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Ten novel neo -clerodane diterpenoids, named cornutins C–L, have been isolated from the leaves of Cornutia grandifolia var . intermedia . Their structures have been elucidated by detailed spectroscopic analysis. In addition, the in vitro antiplasmodial activity of four isolated compounds (cornutin C–F) has been evaluated, revealing only a marginal activity.

Tropical forests are one of the most diverse and endangered habitats on earth. They have also been portrayed as a source of future pharmaceuticals, yet finding useful compounds can be both scientifically and politically challenging. Increasingly, over the past decade, the potential value of medicinal compounds derived from plants, microorganisms, and animals has been proposed as a tangible benefit of biodiversity, and therefore a basis for promoting its preservation. Ecological theories of plant defense can increase the probability of discovering compounds with activity in bioassays against human disease targets. In addition, conducting research in tropical countries with local scientists provides immediate and lasting benefits for the sustainable use of biodiversity. This new approach to drug discovery has been effective in identifying bioactive leads. It is both an important step towards understanding the medicinal value of biodiversity, and a practical way to link drug discovery with conservation.

The phytochemical investigation of the leaves of Siparuna pauciflora yielded three novel sesquiterpenoids: the germacrane sipaucin A, the elemane sipaucin B and sipaucin C, comprising a new type of carbon skeleton. In addition, four known aporphine alkaloids-nor-boldine, boldine, laurotetanine, and N-methyl-laurotetanine-were obtained. The evaluation of the antiplasmodial activity of the isolated compounds against two strains of Plasmodium falciparum (PoW, Dd2) showed a moderate activity of nor-boldine.

In this study, the furofuran lignan (+)-diayangambin [tetrahydro-1,4-bis(3,4,5-trimethoxyphenyl)-(1 R)-1alpha,3abeta,4alpha,6abeta-1 H,3 H-furo [3,4- c]furan] was evaluated in vitro and in vivo for its immunomodulatory and anti-inflammatory efficacy. Human mononuclear cell proliferation was inhibited by diayangambin with an IC 50 value of 1.5 (0.5 - 2.8) microM. In addition, the compound reduced for 40.8 % prostaglandin E 2 generation in stimulated RAW 264.7 macrophage cell line at 10 microM. In vivo, a clear reduction of ear swelling was observed when diayangambin (40 mg/kg) was administered orally to 2,4-dinitrofluorobenzene-treated mice. The inhibition of swelling was associated with a reduction of leukocyte infiltration determined as myeloperoxidase activity. In the carrageenan mouse paw edema model, diayangambin significantly suppressed inflamed paw volume and prostaglandin E 2 levels. Our findings indicate the potential interest of diayangambin in the treatment of immune and inflammatory responses.

Three new quinoline alkaloids have been isolated from the aerial parts of Psychotria glomerulata from Panama. The major alkaloid, glomerulatine A, was identified as 8-8a,8′-8′ a tetradehydro(−)-calycanthine on the basis of spectral data including 1 H, 13 C, COSY-45, HMBC, HMQC and ROESY techniques. Computerized 1 H NMR analysis was used to establish that glomerulatine A possessed the calycanthine- and not the iso-calycanthine-type structure. Two minor alkaloids, glomerulatines B and C, were also isolated and on the basis of spectroscopic evidence it is proposed that they are 8-8a,8′-8′a-tetrahydro-N′-demethyl(−)-calycanthine and 8-8a-didehydro-(−)-calycanthine, respectively.

Three new compounds, 2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-oxo-4H-chromen-3-yl-4,6-bis-O-beta-D-(3,4,5-trihydroxybenzoyl)glucopyranoside (1), 5,7-dihydroxy-2-(4-hydroxyphenyl)-4-oxo-4H-chromen-3-yl-5-O-alpha-L-(3,4,5-trihydroxybenzoyl)arabinofuranoside (2), and 2-hydroxy-4-O-alpha-L-(3,5,7-trihydroxy-4-oxo-4H-chromen-2-yl)phenylarabinofuranoside (3), were isolated from the young leaves of Triplaris cumingiana, together with two known compounds, quercetin 3-O-alpha-L-(5"-O-galloyl)arabinofuranoside (4) and quercetin 3-O-beta-D-(6"-O-galloyl)glucopyranoside (5). The structures of 1-3 were established by spectroscopic methods. Compounds 1-5 were evaluated for their cytotoxic activities against the MCF-7, H-460, and SF-268 human cancer cell lines.

