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Corema album (L.) D. Don (Ericaceae) is an endemic bush that grows along the Atlantic littoral of the Iberian Peninsula. Its edible white berries (known as camarinas, camarinas, camarinhas, white crowberry, among other vernacular names) have been used in popular medicine as an antipyretic and are consumed in localised areas of Portugal and Spain as appetisers and in the preparation of juices and jams. The aim of the present review is to summarise the knowledge of the chemical composition and pharmacological studies performed with C. album fruit and extracts. These berries are rich in phenolic compounds, including phenolic acids, stilbenes, flavonols, flavanones, prenylated flavanone, flavanols, and anthocyanins. The total phenolic content of various extracts of the pulp of these berries has been positively correlated with their antioxidant capacity. In this respect, the treatment with acetone, ethyl acetate, and aqueous extracts of this fruit has protected HepG2 cells against chemically induced oxidative stress. The chemoprotective effect of these extracts is mediated by preventing reactive oxygen species formation, reduced glutathione depletion, antioxidant enzyme over-activity, and oxidative damage to proteins and lipids. Furthermore, the presence of pentacyclic triterpenes, such as ursolic and oleanolic acids, in C. album berries confers reflectance UV properties to this fruit and derived extracts. In short, existing studies suggest that the development of C. album crops should be considered as a promising opportunity to obtain these remarkable berries. Moreover, further experiments should also be designed to evaluate their in vivo effect and to ascertain the underlying mechanism of action.

Se trata de un recurso de Realidad Virtual que sitúa al estudiante en los laboratorios de prácticas de la Facultad de Farmacia de la Universidad de Sevilla. El recurso permite al alumnado realizar de forma virtual una serie de ensayos básicos para la determinación cualitativa de los principios activos de una droga de origen vegetal; así como el estudio de la actividad farmacológica de un extracto elaborado a partir de dicha droga. En concreto, los ensayos se centrarán en Atropa Belladonna L. y sus principios activos, atropina y escopolamina. El recurso se compone de una serie de textos, vídeos didácticos y cuestiones teórico-prácticas que proporcionan soporte al estudiante para avanzar en los diferentes escenarios. Dichos elementos serán liberados mediante la interacción del estudiante con los elementos del laboratorio. Este recurso es una herramienta de gran utilidad para que los alumnos apliquen, de una forma sencilla y con un ejemplo práctico, sus conocimientos adquiridos durante su interacción con el contenido de dichas asignaturas, así como combinarlos con aquellos adquiridos en otras asignaturas como, por ejemplo, la asignatura de Farmacognosia del Grado de Farmacia. Es de destacar que este recurso también es de gran valor como herramienta docente no presencial, ya que permitirá adaptar la docencia práctica a laboratorios virtuales. De esta manera, hace accesible la práctica de laboratorio al alumnado que no pudiera acudir físicamente al laboratorio. La necesidad de este tipo de herramientas virtuales ha quedado evidente con la pandemia del SARS-CoV-2 que se está viviendo desde principios del 2020.

d-Pinitol (3-O-methyl-d-chiro-inositol) is a cyclitol nearly ubiquitous in the Leguminosae and Pinaceae families. It plays an important role in plants as physiological cellular modulator and chemical defense against unfavorable environmental conditions, such as water deficit and high level of salinity. Plants rich in d-pinitol are being used in traditional medicine as empirical treatment for diabetes, inflammation, cancer or infections. This review summarizes the extensive literature published about d-pinitol biosynthesis, plant distribution, biological activities and pharmacological studies, including in vitro, in vivo, and clinical trials.

