The allelopathic, adhesive, hydrophobic and toxic latex of Euphorbia species is the cause of fairy circles investigated at several locations in Namibia.

BACKGROUND: In this multidisciplinary study we present soil chemical, phytochemical and GIS spatial patterning evidence that fairy circles studied in three separate locations of Namibia may be caused by Euphorbia species. RESULTS: We show that matrix sand coated with E. damarana latex resulted in faster water-infiltration rates. GC-MS analyses revealed that soil from fairy circles and from under decomposing E. damarana plants are very similar in phytochemistry. E. damarana and E. gummifera extracts have a detrimental effect on bacteria isolated from the rhizosphere of Stipagrostis uniplumis and inhibit grass seed germination. Several compounds previously identified with antimicrobial and phytotoxic activity were also identified in E. gummifera. GIS analyses showed that perimeter sizes and spatial characteristics (Voronoi tessellations, distance to nearest neighbour ratio, pair correlation function and L-function) of fairy circles are similar to those of fairy circles co-occurring with E. damarana (northern Namibia), and with E. gummifera (southern Namibia). Historical aerial imagery showed that in a population of 406 E. gummifera plants, 134 were replaced by fairy circles over a 50-year period. And finally, by integrating rainfall, altitude and landcover in a GIS-based site suitability model, we predict where fairy circles should occur. The model largely agreed with the distribution of three Euphorbia species and resulted in the discovery of new locations of fairy circles, in the far southeast of Namibia and part of the Kalahari Desert of South Africa. CONCLUSIONS: It is proposed that the allelopathic, adhesive, hydrophobic and toxic latex of E. damarana, E. gummifera, and possibly other species like E. gregaria, is the cause of the fairy circles of Namibia in the areas investigated and possibly in all other areas as well.

Complementation of CTB7 in the Maize Pathogen Cercospora zeina Overcomes the Lack of In Vitro Cercosporin Production.

Gray leaf spot (GLS), caused by the sibling species Cercospora zeina or Cercospora zeae-maydis, is cited as one of the most important diseases threatening global maize production. C. zeina fails to produce cercosporin in vitro and, in most cases, causes large coalescing lesions during maize infection, a symptom generally absent from cercosporin-deficient mutants in other Cercospora spp. Here, we describe the C. zeina cercosporin toxin biosynthetic (CTB) gene cluster. The oxidoreductase gene CTB7 contained several insertions and deletions as compared with the C. zeae-maydis ortholog. We set out to determine whether complementing the defective CTB7 gene with the full-length gene from C. zeae-maydis could confer in vitro cercosporin production. C. zeina transformants containing C. zeae-maydis CTB7 were generated by Agrobacterium tumefaciens-mediated transformation and were evaluated for in vitro cercosporin production. When grown on nitrogen-limited medium in the light-conditions conducive to cercosporin production in other Cercospora spp.-one transformant accumulated a red pigment that was confirmed to be cercosporin by the KOH assay, thin-layer chromatography, and ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Our results indicated that C. zeina has a defective CTB7, but all other necessary machinery required for synthesizing cercosporin-like molecules and, thus, C. zeina may produce a structural variant of cercosporin during maize infection.

Inhibition of the initiation stage of carcinogenesis by Salvia disermas constituents.

Phytochemical studies of an ethanolic extract of the aerial parts of Salvia disermas resulted in the isolation of seven known compounds, rosmarinic (1) and caffeic (2) acids, salvigenin (3), luteolin (4), luteolin 7-O-beta-arabinoside (5), luteolin 7-O-beta-glucoside (6), and ocotillol II (7). The initiation stage of carcinogenesis is triggered by activation of procarcinogens by phase I enzymes, such as cytochrome P-450 1A, and oxidative stress that leads to DNA damage. The initiation stage is countered by phase II detoxification enzymes such as glutathione S-transferases (GST), quinine reductase (QR), epoxide hydrolase (mEH) besides conjugation with thiols. We aimed to investigate the cancer chemopreventive and tumour anti-initiating activity of the ethanolic extract of the aerial parts of Salvia disermas and its constituents. The S. disermas extract was a promising inhibitor of CYP1A activity, inducer of GST, QR, and mEH activities, enhancer of thiol content, radical scavenger, and inhibitor of DNA damage. On the other hand, 3 was an enhancer of thiol content and QR activity, while 4 was an inhibitor of CYP1A activity, inducer of QR activity, and radical scavenger of ROO*, and 5 was an inducer of GST activity and inhibitor of DNA damage. The present study indicated that the ethanolic extract of S. disermas and 4 are promising anti-initiating and multipotent blocking agents.

