New clerodane diterpenoids from Laetia procera (Poepp.) Eichler (Flacourtiaceae), with antiplasmodial and antileishmanial activities

Chemical Constituents and Pharmacological Activities of Family Flacourtiaceae: A Class of Important Phytomedicine

Flacourtiaceae plants are widely used as folk medicines in traditional medicine systems for its chemical diversity and pharmacological activities. In many different areas, Flacourtiaceae plants are used as traditional medicines for the treatment of ulcers, malaria, rheumatism. The Flacourtiaceae plants contain a very plentiful chemical composition, and phytochemical studies show that the Flacourtiaceae plants contained terpenoids, aromatic glycosides, flavnoids, phenylpropanoids, alkaloids, fatty hydrocarbon, and other compounds. In pharmacological studies, various extract and isolated individual compounds exhibited antitumor, anti-oxidation, and anti-inflammatory activities. In this review, the literature data on the chemical constituents and pharmacological investigations of the Flacourtiaceae plants are summarized, to provide information about a more comprehensive chemical composition and detailed pharmacological activities of Flacourtiaceae plants, with a view of further development of clinical medication. However, research on quantitative analysis, toxicity, and drug safety in vitro and in vivo is still insufficient, and further research is required.

Towards the optimization of botanical insecticides research: Aedes aegypti larvicidal natural products in French Guiana

Natural products have proven to be an immeasurable source of bioactive compounds. The exceptional biodiversity encountered in Amazonia, alongside a rich entomofauna and frequent interactions with various herbivores is the crucible of a promising chemodiversity. This prompted us to search for novel botanical insecticides in French Guiana. As this French overseas department faces severe issues linked to insects, notably the strong incidence of vector-borne infectious diseases, we decided to focus our research on products able to control the mosquito Aedes aegypti. We tested 452 extracts obtained from 85 species originating from 36 botanical families and collected in contrasted environments against an Ae. aegypti laboratory strain susceptible to all insecticides, and a natural population resistant to both pyrethroid and organophosphate insecticides collected in Cayenne for the most active of them. Eight species (Maytenus oblongata Reissek, Celastraceae; Costus erythrothyrsus Loes., Costaceae; Humiria balsamifera Aubl., Humiriaceae; Sextonia rubra (Mez) van der Werff, Lauraceae; Piper hispidum Sw., Piperaceae; Laetia procera (Poepp.) Eichl., Salicaceae; Matayba arborescens (Aubl.) Radlk., Sapindaceae; and Cupania scrobitulata Rich., Sapindaceae) led to extracts exhibiting more than 50% larval mortality after 48 h of exposition at 100 µg/mL against the natural population and were considered active. Selectivity and phytochemistry of these extracts were therefore investigated and discussed, and some active compounds highlighted. Multivariate analysis highlighted that solvents, plant tissues, plant family and location had a significant effect on mortality while light, available resources and vegetation type did not. Through this case study we highlighted that plant defensive chemistry mechanisms are crucial while searching for novel insecticidal products.

Non-nitrogenous Plant-derived Constituents with Antiplasmodial Activity

The paper is a compilation of the studies reported in the literature concerning non-nitrogenous natural constituents that have shown antiplasmodial activity and aims to provide a basis for further in vivo studies as well as for clinical trials to develop new antimalarial agents. Due to the increasingly unsatisfactory outcomes for N-heterocyclic drugs, coupled with the rising incidence of the deadly falciparum malaria, the advent of non-nitrogenous lead compounds is timely, signaling a new era of antimalarial chemotherapy. Currently a few non-nitrogenous molecules are used in therapy, but many promising molecules of plant origin are under study, such as peroxide sesquiterpenes, quinoid triterpenes, quassinoids, gallic acid derivatives, lignans, flavonoids and biflavonoids, xanthones, naphthoquinones and phenylanthraquinones. Many of these constituents are isolated from plants used traditionally to treat malaria and fever. Ethnopharmacology can still be considered as a rich source of lead molecules.

