known also for other 6-hydroxycrinine alkaloids, but for the first time they were separated as 6,11-O,O′-di-p-bromobenzoyl esters. The evaluation of the cytotoxic and antiviral potentials of all isolated compounds was undertaken. Lycorine and haemanthidine showed cytotoxic activity on Hacat cells and A431 and AGS cancer cells while, pancracine exhibited selective cytotoxicity against A431 cells. We uncovered that in addition to lycorine and haemanthidine, haemanthamine and pancracine also possess antiretroviral abilities, inhibiting pseudotyped human immunodeficiency virus (HIV)−1 with EC50 of 25.3 µM and 18.5 µM respectively. Strikingly, all the AAs isolated from P. maritimum were able to impede dengue virus (DENV) replication (EC50 ranged from 0.34−73.59 µM) at low to non-cytotoxic concentrations (CC50 ranged from 6.25 µM to >100 µM). Haemanthamine (EC50 = 337 nM), pancracine (EC50 = 357 nM) and haemanthidine (EC50 = 476 nM) were the most potent anti-DENV inhibitors. Thus, this study uncovered new antiviral properties of P. maritimum isolated alkaloids, a significant finding that could lead to the development of new therapeutic strategies to fight viral infectious diseases.

The Chemical Synthesis of the Crinine and Haemanthamine Alkaloids: Biologically Active and Enantiomerically-Related Systems that Serve as Vehicles for Showcasing New Methodologies for Molecular Assembly

The title alkaloids, often referred to collectively as crinines, are a prominent group of structurally distinct natural products with additional members being reported on a regular basis. As such, and because of their often notable biological properties, they have attracted attention as synthetic targets since the mid-1950s. Such efforts continue unabated and more recent studies on these alkaloids have focused on using them as vehicles for showcasing the utility of new synthetic methods. This review provides a comprehensive survey of the nearly seventy-year history of these synthetic endeavors.

A Brief Up-to-Date Overview of Amaryllidaceae Alkaloids: Phytochemical Studies of Narcissus tazetta subsp. tazetta L., Collected in Turkey

A brief up-to-date overview on the isolation, and chemical and biological characterization of new and known alkaloids from different Amaryllidaceae species, including Brunsvigia, Crinum, Cyrtanthus, Narcissus, and Nerine genera, was reported. Furthermore, the isolation and chemical characterization of alkaloids extracted from bulbs of Narcissus tazetta subsp. tazetta L. collected from Muğla, Turkey were described.

ZYH005, a novel DNA intercalator, overcomes all-trans retinoic acid resistance in acute promyelocytic leukemia

Despite All-trans retinoic acid (ATRA) has transformed acute promyelocytic leukemia (APL) from the most fatal to the most curable hematological cancer, there remains a clinical challenge that many high-risk APL patients who fail to achieve a complete molecular remission or relapse and become resistant to ATRA. Herein, we report that 5-(4-methoxyphenethyl)-[1, 3] dioxolo [4, 5-j] phenanthridin-6(5H)-one (ZYH005) exhibits specific anticancer effects on APL and ATRA-resistant APL in vitro and vivo, while shows negligible cytotoxic effect on non-cancerous cell lines and peripheral blood mononuclear cells from healthy donors. Using single-molecule magnetic tweezers and molecule docking, we demonstrate that ZYH005 is a DNA intercalator. Further mechanistic studies show that ZYH005 triggers DNA damage, and caspase-dependent degradation of the PML-RARa fusion protein. As a result, APL and ATRA-resistant APL cells underwent apoptosis upon ZYH005 treatment and this apoptosis-inducing effect is even stronger than that of arsenic trioxide and anticancer agents including 5-fluorouracil, cisplatin and doxorubicin. Moreover, ZYH005 represses leukemia development in vivo and prolongs the survival of both APL and ATRA-resistant APL mice. To our knowledge, ZYH005 is the first synthetic phenanthridinone derivative, which functions as a DNA intercalator and can serve as a potential candidate drug for APL, particularly for ATRA-resistant APL.