A total of 153 crude extracts of Panamanian plants (28 species from 21 families) have been screened for molluscicidal activity against Biomphalaria glabrata, one of the intermediate hosts of schistosomiasis. When tested at 400 ppm, 15 extracts were active. The most potent of these came from Cyperus luzulae (Cyperaceae) and Hymenaea courbaril (Leguminosae).

The essential oil from leaves of Eugenia acapulcensis Steud. obtained by hydrodistillation was analyzed by GC and GC/MS. From the MS data and retention indices obtained 56.7% of the oil consisting of 47 components could be identified. Eighty-five percent of the analyzed oil was comprised of sesquiterpenes, either hydrocarbons or oxygenated, among which α-cadinol (4.2%), spathulenol (4.2%), ω-cadinene (3.8%) and (Z)-nerolidol (3.5%) were the main ones. The oxygenated monoterpene trans-pinocarveol (4.2%) was also found as a major component of the oil.

The chemical compositions of the essential oils from the leaves of Piper aduncum from Panama and Bolivia were investigated by GC-FID, GC-MS and 13C-NMR. In total, 55 components were identified representing 99.3 and 80.3% of each sample, respectively. The oil from Panama was characterized by a high percentage of sesquiterpene hydrocarbons (38.9%), the main ones being β-caryophyllene (17.4%) and aromadendrene (13.4%). In contrast, the oil from Bolivia showed a high content of monoterpenes (76%), the major constituent being 1,8-cineole (40.5%). Phenylpropanoids, mainly sarisan (1-allyl-2-methoxy-4,5-methylenedioxybenzene; 12.9%), were only detected in the latter. Copyright © 2004 John Wiley & Sons, Ltd.

Bioassay-guided fractionation of an EtOAc/MeOH extract of Adenaria floribunda young leaves using MCF-7, H-460, and SF-268 cancer cell lines yielded four new active compounds named adenaflorins A-D (1-4). Their chemical structures were determined by spectroscopic means. Adenaflorin A (1) was the most cytotoxic.

Twenty-six pure plant-derived compounds including alkaloids, quinones, flavonoids, and coumarins, obtained from five species of Central American plants associated with traditional uses, were tested in vitro for antiprotozoal and cytotoxic activities. The quinone, 1-acetyl-benzoisochromanquinone displayed significant antiprotozoal activity against Leishmania donovani promastigotes and amastigotes, Trypanosoma cruzi amastigotes, and T. brucei brucei bloodstream form trypomastigotes, with IC50 values of 2.32, 1.98, 6.60, and 0.65 muM, respectively. The quinones benzo[g]isoquinoline-5,10-dione had an IC50 value of 4.2 muM against Plasmodium falciparum and 1-hydroxybenzoisochromanquirione an IC50 value of 3.3 muM against T. b. brucei trypomastigotes. The remaining compounds were either weakly active or inactive.

Bioassay-guided fractionation of the methanolic extracts of Vismia baccifera, V. jefensis, and V. macrophylla against human breast, CNS, and lung cancer cell lines resulted in the isolation of a new compound, ferruginin C (1), and seven known compounds, ferruginins A (2) and B (3), vismin (4), harunganin (5), vismione B (6), deacetylvismione H (7), and deacetylvismione A (8), as active constituents. In addition, bivismiaquinone (9) and vismiaquinone (10) were obtained as inactive constituents. The structure of ferruginin C was elucidated by spectroscopic means. Compounds 6-8 were the most active, and the cytotoxic activity of compounds 2-5 and 7 is reported for the first time.

Results of an ethnopharmacognostic survey of 90 plants used by the Kuna Indians of San Blas Islands, who live in Ailigandí, are listed. Results of a literature search are also reported, including medical uses, known constituents and pharmacological effects.

The CH2Cl2 extract of the leaves Annona purpurea L. (Annonaceae) showed strong brine shrimp toxicity and pronounced activity against larvae of the yellow-fever mosquito Aedes aegypti. Activity-directed fractionation of the extract by a combination of column chromatography on silica gel, filtration, and high-pressure liquid chromatography led to the isolation of acetogenins 1–6 as the main active principles. The structures of two novel acetogenins named purpureacin 1(5) and purpureacin 2(6) were elucidated by spectroscopic analysis (UV, EI- and DCI-MS, EI-MS of Me3Si derivatives,1H- and 13C-NMR). The configuration of 5 and 6 was not established due to the limited sample amount. Compounds 3–6 also showed antifungal activity against Candida albicans, and 5 was slightly active against Bacillus subtilis.

