A tale of two tumor targets: topoisomerase I and tubulin. The Wall and Wani contribution to cancer chemotherapy

Synthesis and evaluation of homocamptothecin antibody-drug conjugates for cancer treatment

As an emerging tumor therapeutic strategy, antibody-drug conjugates (ADCs) overcome the high toxicity of traditional small molecule chemotherapy and improve the targeting of treatment. In this study, we successfully constructed a novel ADC, Tras-16b, for the first time using homocamptothecin 16b as the payload. Tras-16b, at a dose of 3 mg/kg, exhibited comparable anti-tumor activity to Enhertu and demonstrated an enhanced safety profile in the NCI-N87 xenograft model. Notably, this is the first ADC developed based on homocamptothecin, marking a significant advancement with promising prospects for the structural modification of camptothecin ADCs.

Iron-Catalyzed Synthesis of 13-Aryl-13H-indeno[1,2-l]phenanthrene via Double Annulations of 2-Alkynyl Biaryls

An Fe(III)-catalyzed expedient synthesis of 13-aryl-13H-indeno[1,2-l]phenanthrene is described by a double annulations of 2-alkynyl biaryls, initiated by the activation of acetal. This strategy provides a simple, efficient and regioselective synthesis of varieties of indenophenanthrene derivatives from easily available starting materials under mild conditions in high to excellent yields. A plausible reaction mechanism is proposed.

Nutritional values and phytochemical analysis of Allium calocephalum Wendelbo, a valuable endemic wild garlic to Zagros mountains

Wild edible plants provide the local people with food and medicines and are considered one of the natural ecosystem services. These wild edible diets and herbal medicine always reflect local communities' regional identity and their traditional ecological knowledge. In the new global economy, the natural product field has become a central issue for preserving the traditional culture related to nature, particularly in the context of a sustainable environment. This research study aims to determine the nutritional value and phytochemical contents in a wild population of Allium calocephalum. This wild edible garlic, endemic to the Zagros mountains, is overharvested by Kurdish rural people to enhance their food security at a household level and to perpetuate the preservation of their natural heritage. Here, we estimated the total phenols, flavonoids, carbohydrates, protein, fibers, ash, oil yield, and significant mineral content in both leaves and bulbs of A. calocephalum. Phytochemical analyses were conducted at the Faculty of Agricultural Engineering Sciences (University of Duhok) and the environmental directory of Duhok, Kurdistan Region of Iraq, to get an overview of its nutrients and phytochemical values. Interestingly, a high level of phenolic compounds was obtained from bulbs (0.684 mg gallic acid equivalents/g of dry extract, eq.100g-1). The lowest level of phenolic compounds was found in leaves (0.522 mg gallic acid equivalents/g of dry extract, eq.100g-1). Simultaneously, the bulbs extract gave higher content of flavonoid compounds than the leaves extract (6.31 and 4.73 μg quercetin equivalents/g of dry extract, eq.100g-1, respectively, for the bulbs and leaves). The highest dry weight basis of total carbohydrates, energy value (Kcal), oil content, and moisture content were observed in bulbous parts, and the values were 71.75, 408.86 (Kcal), 9.52, and 92.37, respectively. On the other side, the highest dry weight basis of total protein, fibers, and Ash content was observed in shoot parts, and the values were 15.93, 13.89, and 9.32, respectively. The evidence from this research study supports the idea that this Zagrosian endemic wild garlic enhances the food security and the nutrient diet values of the rural Kurdish people. Keywords: Wild garlic; ethnobotany; edible plants; food security; natural resources; herbal medicine.