Synthetic analogues of the montanine-type alkaloids with activity against apoptosis-resistant cancer cells

In a search of small molecules active against apoptosis-resistant cancer cells, a skeletal rearrangement of alkaloid haemanthamine was utilized to generate a series of compounds possessing the alkaloid montanine ring system. The synthesized compounds were found to inhibit proliferation of cancer cells resistant to apoptosis at micromolar concentrations. Selected compounds were also active against patient-derived glioblastoma cells expressing stem-cell markers. This is the first report describing the preparation of synthetic analogues of the montanine-type alkaloids with antiproliferative activity. The compounds prepared in the current investigation appear to be a useful starting point for the development of agents to fight cancers with apoptosis resistance, and thus, associated with poor prognoses.

The Amaryllidaceae Alkaloid Haemanthamine Binds the Eukaryotic Ribosome to Repress Cancer Cell Growth

Alkaloids isolated from the Amaryllidaceae plants have potential as therapeutics for treating human diseases. Haemanthamine has been studied as a novel anticancer agent due to its ability to overcome cancer cell resistance to apoptosis. Biochemical experiments have suggested that hemanthamine targets the ribosome. However, a structural characterization of its mechanism has been missing. Here we present the 3.1 Å resolution X-ray structure of haemanthamine bound to the Saccharomyces cerevisiae 80S ribosome. This structure reveals that haemanthamine targets the A-site cleft on the large ribosomal subunit rearranging rRNA to halt the elongation phase of translation. Furthermore, we provide evidence that haemanthamine and other Amaryllidaceae alkaloids also inhibit specifically ribosome biogenesis, triggering nucleolar stress response and leading to p53 stabilization in cancer cells. Together with a computer-aided interpretation of existing structure-activity relationships of Amaryllidaceae alkaloids congeners, we provide a rationale for designing molecules with enhanced potencies and reduced toxicities.

Amaryllidaceae alkaloids: Absolute configuration and biological activity

Plants belonging to the Amaryllidaceae family are well known for their ornamental and medicinal use. Plant members of this group are distributed through both tropical and subtropical regions of the world and are dominant in Andean South America, the Mediterranean basin, and southern Africa. Amaryllidaceae plants have been demonstrated to be a good source of alkaloids with a large spectrum of biological activities, the latter being strictly related to the absolute stereochemistry of the alkaloid scaffold. Among them, great importance for practical applications in medicine has galanthamine, which has already spawned an Alzheimer's prescription drug as a potent and selective inhibitor of the enzyme acetylcholinesterase. Furthermore, lycorine as well as its related isocarbostyryl analogs narciclasine and pancratistatine have shown a strong anticancer activity in vitro against different solid tumors with malignant prognosis. This review addresses the assignment of the absolute configuration of several Amaryllidaceae alkaloids and its relationship with their biological activities.

A review of ethnoboatany, therapeutic value, phytochemistry and pharmacology of Crinum macowanii Baker: A highly traded bulbous plant in Southern Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Crinum macowanii is a deciduous bulbous plant which grows in east, central and southern Africa. Crinum macowanii has been used as herbal medicine by the indigenous people of east and southern Africa has for several centuries. The bulb, leaves and roots of C. macowanii are reported to possess diverse medicinal properties and used to treat or manage various human and animal diseases and ailments throughout its distributional range. Crinum macowanii is used traditionally as a remedy for boils, diarrhoea, fever, inflammation, respiratory system problems, skin rashes, tuberculosis, wounds and urinary tract problems.

AIM OF THE REVIEW

The present review aims to summarize comprehensively the research that has been done on the ethnomedicinal uses, botany, phytochemistry and pharmacology of C. macowanii in different locations throughout its geographical range in east, central and southern African region so as to highlight research gaps and provide a foundation for further investigations on the plant species.

MATERIALS AND METHODS

A review of the literature was undertaken and an in-depth analysis of previous research on ethnobotany, therapeutic value, phytochemistry and pharmacology of C. macowanii throughout its distributional range in east, central and southern Africa. Literature sources included papers published in international journals, reports from international, regional and national organizations, conference papers, books, theses, websites and other grey literature. Electronic search engines such as Google, Google scholar, publishing sites such as Elsevier, scienceDirect, BMC, PubMed and other scientific database sites such as ChemSpider, PubChem were used as well as searching the library collections of the National Herbarium and Botanic Gardens (SRGH), Harare, Zimbabwe and the University of Fort Hare, South Africa.