A new kaempferol triglycoside and three known kaempferol glycosides, among them two apiosides, have been isolated from the aerial parts of Monnina sylvatica. The structures were established on the basis of acid and enzymatic hydrolysis and spectral data (UV, 1H and 13CNMR, NOE difference measurements, D/CI and FAB-MS) of the isolates and of some derivatives. The triglycoside kaempferol 3-O-beta-D-glucosyl-(1----2)-O-[alpha-L-rhamnosyl(1----6)]-beta-D- galactoside is a new natural product. The configuration of the apiosyl moiety in kaempferol 3-O-beta-D-apiosyl(1----2)-beta-D-galactoside and kaempferol 3-O-beta-D-apiosyl(1----2)-O-[alpha-L-rhamnosyl(1----6)]- beta-D-galactoside was established through NOE difference measurements on the peracetate.

A new 5-O-beta-D-glucopyranosyl-4-(4-hydroxyphenyl)-7-methoxy-2H-chromen-2-one (1), together with four known compounds, one coumarin, 5-O-beta-D-galactopyranosyl-4-(4-hydroxyphenyl)-7-methoxy-2H-chromen-2-one (2) and three cucurbitacins, 23,24-dihydrocucurbitacin F (3), 23,24-dihydro-25-acetylcucurbitacin F (4) and 2-O-beta-D-glucopyranosyl-23,24-dihydrocucurbitacin F (5) have been isolated and characterised from the ethanol extract of Coutarea hexandra fruits. Their structures have been established by spectroscopic analysis (NMR and MS). Interpretation of the HMQC, HMBC, COSY-45 and NOESY experiments permitted us to establish stereochemistry of the natural products. All compounds were tested in cytotoxicity assays against the breast (MCF-7), lung (H-460), and central nervous system (SF-268) human cancer cell lines.

Bioassay-guided fractionation of the chloroform and ethanol extracts of Tovomita longifolia leaves using cytotoxic and antimicrobial assays resulted in the isolation of four new benzophenones, (E)-3-(2-hydroxy-7-methyl-3-methyleneoct-6-enyl)-2,4,6-trihydroxybenzophenone (1), (E)-3-(6-hydroxy-3,7-dimethylocta-2,7-dienyl)-2,4,6-trihydroxybenzophenone (2), 8-benzoyl-2-(4-methylpenten-3-yl)chromane-3,5,7-triol (3), and 5-benzoyl-1,1,4a-trimethyl-2,3,4,4a,9,9a-hexahydro-1H-xanthene-6,8-diol (4), and two known benzophenones, 4-geranyloxy-2,6-dihydroxybenzophenone (5) and 3-geranyl-2,4,6-trihydroxybenzophenone (6). The structures of 1-4 were established by spectroscopic means and by molecular modeling calculations. Compounds 1 and 3-5 demonstrated cytotoxic activities against breast (MCF-7), central nervous system (SF-268), and lung (H-460) human cancer cell lines, while compounds 3-6 showed antimicrobial activity against Klebsiella pneumoniae, Mycobacterium smegmatis, Pseudomonas aeruginosa, Salmonella gallinarum, and Staphylococcus aureus.

A new prenylated salicylic acid derivative, 3-farnesyl-2-hydroxy benzoic acid (1), was isolated from the leaves of Piper multiplinervium C. DC. (Piperaceae). It showed anti-Helicobacter pylori activity (MIC 37.5 mu g/ml) and antimicrobial activity at MICs between 2.5 and 5 mu g/ml against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Mycobacterium smegmatis, Pseudonionas aeruginosa and Candida albicans. Its structure was elucidated by means of MS, H-1 and C-13 NMR. The ethnomedical claim of Piper multiplinervium to treat stomach aches by the Kuna Indians of Panama may be justified by anti-Helicobacter pylori activity of its MeOH extract. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

A new cucurbitacin D analogue, 2-deoxycucurbitacin D (1), as well as cucurbitacin D (2) and 25-acetylcucurbitacin F (3) were isolated from Sloanea zuliaensis. Compound 1 was found only in the young leaves of the plant and not in the mature leaves, and its structure was established using spectroscopic means. Compounds 1-3 demonstrated potent cytotoxic activity against breast (MCF-7), lung (H-460), and central nervous system (SF-268) human cancer cell lines.