Current Status, Distribution, and Future Directions of Natural Products against Colorectal Cancer in Indonesia: A Systematic Review

In 2020, an estimated 19.3 million new cancer cases and nearly 10 million cancer deaths have occurred worldwide, with colorectal cancer ranking as the third most frequently diagnosed (10.0%). Several attempts have been conducted against cancer, including surgery, radiation, monoclonal antibodies, and chemotherapy. Many people choose natural products as alternatives against cancer. These products will not only help in human life preservation but also work as a source of up-to-date information, leading people away from incorrect information. We discuss the current status, distribution, and future implications of protecting populations with natural products as an alternative against colorectal cancer in Indonesia. Thirty-eight studies were included in this review for data extraction. The distribution of natural products in Indonesia that have potential activity against colorectal cancer cells was predominated by terpenoids, followed by phytosterols, phenolics, alkaloids, and polyisoprenoids. The type of cell line utilized in the cytotoxic activity analysis of natural products was the WiDr cell line, followed by HT-29 cells and HCT-116 cells. This review showed that MTT in vitro assay is a general method used to analyze the cytotoxic activity of a natural product against colorectal cancer cells, followed by other in vitro and in vivo methods. The systematic review provided predictions for several secondary metabolites to be utilized as an alternative treatment against colorectal cancer in Indonesia. It also might be a candidate for a future co-chemotherapy agent in safety, quality, and standardization. In addition, computational methods are being developed to predict the drug-likeness of compounds, thus, drug discovery is already on the road towards electronic research and development.

One pot synthesis, in silico study and evaluation of some novel flavonoids as potent topoisomerase II inhibitors

A library of novel flavonoid derivatives with diverse heterocyclic groups was designed and efficiently synthesized. Structures of the newly synthesized compounds 4a-i and 8a-l have been characterized by ¹H NMR, ¹³C NMR, MS and elemental analysis. Anticancer activities were evaluated against MCF-7, A549, HepG2 and MCF-10A by MTT based assay. Compared with the positive control Adriamycin, compounds 4a, 4b, 4c, 4d, 8d, 8e and 8j were found to be most active anti-proliferative compounds against human cancer cell line. We found that compounds 4a and 4c exhibited inhibition of enzyme topoisomerase II with IC₅₀ values 10.28 and 12.38 μM, respectively. In silico docking study of synthesized compounds showed that compounds 4a and 4c have good binding affinity toward topoisomerase IIα enzyme and have placed in between DNA base pair at active site of enzyme. In silico ADME prediction results that flavonoid coumarin analogues 4a-i could be exploited as an oral drug candidate.

Plant Endophytes and Epiphytes: Burgeoning Sources of Known and "Unknown" Cytotoxic and Antibiotic Agents?

In the last 20 or so years, the influence of endophytes and, quite recently, epiphytes of plants upon the compounds found in those plants, which were usually assumed to be phytochemicals produced by the plant for a variety of reasons, often as a defense against predators, is becoming more evident, in particular in the case of antitumor agents originally isolated from plant sources, though antibiotic agents might also be found, particularly from epiphytes. In this review, we started with the first report in 1993 of a taxol-producing endophyte and then expanded the compounds discussed to include camptothecin, the vinca alkaloids, podophyllotoxin, and homoharringtonine from endophytic microbes and then the realization that maytansine is not a plant secondary metabolite at all, and that even such a well-studied plant such as Arabidopsis thaliana has a vast repertoire of potential bioactive agents in its leaf epiphytic bacteria. We have taken data from a variety of sources, including a reasonable history of these discoveries that were not given in recent papers by us, nor in other papers covering this topic. The sources included the Scopus database, but we also performed other searches using bibliographic tools, thus, the majority of the papers referenced are the originals, though we note some very recent papers that have built on previous results. We concluded with a discussion of the more modern techniques that can be utilized to "persuade" endophytes and epiphytes to switch on silent biosynthetic pathways and how current analytical techniques may aid in evaluating such programs. We also comment at times on some findings, particularly in the case of homoharringtonine, where there are repetitious data reports differing by a few years claiming the same endophyte as the producer.