RESULTS

A total of 32 ethnomedicinal uses of C. macowanii are documented in literature, which can be grouped into seven major ethnomedicinal general purpose usages, namely "fever", "wounds, sores and skin rashes", "boils and inflammation", "respiratory system problems", "blood cleansing", "urinary tract problem" and "veterinary uses". The chemical composition of C. macowanii is dominated by various isoquinoline alkaloids, which have been isolated from the bulbs, flowering stalks, leaves and roots. Major biological activities demonstrated by C. macowanii include antifungal, antiviral and antiplasmodial activities, cardiovascular effects as well as effects on the central nervous system. The population of C. macowanii is declining in the wild as the bulbs are over-collected for sale in medicinal (muthi) markets in southern Africa.

CONCLUSION

A literature search revealed that C. macowanii has a lot of potential as a possible source of pharmaceutical products for the treatment of a wide range of human and animal diseases and ailments. Some of the alkaloids isolated from C. macowanii have demonstrated various biological activities when investigated in in vitro assays. However, some of the ethnomedicinal uses of C. macowanii still require pharmacological investigations. Therefore, further studies are required to improve our knowledge about the mechanisms of action, efficacy, toxicity and clinical relevance of the plant species as well as its bioactive compounds.

The Biological Activity of Alkaloids from the Amaryllidaceae: From Cholinesterases Inhibition to Anticancer Activity

Modern research has shown that Amaryllidaceae alkaloids represent a rich reservoir of potential small chemical molecules exhibiting several medicinal properties through various mechanisms. Among the many Amaryllidaceae compounds, galanthamine has been given a great amount of attention due to the fact that it possesses potent acetylcholinesterase inhibitory activity. In spite of the amount of evidence indicating the potential usefulness of Amaryllidaceae alkaloids in therapy, research groups have focused their attention on the other alkaloids present in this plant family. New investigations have shed light on many aspects of the structure of Amaryllidaceae alkaloids and on their semisynthetic modification, function, and mechanisms underlying in vitro and in vivo activity. In addition, Amaryllidaceae alkaloids have frequently been identified as having promising cytotoxic properties against cancer cell lines. While follow-up studies have repeatedly shown that Amaryllidaceae alkaloids and their derivatives demonstrate antiproliferative, cytotoxic and apoptosis-inducing activity, the mechanisms remain unclear. This review addresses the most important Amaryllidaceae alkaloids with anticancer potential, particularly those that have been studied for the purpose of gaining a better understanding of the basis of the activity at the cellular and molecular level.

5,10b-Ethanophenanthridine amaryllidaceae alkaloids inspire the discovery of novel bicyclic ring systems with activity against drug resistant cancer cells

Plants of the Amaryllidaceae family produce a large variety of alkaloids and non-basic secondary metabolites, many of which are investigated for their promising anticancer activities. Of these, crinine-type alkaloids based on the 5,10b-ethanophenanthridine ring system were recently shown to be effective at inhibiting proliferation of cancer cells resistant to various pro-apoptotic stimuli and representing tumors with dismal prognoses refractory to current chemotherapy, such as glioma, melanoma, non-small-cell lung, esophageal, head and neck cancers, among others. Using this discovery as a starting point and taking advantage of a concise biomimetic route to the crinine skeleton, a collection of crinine analogues were synthetically prepared and evaluated against cancer cells. The compounds exhibited single-digit micromolar activities and retained this activity in a variety of drug-resistant cancer cell cultures. This investigation resulted in the discovery of new bicyclic ring systems with significant potential in the development of effective clinical cancer drugs capable of overcoming cancer chemotherapy resistance.

Synthesis and in vitro growth inhibitory activity of novel silyl- and trityl-modified nucleosides

Seventeen silyl- and trityl-modified (5'-O- and 3',5'-di-O-) nucleosides were synthesized with the aim of investigating the in vitro antiproliferative activities of these nucleoside derivatives. A subset of the compounds was evaluated at a fixed concentration of 100μM against a small panel of tumor cell lines (HL-60, K-562, Jurkat, Caco-2 and HT-29). The entire set was also tested at varying concentrations against two human glioma lines (U373 and Hs683) to obtain GI50 values, with the best results being values of ∼25μM.