Methanolic and aqueous extracts derived from 43 plant species, selected either from ethnobotanical or chemotaxonomical data, were screened for their antiprotozoal activity against Leishmania donovani and Trypanosoma brucei brucei. The cytotoxic activity against KB cells was also determined. Eight extracts had IC50 values of less than 10 microg/ml against Leishmania donovani. The most active was Triclisia patens with an IC50 value of 1.5 microg/ml against Leishmania donovani. Annona purpurea and Alstonia macrophylla had IC50 values below 10 microg/ml against Trypanosoma brucei brucei. Annona purpurea was the most cytotoxic against KB cells.

Ethnomedical uses of 108 medicinal plant species, belonging to 52 families, 89 genera, used by the Teribe Amerindians of Bocas del Toro Province in Panama, along with their socio-cultural practices are reported here. The methods of administration of the herbal remedies, the plant parts used, their families and local names are also documented. The recorded medicinal plants were used mainly for fever, various type of pain and inflammation. The potential value of 26 plants and their traditional uses was elucidated through literature search.

The phytochemical investigation of the leaves of Siparuna pauciflora yielded three novel sesquiterpenoids: the germacrane sipaucin A, the elemane sipaucin B and sipaucin C, comprising a new type of carbon skeleton. In addition, four known aporphine alkaloids-nor-boldine, boldine, laurotetanine, and N-methyl-laurotetanine-were obtained. The evaluation of the antiplasmodial activity of the isolated compounds against two strains of Plasmodium falciparum (PoW, Dd2) showed a moderate activity of nor-boldine.

The type of interaction of 5-methyl-2,3,7,8-bis(methylenedioxy)benzo[ c ]phenanthridinium (sanguinarine), an alkaloid isolated from the root of Bocconia frutescens L., with the human angiotensin AT 1 receptor was evaluated in both intact cells and membrane binding of [ 3 H](2-ethoxy-1-[(2′-(1 H -tetrazol-5-yl)biphenyl-4-yl)methyl]-1 H -benzimidazoline-7-carboxylic acid) ([ 3 H]candesartan). The results indicate that the inhibition of [ 3 H]candesartan binding by sanguinarine is independent of cell viability, since the alkaloid inhibited at a similar extent radioligand binding on both intact Chinese hamster ovary (CHO) cells transfected with the human angiotensin AT 1 receptor (hAT 1 ) and their cell membranes ( K i =0.14 and 1.10 μM, respectively). The unsuccessful recovery of [ 3 H]candesartan binding after washing sanguinarine off the cells suggested a nearly irreversible or slow reversible interaction. Saturation binding studies showed a substantial reduction of the B max without affecting the K d . In addition, the presence of 2- n -butyl-4chloro-5-hydroxymethyl-1-[(2′-(1 H -tetrazol-5-yl)biphenyl-4-yl)methyl]imidazole (losartan) could not prevent sanguinarine inhibition of [ 3 H]candesartan binding neither. The present findings indicate that sanguinarine interacts with the receptor in a slow, nearly irreversible and noncompetitive manner.

A bioassay-guided fractionation of the 70% acetone extract of the bark of Guazuma ulmifolia Lam. on the inhibition of angiotensin II binding to the AT 1 receptor led to the isolation and identification of bioactive oligomeric and polymeric proanthocyanidins consisting mainly of (-)-epicatechin units. The displacement of [3H]-angiotensin II binding was dose-dependent and correlated with the degree of polymerization of the different fractions containing proanthocyanidins. A strong displacement was seen for the residual fraction suggesting that the most active substances corresponding to the highly polymerized proanthocyanidins. Angiotensin II AT 1 receptor binding might be considered as a potentially interesting biological activity of proanthocyanidins contributing to the very broad spectrum of biological activities of the condensed tannins.

Several myrcenylhydroquinone derivatives have been evaluated for their cytotoxic activity against three neoplastic cell line cultures and compared with the activity previously observed on other neoplastic systems. Also a new series of this type of compounds has been prepared and the compounds synthesised have been evaluated by their GI 50 values.