Quinovic acid purified from medicinal plant Fagonia indica mediates anticancer effects via death receptor 5

Plants are major source for discovery and development of anticancer drugs. Several plant-based anticancer drugs are currently in clinical use. Fagonia indica is a plant of medicinal value in the South Asian countries. Using mass spectrometry and NMR spectroscopy, several compounds were purified from the F. indica extract. We have used one of the purified compounds quinovic acid (QA) and found that QA strongly suppressed the growth and viability of human breast and lung cancer cells. QA did not inhibit growth and viability of non-tumorigenic breast cells. QA mediated its anticancer effects by inducing cell death. QA-induced cell death was associated with biochemical features of apoptosis such as activation of caspases 3 and 8 as well as PARP cleavage. QA also upregulated mRNA and protein levels of death receptor 5 (DR5). Further investigation revealed that QA did not alter DR5 gene promoter activity, but enhanced DR5 mRNA and protein stabilities. DR5 is one of the major components of the extrinsic pathway of apoptosis. Accordingly, Apo2L/TRAIL, the DR5 ligand, potentiated the anticancer effects of QA. Our results indicate that QA mediates its anticancer effects, at least in part, by engaging DR5-depentent pathway to induce apoptosis. Based on our results, we propose that QA in combination with Apo2L/TRAIL can be further investigated as a novel therapeutic approach for breast and lung cancers.

Current status and contemporary approaches to the discovery of antitumor agents from higher plants

Higher plant constituents have afforded clinically available anticancer drugs. These include both chemically unmodified small molecules and their synthetic derivatives currently used or those in clinical trials as antineoplastic agents, and an updated summary is provided. In addition, botanical dietary supplements, exemplified by mangosteen and noni constituents, are also covered as potential cancer chemotherapeutic agents. Approaches to metabolite purification, rapid dereplication, and biological evaluation including analytical hyphenated techniques, molecular networking, and advanced cellular and animal models are discussed. Further, enhanced and targeted drug delivery systems for phytochemicals, including micelles, nanoparticles and antibody drug conjugates (ADCs) are described herein.

Sequential Cross-Coupling/Annulation of ortho-Vinyl Bromobenzenes with Aromatic Bromides for the Synthesis of Polycyclic Aromatic Compounds

A sequential cross-coupling/annulation of ortho-vinyl bromobenzenes with aromatic bromides was realized, providing a direct and modular approach to access polycyclic aromatic compounds. A vinyl-coordinated palladacycle was proposed as the key intermediate for this sequential process. Excellent chemoselectivity and regioselectivity were observed in this transformation. The practicability of this method is highlighted by its broad substrate scope, excellent functional group tolerance, and rich transformations associated with the obtained products.

Synthesis and Evaluation of Linear and Macrocyclic Dolastatin 10 Analogues Containing Pyrrolidine Ring Modifications

Because of their potent cytotoxic activity, members of the auristatin family (synthetic analogues of the naturally occurring dolastatin 10) have remained a target of significant research, most notably in the context of antibody drug conjugate payloads. Typically, modifications of the backbone scaffold of dolastatin 10 have focused on variations of the N-terminal (P1) and C-terminal (P5) subunits. Scant attention has been paid thus far to the P4 subunit in the scientific literature. In this paper, we introduce an azide functional group at the P4 subunit, resulting in potent cytotoxic activity seen in vitro. Another highly active compound in this study contained azide functional groups in both the P2 and P4 subunits and required dolavaline as the P1 subunit and a phenylalanine as the P5 subunit. Furthermore, these two azide groups served not only as modifiers of cytotoxicity but also as handles for linker attachment or as a tether for use in the synthesis of a macrocyclic analogue.

Oxidative cyclization of 2-allenyl-1,1'-biphenyls with α-carbonyl alkyl bromides: facile access to functionalized phenanthrenes

A new copper-facilitated oxidative cyclization of 2-allenyl-1,1'-biphenyls with α-carbonyl alkyl bromides for producing functionalized phenanthrenes is presented, which represents the first allene 2,3-dicarbofunctionalization triggered by oxidative radical-medicated C3-addition of the terminal allene moiety and C-Br/C-H functionalization.

