Sandalwood Oils of Different Origins Are Active In Vitro against Madurella mycetomatis, the Major Fungal Pathogen Responsible for Eumycetoma

In the search for new bioactive agents against the infectious pathogen responsible for the neglected tropical disease (NTD) mycetoma, we tested a collection of 27 essential oils (EOs) in vitro against Madurella mycetomatis, the primary pathogen responsible for the fungal form of mycetoma, termed eumycetoma. Among this series, the EO of Santalum album (Santalaceae), i.e., East Indian sandalwood oil, stood out prominently with the most potent inhibition in vitro. We, therefore, directed our research toward 15 EOs of Santalum species of different geographical origins, along with two samples of EOs from other plant species often commercialized as "sandalwood oils". Most of these EOs displayed similar strong activity against M. mycetomatis in vitro. All tested oils were thoroughly analyzed by GC-QTOF MS and most of their constituents were identified. Separation of the sandalwood oil into the fractions of sesquiterpene hydrocarbons and alcohols showed that its activity is associated with the sesquiterpene alcohols. The major constituents, the sesquiterpene alcohols (Z)-α- and (Z)-β-santalol were isolated from the S. album oil by column chromatography on AgNO3-coated silica. They were tested as isolated compounds against the fungus, and (Z)-α-santalol was about two times more active than the β-isomer.

Development and validation of a resazurin assay for in vitro susceptibility testing of Actinomadura madurae: a common causative agent of actinomycetoma

OBJECTIVES

Actinomycetoma is a chronic granulomatous disease affecting skin, subcutaneous tissue, fascia, muscle and bones. With increasing resistance against commonly used treatment regimens, susceptibility testing is urgently needed.

METHODS

We developed an in vitro susceptibility assay for Actinomadura madurae, one of the common causative agents of actinomycetoma, employing resazurin for endpoint reading. Using this assay, reproducible MICs were determined for the most commonly used antibacterial agents for actinomycetoma treatment. The tested antibacterial agents included trimethoprim/sulfamethoxazole, amikacin, streptomycin, amoxicillin, ceftriaxone, gentamicin, ciprofloxacin, doxycycline, imipenem, linezolid, penicillin G and rifampicin.

RESULTS

Following the clinical breakpoints as stated by CLSI, 100% of the tested strains were susceptible to trimethoprim/sulfamethoxazole (MIC 0.03/0.59-1/19 mg/L), amikacin (MIC 0.0078-0.25 mg/L), doxycycline (MIC <0.25-1 mg/L) and linezolid (MIC <0.25-2 mg/L), 90% to ciprofloxacin (MIC <0.25-2 mg/L), 80% to ceftriaxone (MIC <0.5 to >64 mg/L) and imipenem (MIC <0.25-32 mg/L) and only 20% to amoxicillin (MIC <0.5 to >64 mg/L) and rifampicin (MIC 0.5 to >32 mg/L).

CONCLUSIONS

Determinations of MICs by visual readings of colour changes versus spectrophotometric readings were comparable. This convenient visual reading has the advantage of feasible implementation in endemic settings.

An Insight into the Practice of Iron Therapy: Contribution to the On-going Debate with Special Reference to Low- and Middle-income Countries

Background: Iron deficiency anemia is a public health problem of a sizable proportion in developing countries. Recently, emerging biochemical knowledge coupled with the discovery of Hepcidin have greatly advanced our understanding of iron metabolism and offered a better insight into its associated pathophysiology. This knowledge should be applied to iron-deficiency anemia therapy to avoid subsequent sequelae of tissue damage associated with reactive oxygen radicals that are catalyzed by iron, because current practices do not include these advances in the treatment guidelines. In the light of recent progress, the existing iron therapy program in many healthcare settings is controversial. This necessitates adjusting the magnitude of iron dose with respect to the very limited iron bioavailability, as gauged by Hepcidin. The current study was therefore aimed to incorporate newly emerging biochemical knowledge into the current iron-deficiency anemia treatment practice Methods: Literature relevant to iron-deficiency studies published in English between 1964 and 2020 and available online was covered. Conclusion: Evidently, the existing iron-therapy schedule is both inefficient and toxic. The intricate metabolism of iron should be translated into a more rational iron intervention program with special bias towards low- and middle-income countries requiring a more individualized approach. Key words: iron deficiency anemia, hepcidin, oxidative stress, iron therapy

Biopiracy versus One-World Medicine-From colonial relicts to global collaborative concepts

BACKGROUND

Practices of biopiracy to use genetic resources and indigenous knowledge by Western companies without benefit-sharing of those, who generated the traditional knowledge, can be understood as form of neocolonialism.