1H NMR-based metabolomics of antimalarial plant species traditionally used by Vha-Venda people in Limpopo Province, South Africa and isolation of antiplasmodial compounds.

ETHNOPHARMACOLOGICAL RELEVANCE: The Vha-Venda people living in rural areas of Limpopo Province of South Africa regularly use traditional plant-based medicines to treat malaria. In our earlier publication, twenty indigenous plant species used to treat malaria or its symptoms by Vha-Venda people were evaluated for antiplasmodial activity. The main objective of the current study was to assess the robustness of NMR-based metabolomics in discriminating classes of secondary compounds that are responsible for the observed antimalarial activity and the isolation of antiplasmodial compounds. MATERIALS AND METHODS: Twenty dichloromethane extracts were reconstituted in CDCl3, subjected to 1H NMR-based metabolomic analysis on a Varian 600 MHz spectrometer and the acquired 1H NMR spectra were then evaluated collectively using multivariate data analysis (MDA). Principal Component Analysis (PCA) and Orthogonal Projections to Latent Structures-Discriminant Analysis (OPLS-DA) were used to 'globally' discern antiplasmodial profiles. A contribution plot was then generated from the OPLS-DA scoring plot in an attempt to determine the classes of compounds that are responsible for the observed grouping. Further phytochemical analyses were conducted on the lipophilic extracts of Tabernaemontana elegans and Vangueria infausta subsp. infausta. These best candidates were fractionated, purified and their isolated compounds identified based on conventional chromatographic and spectroscopic techniques. RESULTS: The PCA did not separate the acquired profiles according to the detected antiplasmodial bioactivity. Application of a supervised OPLS-DA on the 1H NMR profiles resulted in a discrimination pattern that could be correlated to the observed antimalarial bioactivity. A contribution plot generated from the OPLS-DA scoring plot illustrated the classes of compounds responsible for the observed grouping. Prominent peaks were observed in the aromatic, sugar-based/N-containing and aliphatic spectral regions of the contribution plot. Two known indole alkaloids were isolated from T. elegans, and identified as tabernaemontanine (IC50 = 12.0 ±â€¯0.8 µM) and dregamine (IC50 = 62.0 ±â€¯2.4 µM). Friedelin (IC50 = 7.20 ±â€¯0.5 µM) and morindolide (IC50 = 107.1 ±â€¯0.6 µM) were isolated from V. infausta subsp. infausta. This is the first report of the rare iridoid lactone, morindolide's antimalarial activity. While these two compounds have been previously identified, this is the first account of their occurrence in the genus Vangueria. CONCLUSION: The study illustrated the potential of NMR-based metabolomics in discriminating classes of compounds that may be attributed to antiplasmodial activity. Additionally, the study demonstrated the potential of discovering novel antiplasmodial scaffolds from medicinal plants and the rationale for the bioprospecting antimalarial plant species used by Vha-Venda people.

Bioactive diterpenes and other constituents of Croton steenkampianus.

A new indanone derivative (1) and two new diterpenoids (2 and 3), together with three known flavonoids, have been isolated from an ethanol extract of the leaves of Croton steenkampianus. The structure of 2 was solved by single-crystal X-ray diffraction analysis, whereas those of 1 and 3 were established mainly by 1D and 2D NMR spectroscopic methods. The isolated compounds were tested for their antiplasmodial activity and cytotoxicity. Antiplasmodial assays against chloroquine-susceptible strains (D10 and D6) and the chloroquine-resistant strains (Dd2 and W2) of Plasmodium falciparum showed that compound 2 gave moderate activities at 9.1-15.8 µM, while none of the compounds were cytotoxic against Vero cells.

Novel xanthones from Securidaca longepedunculata with activity against erectile dysfunction.

AIM OF STUDY: Securidaca longepedunculata is used in the treatment of erectile dysfunction in South Africa. The aim of the study was to isolate and identify the active constituents and to determine their activity in the relaxation of corpus cavernosal smooth muscle. MATERIALS AND METHODS: Bioassay guided isolation of the bioactive compounds using a smooth muscle relaxation bioassay and structural elucidation was carried out using different spectroscopic techniques including 2D NMR. RESULTS: Two new xanthones were isolated; one of them showed potent activity to relax the corpus cavernosal smooth muscle by 97 % in comparison to sildenafil (Viagra) at 1.8 x 10(-5) mg/ml. CONCLUSIONS: S. longepedunculata's xanthones stimulate the relaxation of corpus cavenosum smooth muscle, which supports the traditional use of its root bark.