Antileishmanial activity and cytotoxicity of ent-beyerene diterpenoids

We describe the in vitro activity of two natural isomeric ent-beyerene diterpenes, several derivatives and synthetic intermediates. Beyerenols 1 and 2 showed EC₅₀ of 4.6 ± 9.4 and 5.3 ± 9.4 μg/mL against amastigotes of L. (V) brazilensis, with SI of 5.1 and 7.7, respectively. Beyerenol 1 was synthesized from stevioside. In vivo experiments with bereyenols showed cure in 50% of hamsters infected with L. (V) brazilensis topically applied as Cream I (beyerenol 1, 0.81%, w/w) and Cream III (beyerenol 2, 1.96%, w/w). These results suggest that beyerenols are potential candidates for cutaneous leishmaniasis chemotherapy by topical application. In vitro assays of amastigotes of L. (V) brazilensis showed EC₅₀ of 1.1 ± 0.1 and 1.3 ± 0.04 μg/mL, with SI of 3.1 and 3.5 for hydrazone intermediates 10 and 11, respectively.

Corymbulosins I-W, Cytotoxic Clerodane Diterpenes from the Bark of Laetia corymbulosa

The isolation studies of a crude MeOH/CH₂Cl₂ (1:1) extract (N005829) of the bark of Laetia corymbulosa yielded 15 new clerodane diterpenes, designated corymbulosins I-W (1-15), as well as four known diterpenes, 16-19. The structures of 1-15 were characterized on the basis of extensive 1D and 2D NMR and HRMS analyses. The absolute configurations of newly isolated compounds 1-15, as well as known 16-19, which were reported previously with only relative configurations, were determined through ECD experiments, X-ray analysis, chemical methods, including Mosher esterification, and comparison of their spectroscopic data. The isolated compounds were evaluated for cytotoxicity against human cancer cell lines. Flow cytometric and immunocytochemical observations of cells treated with cytotoxic clerodanes demonstrated that the chromatin was fragmented and dispersed with formation of apoptotic microtubules.

Corymbulosins D-H, 2-Hydroxy- and 2-Oxo-clerodane Diterpenes from the Bark of Laetia corymbulosa

A bioactive CH₃OH-CH₂Cl₂ (1:1) extract of the bark of Laetia corymbulosa provided five new clerodane diterpenes with an isozuelanin skeleton, designated as corymbulosins D-H (1-5), as well as the known corymbulosins B (6) and C (7), for which the relative configurations were not previously determined. The structures of 1-5 were characterized on the basis of 1D and 2D NMR spectroscopic and HRMS analysis. The absolute configurations of all isolated compounds 1-7 were verified through chemical methods, including modified Mosher esterifications or oxidation of the hydroxy group at C-2, ECD experiments, and spectroscopic data comparison. The isolated compounds were evaluated for antiproliferative activity against a small panel of human cancer cell lines.

Clerodane diterpenes: sources, structures, and biological activities

Covering: 1990 to 2015The clerodane diterpenoids are a widespread class of secondary metabolites and have been found in several hundreds of plant species from various families and in organisms from other taxonomic groups. These substances have attracted interest in recent years due to their notable biological activities, particularly insect antifeedant properties. In addition, the major active clerodanes of Salvia divinorum can be used as novel opioid receptor probes, allowing greater insight into opioid receptor-mediated phenomena, as well as opening additional areas for chemical investigation. This article provides extensive coverage of naturally occurring clerodane diterpenes discovered from 1990 until 2015, and follows up on the 1992 review by Merritt and Ley in this same journal. The distribution, chemotaxonomic significance, chemical structures, and biological activities of clerodane diterpenes are summarized. In the cases where sufficient information is available, structure activity relationship (SAR) correlations and mode of action of active clerodanes have been presented.

In vitro antimalarial activity of different extracts of Eremostachys macrophylla Montbr. & Auch

Introduction:The risk of drug resistance and the use of medicinal plants in malaria prevention and treatment have led to the search for new antimalarial compounds with natural origin.

Methods:In the current study, six extracts with different polarity from aerial parts and rhizomes of Eremostachys macrophylla Montbr. & Auch., were screened for their antimalarial properties by cell-free β-hematin formation assay.

Results: Dichloromethane (DCM) extracts of both parts of plant showed significant antimalarial activities with IC₅₀ values of 0.797 ± 0.016 mg/mL in aerial parts and 0.324 ± 0.039 mg/mL in rhizomes compared to positive control (Chloroquine, IC₅₀ = 0.014 ± 0.003 mg/mL, IC₉₀ = 0.163 ± 0.004 mg/mL). Bioactivity-guided fractionation of the most potent part (DCM extract of rhizomes) by vacuum liquid chromatography (VLC) afforded seven fractions. Sixty percent ethyl acetate/n-hexane fraction showed considerable antimalarial activity with IC₅₀ value of 0.047 ± 0.0003 mg/mL.