HYPOTHESIS

The One-World Medicine concept attempts to merge the best of traditional medicine from developing countries and conventional Western medicine for the sake of patients around the globe.

STUDY DESIGN

Based on literature searches in several databases, a concept paper has been written. Legislative initiatives of the United Nations culminated in the Nagoya protocol aim to protect traditional knowledge and regulate benefit-sharing with indigenous communities. The European community adopted the Nagoya protocol, and the corresponding regulations will be implemented into national legislation among the member states. Despite pleasing progress, infrastructural problems of the health care systems in developing countries still remain. Current approaches to secure primary health care offer only fragmentary solutions at best. Conventional medicine from industrialized countries cannot be afforded by the impoverished population in the Third World. Confronted with exploding costs, even health systems in Western countries are endangered to burst. Complementary and alternative medicine (CAM) is popular among the general public in industrialized countries, although the efficacy is not sufficiently proven according to the standards of evidence-based medicine. CAM is often available without prescription as over-the-counter products with non-calculated risks concerning erroneous self-medication and safety/toxicity issues. The concept of integrative medicine attempts to combine holistic CAM approaches with evidence-based principles of conventional medicine.

CONCLUSION

To realize the concept of One-World Medicine, a number of standards have to be set to assure safety, efficacy and applicability of traditional medicine, e.g. sustainable production and quality control of herbal products, performance of placebo-controlled, double-blind, randomized clinical trials, phytovigilance, as well as education of health professionals and patients.

Azadirachta indica ethanolic extract protects neurons from apoptosis and mitigates brain swelling in experimental cerebral malaria

BACKGROUND

Cerebral malaria is a rapidly developing encephalopathy caused by the apicomplexan parasite Plasmodium falciparum. Drugs currently in use are associated with poor outcome in an increasing number of cases and new drugs are urgently needed. The potential of the medicinal plant Azadirachta indica (Neem) for the treatment of experimental cerebral malaria was evaluated in mice.

METHODS

Experimental cerebral malaria was induced in mice by infection with Plasmodium berghei ANKA. Infected mice were administered with Azadirachta indica ethanolic extract at doses of 300, 500, or 1000 mg/kg intraperitoneally (i.p.) in experimental groups, or with the anti-malarial drugs chloroquine (12 mg/kg, i.p.) or artemether (1.6 mg/kg, i.p.), in the positive control groups. Treatment was initiated at the onset of signs of brain involvement and pursued for five days on a daily basis. Mice brains were dissected out and processed for the study of the effects of the extract on pyramidal cells' fate and on markers of neuroinflammation and apoptosis, in the medial temporal lobe.

RESULTS

Azadirachta indica ethanolic extract mitigated neuroinflammation, decreased the severity of brain oedema, and protected pyramidal neurons from apoptosis, particularly at the highest dose used, comparable to chloroquine and artemether.

CONCLUSIONS

The present findings suggest that Azadirachta indica ethanolic extract has protective effects on neuronal populations in the inflamed central nervous system, and justify at least in part its use in African and Asian folk medicine and practices.

The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part II

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen "Neglected Tropical Diseases" (NTDs) defined by the WHO. Furthermore, malaria (caused by various Plasmodium species) can be considered a neglected disease in certain countries and with regard to availability and affordability of the antimalarials. Living organisms, especially plants, provide an innumerable number of molecules with potential for the treatment of many serious diseases. The current review attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs. In part I, a general description of the diseases, the current state of therapy and need for new therapeuticals, assay methods and strategies applied in the search for new plant derived natural products against these diseases and an overview on natural products of terpenoid origin with antiprotozoal potential were given. The present part II compiles the current knowledge on natural products with antiprotozoal activity that are derived from the shikimate pathway (lignans, coumarins, caffeic acid derivatives), quinones of various structural classes, compounds formed via the polyketide pathways (flavonoids and related compounds, chromenes and related benzopyrans and benzofurans, xanthones, acetogenins from Annonaceae and polyacetylenes) as well as the diverse classes of alkaloids. In total, both parts compile the literature on almost 900 different plant-derived natural products and their activity data, taken from over 800 references. These data, as the result of enormous efforts of numerous research groups world-wide, illustrate that plant secondary metabolites represent an immensely rich source of chemical diversity with an extremely high potential to yield a wealth of lead structures towards new therapies for NTDs. Only a small percentage, however, of the roughly 200,000 plant species on earth have been studied chemically and only a small percentage of these plants or their constituents has been investigated for antiprotozoal activity. The repository of plant-derived natural products hence deserves to be investigated even more intensely than it has been up to present.

