Apoptosis-inducing effects of distichamine and narciprimine, rare alkaloids of the plant family Amaryllidaceae

Caspase-driven cancer therapies: Navigating the bridge between lab discoveries and clinical applications

Apoptosis is the cell's natural intrinsic regulatory mechanism of normal cells for programmed cell death, which plays an important role in cancer as a classical mechanism of tumor cell death causing minimal inflammation without causing damage to other cells in the vicinity. Induction of apoptosis by activation of caspases is one of the primary targets for cancer treatment. Over the years, a diverse range of natural, synthetic, and semisynthetic compounds and their derivatives have been investigated for their caspase-mediated apoptosis-induced anticancer activities. The review aims to compile the preclinical evidence and highlight the critical mechanistic pathways related to caspase-induced cell apoptosis in cancer treatment. The focus is placed on the key components of the mechanisms, including their chemical nature, and specific attention is given to phytochemicals derived from natural sources and synthetic and semisynthetic compounds. 180+ compounds from the past two decades with potential as anticancer agents are discussed in this review article. By summarizing the current knowledge and advancements in this field, this review provides a comprehensive overview of potential therapeutic strategies targeting apoptosis in cancer cells. The findings presented herein contribute to the ongoing efforts to combat cancer and stimulate further research into the development of effective and targeted anticancer therapies.

Synthesis of Functionalized Isoquinolone Derivatives via Rh(III)-Catalyzed [4+2]-Annulation of Benzamides with Internal Acetylene-Containing α-CF3-α-Amino Carboxylates

A convenient pathway to a new series of α-CF₃-substituted α-amino acid derivatives bearing pharmacophore isoquinolone core in their backbone has been developed. The method is based on [4+2]-annulation of N-(pivaloyloxy) aryl amides with orthogonally protected internal acetylene-containing α-amino carboxylates under Rh(III)-catalysis. The target annulation products can be easily transformed into valuable isoquinoline derivatives via a successive aromatization/cross-coupling operation.

Pediatric acute lymphoblastic leukemia management using multitargeting bioactive natural compounds: A systematic and critical review

Pediatric acute lymphoblastic leukemia (pALL), a malignancy of the lymphoid line of blood cells, accounts for a large percentage of all childhood leukemia cases. Although the 5-year survival rate for children with ALL has greatly improved over years, using chemotherapeutics as its first-line treatment still causes short- and long-term side effects. Furthermore, induction of toxicity and resistance, as well as the high cost, limit their application. Phytochemicals, with remarkable cancer preventive and chemotherapeutic characteristics, may serve as old solutions to new challenges. Bioactive plant secondary metabolites have exhibited promising antileukemic and adjunctive effects by targeting various molecular processes, including autophagy, cell cycle, angiogenesis, and extrinsic/intrinsic apoptotic pathways. Although numerous reports have shown that numerous plant secondary metabolites can interfere with the progression of malignancies, including leukemia, there was no comprehensive review article on the effect of phytochemicals on pALL. This systematic review aims to provide critical and cohesive analysis of the potential of various naturally-occurring metabolites in the management of pALL with the understanding of underlying molecular and cellular mechanisms of action.

Cytotoxic Agents in the Minor Alkaloid Groups of the Amaryllidaceae

Over 600 alkaloids have to date been identified in the plant family Amaryllidaceae. These have been arranged into as many as 15 different groups based on their characteristic structural features. The vast majority of studies on the biological properties of Amaryllidaceae alkaloids have probed their anticancer potential. While most efforts have focused on the major alkaloid groups, the volume and diversity afforded by the minor alkaloid groups have promoted their usefulness as targets for cancer cell line screening purposes. This survey is an in-depth review of such activities described for around 90 representatives from 10 minor alkaloid groups of the Amaryllidaceae. These have been evaluated against over 60 cell lines categorized into 18 different types of cancer. The montanine and cripowellin groups were identified as the most potent, with some in the latter demonstrating low nanomolar level antiproliferative activities. Despite their challenging molecular architectures, the minor alkaloid groups have allowed for facile adjustments to be made to their structures, thereby altering the size, geometry, and electronics of the targets available for structure-activity relationship studies. Nevertheless, it was seen with a regular frequency that the parent alkaloids were better cytotoxic agents than the corresponding semisynthetic derivatives. There has also been significant interest in how the minor alkaloid groups manifest their effects in cancer cells. Among the various targets and pathways in which they were seen to mediate, their ability to induce apoptosis in cancer cells is most appealing.