Plants of the genus Retama (Fabaceae) are used in traditional medicine of the Mediterranean Basin as an emetic, purgative, and vermifuge. Certain Retama species are also employed to treat a multitude of disorders, including diabetes, hepatitis, jaundice, sore throat, skin diseases, joint pain, rheumatism, fever, and inflammation. This review deals with updated information on the distribution, botanical characteristics, ethnopharmacology, phytochemistry, pharmacological activities, and toxicity of the Retama species in order to support their therapeutic potential and to provide an input for future research prospects. The Retama species are mainly employed as ethnomedicinal remedies in Mediterranean countries, including Algeria, Egypt, Italy, Lebanon, Libya, Morocco, and Spain. Previous phytochemical studies show a complex composition, rich in carbohydrates (galactomannans), polyols (pinitol), fatty acids, phenolic compounds (genistein, daidzein) and alkaloids (retamine, lupanine). The pharmacological activity of their various extracts has been widely studied, revealing, among others, the anti-microbial, anti-inflammatory, and anti-diabetic effects of these species. The potential toxicity of these medicinal plants has also been discussed. Although recent experimental evidence confirms the pharmacological interest of this genus, further studies are necessary.

Screening-based photoprotection is a first-line defence of plants against potentially harmful solar radiation. In the Iberian Peninsula, most natural fleshy fruits are red, purple or black, although there do exist a few plants that naturally present white fruit, such as Corema album (L.) D.Don (Ericaceae). This is a wild shrub of Atlantic coastal areas, which presents white fleshy fruit that ripens throughout the summer. We analysed the reflectance of fully ripened fruit in the field, and laboratory (before and after hexane washing and pericarp removal). The aqueous and ethyl acetate extract was successively obtained from the crushed fruit and submitted to column chromatography on Silicagel. The fractions were analysed through gas chromatography/mass spectrometry, and two compounds were separated and identified as oleanolic and ursolic acids. The reflectance measurements were taken with the UniSpec-SC Spectral Analysis System. The fruit in the field and laboratory exhibited elevated UV reflectance. The ethyl acetate extract, fractions, and isolated compounds showed high reflectance in UV, which indicated that these triterpene acids could be responsible for reflectance in natural berries. Ursolic and oleanolic acids can play a photoprotective role in berries of Corema album . In sunny environments white fruit can be more visible to dispersers.

Chalcones constitute a group of phenolic compounds that command an increasing interest on cancer research. Natural chalcones are widespread through the plant kingdom. The most abundant and investigated chalcones are isoliquiritigenin, flavokawain and xanthohumol, which are present in the Fabaceae, Piperaceae, Cannabaceae, and Moraceae families. These chalcones have been shown to be promising lead antitumor-chemopreventive drugs by three different activities: antioxidants, cytotoxic and apoptosis inducers. In the recent years, SAR (structure-activity relationship) has contributed towards the improvement of anticancer properties of chalcones by substituting aryl rings and introducing heterocyclic moieties. This review summarizes the anticancer activities shown by natural chalcones and the SAR and describes how different chemical moiety modifications could lead them to be therapeutically useful in the treatment of cancer.

A fission-yeast bioassay guided screening on several plant extracts is carried out to search for anticancer agents, and an extract from leaves of Corema album (L.) D. Don (Ericaceae) is found to have antiproliferative activity. Further fractionation afforded 2′,4′-dihydroxychalcone (DHC) as the main cytotoxic compound present in the extract. Our detailed biological analysis shows that antiproliferative activity of this flavonoid is likely due to its ability to induce DNA damage which blocks cell cycle progression., This work was supported by grants to RRD from the Spanish Ministry for Science and Innovation (Ministerio de Ciencia e Inovación) BFU2010-21310 and from La Junta de AndaluciaP09-CTS-4697 (PROYECTO DE EXCELENCIA). MAS-P was supported by a fellowship from El Consejo Andaluz de Colegios Oficiales de Farmacéuticos. AJ L-G was supported by a FPU fellowship from the Spanish Ministry for Science and Innovation (Ministerio de Ciencia e Inovación).

