Phytotherapeutic information on plants used for the treatment of tuberculosis in eastern cape province, South Africa.

The current rate of deforestation in Africa constitutes a serious danger to the future of medicinal plants on this continent. Conservation of these medicinal plants in the field and the scientific documentation of our knowledge about them are therefore crucial. An ethnobotanical survey of plants used for the treatment of tuberculosis (TB) was carried out in selected areas of the Eastern Cape, South Africa. These areas were Hala, Ncera, Sheshegu, and Gquamashe, all within the Nkonkobe Municipality. One hundred informants were interviewed. The survey included the identification of scientific and vernacular names of the plants used for treatment of TB as well as the methods of preparation and administration, the part used, dosage, and duration of treatment. The survey revealed 30 plants belonging to 21 families which are commonly used by traditional healers for the treatment of TB and associated diseases. Of these plants Clausena anisata, Haemanthus albiflos, and Artemisia afra were the most cited. The leaves were the most common part used in the medicinal preparations. Our findings are discussed in relation to the importance of the documentation of medicinal plants.

Preventing nanoscale wear of atomic force microscopy tips through the use of monolithic ultrananocrystalline diamond probes.

Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) probes that results in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Diamond is potentially an ideal probe material due to its unrivaled hardness and stiffness, its low friction and wear, and its chemical inertness. However, the manufacture of monolithic diamond probes with consistently shaped small-radius tips has not been previously achieved. The first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes with <5-nm grain sizes and smooth tips with radii of 30-40 nm is reported, which are obtained through a combination of microfabrication and hot-filament chemical vapor deposition. Their nanoscale wear resistance under contact-mode scanning conditions is compared with that of conventional silicon nitride (SiN(x)) probes of similar geometry at two different relative humidity levels (approximately 15 and approximately 70%). While SiN(x) probes exhibit significant wear that further increases with humidity, UNCD probes show little measurable wear. The only significant degradation of the UNCD probes observed in one case is associated with removal of the initial seed layer of the UNCD film. The results show the potential of a new material for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale.

Antidiarrheal activity of aqueous extract of Hermannia incana Cav. leaves in Wistar rats.

Hermannia incana Cav. is a prostrate herb used to treat diarrhea, stomach ache, nausea and vomiting, by the people of Eastern Cape Province, South Africa. The phytochemical screening as well as the antidiarrheal activity of H. incana leaf extract at 200, 400 and 600 mg/kg body weight was evaluated in rats. Phytochemical screening revealed the presence of bioactive agents such as alkaloids, tannins, saponins, phenolics, triterpenes, cardiac glycosides, flavonoids, cardenolides and dienolides. The extract significantly prolonged the time of induction of diarrhea, reduced the frequency of diarrheal episodes and water content of the feces, and inhibited castor oil-induced enteropooling. The extract also suppressed intestinal propulsive movement of a charcoal meal through the gastrointestinal tract. These results demonstrate the antidiarrheal properties of the extract, thereby supporting the folkloric use of the plant as an antidiarrheal agent in the Eastern Cape of South Africa.

In vitro antioxidant activity of extracts from the leaves of Felicia muricata thunb. An underutilized medicinal plant in the Eastern Cape Province, South Africa.

Felicia muricata is a medicinal plant used for the management of different human and livestock diseases in the Eastern Cape Province of South Africa. The antioxidant potential of the leaves from this herb was investigated using its water, methanol, acetone and ethanol extracts. All the extracts were rich in phenols, proanthocyanidins and flavonols but low in flavonoids. The water extract exhibited low DPPH scavenging activity while the methanol, acetone and ethanol extracts showed higher activities. Again all the extracts showed high ABTS scavenging activity with a correlation between total phenolic content (R2 = 0.9965), DPPH (R2 = 0.982) and ABTS (R2 = 0.927). Traditionally, however, plant extracts are prepared with water as infusions, decoction and poultice. Our results have shown that both the water and ethanol extracts from Felicia muricata displayed strong antioxidant activity. Therefore, it would seem likely that both solvents were able to extract those compounds which are responsible for the antioxidant activity of F. muricata.

Effect of administration of aqueous extract of hippobromus pauciflorus leaves in male Wistar rats.