Acetylcholinesterase and human cancers

The enzyme acetylcholinesterase (AChE) is a serine hydrolase whose primary function is to degrade acetylcholine (ACh) and terminate neurotransmission. Apart from its role in synaptic transmission, AChE has several "non-classical" functions in non-neuronal cells. AChE is involved in cellular growth, apoptosis, drug resistance pathways, response to stress signals and inflammation. The observation that the functional activity of AChE is altered in human tumors (relative to adjacent matched normal tissue) has raised several intriguing questions about its role in the pathophysiology of human cancers. Published reports show that AChE is a vital regulator of oncogenic signaling pathways involving proliferation, differentiation, cell-cell adhesion, migration, invasion and metastasis of primary tumors. The objective of this book chapter is to provide a comprehensive overview of the contributions of the AChE-signaling pathway in the growth of progression of human cancers. The AChE isoforms, AChE-T, AChE-R and AChE-S are robustly expressed in human cancer cell lines as well in human tumors (isolated from patients). Traditionally, AChE-modulators have been used in the clinic for treatment of neurodegenerative disorders. Emerging studies reveal that these drugs could be repurposed for the treatment of human cancers. The discovery of potent, selective AChE ligands will provide new knowledge about AChE-regulatory pathways in human cancers and foster the hope of novel therapies for this disease.

Evaluation of the Therapeutic Effect of Lycoramine on Alzheimer's Disease in Mouse Model

BACKGROUND

Alzheimer's disease is one of the leading health problems characterized by the accumulation of Aβ and hyperphosphorylated tau that account for the senile plaque formations causing extensive cognitive decline. Many of the clinical diagnoses of Alzheimer's disease are made in the late stages, when the pathological changes have already progressed.

OBJECTIVE

The objective of this study is to evaluate the promising therapeutic effects of a natural compound, lycoramine, which has been shown to have therapeutic potential in several studies and to understand its mechanism of action on the molecular level via differential protein expression analyses.

METHODS

Lycoramine and galantamine, an FDA approved drug used in the treatment of mild to moderate AD, were administered to 12 month-old 5xFAD mice. Effects of the compounds were investigated by Morris water maze, immunohistochemistry and label- free differential protein expression analyses.

RESULTS

Here we demonstrated the reversal of cognitive decline via behavioral testing and the clearance of Aβ plaques. Proteomics analysis provided in-depth information on the statistically significant protein perturbations in the cortex, hippocampus and cerebellum sections to hypothesize the possible clearance mechanisms of the plaque formation and the molecular mechanism of the reversal of cognitive decline in a transgenic mouse model. Bioinformatics analyses showed altered molecular pathways that can be linked with the reversal of cognitive decline observed after lycoramine administration but not with galantamine.

CONCLUSION

Lycoramine shows therapeutic potential to halt and reverse cognitive decline at the late stages of disease progression, and holds great promise for the treatment of Alzheimer's disease.

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.

Rh(III)-Catalyzed Redox-Neutral [4+2] Annulation for Direct Assembly of 3-Acyl Isoquinolin-1(2H)-ones as Potent Antitumor Agents

By virtue of an efficient rhodium(III)-catalyzed redox-neutral C-H activation/ring-opening of a strained ring/[4+2] annulation cascade of N-methoxybenzamides with propargyl cycloalkanols, diverse 3-acyl isoquinolin-1(2H)-ones were directly obtained in good yields and with excellent functional group compatibility. Additionally, their antitumor activities against various human cancer cells including HepG2, A549, MCF-7 and SH-SY5Y were evaluated and the action mechanism of the selected compound was also investigated in vitro. The results revealed that these products possessed a potent efficacy, by inhibiting proliferation and inducing apoptosis in a time-dependent and dose-dependent manner, suggesting that such compounds can serve as promising candidates for anti lung cancer drug discovery.