Fungal metabolite ophiobolin A as a promising anti-glioma agent: In vivo evaluation, structure-activity relationship and unique pyrrolylation of primary amines

Glioblastoma, the most common form of malignant primary brain tumor, is characterized by resistance to apoptosis, which is largely responsible for the low effectiveness of the classical chemotherapeutic approaches based on apoptosis induction in cancer cells. Previously, a fungal secondary metabolite ophiobolin A was found to have significant activity against apoptosis-resistant glioblastoma cells through the induction of a non-apoptotic cell death, thus, offering an innovative strategy to combat this type of cancer. The current work describes the results of a preliminary evaluation of ophiobolin A in an in vivo glioblastoma model and its chemical derivatization to establish first synthetically generated structure-activity relationship. The synthetic work has also led to the discovery of a unique reaction of ophiobolin A with primary amines suggesting the possibility of pyrrolylation of lysine residues on its intracellular target protein(s).

Wittig derivatization of sesquiterpenoid polygodial leads to cytostatic agents with activity against drug resistant cancer cells and capable of pyrrolylation of primary amines

Many types of cancer, including glioma, melanoma, non-small cell lung cancer (NSCLC), among others, are resistant to proapoptotic stimuli and thus poorly responsive to current therapies based on the induction of apoptosis in cancer cells. The current investigation describes the synthesis and anticancer evaluation of unique C12-Wittig derivatives of polygodial, a sesquiterpenoid dialdehyde isolated from Persicaria hydropiper (L.) Delabre. These compounds were found to undergo an unprecedented pyrrole formation with primary amines in a chemical model system, a reaction that could be relevant in the biological environment and lead to the pyrrolation of lysine residues in the target proteins. The anticancer evaluation of these compounds revealed their promising activity against cancer cells displaying various forms of drug resistance, including resistance to proapoptotic agents. Mechanistic studies indicated that compared to the parent polygodial, which displays fixative general cytotoxic action against human cells, the C12-Wittig derivatives exerted their antiproliferative action mainly through cytostatic effects explaining their activity against apoptosis-resistant cancer cells. The possibility for an intriguing covalent modification of proteins through a novel pyrrole formation reaction, as well as useful activities against drug resistant cancer cells, make the described polygodial-derived chemical scaffold an interesting new chemotype warranting thorough investigation.

Jonquailine, a new pretazettine-type alkaloid isolated from Narcissus jonquilla quail, with activity against drug-resistant cancer

A new alkaloid, belonging to the pretazettine group of Amaryllidaceae alkaloids, was isolated from dried bulbs of Narcissus jonquilla quail and named jonquailine. Its structure, including the absolute configuration, was elucidated using various NMR, ECD and ESI MS techniques. Initial biological evaluation revealed significant antiproliferative effects against glioblastoma, melanoma, uterine sarcoma and non-small-cell lung cancer cells displaying various forms of drug resistance, including resistance to apoptosis and multi-drug resistance. Jonquailine was also found to synergize with paclitaxel in its antiproliferative action against drug-resistant lung cancer cells. The results obtained compared with literature data also showed that the hydroxylation at C-8 is an important feature for the anticancer activity but this seems unaffected by the stereochemistry or the acetalization of the lactol.

Activity of 2-aryl-2-(3-indolyl)acetohydroxamates against drug-resistant cancer cells

Many types of tumor, including glioma, melanoma, non-small cell lung, esophageal, and head and neck cancer, among others, are intrinsically resistant to apoptosis induction and poorly responsive to current therapies with proapoptotic agents. In addition, tumors often develop multidrug resistance based on the cellular efflux of chemotherapeutic agents. Thus, novel anticancer agents capable of overcoming these intrinsic or developed tumor resistance mechanisms are urgently needed. We describe a series of 2-aryl-2-(3-indolyl)acetohydroxamic acids that are active against apoptosis- and multidrug-resistant cancer cells as well as glioblastoma neurosphere stemlike cell cultures derived from patients. Thus, the described compounds serve as a novel chemical scaffold for the development of potentially highly effective clinical cancer drugs.