The Search for Anticancer Agents from Tropical Plants

Many of the clinically used anticancer agents in Western medicine are derived from secondary metabolites found in terrestrial microbes, marine organisms, and higher plants, with additional compounds of this type being currently in clinical trials. If plants are taken specifically, it is generally agreed that the prospects of encountering enhanced small organic-molecule chemical diversity are better if tropical rather than temperate species are investigated in drug discovery efforts. Plant collection in tropical source countries requires considerable preparation and organization to conduct in a responsible manner that abides by the provisions of the 1992 Rio Convention of Biological Diversity and the 2010 Nagoya Protocol on Access to Genetic Resources. Correct taxonomic identifications and enhanced procedures for processing and documenting plant samples when collected in often difficult terrain are required. Phytochemical aspects of the work involve solvent fractionation, known compound dereplication, preliminary in vitro testing, and prioritization, leading to "activity-guided fractionation", compound structure determination, and analog development. Further evaluation of lead compounds requires solubility, formulation, preliminary pharmacokinetics, and in vivo testing in suitable models. Covering the work of the authors carried out in two sequential multidisciplinary, multi-institutional research projects, examples of very promising compounds discovered from plants acquired from Africa, Southeast Asia, the Americas, and the Caribbean region, and with potential anticancer activity will be mentioned. These include plant secondary metabolites of the diphyllin lignan, cyclopenta[b]benzofuran, triterpenoid, and tropane alkaloid types.

Strictosidine Synthase Triggered Enantioselective Synthesis of N-Substituted (S)-3,14,18,19-Tetrahydroangustines as Novel Topoisomerase I Inhibitors

Monoterpenoid indole alkaloids (MIAs) comprise an important class of molecules for drug discovery, and they have variant carbon skeletons with prominent bioactivities. For instance, in spite of limitations to their use, camptothecins are the only clinically approved topoisomerase I (Top1) inhibitors. The enzyme strictosidine synthase, which is key for MIA biosynthesis, was applied to the enantioselective preparation of three N-substituted (S)-3,14,18,19-tetrahydroangustine (THA) derivatives. These non-camptothecin MIAs were shown to have moderate in vitro HepG2 cytotoxicity and Top1 inhibition activities. The (S)-configured MIAs had stronger cytotoxicity and Top1 inhibition than their chemically synthesized (R)-enantiomers, which aligned with the results of molecular dynamics simulations. A series of N-substituted (S)-THAs were then chemoenzymatically synthesized to investigate structure-activity relationships. The most active analogue observed was the N-(2-Cl benzoyl)-substituted derivative (7i). Insight into the binding mode of 7i and a Top1-DNA covalent complex was investigated by molecular dynamics simulations, which will facilitate future efforts to optimize the Top1 inhibitory activities of non-camptothecin MIAs.

A new route to π-extended polycyclic aromatic hydrocarbons via cross-dehydrogenative coupling

A rare example of fruitful construction of highly π-extended PAHs expressly via palladium-catalyzed CDC reaction is demonstrated.

Further insight into the photochemical behavior of 3-aryl-N-(arylsulfonyl)propiolamides: tunable synthetic route to phenanthrenes

Reported herein is further insight into the photochemical behaviour of 3-aryl-N-(arylsulfonyl)-propiolamides, which provides a straightforward way to access meaningful phenanthrenes.

Identification of potential tubulin polymerization inhibitors by 3D-QSAR, molecular docking and molecular dynamics

View of the correlation between experimental and predicted pIC₅₀c values, and the compound 22c docked into the binding site of 3UT5.

A Perspective on the Phytopharmaceuticals Responsible for the Therapeutic Applications

The word phytopharmaceutical deals with a complex mixture of compounds derived from the plant source that is used as a medicine or drug. Primitive human societies have been depending on plants and plant products for various remedies. Several plants in the different forms have been reported in traditional medicine and to find a rational for the treatment of various diseases than to isolated single compounds. Many of the single compounds isolated from the plant origin are effectively used in the medicine. The search of natural products in drug discovery has been greatly enhanced in the last few years. The impetus to use phytopharmaceutical agents for the treatment of disease, most of the plant based drugs are quite safe and have lesser adverse effects and are claimed that it works as synergistic effects.