Encecalol angelate, an unstable chromene from Ageratum conyzoides L.: total synthesis and investigation of its antiprotozoal activity

ETHNOPHARMACOLOGICAL RELEVANCE

In agreement with ethnomedicinal reports, the dichloromethane extract of Ageratum conyzoides L. (Asteraceae) was recently shown to be of considerable activity against Trypanosoma brucei rhodesiense, the etiologic agent of East African Human Trypanosomiasis (East African Sleeping Sickness). Isolated compounds, namely, methoxylated flavonoids as well as the chromene derivative encecalol methyl ether, were less active than the crude extract. The activity of the extract was found to decrease considerably while stored in solution. An unstable compound was detected in the fresh extract by HPLC, which was converted rapidly into the encecalol methyl ether while stored in methanolic solution. This compound, deemed to represent a constituent with antitrypanosomal activity, could not be isolated from the extract in intact form.

AIM OF THE STUDY

To elucidate the structure of this unstable compound and to investigate its potential role in the antitrypanosomal activity of the total extract.

MATERIALS AND METHODS

UHPLC/ESI-qQTOF MSMS and NMR data of the degraded product indicated its chemical identity as encecalol angelate (1) which was therefore prepared by total synthesis via a linear six steps synthesis, starting from resorcinol and 2-methylbut-3-en-2-ol.

RESULTS

Total synthesis, in an overall yield of 15%, led to pure 1, which was chromatographically and spectroscopically identical with the natural product. The compound degraded in methanol with a half-life of approximately 6h to yield encecalol methyl ether (2). The antiprotozoal activity of synthetic encecalol angelate against T. brucei rhodesiense as well as T. cruzi, Leishmania donovani and Plasmodium falciparum was investigated and found to be quite low.

CONCLUSIONS

The synthetic approach applied here for the first time also provides access to the related bioactive chromenes encecalin (7) and encecalol (8) with improved yields compared with reported methods. Encecalol angelate, however, is most likely not responsible for the high antitrypanosomal activity of the freshly prepared dichloromethane extract of A. conyzoides.

The antiprotozoal activity of methylated flavonoids from Ageratum conyzoides L

AIM OF THE STUDY

The dichloromethane extract prepared from aerial parts of Ageratum conyzoides L. (Asteraceae), a plant commonly used in folk medicine for a number of illnesses including sleeping sickness, was recently found to exhibit a prominent activity (IC(50)=0.78 microg/mL) against bloodstream forms of Trypanosoma brucei rhodesiense, the etiologic agent of East African Human Trypanosomiasis (East African Sleeping Sickness). This extract also exhibited noticeable activities against Leishmania donovani (Kala-Azar, IC(50)=3.4 microg/mL) as well as Plasmodium falciparum (Malaria tropica, IC(50)=8.0 microg/mL). In the current study, we sought for potentially active constituents of Ageratum conyzoides.

MATERIALS AND METHODS

Extracts prepared with solvents of different polarity were tested for activity against the above mentioned parasites as well as against Trypanosoma cruzi (Chagas' disease) and for cytotoxicity using established protocols. The dicholoromethane extract showed the highest level of activity and was chosen for phytochemical studies aimed at the isolation of potential active constituents.

RESULTS AND CONCLUSION

Five highly methoxylated flavonoids along with the chromene derivative encecalol methyl ether were isolated. All isolated compounds were previously reported from Ageratum conyzoides. While the chromene turned out to be inactive against the tested parasites, the flavonoids showed activity against the protozoan pathogens, some in the lower micromolar range. However, none of these isolated compounds was as active as the crude extract. This is the first report on antiprotozoal activity of this plant species and some of its constituents. The chemical principle accounting for the high activity of the crude extract, however, remains to be identified.