Antibacterial activities and cytotoxicity of terpenoids isolated from Spirostachys africana.

Spirostachys africana Sond. stem bark is used traditionally for the treatment of diarrhoea and dysentery in Limpopo Province of South Africa. Bioassay-guided fractionation of ethanolic extract from bark of Spirostachys africana led to the isolation of four known compounds, two triterpenoids, compound 1 [d-Friedoolean-14-en-oic acid (3-acetyl aleuritolic acid)] and compound 2 (Lupeol), and two diterpenes, compound 3 [ent-2,6alpha-dihydroxy-norbeyer-1,4,15-trien-3-one (diosphenol 2)] and compound 4 (ent-3beta-hydroxy-beyer-15-ene-2-one). Isolated compounds were tested for antibacterial activity using micro-dilution method. Compound 1, exhibited minimum inhibitory concentration (MIC) of 50 microg/ml against Staphylococcus aureus, Salmonella typhy, Vibrio cholera, Escherichia coli and Shigella dysentery. Compound 2 was not active against all tested microorganisms at 200 microg/ml, which was the highest concentration tested. At this concentration, all four compounds were not active against Shigella sonnei. Cytotoxicity of ethanol crude extracts and isolated compounds from Spirostachys africana was determined using the sodium-2,3-bis-[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay on Vero cells. Compounds 2 and 3, isolated from Spirostachys africana, had up to three times higher [50% inhibitory concentration (IC(50) values; 300.9 and 308.9 microg/ml)] than the ethanol crude extracts (102.8 microg/ml) suggesting higher toxicity of the crude extract as compared to these two compounds. In contrast, compounds 1 and 4 were not cytotoxic to Vero cell lines (African green monkey) in vitro at the concentrations tested (IC(50)>400 microg/ml). This is the first report on the antibacterial activity and cytotoxicity of purified compounds from Spirostachys africana.

Antitumor, antioxidant and antimicrobial activities of Bersama engleriana (Melianthaceae).

The aim of this study was to evaluate the antitumor, antioxidant and antimicrobial activities as well as the phytochemical composition and the acute toxicity of the methanolic extracts from the roots (BER), stem bark (BEB), leaves (BEL) and wood (BEW) of Bersama engleriana. The crown gall tumor and DPPH radical scavenging assays were used to detect respectively the antitumoral and oxidant activities. Agar diffusion and liquid dilution were used for antimicrobial tests and the phytochemical assays were conducted according to Harbone methods. The single-dose oral toxicity test was performed in accordance with the OPPTS 870.1100 and OECD 401 guidelines. The phytochemical tests indicated the presence of flavonoids, phenols, triterpenes and anthraquinones in all extracts. Pronounced tumor reducing activity was observed with the extracts from the roots (69.32%) and leaves (65.42%). The DPPH scavenging activity showed that the extract from the leaves was the most active with 93.71% inhibition rate at the 1000 microg/ml. The results of antimicrobial activity showed that all tested extracts were active against all tested microbial species, including Gram-positive, and negative bacteria, the two Candida species and mycobacteria. The MIC values obtained ranged from 9.76 to 156.25 microg/ml. Under the conditions of the studied toxicity, all extracts were found to be non-toxic. The overall results of this study indicates that the extracts from the roots, stem bark, leaves and wood have interesting antioxidant properties and represent a potential source of medicine for the treatment of infectious diseases and cancer.

Antimicrobial activity of the crude extracts and five flavonoids from the twigs of Dorstenia barteri (Moraceae).