The effect of administration of aqueous extract of Hippobromus pauciflorus (L.f.) Radlk (Sapindaceae) leaves at 50, 100 and 200 mg/kg body weight for 14 days on some biochemical parameters in male Wistar rats was investigated. The extract at all the doses tested did not significantly (P>0.05) alter the levels of white blood cells, red blood cells, mean corpuscular volume, platelets, neutrophils, monocytes, lymphocytes and large unstained cells. While the levels of haemoglobin, packed cell volume and basophils increased significantly (P<0.05) at specific doses, the mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and eosinophils decreased significantly (P<0.05). Again, the extract did not significantly (P<0.05) alter the computed liver- and kidney-body weight ratios, sodium, chloride and total protein, though, the levels of potassium, inorganic phosphorus, globulin, urea, total and conjugated bilirubin increased significantly (P<0.05) at certain doses. In contrast, the levels of albumin and creatinine also decreased significantly (P<0.05) at specific doses. While the activities of alkaline phosphatase, gamma glutamyl transferase and alanine aminotransferase remained significantly (P<0.05) unaltered in the serum, aspartate aminotransferase activity increased only at 200 mg/kg body weight. The atherogenic index as well as the concentrations of cholesterol, high- and low-density lipoprotein cholesterol in the serum of the animals were not significantly (P>0.05) altered. However, the extract significantly (P<0.05) increased the concentration of triacylglycerol. The results suggest that the extract has mild and dose specific haemato-, hepato- and nephrotoxic effects and may not be completely safe as oral remedy at the doses investigated.

Ethnobotanical study of plants used for the treatment of diarrhoea in the Eastern Cape, South Africa.

An ethnobotanical study of plants used for the treatment of diarrhoea in the Eastern Cape Province, South Africa was carried out, using a questionnaire which was administered to herbalists, traditional healers and rural dwellers. Information collected revealed the names of plants used for the treatment of diarrhoea, the parts used and the methods of preparation. This survey indicated a total of 17 plant species from 14 families used in the Province. Elephantorrhiza elephantina, Hermannia incana, Pelargonium reniforme, Alepidea amatymbica and Bulbine latifolia were the most frequently mentioned and highly recommended plants for the treatment of diarrhoea by both the traditional healers and rural dwellers. Roots, bark and leaves are the common parts of plants used, while decoctions and infusions are the main methods of preparation.

The study on foliar micromorphology of Hippobromus pauciflorus using scanning electron microscope.

Foliar micromorphology of Hippobromus pauciflorus (L.f.) Radlk (Sapindaceae) was investigated by scanning electron microscope examination. The leaves were characterized by anisocytic stomata which were found only on the abaxial surface. The leaves have long unicellular non-glandular trichomes which were distributed over the mid rib and densely populated at the edges of the upper and lower surfaces. Crystal deposits were also observed on the abaxial surface of the leaves. Energy dispersive X-ray spectroscopy SEM of the crystals showed predominant mineral components of Na, Al, Si, K and Ca ions. These micro (Si, Na and Al) and macro (K and Ca) elements are very essential to plant growth. Their presence in the trichomes could contribute to the mechanical stability of the leaf appendages.

Foliar micromorphology of Felicia muricata Thunb., A South African medicinal plant.

The foliar micromorphology of Felicia muricata (Thunb.) Nees (Asteraceae) was observed with the JEOL (JSM-6390LV) Scanning Electron Microscope (SEM). Both the abaxial and adaxial surfaces were characterized by anisocytic stomata which were more prevalent on the abaxial surface than the adaxial surface. The leaves have only one type of multicellular non-glandular trichomes that are long and cylindrical, tapering to a sharp point and running parallel to the leaf surface in the direction of the apices. Crystal deposits were also observed on the surfaces of the leaves near the stomata. Energy dispersive X-ray spectroscopy-SEM shows that Na, Al, Si, and K were the major constituents of the crystal analyzed. Since no glandular trichomes were present on the leaves of this herb, the bioactive components present in this plant may be produced in some other tissues in the leaf other than the trichomes.

Origin of ultralow friction and wear in ultrananocrystalline diamond.

The impressively low friction and wear of diamond in humid environments is debated to originate from either the stability of the passivated diamond surface or sliding-induced graphitization/rehybridization of carbon. We find ultralow friction and wear for ultrananocrystalline diamond surfaces even in dry environments, and observe negligible rehybridization except for a modest, submonolayer amount under the most severe conditions (high load, low humidity). This supports the passivation hypothesis, and establishes a new regime of exceptionally low friction and wear for diamond.

Foliar micromorphology of Hermannia icana Cav.

