Leishmanicidal activity of a daucane sesquiterpene isolated from Eryngium foetidum

CONTEXT

Eryngium foetidum L. (Apiaceae) is a traditional herb that has been used for numerous medicinal applications, including as a treatment for parasitic infections, especially in the Neotropics from where it originates.

OBJECTIVE

This study evaluates the in vitro leishmanicidal and cytotoxicity activities of isolated compounds based on a bioassay-guided fractionation approach.

MATERIALS AND METHODS

Defatted aerial parts of E. foetidum were subjected to extraction with methanol followed by partitioning with n-hexane, ethyl acetate and 50% methanol. Then, the first two fractions were subsequently fractionated by column chromatography and HPLC. Compound identity was confirmed by mass spectrometry and NMR spectroscopy. Leishmania tarentolae (promastigotes) and L. donovani (amastigotes) were used as testing parasites. L6 rat myoblasts were used for cytotoxicity. All extracts and fractions were tested at 20 μg/mL.

RESULTS

The initial methanol extract showed 20% growth inhibition of L. tarentolae. Then, the n-hexane and ethyl acetate fractions were also active showing approximately 40% growth inhibition. From these two fractions, the following compounds were isolated: lasidiol p-methoxybenzoate (1), a daucane sesquiterpene; and 4-hydroxy-1,1,5-trimethyl-2-formyl-cyclohexadien-(2,5)-[α-acetoxymethyl-cis-crotonate] (2), a terpene aldehyde ester derivative. Compound 1 inhibited the growth of both L. tarentolae and L. donovani with IC₅₀ values of 14.33 and 7.84 μM, respectively; and showed no cytotoxicity (IC₅₀ > 50 μM). Compound 2 was inactive in the L. tarentolae assay (IC₅₀ > 50 μM).

DISCUSSION AND CONCLUSION

This study presented the bioassay-guided fractionation with the leishmanicidal and cytotoxicity activities of two compounds isolated for the first time from an Eryngium species.

Antiplasmodial activity of cucurbitacin glycosides from Datisca glomerata (C. Presl) Baill

The traditionally used antimalarial plant, Datisca glomerata (C. Presl) Baill, was subjected to antiplasmodial assay guided fractionation. This led to the isolation of seven cucurbitacin glycosides, datiscosides I-O, along with two known compounds, datiscoside and datiscoside B, from the aerial parts of D. glomerata. Their structures and relative stereochemistry were determined on the basis of mass spectrometry, 1D and 2D NMR spectroscopic data. Antiplasmodial IC(50) values were determined for all isolated compounds against a chloroquine sensitive strain of Plasmodium falciparum (D10), which were also evaluated in vitro for their antileishmanial activity against Leishmania tarentolae. Cytotoxicity was evaluated against rat skeletal muscle cells (L6) and Chinese ovarian hamster cells (CHO). The antiplasmodial activity of the compounds was moderate and ranged from 7.7 to 33.3 μM. None of the compounds showed appreciable antileishmanial activity. The compounds displayed cytotoxicity against L6 but not CHO mammalian cells.

Antiplasmodial activity of the ethnobotanical plant Cassia fistula

In our ongoing investigation of new compounds with activity against malaria parasites, we tested the in vitro antiplasmodial activity of fractions and purified compounds from Cassia fistula L., a plant traditionally used by native populations of Tanzania, Zimbabwe, Mozambique and Brazil to treat malaria or symptoms associated with this disease. Crude extracts from leaves, bark and fruits were tested for their antiplasmodial activity against the chloroquine-sensitive strain of Plasmodium falciparum (D10), where leaf extracts showed the highest activity. The chloroform extract of the leaves was further bioassay-guided fractionated using a combination of centrifugal partition chromatography and flash column chromatography. Three main antiplasmodial principles, phytol (1) (IC50 18.9 +/- 0.60 microM), lutein (2) (IC50 12.5 +/- 0.35 microM), and di-lineolylgalactopyranosyl-glycerol (DLGG) (IC50 5.8 +/- 0.27 microM) (3), were isolated and identified using spectroscopic methods. When the three active principles were tested for their cytotoxicity using a Chinese Hamster Ovarian (CHO) cell line, compound 3 showed very weak toxicity (IC50 75.9 +/- 0.28 microM), while the other two compounds were nontoxic, even at the highest concentration tested. The study provides evidence to support the use of Cassia fistula as an antimalarial remedy and describes the antiplasmodial constituents from the leaves.