The aim of this study was to evaluate the antimicrobial activity of the crude extract of the twigs of Dorstenia barteri (DBT) as well as that of four of the five flavonoids isolated from this extract. Gram-positive bacteria (six species), Gram-negative bacteria (12 species) and fungi (four species) were used. The agar disc diffusion test was used to determine the sensitivity of the tested samples while the well micro-dilution was used to determine the minimal inhibition concentrations (MIC) and the minimal microbicidal concentration (MMC) of the active samples. The results of the disc diffusion assay showed that DBT, isobavachalcone (1), and kanzonol C (4) prevented the growth of all the 22 tested microbial species. Other compounds showed selective activity. The inhibitory activity of the most active compounds namely compounds 1 and 4 was noted on 86.4% of the tested microorganisms and that of 4-hydroxylonchocarpin (3) was observed on 72.7%. This lowest MIC value of 19.06microg/ml was observed with the crude extract on seven microorganisms namely Citrobacter freundii, Enterobacter aerogens, Proteus mirabilis, Proteus vulgaris, Bacillus megaterium, Bacillus stearothermophilus and Candida albicans. For the tested compounds, the lowest MIC value of 0.3microg/ml (on six of the 22 organisms tested) was obtained only with compound 1, which appeared as the most active compound. This lowest MIC value (0.3microg/ml) is about 4-fold lower than that of the RA, indicating the powerful and very interesting antimicrobial potential of isobavachalcone (1). The antimicrobial activities of DBT, as well as that of compounds 1, 3, 4, amentoflavone (5) are being reported for the first time. The overall results provide promising baseline information for the potential use of the crude extracts from DBT as well as some of the isolated compounds in the treatment of bacterial and fungal infections.

Antimicrobial activity of the methanolic extract, fractions and compounds from the stem bark of Irvingia gabonensis (Ixonanthaceae).

The antimicrobial activity of the methanolic extract from the stem bark of Irvingia gabonensis (IGM), fractions and compounds isolated from IGM [3-friedelanone (1), betulinic acid (2), oleanolic acid (3), 3,3',4'-tri-O-methylellagic acid (4), 3,4-di-O-methylellagic acid (5) and hardwickiic acid (6)] was evaluated against Gram-positive bacteria (6 species), Gram-negative bacteria (13 species) and three Candida species using dilution methods for the determination of the minimal inhibition concentration (MIC) and the minimal microbicidal concentration (MMC). From the obtained results, IGM prevented the growth of all the species of microorganisms tested at a concentration limit of 312.50 microg/ml. Compounds 4-6 also inhibited the growth of all the tested microbial species while compounds 1-3 showed selective activities. The lowest MIC values (78.12 microg/ml) were obtained with IGM on 13 of the 22 microorganisms tested. The corresponding value of 1.22 microg/ml (4.26 microM) for compounds was recorded with compound 6 on Neisseria gonorrhoeae. The obtained results confirmed the use of Irvingia gabonensis in the treatment of bacterial and fungal infections.

Evaluation of selected South African medicinal plants for inhibitory properties against human immunodeficiency virus type 1 reverse transcriptase and integrase.

Seventeen aqueous and methanol extracts from nine South African medicinal plants, ethnobotanically selected, were screened for inhibitory properties against HIV-1 reverse transcriptase (RT). Isolated compounds were additionally evaluated on HIV-1 integrase (IN). The strongest inhibition against the RNA-dependent-DNA polymerase (RDDP) activity of RT was observed with the methanol extract of the stem-bark of Peltophorum africanum Sond. (Fabaceae) (IC(50) 3.5 microg/ml), while the methanol extract of the roots of Combretum molle R.Br. ex G. Don (Combretaceae) was the most inhibitory on the ribonuclease H (RNase H) activity (IC(50) 9.7 microg/ml). The known compounds bergenin and catechin, and a red coloured gallotannin composed of meta-depside chains of gallic and protocatechuic acids esterified to a 1-O-isobutyroly-beta-D-glucopyranose core, were isolated from the methanol extract of the roots and stem-bark of Peltophorum africanum. The gallotannin inhibited the RDDP and RNase H functions of RT with IC(50) values of 6.0 and 5.0 microM, respectively, and abolished the 3'-end processing activity of IN at 100 microM. Catechin showed no effect on RT but had a moderate activity on HIV-1 IN. Bergenin was inactive on both enzymes. The aqueous and methanol extracts were non-toxic in a HeLaP4 cell line at a concentration of 400 microg/ml.

Characterization of Intracellular Activity of Antitubercular Constituents the Roots of Euclea natalensis.

Naphthoquinones and triterpenes isolated from the roots of Euclea natalensis. A.DC (Ebenaceae) were evaluated for their inhibitory activity against Mycobacterium tuberculosis.. Crude extract, diospyrin and 7-methyljuglone isolated from the plant, exhibited minimum inhibitory concentrations of 8.0, 8.0, and 0.5 µg ml-1, respectively, against M. tuberculosis. H37 Rv (ATCC 27294), a drug-sensitive strain. Minimum inhibitory concentrations (MICs) of 7- methyljuglone against a panel of clinical pan-sensitive and drug-resistant strains of M. tuberculosis. ranged from 0.32 to 1.25 µg/ml. The concentration of 7-methyljuglone that effected a 90% reduction of growth of M. tuberculosis. Erdman within J774.1 macrophages was 0.57 µg/ml. The superior intracellular and extracellular inhibition of M. tuberculosis. by 7-methyljuglone relative to that of the antituberculosis drugs streptomycin and ethambutol suggests that this compound be considered as a lead for further investigations.