Background The low efficacy of cancer therapy for the treatment of patients with advanced disease makes the development of new anticancer agents necessary. Because natural products are a significant source of anticancer drugs, it is important to explore cytotoxic activity of novel compounds from natural origin. Purpose The aim of this work is to evaluate the cytotoxic capacity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves. Hirsutanone cytotoxic way of action was also studied. Material and methods The cytotoxic ability of Alnus glutinosa leaves ethyl acetate extract was studied over HeLa and PC-3 cell lines, with the MTT colorimetric assay. Hirsutanone was isolated from this extract using chromatographic methods, and its structure elucidated by spectroscopic analysis. HT-29 cell viability after hirsutanone treatment was determined using SRB assay. In order to understand hirsutanone way of action, cytotoxicity was evaluated adding the diarylheptanoid and antioxidants. DNA topoisomerase II (topo II) poison activity, was also evaluated using purified topo II and a supercoiled form of DNA that bears specific topo II recognition and binding region; topo II poisons stabilize normally transient DNA-topo II cleavage complexes, and lead an increased yield of linear form as a consequence of a lack of double-strand breaks rejoining. Results The diarylheptanoid hirsutanone was isolated from Alnus glutinosa (L.) Gaertn. (Betulaceae) leaves extract that showed cytotoxic activity against PC-3 and HeLa cell lines. Hirsutanone showed cytotoxic activity against HT-29 human colon carcinoma cells. Pre-treatment with the antioxidants NAC (N-acetylcysteine) and MnTMPyP (Mn(III)tetrakis-(1-methyl-4-pyridyl)porthyrin) reduced this activity, suggesting that reactive oxygen species (ROS) participate in hirsutanone-induced cancer cell death. Using human topo II and a DNA supercoiled form, hirsutanone was found to stabilize topo II-DNA cleavage complexes, acting as a topo II poison. Conclusion Our data suggest that, like curcumin, an induction of oxidative stress and topo II-mediated DNA damage may play a role in hirsutanone-induced cancer cell death. Since both compounds share similar structure and cytotoxic profile, and curcumin is in clinical trials for the treatment of cancer, our results warrant further studies to evaluate the anticancer potential of hirsutanone.

During tumour progression, cells accumulate secondary mutations and/or chromosomal aberrations that generate genetic diversity within the tumour cell population. This may result in the acquisition of new properties that increase tumour malignancy, such as invasiveness or resistance to chemotherapy. One of the important mechanisms of chemotherapy resistance is overexpression or biochemical activation of ABC family transporters. ABC transporters remove antitumour drugs from the cell, reducing their intracellular concentration and producing resistance against a wide range of chemically unrelated drugs, known as multidrug resistant phenotype (MDR). During recent decades, much effort has been devoted to the isolation of compounds able to inhibit the activity of these transporters. However, few such compounds have reached clinical practice and MDR remains a serious complication in cancer therapy. In an innovative approach to finding new ABC inhibitors, we propose using fission yeast Schizosaccharomyces pombe as a biosensor of detoxification that would enable cost-efficient screening of natural compounds and chemical libraries for molecules that revert the MDR phenotype. Existing fission yeast tools provide genetic, biochemical and cell biological analysis, thereby facilitating identification of drug targets. Putative inhibitors and modulators of ABC transporters could be used in combination with chemotherapeutic drugs for the treatment of multidrug resistant tumours.

Retama raetam (RR) and R. sphaerocarpa (RS) are shrubs growing in Algeria desert areas, where are commonly used as healing remedies because of their antiseptic, antipyretic and anti-diarrheal properties. Phytochemical studies have shown that these species are very rich in flavonoids (isoflavones) and alkaloids (quinolizidine and bipiperidyl). The aim of this study was to compare the chemical composition of both Retama species by GC/MS and LC/MS and to determinate their antimicrobial activity of two Retama species growing naturally in Algeria. Ten alkaloids and seven flavonoids were identified in cladodes of RR and RS. The quantitative analysis showed that the most abundant flavonoid of both the aqueous extract from RR and RS was the isoflavone genistein (610.0±2.8 and 408.0±14.1 mg/100 g respectively), whereas sparteine was the predominant alkaloid in RR and retamine in RS. The antibacterial activity of Retama extracts against standard strains was performed by minimum inhibitory concentration (MIC), and by the disc diffusion method (expressed by inhibition zone, IZ). Both Retama species showed the best activity against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA), being RS aqueous extract more active than RR aqueous extract, with MIC 125 µg/mL and bactericidal activity against both strains.