The structure and distribution of foliar appendages on the leaves of this plant were investigated with the JEOL (JSM-6390LV) scanning electron microscope (SEM). Both glandular and non-glandular trichomes were observed, which differed from each other in morphology and location on the leaves. Long stalked glandular trichomes were present on both the abaxial and adaxial surfaces while short stalked glandular trichomes were present only on the adaxial surface. Glandular trichomes were capitate while non-glandular trichomes were stellate with many arms. Some crystal deposits were observed on the surfaces of the leaves. Energy dispersive X-ray spectroscopy-SEM of these crystals showed that Al, Ca, K, Na, Ti and Si were the major constituents. We hypothesize that the bioactive therapeutic compounds secreted by H. incana may be produced in the glandular trichomes.

An ethnobotanical study of plants used for the treatment of eye infections in the Eastern Cape Province, South Africa.

Information on medicinal plants, used by the people of the Eastern Cape for the treatment of eye infections, was collected through questionnaires which were administered to herbalists, traditional healers and rural dwellers. The information collected revealed 12 plant species. These plants belong to 9 families, of which Sapindaceae was the most prominent. The leaves were reported to be the most used part of the plants, constituting 75% of herbal preparations. This was followed by bark and roots which constituted 25%. Generally, the plant parts are crushed and the sap squeezed directly into the infected eyes. In few cases, the material is mixed with water and boiled; after cooling, the extract is applied to the infected eyes. Hippobromus pauciflorus was the most commonly used plant species for the treatment of eye infections in the province. Majority of the plants used have been reported in literature to possess some other pharmacological activities.

Volatile components from the roots of Solanum pseudocapsicum.

The volatile components obtained by hydrodistillation of Solanum pseudocapsicum roots were analyzed by gas chromatography-mass spectrometry. A total of 41 compounds, representing 50% of the oil, were identified. The oil was found to contain fatty acids (26.8%), terpenoids (7.6%), and aldehydes (5.3%) as the major components. The dominant compounds were hexadecanoic acid (24.1%), 2-methoxy-3-isopropylpyrazine (2.8%), and 15-methylhexadecanoic acid (2.1%). Other notable components include beta-elemene and delta-elemene. The high proportion of fatty acids in this plant could contribute to its medicinal properties.

In vitro phototoxicity of glycoconjugated porphyrins and chlorins in colorectal adenocarcinoma (HT29) and retinoblastoma (Y79) cell lines.

BACKGROUND: Retinoblastoma is the most common malignant intraocular tumor in children. The current treatment gives a good vital prognostic but there are several drawbacks to the arsenal of "classical antitumoral" therapies. Photodynamic therapy (PDT) could be an exciting non-toxic and non-mutagenic alternative protocol. METHOD: In this paper, we report about the screening of the in vitro photocytotoxicity of hydrophenylporphyrins and chlorins and their glycoconjugated derivatives in a human retinoblastoma cell line (Y79) and for comparison in a colorectal adenocarcinoma cell line (HT29). RESULTS: Despite lower photodynamic activity than that observed for hydroxylated photosensitizers, in particular Foscan(®) glycoconjugated derivatives display phototoxicity (IC50 2.4-0.05µM ±10%) against Y79 cells with examples of significant intrinsic cytotoxicity. Amongst them the triglucosyl porphyrin 10 is highly photocytotoxic (IC50 0.9µM ±10%) but is fully devoid of cytotoxicity (IC50>15µM). The photoactivity is highly modulated by the presence of a diethyleneglycol spacer between the chromophore and the glycoside (compounds 14-17, IC50 0.5, 0.6, 0.05 and 0.35µM ±10%) and by the anomeric configuration of the sugar (compound 15 and 17, IC50 0.6 and 0.05µM ±10% respectively). One of the main problems for the use of Foscan(®) is its poor solubility which might be improved by glycoconjugation. Moreover Foscan has been shown to induce necrosis after PDT leading to a possible ulceration of surrounding tissues unsuitable for a conservative treatment. A preferential mitochondrial subcellular localization which has been previously reported for some glycoconjugated photosensitizers could enhance the contribution of apoptosis process. CONCLUSION: Tri-α-O-galactosyl porphyrin 16 is a better candidate than Foscan(®) for a clinical application of PDT for a conservative therapy of retinoblastoma.

Bioactive sesquiterpene lactones from the leaves of Vernonia amygdalina.