A simple method to improve the stability of docetaxel micelles

Self-assembled polymeric micelles have been widely applied in drug delivery systems. In this study, we found that pH value of micellar system solution was the decisive factor of physical stability. Furthermore, the weak basic solution could maintain the solution clarification for a relative long time. To investigate the stability of polymeric micelles in different pH solutions, the micellar particle size and the docetaxel content remaining in solution were detected at predetermined time points. The crystallographic assay of freeze-drying powder was characterized by an X-ray diffractometer. In vitro release results indicated that the PBS had little influence on the sustained-release effect of docetaxel-loaded polymeric micelles (DPM). Besides, the safety of micellar formulation was determined by an MTT assay on HEK293 cells, and the anti-tumor activity was tested on MCF-7 cells. The results demonstrated that DPM adjusted with PBS (DPM (PBS)) was of low toxicity and maintained the effectiveness of docetaxel. In vivo antitumor results indicated that DPM (PBS) had better antitumor efficacy than common docetaxel injection (DTX). Thus it was concluded that regulation of micellar solution PH by PBS is a safe and effective method to improve the physical stability of DPM. It might promote the application of micellar formulation in clinical applications.

Appraisals of Bangladeshi Medicinal Plants Used by Folk Medicine Practitioners in the Prevention and Management of Malignant Neoplastic Diseases

Cancer is a group of diseases which is categorized to differentiate into diverse cell types and move around in the body to sites of organogenesis that is key to the process of tumor genesis. All types of cancer fall into the group of malignant neoplastic diseases. In Bangladesh, cancer is now one of the foremost killer diseases and its personal, social, and economic bearing are huge. Plant-derived natural compounds (vincristine, vinblastine, etoposide, paclitaxel, camptothecin, topotecan, and irinotecan) are useful for the treatment of cancer. Since there is no extensive ethnobotanical research study in Bangladesh regarding the traditional uses of medicinal plants against neoplasms, therefore, a randomized ethnopharmacological surveys were carried out in 3 districts of Bangladesh to learn more about the usage of anticancer medicinal plants and their chemical constituents having antineoplastic activity. Comprehensive interviews were conducted to the folk medicine practitioners and medicinal plants as pointed out by them were photographed, collected, deposited, and identified at the Bangladesh National Herbarium. The various plant parts have been used by the healers which included whole plant, leaves, fruits, barks, roots, and seeds. This study evaluated considerable potential for discovery of novel compounds with less side effects in the management and prevention of malignancy in cancer.

Ascorbic acid promoted [4 + 2] benzannulation: a mild, operationally simple approach to the synthesis of phenanthrenes

Ascorbic acid-promoted radical [4 + 2] benzannulation for the generation of substituted phenanthrenes at room temperature has been developed.

Strategies for the Optimization of Natural Leads to Anticancer Drugs or Drug Candidates

Natural products have made significant contribution to cancer chemotherapy over the past decades and remain an indispensable source of molecular and mechanistic diversity for anticancer drug discovery. More often than not, natural products may serve as leads for further drug development rather than as effective anticancer drugs by themselves. Generally, optimization of natural leads into anticancer drugs or drug candidates should not only address drug efficacy, but also improve absorption, distribution, metabolism, excretion, and toxicity (ADMET) profiles and chemical accessibility associated with the natural leads. Optimization strategies involve direct chemical manipulation of functional groups, structure-activity relationship directed optimization and pharmacophore-oriented molecular design based on the natural templates. Both fundamental medicinal chemistry principles (e.g., bioisosterism) and state-of-the-art computer-aided drug design techniques (e.g., structure-based design) can be applied to facilitate optimization efforts. In this review, the strategies to optimize natural leads to anticancer drugs or drug candidates are illustrated with examples and described according to their purposes. Furthermore, successful case studies on lead optimization of bioactive compounds performed in the Natural Products Research Laboratories at UNC are highlighted.

Identification of gallic acid based glycoconjugates as a novel tubulin polymerization inhibitors

A novel class of gallic acid based glycoconjugates were designed and synthesized as potential anticancer agents. Among all the compounds screened, compound 2a showed potent anticancer activity against breast cancer cells. The latter resulted in tubulin polymerization inhibition and induced G2/M cell cycle arrest, generation of reactive oxygen species, mitochondrial depolarization and subsequent apoptosis in breast cancer cells. In addition, ultraviolet-visible spectroscopy and fluorescence quenching studies of the compound with tubulin confirmed direct interaction of compounds with tubulin. Molecular modeling studies revealed that it binds at the colchicine binding site in tubulin. Further, 2a also exhibited potent in vivo anticancer activity in LA-7 syngeneic rat mammary tumor model. Current data projects its strong candidature to be developed as anticancer agent.