Pyrano-isoflavones with erectile-dysfunction activity from Eriosema kraussianum.

Five pyrano-isoflavones have been isolated from the rootstock of Eriosema kraussianum N. E. Br (Papilionaceae). Spectral data and single crystal X-ray analyses were used for structural elucidation. The most active of the compounds had an activity of 75% of that found in Viagra in the erectile dysfunction test on rabbit penile smooth muscle.

Minor pyrano-isoflavones from Eriosema kraussianum: activity-, structure-, and chemical reaction studies.

The isolation and identification of two minor pyrano-isoflavones from Eriosema kraussianum is described. New studies on the original pyrano-isoflavones shows that: (i) kraussianone 2 (a major compound in the plant) can be cyclised under acid conditions, (ii) kraussianones 3 and 5 cause contraction (not relaxation as anticipated) of corpus cavernosum tissue and (iii) the structures proposed previously for 4 and 5 are confirmed by the data obtained from an X-ray study of 5.

In vitro antiplasmodial screening of ethnopharmacologically selected South African plant species used for the treatment of malaria.

ETHNOPHARMACOLOGICAL RELEVANCE: Plant species used by Venda people of South Africa in the treatment of malaria and associated symptoms were evaluated for their antiplasmodial efficacy as well as cytotoxic properties and some showed significant activity. MATERIALS AND METHODS: In vitro antiplasmodial activity and cytotoxic properties were evaluated on 20 indigenous plant species. Ground plant material was extracted in dichloromethane: 50% methanol (1:1). Antiplasmodial activity was evaluated against the chloroquine-sensitive strain of Plasmodium falciparum (NF54). The cytotoxicity of the plant extracts were assessed against mammalian L-6 rat skeletal myoblast cells and the selectivity index (SI) calculated. RESULTS: Of the 43 plant extracts evaluated, 10 exhibited pronounced antiplasmodial activity (IC50 ≤ 5 µg/ml) with good therapeutic indices (SI ≥ 10). Lipophilic plant extracts were relatively more potent than polar extracts. Tabernaemontana elegans Stapf. (Apocynaceae) and Vangueria infausta Burch. subsp. infausta (Rubiaceae) extracts displayed significant antiplasmodial activity (IC50 < 2 µg/ml). CONCLUSION: Findings of this study partly support the ethnomedical use of the investigated plant species by Venda people as antimalarial remedies. The study also highlights some of the knowledge gaps that require further phytochemical studies on the specified plant species.

Isolation and identification of poisonous triterpenoids from Elaeodendron croceum.

A phytochemical investigation of the poisonous Elaeodendron croceum leaves guided by cytotoxicity against Vero cells led to the isolation of five known compounds: 20-hydroxy-20-epi-tingenone (1), tingenone (2), tingenine B (3), 11alpha-hydroxy-beta-amyrin (4) and naringenin (5). Compounds 1 and 2 showed the highest toxicity against Vero cells (IC(50) values 2.65 nM and 8.23 microM, respectively). Cytotoxicity of the isolated compounds against three human cancer cell lines, HeLa, MCF-7 and SNO was also determined. Compounds 1 and 2 again showed the highest cytotoxicity, with IC(50) values ranging between 2.47 and 0.43 microM. This is the first report on the isolation of poisonous compounds from E. croceum, a species well known for its toxicity.

Evaluation of flavonoids from Dorstenia barteri for their antimycobacterial, antigonorrheal and anti-reverse transcriptase activities.