The antiprotozoal activity of sixteen asteraceae species native to Sudan and bioactivity-guided isolation of xanthanolides from Xanthium brasilicum

In vitro screening of the dichloromethane extracts of 16 Asteraceae species native to Sudan for activity against major protozoan pathogens revealed that a Xanthium brasilicum Vell. [syn. X. strumarium var. brasilicum (Vell.) Baker in Mart.] extract was the most active against Trypanosoma brucei rhodesiense, the etiological agent of East African human trypanosomiasis (IC(50) = 0.1 microg/mL). This plant extract also exhibited noticeable activities against T. cruzi (Chagas disease), Leishmania donovani (Kala-Azar) as well as Plasmodium falciparum (Malaria tropica). Bioactivity-guided fractionation resulted in the isolation of four bioactive sesquiterpene lactones (STL) of the xanthanolide series (4,5-seco-guaianolide-type). They were identified by spectroscopic means as 8-epixanthatin (1), 8-epixanthatin 1beta,5beta-epoxide (2), and as the dimers pungiolide A (4) as well as pungiolide B (5). Two further modified xanthanolide sesquiterpene lactones, xanthipungolide (3) and 4,15-dinor-1,11(13)-xanthadiene-3,5beta:12,8beta-diolide (6) were isolated. While xanthipungolide turned out to be inactive against the tested parasites, the dinor-xanthanlide showed significant activity against T. brucei rhodesiense and L. donovani. All isolated compounds were previously known from other Xanthium species but this is the first report on their occurrence in X. brasilicum, and, most notably, on their antiprotozoal activity. As the most active single compound from this extract, 8-epixanthatin 1beta,5beta-epoxide showed IC(50) values of 0.09, 2.95, 0.16 and 1.71 microg/mL (0.33, 11.3, 0.6 and 6.5 microM) against T. brucei rhodesiense, T. cruzi, L. donovani and P. falciparum, respectively, while its cytotoxicity against rat myoblast cells used as control was determined at 5.8 microg/mL (22.1 microM). Besides assessment of their antiprotozoal activity, the structural assignments for the dimeric xanthanolides pungiolide A and B were reinvestigated and fully established.

Decades of phytochemical research on African biodiversity

This review provides a panoramic view of Prof. Kurt Hostettmann's contribution to the study of African medicinal plants as documented in over 85 publications with collaborators from about a dozen African countries. Many novel bioactive secondary metabolites were isolated, their structures elucidated by hyphenated HPLC techniques and their biological activity determined.

Evaluation of selected Sudanese medicinal plants for their in vitro activity against hemoflagellates, selected bacteria, HIV-1-RT and tyrosine kinase inhibitory, and for cytotoxicity

Ethnobotanical investigations led to the selection of 19 plant species, used traditionally in Sudan against malaria and other similar tropical diseases, for further studies. Pamianthe peruviana (Amaryllidaceae) exhibited significant activity against a chloroquine-resistant Plasmodium falciparum strain (K1) and a chloroquine-sensitive strain (NF54) with IC(50) values of 0.6 and 1.1 microg/ml, respectively. Additionally, P. peruviana showed considerable activities against Trypanosoma brucei rhodesiense (IC(50) 1.5 microg/ml) and T. cruzi (IC(50) 11.8 microg/ml). The antiplasmodial activity of the different extracts of Salvadora persica (Salvadoraceae) against P. falciparum NF54 strain were found to be 0.6 microg/ml (stems) and 0.7 microg/ml (leaves). Extracts of different parts of Combretum hartmannianum (Combretaceae) possessed significant activity against the chloroquine-sensitive P. falciparum strain (NF54) with IC(50) values of 0.2 microg/ml (bark), 0.4 microg/ml (stem) and 4.3 microg/ml (leaves). Most interestingly, the extracts of the leaves of C. hartmannianum totally inhibited the enzyme HIV-1 reverse transcriptase (HIV-1 RT) at a concentration of 66 microg/ml. A comparably strong activity against p56(lck) tyrosine kinase was also seen for this extract.

Anti-trypanosomal activity of helenalin and some structurally related sesquiterpene lactones

The anti-trypanosomal activity of six sesquiterpene lactones (helenalin, mexicanin I, 11alpha,13-dihydrohelenalin acetate, chamissonolide, ivalin and isoalantolactone) against the African Trypanosoma brucei rhodesiense and American T. cruzi was investigated. All tested compounds were found active towards both parasites, the former being generally more sensitive. Helenalin was the most active compound in the series with IC50 values of 0.051 and 0.695 microM against T. brucei rhodesiense and T. cruzi, respectively. The low IC50 value for T. b. rhodesiense indicates that helenalin type compounds may be interesting candidates for further evaluation.