Recent progress on C-4-modified podophyllotoxin analogs as potent antitumor agents

Podophyllotoxin (PPT), as well as its congeners and derivatives, exhibits pronounced biological activities, especially antineoplastic effects. Its strong inhibitory effect on tumor cell growth led to the development of three of the most highly prescribed anticancer drugs in the world, etoposide, teniposide, and the water-soluble prodrug etoposide phosphate. Their clinical success as well as intriguing mechanism of action stimulated great interest in further modification of PPT for better antitumor activity. The C-4 position has been a major target for structural derivatization aimed at either producing more potent compounds or overcoming drug resistance. Accordingly, numerous PPT derivatives have been prepared via hemisynthesis and important structure-activity relationship (SAR) correlations have been identified. Several resulting compounds, including GL-331, TOP-53, and NK611, reached clinical trials. Some excellent reviews on the distribution, sources, applications, synthesis, and SAR of PPT have been published. This review focuses on a second generation of new etoposide-related drugs and provides detailed coverage of the current status and recent development of C-4-modified PPT analogs as anticancer clinical trial candidates.

Synthesis of novel spin-labeled podophyllotoxin derivatives as potential antineoplastic agents: Part XXV

A series of novel spin-labeled 4β-[(4-substituted)-1,2,3-triazol-1-yl]podophyllotoxin derivatives (17a-h) were firstly designed and synthesized with significant regioselectivity by employing Cu(I) catalyzed click approach, and evaluated for cytotoxicity against four human tumor cell lines (A-549, DU145, KB, and KBvin). Among them, compound 17h displayed the highest cytotoxic activity against the tumor cell lines tested. Significantly, compound 17h showed superior cytotoxic activity compared with etoposide (IC₅₀ 6.30 to>10 μM), a clinically available anticancer drug. Significant activity toward the drug resistant KBvin cell line revealed promising future for compound 17h as a new generation of epipodophyllotoxin-derived antitumor clinical trial candidate.

New horizons for old drugs and drug leads

There is mounting urgency to find new drugs for the treatment of serious infectious diseases and cancer that are rapidly developing resistance to previously effective drugs. One approach to addressing this need is through drug repurposing, which refers to the discovery of new useful activities for "old" clinically used drugs through screening them against relevant disease targets. A large number of potential drug that, for various reasons, have failed to advance to clinical and commercial use can be added to the candidates available for such purposes. The application of new techniques and methodology developed through the impressive progress made in multidisciplinary, natural product-related research in recent years should aid substantially in expediting the discovery and development process. This review briefly outlines some of these developments as applied to a number of selected natural product examples, which may also include advances in chemical synthesis of derivatives with extended biological activities.

Synthesis and anticancer activity of focused compound libraries from the natural product lead, oroidin

Oroidin (1), (E)-N-(3-(2-amino-1H-imidazol-4-yl)allyl)-4,5-dibromo-1H-pyrrole-2-carboxamide, is a pyrrole alkaloid isolated from the marine sponge Agelas oroides. Routine screening in a panel of twelve cancer cell lines revealed 1 to be poorly cytotoxic with the 50% growth inhibition concentration (GI50) of 42 μM in MCF-7 (breast) cells and 24 μM in A2780 (ovarian) cells and >50 μM in all other cell lines tested. The development of eight focused libraries comprising thirty compounds total identified N-(biphenyl-4-ylmethyl)-1H-pyrrole-2-carboxamide (4l), N-benzyl-4,5-dibromo-1H-pyrrole-2-carboxamide (5a) and N-(biphenyl-4-ylmethyl)-4,5-dibromo-1H-pyrrole-2-carboxamide (5l) as potent inhibitors of cell growth in our panel of cell lines. Of these compounds GI50 values of <5 μM were observed with 4l against HT29 (colon) and SW480 (colon); 5a against HT29; and 5l against HT29, SW480, MCF-7, A431 (skin), Du145 (prostate), BE2-C (neuroblastoma) and MIA (pancreas) cell lines. As a cancer class, colon cancer appears to be more sensitive to the oroidin series of compounds, with analogue 5l being the most active.