Phytochemical analysis of the leaves of Vernonia amygdalina yielded two known sesquiterpene lactones: vernolide and vernodalol. The two compounds were tested by agar dilution method against 10 bacteria strains and 5 fungi species. Both compounds exhibited a significant bactericidal activity against five Gram positive bacteria while lacking efficacy against the Gram negative strains. In the antifungal test, while vernolides exhibited high activity with LC(50) values of 0.2, 0.3 and 0.4 mg/ml against Penicillium notatum, Aspergillus flavus, Aspergillus niger and Mucor hiemalis, respectively, vernodalol showed moderate inhibitions against Aspergillus flavus, Penicillium notatum and Aspergillus niger with LC(50) values of 0.3, 0.4 and 0.5 mg/ml, respectively. Both compounds were ineffective against Fusarium oxysporum, a microbe known to be highly resistant to chemical agents. However, the antimicrobial results of this study correspond positively with the claimed ethnomedical uses of the leaves of Vernonia amygdalina in the treatment of various infectious diseases.

A study of the stability of tri(glucosyloxyphenyl)chlorin, a sensitizer for photodynamic therapy, in human colon tumoural cells: a liquid chromatography and MALDI-TOF mass spectrometry analysis.

Asymmetrical glycoconjugated tetrapyrrolic macrocycles are under study as efficient sensitizers for photodynamic therapy (PDT). In this context, tri(meta-O-beta-glucopyranosyloxyphenyl)chlorin [TPC(m-O-Glu)(3)] 2a/3a was found to be four times more photoactive in vitro than Foscan. In a further study of this interesting glycoconjugate, its metabolism by cellular glycosidases in HT29 cells has to be explored. Cellular extracts of HT29 cells incubated with TPC(m-O-Glu)(3) (24h, 6microM) were analyzed by MALDI-TOF mass spectrometry and high performance liquid chromatography (HPLC). In MALDI-TOF mass spectra, the presence of compounds distinct from TPC(m-O-Glu)(3) (m/z 1151) were observed at m/z 989, 827 and 665 corresponding to the loss of one, two or three glucose units (162u) and were be ascribed to TPC(m-OH)(m-O-Glu)(2) 2/3b,b',b", TPC(m-OH)(2)(m-O-Glu) 2/3c,c',c" and TPC(m-OH)(3) isomers 2d/3d, respectively. The porphyrins resulting from chlorin oxidation TPP(m-O-Glu)(3) 4a, TPP(m-OH)(m-O-Glu)(2) 4b,b", TPP(m-OH)(2)(m-O-Glu) 4c,c" and TPP(m-OH)(3) 4d were also observed. The HPLC profile (lambda(anal)=420 nm) showed eight peaks consistent with mass spectra. The kinetics of deglucosylation was studied from HPLC profiles between 1 and 48h incubation. The concentration of triglucoconjugated and diglucoconjugated molecules was maximum around 3 and 8h incubation, respectively, whereas, totally deglucosylated species appeared only after incubation for more than 10h. The fully deglycosylated porphyrin TPP(m-OH)(3) is the final metabolite, being observed at a concentration 15 times higher than that of the remaining TPC(m-O-Glu)(3) 2a/3a. Compared to the photobiological activity of the parent molecule [TPC(m-O-Glu)(3)], a three times higher TPP(m-OH)(3) concentration was necessary to observe a similar in vitro photoactivity.

Synthesis, cellular internalization and photodynamic activity of glucoconjugated derivatives of tri and tetra(meta-hydroxyphenyl)chlorins.

Glucoconjugated tri and tetra(meta-hydroxyphenyl)chlorins have been synthesized in order to explore how glucoconjugation of the macrocycle affects the photoactivity of the molecule. Internalization processes, photosensitizing efficacy of TPC(m-O-GluOH)(3) and TPC(m-O-GluOH)(4), in HT29 human adenocarcinoma cells have been compared to those of tetra(meta-hydroxyphenyl) chlorin (m-THPC, Foscan). The tetra glucoconjugated chlorin, TPC(m-O-GluOH)(4), was found to be poorly internalized and weakly photoactive. In contrast, the asymmetric and more amphiphilic compound TPC(m-O-GluOH)(3), exhibited superior phototoxicity compared to m-THPC. Drug concentration, temperature and sodium azide effects indicated that TPC(m-O-GluOH)(3) internalization partly proceeds via an active receptor-mediated endocytosis mechanism. Cellular uptake appeared as a saturable process and remained 30% lower than for mTHPC. However, a maximum phototoxicity in HT29 cells (survival fraction of 2+/-0.6%) were observed for concentration as low as 2 microM. A 4-fold higher concentration of m-THPC was necessary to observe the same level of photoactivity. This higher phototoxicity has been correlated to a greater mitochondrial affinity. On the basis of these results, work is in progress to further evaluate the potential of glycosylated chlorins in photodynamic therapy (PDT).