Traditional fermentation increases goitrogenic activity in pearl millet

Epidemiological evidence suggests that millet might play a role in the etiology of endemic goiter. Recently, we showed that a traditional fermentation procedure of two pearl millet (Pennisetum americanum L. Lecke) cultivars grown in Sudan modified their effects on the weight of the thyroid gland and thyroid hormone profile in rats. In the present study, we report that this fermentation procedure reduced the ash contents of millet by about 40% and removed considerable amounts of Mg (>50%), Zn (27-39%) and K (45%). Other minerals (Ca, Fe, Cu) were not affected. Feeding of one fermented cultivar resulted in significant reduction in bone Mg and Zn contents, whereas feeding of the other fermented cultivar resulted in reduction of bone Mg only. Dietary Mg intake and bone Mg contents correlated negatively with serum T3. Groups fed the millet diets had higher serum Se level compared to those fed wheat or casein diets and feeding of fermented millet resulted in a further increase in serum Se level. Thus our data indicate that in rats the enhanced effects of millet on the thyroid induced by fermentation is likely related to removal of minerals from millet and/or chemical transformation of the goitrogens contained in millet.

Antiplasmodial activity of selected sudanese medicinal plants with emphasis on Acacia nilotica

Twenty-two plant organs from eleven plants comprising five families were extracted and screened for antiplasmodial activity in vitro against Plasmodium falciparum 3D7 (chloroquine sensitive) and Dd2 (chloroquine resistant and pyrimethamine sensitive). Fifty nine percent of plant extracts from 22 extracts exerted activity on P. falciparum strain 3D7 with an IC(50) less than 50 microg/mL, whereas 43% of plant extracts showed an IC(50) value within 50 microg/mL on Dd2 strains. Plant extracts from Gardenia lutea, Haplophyllum tuberculatum, Cassia tora, Acacia nilotica and Aristolochia bracteolata possessed IC(50) values less than 5 microg/mL on both tested strains. Bioassay guided fractionation of A. nilotica revealed that the ethyl acetate extract possessed the highest activity (IC(50) = 1.5 microg/mL). Fraction 2 (R(f) = 0.75) prepared by preparative chromatography showed the highest activity on P. falciparum (IC(50) = 1.7 microg/mL). Phytochemical analysis indicated that the most active phase contained terpenoids and tannins and was devoid of alkaloids and saponins. The effect of plant extracts on lymphocyte proliferation showed low toxicity to the human cells. This plant has been subjected to long term clinical trials in folk medicine and is a promising plant.

Simultaneous determination of artemether and its major metabolite dihydroartemisinin in plasma by gas chromatography-mass spectrometry-selected ion monitoring

A sensitive, selective, and reproducible GC-MS-SIM method was developed for determination of artemether (ARM) and dihydroartemisinin (DHA) in plasma using artemisinin (ART) as internal standard. Solid phase extraction was performed using C18 Bond Elut cartridges. The analysis was carried out using a HP-5MS 5% phenylmethylsiloxane capillary column. The recoveries of ARM, DHA and ART were 94.9 +/- 1.6%, 92.2 +/- 4.1% and 81.3 +/- 1.2%, respectively. The limit of quantification in plasma was 5 ng/ml (C.V. < or = 17.4% for ARM and 15.2% for DHA). Calibration curves were linear with R2 > or = 0.988. Within day coefficients of variation were 3-10.4% for ARM and 7.7-14.5% for DHA. Between day coefficients of variations were 6.5-15.4% and 7.6-14.1% for ARM and DHA. The method is currently being used for pharmacokinetic studies. Preliminary data on pharmacokinetics showed Cmax of 245.2 and 35.6 ng/ml reached at 2 and 3 h and AUC0-8 h of 2463.6 and 111.8 ngh/ml for ARM and DHA, respectively.

Antiplasmodial activity of selected Sudanese medicinal plants with emphasis on Maytenus senegalensis (Lam.) Exell