The Genus Nerine Herb. (Amaryllidaceae): Ethnobotany, Phytochemistry, and Biological Activity

Nerine Herbert, family Amaryllidaceae, is a genus of about 30 species that are native to South Africa, Botswana, Lesotho, Namibia, and Swatini (formerly known as Swaziland). Species of Nerine are autumn-flowering, perennial, bulbous plants, which inhabit areas with summer rainfall and cool, dry winters. Most Nerine species have been cultivated for their elegant flowers, presenting a source of innumerable horticultural hybrids. For many years, species of Nerine have been subjected to extensive phytochemical and pharmacological investigations, which resulted in either the isolation or identification of more than fifty Amaryllidaceae alkaloids belonging to different structural types. Amaryllidaceae alkaloids are frequently studied for their interesting biological properties, including antiviral, antibacterial, antitumor, antifungal, antimalarial, analgesic, cytotoxic, and cholinesterase inhibition activities. The present review aims to summarize comprehensively the research that has been reported on the phytochemistry and pharmacology of the genus Nerine.

Phytochemistry and Pharmacology of the Family Amaryllidaceae: An Overview of Research at RCPGD

Professor Johannes van Staden, Director of the Research Centre for Plant Growth and Development-University of KwaZulu Natal, conducts research in the field of plant physiology, biotechnology, and ethnomedicine. The research span over a wide range of plant families growing in the southern African region. The plant family Amaryllidaceae, known for its ornamental and pharmacological values, received much attention by his research group. This review covers research conducted by his group on the chemistry of some members of Amaryllidaceae and biological activities of their constituents.

Application of Electrocyclic Ring-Opening and Desymmetrizing Nucleophilic Trappings of meso-6,6-Dibromobicyclo[3.1.0]hexanes to Total Syntheses of Crinine and Haemanthamine Alkaloids

The thermally induced electrocyclic ring-opening of C₂-symmetric ( meso) 6,6-dibromobicyclo[3.1.0]hexanes such as 10 in the presence of the chiral, nonracemic 1°-amine 28 afforded a ca. 1:1 mixture of the diastereoisomeric and chromatographically separable 1-amino-2-bromo-2-cyclohexenes 37 (42%) and 38 (45%). Each of these was elaborated over 13 steps, including Suzuki-Miyaura cross-coupling, radical cyclization, and Pictet-Spengler reactions, into (-)- or (+)-crinane (1 or ent-1, respectively). Variations on these protocols were applied to the total syntheses of (+)- and (-)-11-hydroxyvattitine [(+)- and (-)-3], (+)- and (-)-bulbispermine [(+)- and (-)-4], (+)- and (-)-haemanthamine [(+)- and (-)-5], (+)- and (-)-pretazettine [(+)- and (-)-6], and (+)- and (-)-tazettine [(+)- and (-)-7] as well as (±)-hamayne [(±)-8] and (±)-apohaemanthamine [(±)-9]. A number of these alkaloids were synthesized for the first time.

Phenanthridone Alkaloids of the Amaryllidaceae as Activators of the Apoptosis-related Proteolytic Enzymes, Caspases

Apoptosis-inducing anticancer drugs have garnered widespread interest in recent years. Targets which concomitantly also exhibit minimal adverse effects in normal, healthy cells have been particularly well-received. The phenanthridone alkaloids such as pancratistatin and narciclasine exemplify such a class of chemotherapeutics, with potent and selective cytotoxic effects in a wide variety of cancer cells which are manifested via the apoptotic mode of cell death. Caspases are central to the apoptotic process through their key function as effector molecules in apoptosis-related signaling pathways. Any attempt to mediate in such pathways, for example to probe the efficacy or mechanism of action of a drug, would inexorably serve to have a modulatory effect on these proteolytic enzymes. Apoptosis studies of phenanthridone alkaloids of the Amaryllidaceae have only gathered momentum over the past decade, following which caspases have understandably emerged as reliable biochemical markers of the process in an assortment of cancers. This review covers such studies of these alkaloids based on their structural-type, pointing out the various caspases which have been activated in different cancer cells and how structure modification can to a certain extent have a bearing on such activity. Also considered are clues to the apoptosis signaling pathways mediated following phenanthridone-induced activation of caspases.