The aim of this study was to evaluate the antimycobacterial, antigonorrheal and reverse transcriptase activities of five flavonoids: isobachalcone (IBC); kanzanol C (KAN); 4-hydroxylonchocarpin (4-LCP); stipulin (SPL) and amentoflavone (AMF) from Dortenia barteri, together with the crude extract from this plant. The Agar disc diffusion, broth microdilution, microplate alamar blue assay (MABA), radiometric respiratory technique using BACTEC 460 system and the reverse transcriptase (RT) assay were used for the investigations. The results of the antimycobacterial assay showed that the crude extract and compounds were able to prevent the growth of Mycobacteria with MIC<10 microg/ml being recorded with IBC on M. tuberculosis. Results of the killing rate experiment revealed that total inhibition effect on M. tuberculosis H37Rv strain was noted with IBC and SPL at day 9 when tested at 4x MIC. The results of the antigonorrheal assay indicated that MIC values below 10 microg/ml were also recorded with IBC on all the tested N. gonorrhoeae strains, meanwhile good activities (MIC<10 microg/ml) were also noted with the extract, KAN, 4-LCP and SPL on some of these strains. The anti-reverse transcriptase activities of extract and compounds also demonstrated that all samples were able to inhibit at various extents the reverse transcriptase activity, with IBC and 4-LCP showing the best effects. The overall results of this work provided evidence that the crude extract as well as some flavonoids from D. barteri could be potential sources of new antimicrobial drug against tuberculosis (TB), gonorrhea and probably the acquired immunodeficiency syndrome.

A cardiac glucoside with in vitro anti-HIV activity isolated from Elaeodendron croceum.

Human immunodeficiency virus (HIV) affects more than 40 million people worldwide and more than 5 million in South Africa alone. There is no cure for the disease yet, and novel effective drugs need to be discovered to make any progress in combating the disease. Twelve extracts from indigenous South African plants were analysed, of which Elaeodendron croceum showed potent inhibition of transcription factors and a recombinant HIV strain in an MT-2 VSV-pseudotyped recombinant virus assay at 100 ng mL(-1). Bioassay guided isolation of an ethanolic extract of E. croceum yielded a well-known digitoxigenin-glucoside as the only active compound. It showed significant inhibition (90%) at 0.2 µM. The in vitro toxicity of digitoxigenin-glucoside proved to be quite low, and its therapeutic index was 250. This observation indicates that digitoxigenin-glucoside could represent a potential pharmacophore for the treatment of HIV from natural sources.

Diospyrone, crassiflorone and plumbagin: three antimycobacterial and antigonorrhoeal naphthoquinones from two Diospyros spp.

The aim of this study was to evaluate the antimycobacterial and antigonorrhoeal activities of three naphthoquinones (diospyrone, crassiflorone and plumbagin) from Diospyros canaliculata and Diospyros crassiflora as well as the crude extracts from these plants. The agar disk diffusion assay, broth microdilution method, microplate Alamar blue assay (MABA) and radiometric respiratory technique using the BACTEC 460 TB system were used. Results of the antimycobacterial assays indicated that the minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations ranged from 1.22 microg/mL to 39.06 microg/mL for Mycobacterium smegmatis and all studied Mycobacterium tuberculosis strains for the crude extract from D. crassiflora, diospyrone and crassiflorone. Results of the killing rate experiment revealed that a total inhibition effect on M. tuberculosis H37Rv strain was observed at Day 18 for D. crassiflora and Day 21 for the crude extract from D. canaliculata and diospyrone at 4x MIC as determined by MABA. Results of the antigonorrhoeal assay indicated that diospyrone was able to prevent the growth of all studied strains of Neisseria gonorrhoeae. The overall results of this work provide evidence that the studied plant extracts (diospyrone, crassiflorone and plumbagin) might be potential sources of new antimicrobial drugs against tuberculosis and gonorrhoea.

Bioactive compounds from Lippia javanica and Hoslundia opposita.

Lippia javanica and Hoslundia opposita are aromatic herbs that occur all over Mozambique and are well known for their medicinal properties. A Phytochemical investigation of L. javanica led to the isolation of eight compounds, 4-ethyl-nonacosane (1), (E)-2(3)-tagetenone epoxide (2), myrcenone (3), piperitenone (4), apigenin (5), cirsimaritin (6), 6-methoxyluteolin 4'-methyl ether (7), 6-methoxyluteolin and 3',4',7-trimethyl ether (8). Three known compounds, 5,7-dimethoxy-6-methylflavone (9), hoslunddiol (10) and euscaphic acid (11) were isolated from H. opposita. This is the first report of compounds 1, 2, 5-8 from L. javanica and of compound (9) from H. opposita. The compounds were tested against Mycobacterium tuberculosis and HIV-1 reverse transcriptase for bioactivity. It was found that compounds 2, 4 and 9 inhibited the HIV-1 reverse transcriptase enzyme by 91, 53 and 52%, respectively, at 100 microg mL(-1). Of all the compounds tested against a drug-sensitive strain of M. tuberculosis, euscaphic acid (11) was found to exhibit a minimum inhibitory concentration of 50 microg mL(-1) against this strain.