Cancer cells produce high levels of reactive oxygen species (ROS) that lead to a state of increased basal oxidative stress. Since this state of oxidative stress makes cancer cells vulnerable to agents that further augment ROS levels, the use of pro-oxidant agents is emerging as an exciting strategy to selectively target tumor cells. Natural products have provided a significant contribution to the development of several drugs currently used in cancer chemotherapy. Although many natural products are known to affect the redox state of the cell, most studies on these compounds have focused on their antioxidant activity instead of on their pro-oxidant properties. This article provides an overview of natural products with pro-oxidant and anticancer activities, with special focus on plant secondary metabolites, and discusses their possible use as cancer chemotherapeutic agents.

Methanolic extracts from seven Plantago species used in traditional medicine for the treatment of cancer, were evaluated for cytotoxic activity against three human cancer cell lines recommended by the National Cancer Institute (NCI, USA). The results showed that Plantago species exhibited cytotoxic activity, showing a certain degree of selectivity against the tested cells in culture. Since the flavonoids are able to strongly inhibit the proliferation of human cancer cell lines, we have identified luteolin-7-O-beta-glucoside as major flavonoid present in most of the Plantago species. Also, we have evaluated this compound and its aglycon, luteolin, for their cytotoxic and DNA topoisomerase I poisons activities. These results could justify the traditional use of the Plantago species and topoisomerase-mediated DNA damage might be a possible mechanism by which flavonoids of Plantago exert their cytotoxicity potential.

The leaves of Corema album (Ericaceae), an endemic shrub which grows in Atlantic coastal areas of the Iberian Peninsula, are rich in flavonoids and other secondary metabolites. Silica gel column chromatography of the ethyl acetate extract from dried leaves was performed and a flavonic active fraction was obtained. The cytotoxic activity of this fraction was assessed using the colon cancer cell lines HCT116 and HT29. After 48 hours of treatment, cell viability was determined with luminescence-based ATPLite assay, showing IC50 values of 7.2 +/- 0.7 and 6.8 +/- 1.2 microg/mL, respectively. The study by flow cytometry revealed that the cytotoxicity of this fraction was mediated, at least in part, by induction of apoptosis and G2/M cell cycle arrest. The active fraction was then subjected to Sephadex LH-20 chromatography and two flavonoids were separated and identified as the flavanone pinocembrin and 2',4'-dihydroxychalcone after UV, MS and NMR analysis.

The cytotoxic activity of two pentacyclic triterpenoids (ursolic acid and α-amyrine) isolated from the methanolic extract of the aerial parts from Erica andevalensis, whose structures have been established on the basis of spectroscopic and chemical evidence, has been assessed against three human cancer cell lines, TK -10 (renal adenocarcinom a), MCF-7 (breast adenocarcinoma) and UACC-62 (melanoma), recommended by NCI (National Cancer Institute) and we also evaluated the antimitotic effect in root meristematic cells of Allium cepa. Ursolic acid was found to possess the highest cytotoxic activity.

Flavonoids are secondary plant metabolites whose anticancer properties are actually being studied from an epidemiological and pharmacological point of view. They are believed to be implicated in the lower risk of some forms of cancer observed in Asian countries, due to their capacity to control cell proliferation, to act on certain regulatory enzymes as protein kinases or topoisom erases. Based on these precedents, three flavonols isolated from a cytotoxic butanol extract from Retama sphaerocarpa Boissier have been assessed to study their topoisom erase I and II activity. Two new rhamnazin glycosides were found to have the ability to stabilize the cleavage com plex hum an D N A topoisom erase I at concentrations in the 100- 250 μm range, acting as topoisom ersase I poisons.