A bioassay-guided fractionation of the 80 % ethanolic extract from Bocconia frutescens L. roots, showing a dose-dependent inhibitory effect towards both [(3)H]-angiotensin II and [(3)H]-BQ-123 binding to the human angiotensin II AT 1 and endothelin 1 ET(A) receptors, led to an alkaloidal subfraction as the only responsible fraction for the activity of the whole extract. Among the alkaloids present in this fraction sanguinarine and chelerythrine were significant inhibitors of [(3)H]-angiotensin II binding (hAT 1 receptor), with IC(50) values within the micromolar range. On the contrary, the [(3)H]-BQ-123 binding (ET(A) receptor) was only weakly inhibited. Moreover, other members of the isoquinoline alkaloid family such as chelidonine and some protoberberine alkaloids exhibited no affinity for the two receptors. The present work shows the possible structure-activity relationship for these benzophenanthridine alkaloids on a screening bioassay using both stably transfected Chinese hamster ovary (CHO) and the human neuroblastoma SK-N-MC cells. Furthermore, the ability of these compounds to block AT(1) and/or ET(A) receptors may provide some justification for the traditional use of Bocconia frutescens L. to control hypertension.

A new indole alkaloid, vallesiachotamine lactone, and four known compounds strictosidine, strictosamide, vallesiachotamine and angustine were isolated from the aerial parts of Cephaelis dichroa. Structures were established by spectroscopic methods (UV, IR, mass spectrometry, 1H and 13C NMR, including COSY 45 and 1H13C heterocorrelation). Isovallesiachotamine was detected as a degradation product of vallesiachotamine.

Summary Nineteen plants from the Republic of Panama were selected by their traditional uses in the treatment of hypertension, cardiovascular, mental and feeding disorders and 149 extracts were screened using radioligand-receptor-binding assays. The methanol:dicloromethane extracts of the bark and leaves of Anacardium occidentale L., the leaves of Begonia urophylla Hook., the roots of Bocconia frutescens L., the stems and leaves of Cecropia cf.obtusifolia Bertol., the branches of Clusia coclensis Standl., the bark of Cochlospermum vitifolium (Willd.)Spreng., the roots of Dimerocostus strobilaceus Kuntze, the bark of Guazuma ulmifolia Lam., the leaves of Persea americana Mill. and the branches of Witheringia solanaceae L'Her. inhibited the [3H]-AT II binding (angiotensin II AT1 receptor) more than 50%. Only extracts of the roots of Dimerocostus strobilaceus Kuntze and the stems of Psychotria elata (Sw.) Hammel were potent inhibitors of the [3H] NPY binding (neuropeptide Y Y1 receptor) more than 50% and the ethanolic extracts of the leaves of Cecropia cf.obtusifolia Bertol., the leaves of Hedyosmum bonplandianum H.B.K., the roots of Bocconia frutescens L., the stem of Cecropia cf.obtusifolia Bertol. and the branches of Psychotria elata (Sw.) Hammel showed high inhibition of the [3H] BQ-123 binding (endothelin-1 ETA receptor) in a preliminary screening. These results promote the further investigation of these plants using the same assays.

Reinvestigation of the polar fractions from the stem bark of STEMMADENIA MINIMA A. Gentry (Apocynaceae) afforded two known and four new lignan glucosides. Their structures were deduced by spectroscopic and chemical methods.

From a lipophilic extract of leaves of Siparuna andina (Monimiaceae), which exhibited antiplasmodial activity in vitro, two new compounds have been isolated: sipandinolide (1), a compound with a novel type of carbon skeleton and (-)-cis-3-acetoxy-4',5,7-trihydroxyflavanone (2). Their structures were established by spectroscopic methods; 2 showed moderate antiplasmodial activity whereas 1 was inactive.

Four compounds including a flavone, an acetylenic lactone, a prenylated coumarin, and a 3-methyl ether flavone were isolated from the dichloromethane leaf extract of Baccharis pedunculata (Mill.) Cabr. (Asteraceae). The latter three compounds were identified to be responsible for the antifungal activity against some human pathogenic and phytopathogenic fungi. The most active compound, lachnophyllum lactone, an acetylenic lactone, showed a very high toxicity (LD50 2 micrograms/ml) against human keratinocytes.

A new benzoquinone (1-hydroxybenzoisochromanquinone) and benz [g]isoquinoline-5, 10-dione have been isolated from the woody parts of Psychotria camponutans, as a result of bioactivity-guided fractionation. The compounds were characterized by UV, IR, EI-mass, 1H-, and 13C-NMR, and HETCOR NMR spectroscopy. Both compounds, together with acetylbenzoisochromanquinone, showed in vitro strong activity against brine shrimp, KB cells, and chloroquine-resistant P. falciparum.