Exposure to nicotine-derived nitrosamine ketone and arecoline synergistically facilitates tumor aggressiveness via overexpression of epidermal growth factor receptor and its downstream signaling in head and neck squamous cell carcinoma

Long-term nicotine-derived nitrosamine ketone (NNK) and arecoline exposure promotes carcinogenesis and head and neck squamous cell carcinoma (HNSCC) progression, although most associated data on the two were analyzed individually. The molecular mechanisms underlying tumor progression associated with the synergistic effects of NNK and arecoline remain unclear. We treated SCC-25 and FaDu cells with NNK and arecoline (separately or in combination) for 3 months. Comparative analysis was performed to investigate the mechanism underlying the acquisition of properties related to tumor promotion, including stemness, anti-apoptosis, and resistance to HNSCC therapeutics. Long-term exposure to NNK and arecoline resulted in an increase in cancer stem cell properties, anti-apoptosis, and the resistance to cisplatin in HNSCC. We detected abundant epidermal growth factor receptor (EGFR) expression in HNSCC cells after combined treatment with NNK and arecoline. EGFR was pivotal in inducing tumor promotion and anti-apoptosis in cancer cells by inducing pAKT and NFκB. Combined treatment with NNK and arecoline synergistically facilitated tumor aggressiveness via EGFR–AKT signaling. Targeting EGFR–AKT signaling may be a feasible strategy for treating HNSCC.

Short, Gram-Scale Syntheses of β- and γ-Lycorane Using Two Distinct Photochemical Approaches

The synthesis of two diastereomeric members of the lycorane alkaloid family is reported. Although the routes are quite different in their approach, both involve the use of photochemistry as a key step, enabling the synthesis of gram quantities in the case of β-lycorane.

Haemanthamine alters sodium butyrate-induced histone acetylation, p21WAF1/Cip1 expression, Chk1 and Chk2 activation and leads to increased growth inhibition and death in A2780 ovarian cancer cells

BACKGROUND

Haemanthamine (HA) and sodium butyrate (NaB) are promising candidates for chemotherapy as a treatment for cancer.

PURPOSE

We aimed to determine the anticancer potential of HA and NaB, alone and in combination, in A2780 ovarian cancer cells and concurrently investigated anticancer potential in contrast to non-cancer human MRC-5 fibroblasts.

METHODS

Antiproliferative effects were determined by WST-1 assay and by Trypan blue exclusion staining. Cell cycle distributions were studied by flow cytometry and protein levels were determined by Western blotting.

RESULTS

The combination of HA and NaB caused a significant decrease in the proliferation of A2780 cells compared to the stand-alone treatment of cells by HA or NaB. This effect was less pronounced in non-cancer MRC-5 fibroblasts. In the later intervals, the number of A2780 living cells was strongly decreased by treatment using a combination of NaB and HA. This simultaneous application had no considerable effect in MRC-5 fibroblasts. The combination of NaB and HA led to the suppression of cells in the G1 phase and caused an accumulation of cells in the S and G2 phase in comparison to those treated with NaB and HA alone. Treatment of cells with NaB alone led to the activation of proteins regulating the cell cycle. Notably, p21^WAF1/Cip1 was upregulated in both A2780 and MRC-5 cells, while checkpoint kinases 1 and 2 were activated via phosphorylation only in A2780 cells. Unexpectedly, NaB in combination with HA suppressed the phosphorylation of Chk2 on threonine 68 and Chk1 on serine 345 in A2780 cells and downregulated p21^WAF1/Cip1 in both tested cell lines. The sensitization of cells to HA and NaB treatment seems to be accompanied by increased histone acetylation. NaB-induced acetylation of histone H3 and H4 and histone acetylation increased markedly when a combination of NaB and HA was applied. Whereas the most prominent hyperacetylation after HA and NaB treatment was observed in A2780 cells, the acetylation of histones occurred in both cell lines.