Combretastatin A-4 inspired novel 2-aryl-3-arylamino-imidazo-pyridines/pyrazines as tubulin polymerization inhibitors, antimitotic and anticancer agents

Novel 2-aryl-3-arylamino-imidazo-pyridines/pyrazines that exhibit potent tubulin polymerization inhibition, anticancer activity, anti-migration of cancer cells, chromosomal damage, and apoptosis have been developed.

Lappaol F, a novel anticancer agent isolated from plant arctium Lappa L

In an effort to search for new cancer-fighting therapeutics, we identified a novel anticancer constituent, Lappaol F, from plant Arctium Lappa L. Lappaol F suppressed cancer cell growth in a time- and dose-dependent manner in human cancer cell lines of various tissue types. We found that Lappaol F induced G(1) and G(2) cell-cycle arrest, which was associated with strong induction of p21 and p27 and reduction of cyclin B1 and cyclin-dependent kinase 1 (CDK1). Depletion of p21 via genetic knockout or short hairpin RNA (shRNA) approaches significantly abrogated Lappaol F-mediated G(2) arrest and CDK1 and cyclin B1 suppression. These results suggest that p21 seems to play a crucial role in Lappaol F-mediated regulation of CDK1 and cyclin B1 and G(2) arrest. Lappaol F-mediated p21 induction was found to occur at the mRNA level and involved p21 promoter activation. Lappaol F was also found to induce cell death in several cancer cell lines and to activate caspases. In contrast with its strong growth inhibitory effects on tumor cells, Lappaol F had minimal cytotoxic effects on nontumorigenic epithelial cells tested. Importantly, our data also demonstrate that Lappaol F exhibited strong growth inhibition of xenograft tumors in nude mice. Lappaol F was well tolerated in treated animals without significant toxicity. Taken together, our results, for the first time, demonstrate that Lappaol F exhibits antitumor activity in vitro and in vivo and has strong potential to be developed as an anticancer therapeutic.

Design, synthesis, and antitumor activity of novel podophyllotoxin derivatives as potent anticancer agents

In order to find novel synthetic compounds with superior antitumor activity and overcome multidrug resistance, a series of novel 4β-N-substituted podophyllotoxin derivatives were synthesized under mild conditions with satisfactory yield. Nine novel podophyllotoxin derivatives were synthesized by linking 4β-amino-podophyllotoxin with aldehydes via the formation of a Schiff's base, and imines were reducted to secondary amines. These novel derivatives have been evaluated for cytotoxicity against human cancer cell lines Hela, K562, and K562/AO2. The results indicated that these compounds possess superior bioactivity (IC50 values were found at the range of 10(- 6)-10(- 8) mol/l) and weak multidrug resistance.

Cytotoxic activity of ursolic acid derivatives obtained by isolation and oxidative derivatization

Structure-activity relationships of ursane-type pentacyclic triterpenes obtained from natural sources and by chemical derivatization are reviewed. Ursolic acid, corosolic acid, and a new ursane-type pentacyclic triterpene, 7,24-dihydroxyursolic acid, were isolated from the methanolic extract of the leaves of the Bangladeshi medicinal plant, Saurauja roxburghii. Derivatization of ursolic acid by oxidation with dioxoruthenium (VI) tetraphenylporphyrins was investigated. Oxidation selectivity on the terpene structure was modulated by the auxiliaries introduced on the tetraphenylporphyrin. The natural triterpenes and oxidized derivatives were tested for cytotoxicity against the C6 rat glioma and A431 human skin carcinoma cell lines. Although they have the same ursane-type pentacyclic triterpene cores, the position and numbers of hydroxyls on the terpene structures significantly affected the activity and the selectivity towards the tested cell lines.