Fruits (berries) of Viscum cruciatum accumulate bipiperidyl (ammodendrine) and quinolizidine (retamine and lupanine) alkaloids. Viscum obtains the alkaloids by root parasitism on the host plant Retama sphaerocarpa. The presence of these alkaloids in the fruits of Viscum cruciatum may represent some competitive disadvantage to mistletoe itself because the seeds may not be so well dispersed by blackcaps (Sylvia atricapilla).

During our search for cytotoxic compounds from Andalusian vascular plants, the ethyl acetate extract from the leaves of Corema album (L.) D. Don (Ericaceae) was selected for its cytotoxic activity against the HT-29 human colon adenocarcinoma cell line. Two dihydrochalcones, 2',4'-dihydroxydihydrochalcone (1) and 2'-methoxy-4'-hydroxydihydrochalcone (2), have been isolated from the leaves of C. album. Their structural identification was based on 1H NMR and 13C NMR data, including 2D NMR, and mass spectrometry. These compounds were subjected to the sulfhorhodamine B (SRB) cytotoxic assay against human colon adenocarcinoma cells (HT-29). Compounds 1 and 2 showed higher cytotoxicity than the positive control 5-fluorouracil (5-FU); the IC50 values (microM +/- SEM) were 1.8 +/- 0.4 for compound 1, 8.5 +/- 2.1 microM for compound 2, and 8.7 +/- 4.0 for 5-FU. The cytotoxic activity of 1 and 2 was reduced in the presence of the antioxidants N-acetylcysteine (NAC) and Mn(III) Tetrakis(1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), therefore suggesting that reactive oxygen species generation participates in the cytotoxic activity of these dihydrochalcones.

Inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn’s disease, is a chronic intestinal disorder resultant from a dysfunctional epithelial, innate and adaptive immune response to intestinal microorganisms. Current IBD treatment presents limitations in both efficacy and safety that stimulated for new active drugs. Retama spp. have been traditionally used in the Mediterranean region in treatment of pain and inflammation. In this study, the anti-inflammatory and protective properties of a standardised aqueous extract from Retama monosperma (RmE) was evaluated in vivo, by intra-colonic administration of trinitrobenzene sulfonic acid (TNBS) in rats as a Crohn’s disease model. The qualitative and quantitative analysis of flavonoids from RmE was performed by high-performance liquid chromatography–tandem mass spectrometry. Oral administration of RmE diminished the severity and extension of the intestinal injuries induced by TNBS. In addition, RmE increased mucus production in goblet cells in colon mucosa, decreased neutrophil infiltration and cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) overexpression. Similarly, RmE significantly reduced p38 mitogen-activated protein kinase activation, preventing the inhibitory protein IκB degradation in colonic mucosa. RmE anti-inflammatory effects seem to be related to impairment of neutrophil function and COX-2 and iNOS down-regulation possibly through p38 MAPK and nuclear transcription factor kappa B signalling pathways. These results suggest that RmE might contribute to the development of new pharmaceutical products for inflammatory bowel disease.

Oral treatment with the ether fraction of the flavonoid extract of Erica andevalensis (62.5, 125 and 250 mg/kg) was found to be effective in the prevention of gastric ulceration induced by cold-restraint stress in rats. Statistically significant ulcer index values with respect to the control group were observed. Mucus content was not increased although it was accompanied by an increase in proteins and hexosamines. In pyloric-ligated animals flavonoids showed a significant reduction in the severity of the ulcers, however, it did not significantly alter the gastric secretion volume or acidity compared with the control. Gastric ulcers induced by oral administration of absolute ethanol were reduced by pretreatment with the highest dose of the ether fraction of the flavonoid extract (250 mg/kg), however it did not induce significant changes in the amount and glycoprotein content of gastric mucus.