CONCLUSION

In summary, we have demonstrated the enhanced activity of HA and NaB against A2780 cancer cells, while eliciting no such effect in non-cancer MRC-5 cells.

Phytochemical and biological investigations of Amaryllidaceae alkaloids: a review

Amaryllidaceae is a family that includes 75 genera and about 1100 species, which have a long history of medicinal use. Many plants have been proven to possess efficacy for neurological injury and inflammatory conditions. This article summarizes 357 Amaryllidaceae alkaloids, and cites 166 174 references over the last three decades. These alkaloids are classified into 14 skeleton types, and their abundant sources are also included. Modern pharmacology studies demonstrate that alkaloids that exclusively occur in Amaryllidaceae plant possess wide-ranging pharmacological actions, especially effects on the central nervous system, as well as antitumor, antimicrobial, and anti-inflammatory activities. Effective monomeric compounds from Amaryllidaceae screened for pharmacological activity in vivo and in vitro are also summarized.

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.

Isolation of Amaryllidaceae alkaloids from Nerine bowdenii W. Watson and their biological activities

Twenty-two isoquinoline alkaloids (1–22) were isolated from fresh bulbs of Nerine bowdenii (Amaryllidaceae) by standard chromatographic methods.

Amaryllidaceae and Sceletium alkaloids

The latest progress on the isolation, identification, biological activity and synthetic studies of the structurally diverse alkaloids from plants of family Amaryllidaceae has been summarized in this review.

Molecular docking study of natural alkaloids as multi-targeted hedgehog pathway inhibitors in cancer stem cell therapy

Cancer is responsible for millions of deaths throughout the world every year. Increased understanding as well as advancements in the therapeutic aspect seems suboptimal to restrict the huge deaths associated with cancer. The major cause responsible for this is high resistance as well as relapse rate associated with cancers. Several evidences indicated that cancer stem cells (CSC) are mainly responsible for the resistance and relapses associated with cancer. Furthermore, agents targeting a single protein seem to have higher chances of resistance than multitargeting drugs. According to the concept of network model, partial inhibition of multiple targets is more productive than single hit agents. Thus, by fusing both the premises that CSC and single hit anticancer drugs, both are responsible for cancer related resistances and screened alkaloids for the search of leads having CSC targeting ability as well as the capability to modulating multiple target proteins. The in silico experimental data indicated that emetine and cortistatin have the ability to modulate hedgehog (Hh) pathway by binding to sonic hedgehog (Hh), smoothened (Smo) and Gli protein, involved in maintenance CSCs. Furthermore, solamargine, solasonine and tylophorine are also seems to be good lead molecules targeting towards CSCs by modulating Hh pathway. Except solamargine and solasonine, other best lead molecules also showed acceptable in silico ADME profile. The predicted lead molecules can be suitably modified to get multitargeting CSC targeting agent to get rid of associate resistances.

Biological and pharmacological activities of amaryllidaceae alkaloids

This review discusses the recent developments on biological and pharmacological activities of amaryllidaceae alkaloids with IC₅₀or EC₅₀values since 2005, supporting the potential therapeutic possibilities for the use of these compounds.

Efficient synthesis of tetrahydronaphthalene- or isochroman-fused spirooxindoles using tandem reactions

The cascade reaction involving a Michael–aldol or vinylogous Henry-acetalization relay is described. We have used the cascade reaction to assemble tetrahydronaphthalene- or isochroman-fused spirooxindoles and other drug-like spirocyclic scaffolds.

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.

Cytotoxicity Studies of Lycorine Alkaloids of the Amaryllidaceae

The plant family Amaryllidaceae is renowned for its unique alkaloid constituents which possess a significant array of structural diversity. Several of these alkaloids are known for their interesting biological properties, of which galanthamine and pancratistatin have acquired a privileged status due to their relevance in the pharmaceutical arena. In particular, galanthamine represents the first prescription drug emanating from the Amaryllidaceae after its approval by the FDA in 2001 for the treatment of Alzheimer's disease. Following on this commercial success there have been sustained projections for the emergence of an anticancer agent related to pancratistatin due to the potency, selectivity, low toxicity and high tolerability typifying targets of this series of alkaloids. The lycorine series of alkaloids have also garnered widespread interest as cytotoxic agents and were amongst the earliest of the Amaryllidaceae constituents to exhibit such activity. To date over 100 of such naturally-occurring or synthetically-derived alkaloids have been screened for cytotoxic effects against a number of cancer cell lines. This survey examines the cytotoxic properties of lycorine alkaloids, highlights the outcomes of structure-activity relationship orientated studies and affords plausible insights to the mechanistic rationale behind these effects.