Conclusion: From 6 extracts with different polarity of E. macrophylla,s aerial parts and rhizomes, the DCM extract of both parts were the most active extract in this assay. The preliminary phytochemical study on the VLC fractions of the most potent part persuades us to focus on purifying the active components of these extracts and to conduct further investigation towards in vivo evaluation.

Clerodane diterpenes from Polyalthia longifolia (Sonn) Thw. var. pendula: Potential antimalarial agents for drug resistant Plasmodium falciparum infection

BACKGROUND

Plasmodium falciparum drug resistance is a major public health challenge in sub-Sahara Africa. Many people are now resorting to the use of herbs in managing malaria due to the increasing treatment failures with the conventional drugs. In this study the ethanolic extract of Polyalthia longifolia (Sonn) Thw. var. pendula, a variety fondly used in folklore medicine in Ghana was investigated for potential antimalarial drug development.

METHOD

The ethanolic extract of P. longifolia (Sonn) Thw. var. pendula stem bark was screened against the multidrug resistant, K1 strain of P. falciparum by the parasite lactate dehydrogenase (pLDH) assay and a good antiplasmodial activity (IC50 22.04± 4.23µg/ml) was observed which led to further chromatographic analysis in search for actives.

RESULTS

Bioassay guided fractionation of the extract yielded; three clerodane diterpenes [16-hydroxycleroda-3,13-dien-16,15-olide (1), 16-oxocleroda-3,13E-dien-15-oic acid (2) and 3,16-dihydroxycleroda-4(18),13(14)Z-dien-15,16-olide (3)], a steroid [beta-stigmasterol (4)] and two alkaloids [darienine (5) and stepholidine (6)]. While compounds 4, 5 and 6 exhibited weak antiplasmodial activity (IC50 22-105µg/ml), the clerodane diterpenes exhibited significantly potent (p<0.005) blood schizonticidal activity (IC50: 3-6µg/ml). This is the first report of the antiplasmodial activity of compounds 2 and 3. In combination assay with chloroquine, compounds 1, 2, 3 and 5 antagonized the antiplasmodial activity of chloroquine while 4 and 6 demonstrated a synergistic action.

CONCLUSION

The potent antiplasmodial activity of the extract of P. longifolia (Sonn) Thw. var. pendula and compounds therein strongly suggests its usefulness as an antimalarial agent and supports its inclusion or exploitation in formulations of herbal remedies for malaria in Ghana.

Antileishmanial activity of essential oil and 6,7-dehydroroyleanone isolated from Tetradenia riparia

Tetradenia riparia plant is used as a traditional medicine in Africa for the treatment of inflammatory and infectious diseases as like parasitic. Therapy for leishmaniasis caused by Leishmania (Leishmania) amazonensis specie often fails, and the conventional drugs are toxic, expensive, require a long period of treatment, and adverse effects are common. The alternative therapies using natural products are inexpensive and have few or any adverse reaction. These reasons are sufficient to investigate the new natural therapeutic for leishmaniasis. We evaluated the potential of the essential oil (TrEO) and 6,7-dehydroroyleanone (TrROY) isolated from T. riparia on L. (L.) amazonensis promastigote and amastigote forms, cytotoxicity on human erythrocytes and murine macrophages, nitric production and inducible nitric oxide synthase (iNOS) mRNA expression. TrEO was the most effective to promote the Leishmania promastigote death. After 72 h incubation, the lethal dose of TrEO and TrROY that promoted 50% Leishmania death (LD50) were 0.8 μg/mL and 3 μg/mL, respectively. TrEO and TrROY were not cytotoxic to human erythrocytes, but TrROY was toxic to murine macrophages resulting in a low selectivity index. The transmission electronic microscopy showed that TrEO (0.03 μg/mL) was able to modify the promastigote ultrastructures suggesting autophagy as chromatin condensation, blebbing, membranous profiles and nuclear fragmentation. Infected-macrophages treated with TrEO (0.03 μg/mL) or TrROY (10 μg/mL) had an infection index decreased in 65 and 48%. TrEO did not induce iNOS mRNA expression or nitrite production in macrophages infected with Leishmania. TrROY and mainly TrEO promoted the Leishmania death, and TrROY showed loss toxicity to erythrocytes cells. Other compounds derived from T. riparia and the essential oil could be explored to develop a new alternative treatment for leishmaniasis.