Antiplasmodial Activity of the Ethnobotanical Plant Cassia fistula

In our ongoing investigation of new compounds with activity against malaria parasites, we tested the in vitro antiplasmodial activity of fractions and purified compounds from Cassia fistula L., a plant traditionally used by native populations of Tanzania, Zimbabwe, Mozambique and Brazil to treat malaria or symptoms associated with this disease. Crude extracts from leaves, bark and fruits were tested for their antiplasmodial activity against the chloroquine-sensitive strain of Plasmodium falciparum(D10), where leaf extracts showed the highest activity. The chloroform extract of the leaves was further bioassay-guided fractionated using a combination of centrifugal partition chromatography and flash column chromatography. Three main antiplasmodial principles, phytol (1) (IC50 18.9 ± 0.60 μM), lutein (2) (IC50 12.5 ± 0.35 μM), and di-lineolylgalactopyranosyl-glycerol (DLGG) (IC50 5.8 ± 0.27 μM) (3), were isolated and identified using spectroscopic methods. When the three active principles were tested for their cytotoxicity using a Chinese Hamster Ovarian (CHO) cell line, compound 3 showed very weak toxicity (IC50 75.9 ± 0.28 μM), while the other two compounds were nontoxic, even at the highest concentration tested. The study provides evidence to support the use of Cassia fistula as an antimalarial remedy and describes the antiplasmodial constituents from the leaves.

Antiparasitic compounds from Cornus florida L. with activities against Plasmodium falciparum and Leishmania tarentolae

AIM OF THE STUDY

The objective of this study was to identify the antiplasmodial constituents from the bark of Cornus florida L., a plant traditionally used in North America for the treatment of malaria.

METHODS AND MATERIALS

Dried and powdered bark was extracted with 95% ethanol. The resultant extract was subjected to in vitro antiplasmodial-guided fractionation against Plasmodium falciparum (D10 strain). Antiplasmodial IC(50) values were calculated for pure compounds. Compounds were also assayed against Leishmania tarentolae, and rat skeletal myoblast L6 cells to assess antileishmanial activity and cytotoxicity, respectively.

RESULTS

Antiplasmodial-guided fractionation afforded 8 compounds: betulinic acid (1), ursolic acid (2), β-sitosterol (3), ergosta-4,6,8,22-tetraene-3-one (4), 3β-O-acetyl betulinic acid (5), 3-epideoxyflindissol (6), 3β-O-cis-coumaroyl betulinic acid (7), 3β-O-trans-coumaroyl betulinic acid (8), of which, (6) is for the first time here isolated from a natural product and (4), (7) and (8) are reported for the first time from this genus. In vitro IC(50) values against P. falciparum for (4) (61.0 μM) (6) (128.0 μM), (7) (10.4 μM), (8) (15.3 μM) are reported for the first time. Antileishmanial IC(50) values are reported here for the first time for (4) (11.5 μM), (6) (1.8 μM), (7) (8.3 μM) and (8) (2.2 μM). Cytotoxicity against L6 cells is reported for all compounds.

CONCLUSIONS

The compounds isolated in this study, while displaying moderate in vitro antiplasmodial activity, do not fully support the historical importance of C. florida as an antimalarial remedy in North America. The traditional remedy may exert its well documented effects by mechanisms unrelated to direct antiplasmodial action. While not traditionally used to treat Leishmania, this work shows that several constituents of C. florida possess promising in vitro antileishmanial activity.

Do ethnobotanical and laboratory data predict clinical safety and efficacy of anti-malarial plants?

Background

Over 1200 plant species are reported in ethnobotanical studies for the treatment of malaria and fevers, so it is important to prioritize plants for further development of anti-malarials.

Methods

The “RITAM score” was designed to combine information from systematic literature searches of published ethnobotanical studies and laboratory pharmacological studies of efficacy and safety, in order to prioritize plants for further research. It was evaluated by correlating it with the results of clinical trials.

Results and discussion

The laboratory efficacy score correlated with clinical parasite clearance (r_s=0.7). The ethnobotanical component correlated weakly with clinical symptom clearance but not with parasite clearance. The safety component was difficult to validate as all plants entering clinical trials were generally considered safe, so there was no clinical data on toxic plants.

Conclusion

The RITAM score (especially the efficacy and safety components) can be used as part of the selection process for prioritising plants for further research as anti-malarial drug candidates. The validation in this study was limited by the very small number of available clinical studies, and the heterogeneity of patients included.