Phenylisoserine: a versatile amino acid for the construction of novel beta-peptide structures.

The N-Boc O-tert-butyldimethysilyl-substituted hexa-beta-peptide methyl ester 18 was constructed from the O-TBS ether of (-)-(2R, 3S)-phenylisoserine. By NMR, it was determined that this homo beta-peptide adopts a highly stable beta-strand-type secondary structure in chloroform solution, which is stabilized by both hydrophobic interactions involving the OTBS methyl groups of residues i and i + 2, and inter-(five-membered)/intra (six-membered)-residue H-bonding interactions. These interactions are systematically repeated along the peptide chain and, thereby, operate in concert to stabilize the observed conformation of 18.

3D-QSAR CoMFA on cyclin-dependent kinase inhibitors.

Several series of cyclin-dependent kinase inhibitors previously prepared in our laboratory were compared using 3D-QSAR (CDK1) and docking (CDK2) techniques. Evaluation of our own library of 93 purine derivatives served to establish the model which was validated by evaluation of an external library of 71 compounds. The best predictions were obtained with the CoMFA standard model (q(2) = 0.68, r(2) = 0.90) and with the CoMSIA combined steric, electrostatic, and lipophilic fields (q(2) = 0.74, r(2) = 0.90). The CDK1 3D-QSAR model was then superimposed to the ATP/CDK2 binding site, giving direct contour maps of the different fields. Although too few compounds were evaluated on CDK5 to derive a 3D-QSAR model, some interesting SARs have been deduced. Comparison of the results obtained from both methods helped with understanding the specific activity of some compounds and designing new specific CDK inhibitors.

Synthesis and evaluation of "AZT-HEPT", "AZT-pyridinone", and "ddC-HEPT" conjugates as inhibitors of HIV reverse transcriptase.

To test the concept that HIV reverse transcriptase could be effectively inhibited by "mixed site inhibitors", a series of seven conjugates containing both a nucleoside analogue component (AZT 1, ddC 2) and a nonnucleoside type inhibitor (HEPT analogue 12, pyridinone 27) were synthesized and evaluated for their ability to block HIV replication. The (N-3 and C-5)AZT-HEPT conjugates 15, 22, and 23 displayed 2-5 microM anti-HIV activity, but they had no effect on the replication of HIV-2 or the HIV-1 strain with the Y181C mutation. The (C-5)AZT-pyridinone conjugates 34-37 were found to be inactive. In marked contrast, the ddC-HEPT molecule 26 displayed the same potency (EC(50) = 0.45 microM) against HIV-1 (wild type and the Y181C nevirapine-resistant strain) and HIV-2 in cell culture. No synergistic effect was observed for these bis-substrate inhibitors, suggesting that the two individual inhibitor components in these molecules do not bind simultaneously in their respective sites. Interestingly, however, the results indicate that the AZT-HEPT conjugates and the ddC-HEPT derivative 26 inhibit reverse transcriptase (RT) in an opposite manner. One explanation for this difference is that the former compounds interact preferentially with the hydrophobic pocket in RT, whereas 26 (after supposed triphosphorylation) inhibits RT through binding in the catalytic site.

Cyclin-dependent kinase inhibition by new C-2 alkynylated purine derivatives and molecular structure of a CDK2-inhibitor complex.

A new series of 2,6,9-trisubstituted purines, characterized by the presence of a common alkynyl substituent at C-2 and a range of different anilino/benzylamino groups at C-6, were synthesized. These compounds were evaluated for their capacity to inhibit cyclin-dependent kinase activity (CDK1-cyclin B) in vitro. Compounds 4e (N-6-p-Cl-benzylamino derivative) and 5e (N-6-m-Cl-anilino derivative) exhibited the strongest inhibitory activity with an IC(50) of 60 nM. The structure of compound 4b (N-6-p-methoxybenzylamino derivative) in complex with human CDK2 was determined by X-ray crystallography, revealing the molecular basis of inhibition by this molecule. Subsequent molecular modeling studies allowed us to rationalize the SAR observed for these compounds.