Peltate glandular trichomes of Colquhounia seguinii harbor new defensive clerodane diterpenoids

Glandular trichomes produce a wide variety of secondary metabolites that are considered as major defensive chemicals against herbivore attack. The morphology and secondary metabolites of the peltate glandular trichomes of a lianoid Labiatae, Colquhounia seguinii Vaniot, were investigated. Three new clerodane diterpenoids, seguiniilactones A-C (1-3), were identified through precise trichome collection with laser microdissection, metabolic analysis with ultra performance liquid chromatography-tandem mass spectrometer, target compound isolation with classical phytochemical techniques, structure elucidation with spectroscopic methods. All compounds showed significant antifeedant activity against a generalist plant-feeding insect Spodoptera exigua. Seguiniilactone A (1) was approximately 17-fold more potent than the commercial neem oil. α-Substituted α,β-unsaturated γ-lactone functionality was found to be crucial for strong antifeedant activity of this class of compounds. Quantitative results indicated that the levels of these compounds in the peltate glandular trichomes and leaves were sufficiently high to deter the feeding by generalist insects. Moderate antifungal activity was observed for seguiniilactone C (3) against six predominant fungal species isolated from the diseased leaves of C. seguinii, while seguiniilactones A and B were generally inactive. These findings suggested that seguiniilactones A-C might be specialized secondary metabolites in peltate glandular trichomes for the plant defense against insect herbivores and pathogens.

Antiparasitic activity and effect of casearins isolated from Casearia sylvestris on Leishmania and Trypanosoma cruzi plasma membrane

Leishmaniasis and Chagas disease are infectious diseases caused by parasite Leishmania sp. and Trypanosoma cruzi, respectively, and are included among the most neglected diseases in several underdeveloped and developing countries, with an urgent demand for new drugs. Considering the antiparasitic potential of MeOH extract from leaves of Casearia sylvestris Sw. (Salicaceae), a bioguided fractionation was conducted and afforded four active clerodane diterpenes (casearins A, B, G, and J). The obtained results indicated a superior efficacy of tested casearins against trypomastigotes of T. cruzi, with IC50 values ranging from 0.53 to 2.77 μg/ml. Leishmania infantum promastigotes were also susceptible to casearins, with IC50 values in a range between 4.45 and 9.48 μg/ml. These substances were also evaluated for mammalian cytotoxicity against NCTC cells resulting in 50% cytotoxic concentrations (CC50) ranging from 1.46 to 13.76 μg/ml. Additionally, the action of casearins on parasite membranes was investigated using the fluorescent probe SYTOX Green. The obtained results demonstrated a strong interaction of casearins A and B to the plasma membrane of T. cruzi parasites, corroborating their higher efficacy against these parasites. In contrast, the tested casearins induced no alteration in the permeability of plasma membrane of Leishmania parasites, suggesting that biochemical differences between Leishmania and T. cruzi plasma membrane might have contributed to the target effect of casearins on trypomastigotes. Thus, considering the importance of studying novel and selective drug candidates against protozoans, casearins A, B, G, and J could be used as tools to future drug design studies.

First chemical evaluation and toxicity of Casinga-cheirosa to Balb-c male mice

Laetia suaveolens, known as “casinga-cheirosa”, crude extract EB719 has previously shown cytotoxic activity against prostate cancer and squamous cell carcinoma. For the first time, seven molecules were isolated from its apolar—α-tocopherol (1) and sitosterol (2)—and polar—3-O-caffeoylquinic acid (3), 4-O-caffeoylquinic acid (4), 5-O-feruloylquinic acid (5), hyperoside (6), and isoquercitrin (7)—fractions. Acute toxicity was determined in a two-stage experiment: (1) a reduced number of Balb-c male mice received 5000 mg/kg of EB719 to allow evaluation of general activity and other 27 parameters, plus death, up to the establishment of non-lethal dose (NLD), as well as lethal dose 50% (LD₅₀); (2) NLD was administered and diazepam introduced as reference drug. EB719 showed LD₅₀ = 178.0 mg/kg, and NLD 156.3 mg/kg. In stage one EB719 did not influence general activity, but provoked impairment in grasp reflexes, tail squeeze and breathing; piloerection and cyanosis were increased. In stage two, alterations occurred in auricular reflex, piloerection and breathing after diazepam administration, but not in response to EB719. Intestinal hemorrhage caused by local bleeding was observed after necropsy, and may be the main cause of animals’ death other than a systemic effect of the extract. Although the isolated compounds are biologically and pharmacologically active in both men and animal systems, it is premature to relate their occurrence in EB719 to the observed intestine hemorrhage in mice.