The genus Retama (Fabaceae) is widely distributed in the Mediterranean region. In the present study, pinitol (3- O-methyl- chiro-inositol), an anti-inflammatory and antidiabetic molecule, was isolated from aerial parts of R. monosperma, and its structure established on the basis of spectroscopic techniques (1D/2D NMR) and MS. Identification and quantification of pinitol in R. raetam and R. sphaerocarpa were also performed. R. monosperma had the highest concentration of pinitol (2.3%). The presence of pinitol in aqueous extracts of Retama spp. may explain the adaptation of these plants to drought and salinity. Furthermore, pinitol could be considered as a mediator in the anti-inflammatory and hypoglycemic activities of Retama spp., which are traditionally used to treat diabetes.

There is currently substantial interest in the cyto-protective effects of natural compounds against oxidative stress and in studying of the defense mechanisms involved. Corema album fruit is an edible berry consumed along the Atlantic littoral of the Iberian Peninsula. The aim of this study was to characterize the phenolic composition and evaluate the chemo-protective effects against oxidative stress of three phenolic extracts from this fruit on liver cells. Characterization of phenolic compounds, achieved by liquid chromatography and diode-array, mass spectrometry and electrospray ionization-time of flight-mass spectrometry detection, showed a main fraction of hydroxycinnamic acids. Liver HepG2 cells were treated with 1-40. οg/mL of the extracts and exposed to oxidative stress chemically induced. Cell viability, reactive oxygen species (ROS), reduced glutathione (GSH), antioxidant enzymes and biomarkers of oxidative damage were evaluated. Treatment of HepG2 cells with the extracts partially prevented ROS increase, GSH depletion, antioxidant enzymes over-activity and oxidative damage to proteins and lipids induced by stress. The results support the traditional use of C. album as a medicinal plant and suggest that inclusion of its berries in the diet would contribute to the protection afforded by fruits, vegetables and plant-derived beverages against oxidative stress related diseases. © 2012 Elsevier Ltd., This work was supported by the grants AGL2010-17579, AGL2010-18269 and project CSD2007-00063 from Programa Consolider-Ingenio from the Spanish Ministry of Science and Innovation (CICYT). A. L.-G. received a pre-doctoral fellowship from Ministerio de Ciencia e Innovación (FPU).

A diarylheptanoid, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, hirsutanone, has been isolated from the methanolic extract of the aerial parts of Viscum cruciatum (Viscaceae) and characterized by spectroscopic methods and chemical transformations. This compound showed cytotoxic activity against melanoma (UACC-62), renal (TK-10) and breast (MCF-7) cancer cell lines.

A diarylheptanoid, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, hirsutanone, has been isolated from the methanolic extract of the aerial parts of Viscum cruciatum (Viscaceae) and characterized by spectroscopic methods and chemical transformations. This compound showed cytotoxic activity against melanoma (UACC-62), renal (TK-10) and breast (MCF-7) cancer cell lines.

A new flavonol triglycoside, retamatrioside (1), has been isolated from the aerial parts of Retama sphaerocarpa. The structure of 1 has been determined as rhamnazin 3-O-beta-D-glucopyranosyl-(1-->5)-[beta-D-apiofuranosyl(1-->2)]-al pha -L-arabinofuranoside, using spectroscopic methods.

A novel flavonol glycoside, rhamnazin-3- O - β -glucopyranosyl-(1→5)- α -arabinofuranoside, was isolated from the aerial parts of Retama sphaerocarpa (Fabaceae) and its structure determined by mp, UV, IR, FAB-MS, GC–MS and NMR data.

The pharmacological assays and activities of natural phenylpropanoid glycosides, extracted from a variety of plants are summarized in this review, such as antioxidant, anti-inflammatory, healing, antimicrobial and antitumoral-chemopreventive. Structure-activity relationships are also discussed.

The aim of this study was to evaluate the in vitro antioxidant activity of the methanol extract of Plantago bellardii All. aerial parts. This was assessed by two different tests, scavenging of 1,1-diphenyl-2-picrylhydrazil (DPPH) radical, and inhibition of lipid peroxidation on liposomes prepared from bovine brain extract. In both tests the extract showed a potent antioxidant effect. The characterization of the major compounds in the extract as rutin, geniposide and verbascoside was performed by isolation and HPLC comparison with authentic samples. They were quantified by HPLC for the flavonoids and colorimetry for iridoids. The compounds that contribute most to the antioxidant activity were shown to be verbascoside and rutin.