A bioactivity guided fractionation, using KB cells and brine shrimp assays, of the methanolic extract from the leaves of Picramnia antidesma yielded two known anthraquinones, aloe-emodin and aloe-emodin anthrone, and three new aloe-emodin C-glycosides, named picramnioside A, picramnioside B and picramnioside C. Structures were established by spectroscopic methods (UV, IR, mass spectrometry, 1H and 13C and 2D NMR including COSY 45, HMQC, HMBC and ROESY). CD was used to establish the absolute configuration of the picramniosides.

The essential oil from the leaves of Siparuna thecaphora was analyzed by GC and GC/MS. Forty-six components were identified representing approximately 60% of the oil, among which oxygenated sesquiterpenes (27%), sesquiterpene hydrocarbons (18%) and linear oxygenated compounds (11%) were the major groups of constituents, with spathulenol (9.4%), 2-tridecanone (5.3%) and α-copaene (4.5%) being the main components. The oil exhibited bacteriostatic activity against Staphylococcus aureus and Mycobacterium smegmatis (MIC 250 (μg/mL), but no larvicidal activity against Aedes aegypti.

A new microplate assay for cytotoxicity testing using A. salina has been developed and shown to give results comparable to a previously published test-tube method. The assay reliably detected all of the compounds toxic to KB cells in a series of 21 pharmacologically active agents, except for two which require metabolic activation in man. Four quassinoids with cytotoxic and antiplasmodial activity were also toxic to the brine shrimp while quassin itself was inactive in all three systems. It is proposed that this assay provides a convenient means by which the presence of cytotoxic quassinoids may be detected during the fractionation of plant extracts.

Bioprospecting has frequently been cited as a sustainable use of biodiversity. Nevertheless, the level of bioprospecting in biodiversity-rich tropical regions falls below its potential, with the result that bioprospecting has produced only limited economic benefits. We present a bioprospecting program that, in addition to promoting drug discovery, provides economic benefits to and promotes conservation in Panama through the sustainable use of biodiversity. The program was initiated using insights from 20 years of nonapplied ecological research to enhance the likelihood of finding treatments for human disease. Samples are not sent abroad; rather, most of the research is carried out in Panamanian laboratories. Panama has received immediate benefits for the use of its biodiversity in the form of research funding derived from sources outside Panama, training for young Panamanian scientists, and enhanced laboratory infrastructure. Over the long term, discoveries derived from bioprospecting may help to establish research-based industries in Panama.

From the upper parts of SPIGELIA ANTHELMIA L. besides some widely distributed phenolcarboxylic acids and flavonoids two volatile alkaloids have been isolated and identified as isoquinoline and an iridoid compound of the actinidine type. In the water extract choline, benzoylcholine and 3,3-dimethyl-acryloylcholine could be identified. Preliminary pharmacological investigations revealed that the alkaloids are involved in the cardiotonic activity of the plant.

A novel betaine-type indole alkaloid, 16-epi-panarine, was isolated from Stemmadenia minima. Its structure was determined by spectral studies and chemical interconversion to panarine

Crude extracts from 20 Panamanian plants used in traditional medicine have been screened for brine shrimp toxicity, tumor inhibition, DNA-intercalation and cytotoxicity tests in a clonogenic assay in V79 suspension culture gassed with air or nitrogen. Of the 20 plant extracts, 8 (40%) proved active in DNA intercalation. The most active were the methanol extracts of Bidens pilosa (root), Jatropha curcas (leaf), Pereskia bleo (whole plant), Isertia hypoleuca (leaf), Cyperus luzulae (root), Vernonia patens (leaf and stem), Alibertia edulis (stem) and Justicia graciliflora (aerial parts). Sixteen (80%) of the 20 methanol plant extracts were active in potato disc tumor inhibition assay; Cyperus luzulae (root), Justicia graciliflora (aerial parts), Pereskia bleo (whole plant) and Vernonia patens (leaf and stem) being the most active. Cytotoxicity in the clonogenic assay was observed only in three plant extracts: Cyperus luzulae, Piper auritum and Psychotria correae, whereas high brine shrimp toxicity (LC 50 &lt...