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).

The effect of Amaryllidaceae alkaloids haemanthamine and haemanthidine on cell cycle progression and apoptosis in p53-negative human leukemic Jurkat cells

Plants from the Amaryllidaceae family have been shown to be a promising source of biologically active natural compounds of which some selected are currently in pre-clinical development. Regardless of interesting pioneer works, little is known about Amaryllidaceae alkaloids that have shown promising anti-cancer activities. The crinane group of the Amaryllidaceae, including haemanthamine and haemanthidine, was amongst the first of these compounds to exhibit an interesting cytotoxic potential against cancer cell lines. However, the mechanism of cytotoxic and anti-proliferative activity is not yet entirely clear. The primary objectives of the current study were to investigate the effects of haemanthamine and haemanthidine on the induction of apoptosis and the cell cycle regulatory pathway in p53-null Jurkat cells. Results indicate that haemanthamine and haemanthidine treatment decreases cell viability and mitochondrial membrane potential, leads to a decline in the percentage of cells in the S phase of the cell cycle, induces apoptosis detected by Annexin V staining and increases caspase activity. Dose dependent apoptosis was cross verified by fluorescence and bright field microscopy through Annexin V/propidium iodine staining and morphological changes which characteristically attend programmed cell death. The apoptotic effect of haemanthamine and haemanthidine on leukemia cells is more pronounced than that of gamma radiation. Contrary to gamma radiation, Jurkat cells do not completely halt the cell cycle 24h upon haemanthamine and haemanthidine exposure. Both Amaryllidaceae alkaloids accumulate cells preferentially at G1 and G2 stages of the cell cycle with increased p16 expression and Chk1 Ser345 phosphorylation. Concerning the pro-apoptotic effect, haemanthidine was more active than haemanthamine in the Jurkat leukemia cell line.

Traditional usage, phytochemistry and pharmacology of the South African medicinal plant Boophone disticha (L.f.) Herb. (Amaryllidaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Boophone disticha is the most common member of the South African Amaryllidaceae used extensively in traditional medicine of the various indigenous population groups, including the Sotho, Xhosa and Zulu as well as the San. This survey was carried out to identify and highlight areas relevant to the traditional usage of Boophone disticha. Pharmacological aspects were examined with the purpose of reconciling these with the traditional usage of the plant. In relation to phytochemical make-up, particular attention was paid on how its alkaloid constitution might corroborate the various biological effects manifested by the plant.

MATERIALS AND METHODS

Information gathering involved the use of four different database platforms, including Google Scholar, ScienceDirect, SciFinder(®) and Scopus. Arrangement and detailing of this information is as reflected in the various sections of the paper.

RESULTS

Sixteen categories were identified under which Boophone disticha finds use in traditional medicine. These were shown to include general usage purposes, such as 'cultural and dietary', 'well-being', 'personal injury', 'divinatory purposes', 'psychoactive properties' and 'veterinary uses'. Furthermore, traditional usage was seen to involve six body systems, including functions pertaining to the circulatory, gastrointestinal, muscular, neurological, respiratory and urinary systems. The four remaining categories relate to use for inflammatory conditions, cancer, malaria and tuberculosis. Overall, three areas were discernible in which Boophone disticha finds most usage, which are (i) ailments pertaining to the CNS, (ii) wounds and infections, and (iii) inflammatory conditions. In addition, several aspects pertaining to the toxic properties of the plant are discussed, including genotoxicity, mutagenicity and neurotoxicity.