Antioxidative activities of methanol extracts from five Plantago species (P. afra, P. coronopus, P. lagopus, P. lanceolata, and P. serraria) were characterized by the DPPH scavenging test and the inhibition of Fe2+/ascorbate-induced lipid peroxidation on bovine brain liposomes. All extracts showed antioxidant activity in both methods. Whereas P. serraria exhibited the strongest activity as a DPPH scavenger, P. lanceolata and P. serraria were found to be the most active in the lipid peroxidation inhibition assay. The extracts were investigated regarding their composition by different colorimetric techniques, such as the content of total phenolic compounds by the Folin-Ciocalteu assay, flavonoids by AlCl3 reagent, phenylpropanoid glycosides (PPGs) by Arnow reagent, and iridoids by Trim-Hill assay. A high correlation was found between the scavenging potency and the total phenolic and phenylpropanoid content of the extracts but not between the lipid peroxidation potency and the extract composition. P. serraria is presented as a possible new source of natural antioxidants.

The pharmacological assays and activities of natural iridoids biosynthesized by route II, extracted from a variety of plants are summarized in this review, such as anti-inflammatory, antitumoral-chemopreventive, hepatoprotective and healing. Structure-activity relationships are also discussed.

Recent research has shown the anticancer effects of digitalis compounds suggesting their possible use in medical oncology. Four extracts obtained from the leaves of Digitalis purpurea subsp. heywoodii have been assessed for cytotoxic activity against three human cancer cell lines, using the SRB assay. All of them showed high cytotoxicity, producing IC50 values in the 0.78 - 15 microg/mL range with the methanolic extract being the most active, in non toxic concentrations. Steroid glycosides (gitoxigenin derivatives) were detected in this methanolic extract. Gitoxigenin and gitoxin were evaluated in the SRB assay using the three human cancer cell lines, showing IC50 values in the 0.13 - 2.8 microM range, with the renal adenocarcinoma cancer cell line (TK-10) being the most sensitive one. Morphological apoptosis evaluation of the methanolic extract and both compounds on the TK-10 cell line showed that their cytotoxicity was mediated by an apoptotic effect. Finally, possible mechanisms involved in apoptosis induction by digitalis compounds are discussed.

Curcumin, the major active component of the spice turmeric, is recognised as a safe compound with great potential for cancer chemoprevention and cancer therapy. It induces apoptosis, but its initiation mechanism remains poorly understood. Curcumin has been assessed on the human cancer cell lines, TK-10, MCF-7 and UACC62, and their IC50 values were 12.16, 3.63, 4.28 mM respectively. The possibility of this compound being a topoisomerase II poison has also been studied and it was found that 50 mM of curcumin is active in a similar fashion to the antineoplastic agent etoposide. These results point to DNA damage induced by topoisomerase II poisoning as a possible mechanism by which curcumin initiates apoptosis, and increase the evidence suggesting its possible use in cancer therapy. Ministerio de Ciencia y Tecnología de España. SAF 2000-0167

The therapeutic potential of flavonoids shownby recent research, makes a greater understanding of these compounds that leads to new drug discovery necessary. An important part of the available literature aboutanticancer activity of flavonoids shows lots of reports about natural and synthetic flavonoids inhibiting diverse cancer cell lines; but this information is very scattered and there is very little understanding about a possible structure-activity relationship. Throughout our present research we have reviewed this literature and we have compiled the cancer cell lines inhibited by more than 500 natural and synthetic flavonoids and we have discussed structural requirements implicated in the activity to obtain a working hypothesis to help to rationalize the development of flavonoids as antitumor agents.