Mechanistic Insights to the Cytotoxicity of Amaryllidaceae Alkaloids

With over 500 individual compounds, the Amaryllidaceae alkaloids represent a large and structurally diverse group of phytochemicals. Coupled to this structural diversity is the significant array of biological properties manifested by many of its members, of which their relevance in motor neuron disease and cancer chemotherapy has attracted considerable attention. To this extent, galanthamine has evolved into a successful commercial drug for Alzheimer's disease since its approval by the FDA in 2001. Concurrently, there have been several positive indicators for the emergence of an anticancer drug from the Amaryllidaceae due to the potency of several of its representatives as cell line specific antiproliferative agents. In this regard, the phenanthridones such as pancratistatin and narciclasine have offered most promise since their advancement into clinical trials, following which there has been renewed interest in the cytotoxic properties of these alkaloids. Given this background, this review seeks to highlight the various mechanisms which have been invoked to corroborate the cytotoxic effects of Amaryllidaceae alkaloids.

Crinane Alkaloids of the Amaryllidaceae with Cytotoxic Effects in Human Cervical Adenocarcinoma (HeLa) Cells

The family Amaryllidaceae has a long history of usage in the traditional medicinal practices of the indigenous peoples of South Africa, with three of its species known to be used for cancer treatment. Furthermore, the Amaryllidaceae is widely recognized for its unique alkaloid constituents, several of which exhibit potent and selective cytotoxic activities. In this study, several crinane alkaloids derived from local Amaryllidaceae species were examined for cytotoxic effects against the human cervical adenocarcinoma cell line, of which distichamine was the most potent (IC50 2.2 μM).

Alkaloids of the South African Amaryllidaceae: A Review

The plant family Amaryllidaceae is known for its horticultural and ornamental appeal as well as its medicinal value. In relation to these characteristics, trade in Amaryllid flower varieties (especially daffodils) is a multi-million dollar revenue generator for the floriculture industry. Of greater significance are the medicinal attributes of the family, which has already spawned the Alzheimer's prescription drug galanthamine, a potent and selective inhibitor of the enzyme acetylcholinesterase, of significance in the progression of neurodegeneration associated with motor neuron diseases, with annual global sales of around $150 million. Furthermore, it is anticipated that an anticancer drug target related to the Amaryllidaceae alkaloid pancratistatin, presently under advanced clinical evaluation, will enter commercial circulation within the next decade. Members of the Amaryllidaceae are distributed through both tropical and subtropical regions of the globe, but are of prominence within three distinct geographical locations, including Andean South America, the Mediterranean basin, and southern Africa. The southern African zone is known to harbor at least a third of the worldwide complement of around 1000 species, many of which are widely utilized in the traditional medicinal practices of the indigenous people of the region. Given its therapeutic and economic value, its natural abundance in the southern African region, coupled to its widespread usage in ethnic medicine, the family Amaryllidaceae provides a diverse and accessible platform for phytochemical based drug discovery. A consolidation of its traditional usage as well as its chemical and pharmacological profiles will thus guide efforts aimed at maximizing this potential. In undertaking this survey of the Amaryllidaceae of southern African, we aimed to achieve these goals.

Amaryllidaceae and Sceletium alkaloids

Covering: July 2010 to June 2012. Previous review: Nat. Prod. Rep., 2011, 28, 1126-1142. Recent progress on the isolation, identification, biological activity and synthetic studies of structurally diverse alkaloids from plants of the family Amaryllidaceae is summarized in this review. In addition, the structurally related alkaloids isolated from Sceletium species are discussed as well.

Towards a molecular understanding of the biosynthesis of amaryllidaceae alkaloids in support of their expanding medical use

The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor used to treat symptoms of Alzheimer's disease, is produced commercially as a drug from cultivated plants. However, several Amaryllidaceae alkaloids have shown great promise as anti-cancer drugs, but their further clinical development is restricted by their limited commercial availability. Amaryllidaceae species have a long history of cultivation and breeding as ornamental bulbs, and phytochemical research has focussed on the diversity in alkaloid content and composition. In contrast to the available pharmacological and phytochemical data, ecological, physiological and molecular aspects of the Amaryllidaceae and their alkaloids are much less explored and the identity of the alkaloid biosynthetic genes is presently unknown. An improved molecular understanding of Amaryllidaceae alkaloid biosynthesis would greatly benefit the rational design of breeding programs to produce cultivars optimised for the production of pharmaceutical compounds and enable biotechnology based approaches.