New plant sources of the anti-cancer alkaloid, camptothecine from the Icacinaceae taxa, India

In this study, the production of camptothecine and its derivatives, in thirteen species of the family Icacinaceae, namely, Apodytes dimidiata, Codiocarpus andamanicus, Gomphandra comosa, Gomphandra coriacea, Gomphandra polymorpha, Gomphandra tetrandra, Iodes cirrhosa, Iodes hookeriana, Miquelia dentata, Miquelia kleinii, Natsiatum herpeticum, Pyrenacantha volubilis and Sarcostigma kleinii is reported. Seeds of M. dentata were found to produce the highest content of camptothecine (1.0-1.4% by dry weight of seeds). Full scan LC-MS and ESI-MS/MS analysis of M. dentata revealed, besides camptothecine, a number of other derivatives, namely, 10-hydroxycamptothecine, 9-methoxycamptothecine, 20-deoxycamptothecine. Crude extract preparations of the seeds of M. dentata were effective against a breast cancer cell line (IC50=3.82 μg/ml for MDA MB273 cell lines) and two ovarian cancer cell lines (IC50=2.8 μg/ml for NCI/ADR-RES and 4.5 μg/ml for SKOV). These results are the first reports of camptothecine and its derivatives in these species and offer rich alternative plant sources for the anticancer compound, camptothecine.

Paclitaxel-PHBV nanoparticles and their toxicity to endometrial and primary ovarian cancer cells

This report is an integrated study to include the molecular simulation, physicochemical characterization and biological analysis of a paclitaxel-loaded PHBV nanoparticle that demonstrates uptake, release and cytotoxicity in cancer cell lines. Taking this nanoparticle one step closer to its use in a clinical setting, we demonstrate that it causes significant cell death in primary cultures of stage IIIc serous ovarian cancer cells isolated from six patients. Molecular simulations revealed a high affinity of paclitaxel for the water-polymer interface, thus the drug is delivered only when the polymer near it is degraded. The Fourier transform infrared spectroscopy suggests the formation of a short-lived crystalline phase, also observed in the CG simulations, and transmission electron microscopy revealed branched structures on the surface of particles, which disappeared after 4 days. Biological analyses indicated that these particles have a 48-h window of toxicity protection, allowing for the endocytosis of the particle by the cells; this finding was corroborated by confocal microscopy and flow cytometry. The low cost to synthesize PHBV using microorganisms and the potential chemical modifications of the polymer make it attractive for inexpensive, large-scale pharmaceutical production.

The traditional medical uses and cytotoxic activities of sixty-one Egyptian plants: discovery of an active cardiac glycoside from Urginea maritima

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants from the Sinai desert are widely used in traditional Bedouin medicine to treat a range of conditions including, cancers, and may thus be useful sources of novel anti-tumor compounds. Information on plants used in this way was obtained through collaboration with Bedouin herbalists.

AIM OF THE STUDY

To document the traditional uses of 61 species from 29 families of Egyptian medicinal plants and to investigate their biological activity using a cytotoxicity assay.

MATERIAL AND METHODS

MeOH extracts of the 61 plant species investigated were dissolved in 10% DMSO and their cytotoxic activity was evaluated. The extracts were tested in duplicate on three separate occasions at three different concentrations (1, 10 and 100μg/ml) against human lymphoma U-937 GTB. The most active extract was subjected to bioassay-guided fractionation using HPLC and LC/ESI-MS to isolate and identify its active components.

RESULTS AND DISCUSSION

The most potent extracts were those from Asclepias sinaica, Urginea maritima, Nerium oleander and Catharanthus roseus, followed by those from Cichorium endivia, Pulicaria undulate and Melia azedarach. Literature reports indicate that several of these plants produce cardiac glycosides. Bioassay-guided fractionation of alcoholic U. maritima extracts led to the isolation of a bioactive bufadienolide that was subsequently shown to be proscillaridin A, as determined by 1D and 2D NMR spectroscopy. This result demonstrates the value of plants used in traditional medicine as sources of medicinally interesting cytotoxic compounds.