CONCLUSION

The widespread ethnic usage of Boophone disticha has justified its standing as a flagship for the Amaryllidaceae and its relevance to South African traditional medicine. Furthermore, its promising pharmacological and phytochemical profiles have stimulated significant interest in the clinical realm, especially in the areas of cancer and motor neuron disease chemotherapy. These collective properties should prove useful in steering the progress of the plant towards a wider audience.

In vitro neuroprotective potential of four medicinal plants against rotenone-induced toxicity in SH-SY5Y neuroblastoma cells

BACKGROUND

Lannea schweinfurthii, Zanthoxylum capense, Scadoxus puniceus and Crinum bulbispermum are used traditionally to treat neurological disorders. The aim of this study was to evaluate the cytoprotective potential of the four plants, after induction of toxicity using rotenone, in SH-SY5Y neuroblastoma cells.

METHODS

Cytotoxicity of the plant extracts and rotenone was assessed using the sulforhodamine B (SRB) assay. Fluorometry was used to measure intracellular redox state (reactive oxygen species (ROS) and intracellular glutathione content), mitochondrial membrane potential (MMP) and caspase-3 activity, as a marker of apoptotic cell death.

RESULTS

Of the tested plants, the methanol extract of Z. capense was the least cytotoxic; LC50 121.3 ± 6.97 μg/ml, while S. puniceus methanol extract was the most cytotoxic; LC50 20.75 ± 1.47 μg/ml. Rotenone reduced intracellular ROS levels after 24 h exposure. Pre-treating cells with S. puniceus and C. bulbispermum extracts reversed the effects of rotenone on intracellular ROS levels. Rotenone exposure also decreased intracellular glutathione levels, which was counteracted by pre-treatment with any one of the extracts. MMP was reduced by rotenone, which was neutralized by pre-treatment with C. bulbispermum ethyl acetate extract. All extracts inhibited rotenone-induced activation of caspase-3.

CONCLUSION

The studied plants demonstrated anti-apoptotic activity and restored intracellular glutathione content following rotenone treatment, suggesting that they may possess neuroprotective properties.

Alkaloids from Boophone haemanthoides (Amaryllidaceae)

In this study, the South African Amaryllid Boophone haemanthoides was examined for its phytochemical composition and cytotoxicity. In the process eight alkaloid structures, including the new compound distichaminol, were identified in bulb ethanolic extracts. Of the isolates, lycorine and distichamine exhibited strong activities against human acute lymphoblastic leukemia (CEM), breast adenocarcinoma (MCF7) and cervical adenocarcinoma (HeLa) cells with IC50s ranging from 1.8 to 9.2 μM.

Research Progress on the Anti-Leukemia Effect of Lycorine

Lycorine is a kind of natural alkaloid extracted from Amaryllidaceae that has shown various pharmacological effects. Recent studies have focused on the potential antitumor activity of lycorine. The inhibition effects of lycorine on the cell proliferation of leukemia HL-60 cells, K562 cells, chronic lymphocytic leukemia, U937 cells and structure-activity studies on the lycorine pharmacophore in leukemia cells were summarized in the article. The review of pharmacological effects and structure-activity on leukemia of lycorine can provide a reference for the further development and utilization on the kind of natural products.

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.

Pharmacological and toxicological insights to the South African Amaryllidaceae

The plant family Amaryllidaceae is of provenance in the South African region which is known to harbor about a third of the global complement of around 1000 species. It has widespread usage in the traditional medicinal practices of the indigenous peoples of the region. As a consequence and given its unique alkaloid principles, its members have provided a viable platform for phytochemical based drug discovery. The medicinal potential of the family has been realized through the commercialization of galanthamine as an Alzheimer's drug due to its potent and selective inhibitory activity against the enzyme acetylcholinesterase. Further promising chemotherapeutic candidates of the family reside with the phenanthridone class of alkaloids such as pancratistatin which exhibit potent and cell line specific antiproliferative properties with significant potential for clinical development. Despite these interesting medicinal attributes, plants of the Amaryllidaceae are known to be poisonous and several of them have been classified as such. This survey taking into consideration Amaryllidaceae plants native to South Africa aims to strike a balance between the medicinal potential of the family on one hand and its adverse and toxic effects on the other.

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.

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.

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.