The therapeutic anticancer potential of flavonoids shown by recent research needs a greater understanding of these compounds. They are antioxidants and antimutagenic agents that can inhibit tumor promotion and transformation and can modify the activity of a large number of mammalian enzyme systems, such as human DNAtopoisomerases. Poisons of topoisomerases generate toxic DNA damage by stabilization of the covalent DNA-topoisomerase cleavage complex and some of them have therapeutic efficacy in human cancer. The present investigation has assayed ten flavonoids, isolated in our laboratory, as topoisomerase I poisons obtaining myricetin and myricetin-3-galactoside as two new topoiosomerase I poisons. These two flavonoids, and the plant extract from which they were isolated, were assayed for cytotoxic activity against three human cancer cell lines using the SRB assay. Taking into account our previous research, structural requisites implicated in the topoisomerase poisoning are discussed. Ministerio de Ciencia y Tecnología de España. SAF 2000-0167

Since topoisomerase poisons allow the enzyme to cut and covalently bind to DNA but abort the subsequent rejoining of the molecule after relieving the torsional stress. To study their action we have made use of a supercoiled form of the pRYG plasmid that bears a specific topoisomerase recognition and binding region. The conversion of the supercoiled circular double-stranded DNA to the linear and open circle forms in the presence of a topoisomerase II poison and a denaturation step by proteinase K-SDS is indicative of the efficiency of our test agents to stabilize the cleavable complex. Using this system, three glucosylated isoflavones (6′-methoxy-pseudobaptigenin-7-O-β-glucoside, genistin, and daidzin) isolated from cytotoxic chloroform and ethyl acetate extracts of Retama sphaerocarpa Boissier, were found to have the ability to stabilize the cleavage complex human DNA topoisomerase II.

The new isoflavone, 7-hydroxy-6′-methoxy-3′,4′-methylenedioxyisoflavone 7- O - β -glucoside (6′-methoxypseudobaptigenin 7- O - β -glucoside) and two known isoflavones, genistein 7- O - β -glucoside (genistin) and daidzein 7- O - β -glucoside (daidzin) have been isolated from the aerial parts of Retama sphaerocarpa and characterized by mp, UV, IR, FAB-MS and NMR data.

During our search for cytotoxic compounds from Andalusian vascular plants, the ethyl acetate extract from the leaves of Corema album (L.) D. Don (Ericaceae) was selected for its cytotoxic activity against the HT-29 human colon adenocarcinoma cell line. Two dihydrochalcones, 2′,4′-dihydroxydihydrochalcone (1) and 2′-methoxy-4′-hydroxydihydrochalcone (2), have been isolated from the leaves of C. album. Their structural identification was based on 1H NMR and 13C NMR data, including 2D NMR, and mass spectrometry. These compounds were subjected to the sulfhorhodamine B (SRB) cytotoxic assay against human colon adenocarcinoma cells (HT-29). Compounds 1 and 2 showed higher cytotoxicity than the positive control 5-fluorouracil (5-FU); the IC50 values (μM ± SEM) were 1.8 ± 0.4 for compound 1, 8.5 ± 2.1 μM for compound 2, and 8.7 ± 4.0 for 5-FU. The cytotoxic activity of 1 and 2 was reduced in the presence of the antioxidants N-acetylcysteine (NAC) and Mn(III) Tetrakis(1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP), therefore suggesting that reactive oxygen species generation participates in the cytotoxic activity of these dihydrochalcones.

Seven flavonoids isolated from chloroform , ethyl acetate and butanol extracts, obtained from the aerial parts of Retama sphaerocarpa, have been assessed for cytotoxic activity against three human cancer cell lines: TK-10 (renal adenocarcinom a), MCF-7 (breast adenocarcinom a) and UACC-62 (m elanom a), using the SRB assay. All of them , extracts and flavonoids, were actives in, at least, one of the three cell lines at the recom m ended N ational C ancer Institute doses. They produce a d ose-dependent inhibition of cell grow th at concentrations in the 10-6-10-4 ᴍ and 25 -250 μg/ml range for the flavonoids and extracts respectively, being the flavonol rhamnazin the most cytotoxic.