In vivo antimalarial activity of a labdane diterpenoid from the leaves of Otostegia integrifolia Benth

In Ethiopian traditional medicine, the leaves of Otostegia integrifolia Benth. are used for the treatment of several diseases including malaria. In an ongoing search for effective, safe and cheap antimalarial agents from plants, the 80% methanol leaf extract O. integrifolia was tested for its in vivo antimalarial activity, in a 4-day suppressive assay against Plasmodium berghei. Activity-guided fractionation of this extract which showed potent antiplasmodial activity resulted in the isolation of a labdane diterpenoid identified as otostegindiol. Otostegindiol displayed a significant (P < 0.001) antimalarial activity at doses of 25, 50 and 100 mg/kg with chemosuppression values of 50.13, 65.58 and 73.16%, respectively. Acute toxicity studies revealed that the crude extract possesses no toxicity in mice up to a maximum dose of 5000 mg/kg suggesting the relative safety of the plant when administered orally. The results of the present study indicate that otostegindiol is among the antimalarial principles in this medicinal plant, and further support claims for the traditional medicinal use of the plant for the treatment of malaria.

In vitro cytotoxic effects of Brazilian plant extracts on squamous cell carcinoma of the oral cavity

Squamous cell carcinoma (SCC) is the most prevalent cancer of the oral cavity and the fifth most prevalent of all malignancies in males. Many researchers have attempted to develop new treatments that will improve the prognosis of SCC patients. Over 20% of the world's biodiversity is located within the Brazilian forests, but little is known about the chemical and/or pharmacological potential of these plants. Certain extracts obtained from Amazon and Atlantic Forest plants have previously been shown to have cytotoxic activity against various cancers. The aim of this study was to screen these extracts for cytotoxic activity against oral SCC cells. The extracts were analyzed for activity against the KB-ADL#12 cell line at various concentrations up to a maximum dose of 100 µg/mL. Comparisons with a control group were performed using one-way ANOVA. Significant cytotoxicity was induced by the extracts obtained from the aerial parts of Picrolemma sprucei (Simaroubaceae), from the leaves and stems of Laetia suaveolens (Salicaceae), from the aerial parts of Abarema auriculata (Fabaceae-Mimosoideae) and from the stem of A. auriculata.

Recent advances in leishmaniasis treatment

About 1.5 million new cases of cutaneous leishmaniasis and 500,000 new cases of visceral leishmaniasis occur each year around the world. For over half a century, the clinical forms of the disease have been treated almost exclusively with pentavalent antimonial compounds. In this review, we describe the arsenal available for treating Leishmania infections, as well as recent advances from research on plants and synthetic compounds as source drugs for treating the disease. We also review some new drug-delivery systems for the development of novel chemotherapeutics. We observe that the pharmaceutical industry should employ its modern technologies, which could lead to better use of plants and their extracts, as well as to the development of synthetic and semi-synthetic compounds. New studies have highlighted some biopharmaceutical technologies in the design of the delivery strategy, such as nanoparticles, liposomes, cochleates, and non-specific lipid transfer proteins. These observations serve as a basis to indicate novel routes for the development and design of effective anti-Leishmania drugs.

Cytotoxic clerodane diterpenes from Casearia rupestris

Four new clerodane diterpenes, casearupestrins A-D (1-4), were isolated from the leaves of Casearia rupestris. Compounds 1 and 4 were acetylated to yield 2,7-di-O-acetylcasearupestrin A (5) and 2,6-di-O-acetylcasearupestrin D (6). All compounds were evaluated for cytotoxicity against a small panel of human cancer cell lines. Casearupestrin A (1) exhibited the most potent activity against MDA/MB-435 (human melanoma) and SF-295 (human glioblastoma) cells, superior to that of the standard drug doxorubicin.

Antiplasmodial activity of New Caledonia and Vanuatu traditional medicines

CONTEXT

With the emergence of strains multiresistant to antimalarial drugs, the search for new active molecules remains a priority. Ethnopharmacology appears to be a good method of selection in such investigations.

OBJECTIVE

The aim of this research work is to select plants used in Melanesian traditional medicine, in New Caledonia and Vanuatu, which should be a promising source for the isolation of new antimalarial drugs.

MATERIALS AND METHODS

Forty-seven plant extracts belonging to 12 families, traditionally used by the Melanesian people or belonging to an antimalarial known genus, were screened in vitro for antimalarial activity on Plasmodium falciparum chloroquine (CQ)-resistant (FcB1) and CQ-sensitive (HB3) strains. They were also tested for their inhibitory effects on a protein kinase (Pfnek) and their cytotoxicity on human breast adenocarcinoma (MCF7) cells.