Antiplasmodial activity of aporphine alkaloids and sesquiterpene lactones from Liriodendron tulipifera L

AIM OF THE STUDY

The objective of this study was to isolate and characterize the active constituents of the traditionally used antimalarial plant Liriodendron tulipifera by antiplasmodial-assay guided fractionation.

MATERIALS AND METHODS

Bark and leaves were extracted with solvents of increasing polarity. Fractions were generated using flash chromatography, counter current chromatography and preparative HPLC and subjected to in vitro antiplasmodial and cytotoxicity assays. Active fractions were subjected to further fractionation until pure compounds were isolated, for which the IC(50) values were calculated.

RESULTS AND DISCUSSION

Six known aporphine alkaloids, asimilobine (1), norushinsunine (2), norglaucine (3), liriodenine (4), anonaine (5) and oxoglaucine (6) were found to be responsible for the antiplasmodial activity of the bark. Leaves yielded two known sesquiterpene lactones, peroxyferolide (7) and lipiferolide (8) with antiplasmodial activity. The antiplasmodial activity of (2) (IC(50)=29.6 μg/mL), (3) (IC(50)=22.0 μg/mL), (6) (IC(50)=9.1 μg/mL), (7) (IC(50)=6.2 μg/mL) and (8) (IC(50)=1.8 μg/mL) are reported for the first time.

CONCLUSION

This work supports the historical use of Liriodendron tulipifera as an antimalarial remedy of the United States and characterizes its antiplasmodial constituents.

Antiplasmodial and Cytotoxic Activities of Drimane Sesquiterpenes from Canella winterana

The hexane extract from the leaves of Canella winterana exhibited strong activity against the chloroquine sensitive (CQS) strain of Plasmodium falciparum (D10) in vitro (IC50 2.53 μg/mL). Bioassay guided fractionation of this extract has led to the isolation of 5 drimane-type sesquiterpenoids: 9-epideoxymuzigadial, 9-deoxymuzigadial, muzigadial, 3-β-acetoxypolygodial and the newly isolated hemiacetal, named muzigodiol, with IC50-values of 1.01, 2.19, 0.31, 2.77 and 7.43 μg/mL, respectively. The first four compounds were tested for their cytotoxicity using Chinese Hamster Ovarian (CHO) cells, where they showed IC50-values of 1.82, 33.69, 1.18, and 58.31 μg/mL, respectively. A structure-activity relationship is discussed.

Antiplasmodial and cytotoxic activities of drimane sesquiterpenes from Canella winterana

The hexane extract from the leaves of Canella winterana exhibited strong activity against the chloroquine sensitive (CQS) strain of Plasmodium falciparum (D10) in vitro (IC50 2.53 microg/mL). Bioassay guided fractionation of this extract has led to the isolation of 5 drimane-type sesquiterpenoids: 9-epideoxymuzigadial, 9-deoxymuzigadial, muzigadial, 3-beta-acetoxypolygodial and the newly isolated hemiacetal, named muzigodiol, with IC50-values of 1.01, 2.19, 0.31, 2.77 and 7.43 microg/mL, respectively. The first four compounds were tested for their cytotoxicity using Chinese Hamster Ovarian (CHO) cells, where they showed IC50-values of 1.82, 33.69, 1.18, and 58.31 microg/mL, respectively. A structure-activity relationship is discussed.

Merging traditional Chinese medicine with modern drug discovery technologies to find novel drugs and functional foods

Traditional Chinese Medicines (TCM) are rapidly gaining attention in the West as sources of new drugs, dietary supplements and functional foods. However, lack of consistent manufacturing practices and quality standards, fear of adulteration, and perceived deficiencies in scientific validation of efficacy and safety impede worldwide acceptance of TCM. In addition, Western pharmaceutical industries and regulatory agencies are partial toward single ingredient drugs based on synthetic molecules, and skeptical of natural product mixtures. This review concentrates on three examples of TCM-derived pharmaceuticals and functional foods that have, despite these usual obstacles, risen to wide acceptance in the West based on their remarkable performance in recent scientific investigations. They are: Sweet wormwood (Artemisia annua), the source of artemisinin, which is the currently preferred single compound anti-malarial drug widely used in combination therapies and recently approved by US FDA; Thunder god vine (Tripterygium wilfordii) which is being developed as a botanical drug for rheumatoid arthritis; and green tea (Camellia sinensis) which is used as a functional beverage and a component of dietary supplements.