Cytotoxic Agents of the Crinane Series of Amaryllidaceae Alkaloids

In the alkaloid galanthamine, the plant family Amaryllidaceae has endowed the pharmaceutical community with a potent and selective inhibitor of the enzyme acetylcholinestersae (AChE), of prominence in the chemotherapeutic approach towards motor neuron diseases. Following on the commercial success of this prescription drug in the treatment of Alzheimer's disease, it is anticipated that other drug candidates will in future emerge from the family. In this regard, the phenanthridones, exemplified by narciclasine and pancratistatin, of the lycorine series of Amaryllidaceae alkaloids have shown much promise as remarkably potent and selective anticancer agents, with a drug target of the series destined for the clinical market within the next decade. Given these interesting biological properties and their natural abundance, plants of the Amaryllidaceae have provided a diverse and accessible platform for phytochemical-based drug discovery. The crinane series of Amaryllidaceae alkaloids are also enriched with a significant array of biological properties. As a consequence of their close structural similarity to the anticancer agents of the lycorine series, the cytotoxic potential of crinane alkaloids has been realized through structure-activity relationship (SAR) studies involving targets of both semi-synthetic and natural origin, which has identified several members as leads with promising antiproliferative profiles. As the first of its kind, this review seeks to collate such information from the past few decades in advancing the crinane group as a viable platform for anticancer drug discovery.

Antiproliferative activity of 2,3-disubstituted indoles toward apoptosis-resistant cancers cells

Many types of cancer, including glioma, melanoma, NSCLC, among others, are resistant to apoptosis induction and poorly responsive to current therapies with propaptotic agents. We describe a series of 2,3-disubstituted indoles, which display cytostatic rather than cytotoxic effects in cancer cells, and serve as a new chemical scaffold to develop anticancer agents capable of combating apoptosis-resistant cancers associated with dismal prognoses.

Cytotoxic Agents of the Crinane Series of Amaryllidaceae Alkaloids

In the alkaloid galanthamine, the plant family Amaryllidaceae has endowed the pharmaceutical community with a potent and selective inhibitor of the enzyme acetylcholinestersae (AChE), of prominence in the chemotherapeutic approach towards motor neuron diseases. Following on the commercial success of this prescription drug in the treatment of Alzheimer's disease, it is anticipated that other drug candidates will in future emerge from the family. In this regard, the phenanthridones, exemplified by narciclasine and pancratistatin, of the lycorine series of Amaryllidaceae alkaloids have shown much promise as remarkably potent and selective anticancer agents, with a drug target of the series destined for the clinical market within the next decade. Given these interesting biological properties and their natural abundance, plants of the Amaryllidaceae have provided a diverse and accessible platform for phytochemical-based drug discovery. The crinane series of Amaryllidaceae alkaloids are also enriched with a significant array of biological properties. As a consequence of their close structural similarity to the anticancer agents of the lycorine series, the cytotoxic potential of crinane alkaloids has been realized through structure-activity relationship (SAR) studies involving targets of both semi-synthetic and natural origin, which has identified several members as leads with promising antiproliferative profiles. As the first of its kind, this review seeks to collate such information from the past few decades in advancing the crinane group as a viable platform for anticancer drug discovery.

Extracts of Lycoris aurea induce apoptosis in murine sarcoma S180 cells

Lycoris species have been known since long ago as a multi-utility ethnomedicinal herbal in China. It has been reported to exhibit a number of properties such as anticancer, neuroprotective, and antibacterial activities. In the present study, the anticancer efficacy of dichloromethane extracts of Lycoris aurea (DELA), was evaluated both in vivo and in vitro using murine sarcoma 180 cells. To evaluate the effects of DELA on apoptotic cell death, flow cytometry and Western blotting were performed. DELA demonstrated promising inhibition effects on sarcoma 180 cells in vitro and a 53.49% inhibitory rate on cancer cells in vivo. DELA treatment increased thymus indices and spleen indices in vivo, indicating that it reduced tumours, but did not damage the main immune organs. The DELA-evoked increase in apoptotic cell death was accompanied by occurrence of cleaved caspase-3 and decreases in the ratio of Bcl-2/Bax. Further purification and LCMS analysis showed DELA contained homolycorine, 2α-hydroxyoduline, oduline, hippeastrine, 2α-hydroxy-6-O- methyloduline, and 2α-methoxy-6-O-methyloduline. These results indicate that DELA exerted its anticancer effects, at least in part, by inducing cancer cell apoptosis and thus can be considered as a potential candidate agent for treatment of cancer.