The antiplasmodial activity of plant extracts related to four families was tested on chloroquine sensitive strain 3D7 and chloroquine resistant strain Dd2 of Plasmodium falciparum. The methanolic extract of Harrisonia abyssinica (Simaroubaceae) inhibited Dd2 with IC50 value of 4.7 microg/ml, while in 3D7, the IC50 value was 10 microg/ml. Most of the plants from the family Meliaceae showed highly potent antiplasmodial activity against the two tested strains. Khaya senegalensis, Azadirachta indica and Trichilia emetica showed IC50 values less than 5 microg/ml. The methanolic extract of Annona squamosa (Annonaceae) leaves showed high antiplasmodial activity with IC50 values of 2 and 30 microg/ml on 3D7 and Dd2, respectively. While stem bark showed moderate activity with IC50 values of 8.5 and 120 microg/ml on Dd2. Maytenus senegalensis (Celastraceae) possessed IC50 values of 3.9 on 3D7, 10 microg/ml on Dd2 and had no effect on lymphocyte proliferation even at the highest tested concentration; the IC50 was greater than 100 microg/ml. Liquid-liquid separation of the methanolic extract of M. senegalensis revealed that the dichloromethane extract possessed an IC50 value of only 2.1 microg/ml. Column fractionation of dichloromethane extract gave four fractions and fraction two showed an IC50 value of 0.5 microg/ml. Preliminary phytochemical analysis of dichloromethane fraction revealed terpenoids and traces of phenolic principles but no alkaloid, tannins or flavonoids were detected.

limonoids from Khaya senegalensis

A new limonoid was isolated from the bark of Khaya senegalensis and identified as 2,6-dihydroxyfissinolide. The assignments of some signals in the (13)C NMR spectrum of fissinolide have been reversed and the signals of the (1)H NMR spectrum of methyl 3beta-acetoxy-6-hydroxy-1-oxomeliac-14-enoate have been assigned. The limonoids only showed moderate antiprotozoal activities.

Toxicological interactions of Abrus precatorius and Cassia senna in the diet of Lohmann broiler chicks

The combination of 0.5% Abrus precatorius seed and 2% Cassia senna fruit in the diet of Lohmann broiler chicks caused severe lesions, reduced weight gain, inefficient feed utilization and anemia. Organ lesions correlated with changes in clinical chemistry and hematology. Tissue recovery was not complete 2 w following withdrawal of the test diet. Feeding 0.5% Abrus or 2% Senna diets alone produced decreased growth and tissue lesions that did not return to normal 2 w following return to normal rations.

Experimental Azadirachta indica toxicosis in chicks

Brown Hisex chicks were fed Azadirachta indica ripe fruit at 2, 5 or 10% of basic diet from their 7th to 35th d of age. Decreased body weight gain and efficiency of feed utilization and hepatonephropathy were most severe in chicks fed the 10% A indica diet. These changes were accompanied by anemia and increases in LDH, GOT and ALP activities and uric acid concentration and by decreased serum total protein. Hepatocytes and renal tubular cells did not completely revert to normal 2 w after removal from the test diets.

(+)-Catechin-5-galloyl Ester as a Novel Natural Polyphenol from the Bark of Acacia nilotica of Sudanese Origin1

From the bark of ACACIA NILOTICA subsp. TOMENTOSA a novel polyphenol, (+)-catechin-5-galloyl ester ( 5), was isolated along with gallic acid ( 1), its methyl ester ( 2), naringenin ( 3), and (+)-catechin ( 4). The structure of 5 was determined by use of mass spectrometry as well as (1)H- and (13)C-NMR spectroscopy.

Potential antimalarial candidates from African plants: and in vitro approach using Plasmodium falciparum

Twenty-one compounds isolated from nine medicinal plants used in traditional medicine in the Sudan and other African countries were examined in vitro for antimalarial activity against Plasmodium falciparum, the major human malaria parasite. Compounds tested include alkaloids, lignans, triterpenes, coumarins, limonoids and flavonoids. Most were relatively inactive; one limonoid, gedunin, had an IC50 value of about 1 microM after 48 h exposure (0.3 microM after 96 h), roughly equivalent to quinine. In this protocol, the flavonoid quercetin purified from Diosma pilosa was found to have the same activity as a commercially obtained preparation. Simple radiometric assays for antimalarial activity can thus be used to rapidly screen purified plant material or secondary plant metabolites. The high potency and efficacy of quinine and the Chinese herbal antimalarial quinghaosu (artemisinine) illustrate the merit of this approach.

Alkaloid, lignan and flavonoid constituents of Haplophyllum tuberculatum from Sudan

The aerial parts of Haplophyllum tuberculatum collected in Sudan have yielded the furoquinoline alkaloid skimmianine, the lignan justicidin-A, and 5,7,4'-trihydroxy-6-methoxy-3-O-glucosyl flavone. Skimmianine was identified by direct comparison with authentic material; justicidin-A by analysis of spectral data and by examination of lanthanide induced shifts in the PMR spectrum; and 5,7,4'-trihydroxy-6-methoxy-3-O-glucosyl flavone by spectral analysis of the original isolate and of its hydrolysis product.