RESULTS

Among all extracts, four displayed strong in vitro activities against P. falciparum: Gardenia urvillei Montrouzier, Scleria polycarpa Boeckeler, Terminalia catappa L. and Acronychia laevis J.R. & J.G. Forster, the latter being also toxic on MCF7 cells. Except for the extracts of S. polycarpa, all others that were active on P. falciparum, also possess an inhibitory effect on Pfnek.

DISCUSSION AND CONCLUSION

These results confirm that ethnopharmacology is an excellent approach for such investigations. The two countries considered clearly present advantages in the field. Indeed, local populations keep their traditional knowledge alive, and their flora is exceptionally rich. In New Caledonia, the high endemicity rate (74%) ranks the island as one of the world's biodiversity hotspots. As a consequence, chances to discover new active natural compounds are also high.

Clerodane diterpenes from Casearia arguta that act as synergistic TRAIL sensitizers

Casearia arguta was investigated as part of the ongoing search for synergistic TRAIL (tumor necrosis factor-α-related apoptosis-inducing ligand) sensitizers. As a result of this study, argutins A-H, eight new highly oxygenated clerodane diterpenes, were isolated from the plant Casearia arguta collected in Guatemala. The modified Mosher ester method was utilized to establish the absolute configuration of argutins A and F. Each of the argutins showed varying levels of synergy with TRAIL. Argutin B showed the highest TRAIL sensitization; the synergistic effect of argutin B and TRAIL together was 3-fold greater than argutin B alone.

Antimalarial compounds isolated from plants used in traditional medicine

Objectives

This review covers the compounds with antiplasmodial activity isolated from plants published from 2005 to the end of 2008, organized according to their phytochemical classes. Details are given for substances with IC50 values ≤ 11 μM.

Key findings

Malaria is a major parasitic disease in many tropical and subtropical regions and is responsible for more than 1 million deaths each year in Africa. The rapid spread of resistance encourages the search for new active compounds. Nature and particularly plants used in traditional medicine are a potential source of new antimalarial drugs as they contain molecules with a great variety of structures and pharmacological activities.

Summary

A large number of antimalarial compounds with a wide variety of structures have been isolated from plants and can play a role in the development of new antimalarial drugs. Ethnopharmacological approaches appear to be a promising way to find plant metabolites that could be used as templates for designing new derivatives with improved properties.

Four anti-protozoal and anti-bacterial compounds from Tapirira guianensis

Tapirira guianensis is a common tree used in traditional medicine in French Guiana against several infectious diseases (malaria, leishmaniasis, bacteria, etc.). The bioassay-guided purification of CH(2)Cl(2) bark extract led to the isolation of four cyclic alkyl polyol derivatives: 4,6,2'-trihydroxy-6-[10'(Z)-heptadecenyl]-1-cyclohexen-2-one (1a), 1,4,6-trihydroxy-1,2'-epoxy-6-[10'(Z)-heptadecenyl]-2-cyclohexene (1b), 1,4,5,2'-tetrahydroxy-1-[10'(Z)-heptadecenyl]-2-cyclohexene (2), and 1,3,4,6-tetrahydroxy-1,2'-epoxy-6-[10'(Z)-heptadecenyl]-cyclohexane (3). The structures were established on the basis of 1D and 2D NMR analyses. The anti-leishmanial, anti-plasmodial, anti-bacterial (on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli), and anti-fungal (on Candida albicans) activities of the extracts and of these original compounds were evaluated. Two showed medicinal interest supporting the traditional uses of the plant. The structures were established through spectral analyses of the isolates and their derivatives.

Cytotoxic clerodane diterpenoids and their hydrolysis products from Casearia nigrescens from the rainforest of Madagascar

Bioassay-guided fractionation of the cytotoxic leaf and flower extract of Casearia nigrescens led to the isolation of four new clerodane diterpenoids, designated caseanigrescens A-D (1-4). These compounds were subject to hydrolysis to dialdehydes when stored in CDCl3. The structures of compounds 1-4 were determined using 1D and 2D NMR spectroscopy. All four compounds showed moderate cytotoxicity to the A2780 human ovarian cancer cell line, with an IC50 range of 0.83-1.4 microM.

Diterpenoids

This review covers the isolation and structures of diterpenoids, including labdanes, clerodanes,pimaranes, abietanes, kauranes, cembranolides, taxanes and marine diterpenoids. The literature from January to December 2005 is reviewed, and 195 references are cited.