A comparison of the leaf gel extracts of Aloe ferox and Aloe vera in the topical treatment of atopic dermatitis in Balb/c mice.

Aloe vera gel is widely used in the treatment of an array of disturbances, especially skin disorders. The wound-healing effects have been attributed to its moisturizing and anti-inflammatory effects as well as its beneficial effect on the maturation of collagen. The aim of the present study is to compare the effects of topically applied extracts of Aloe ferox with that of Aloe vera on the symptoms as well as IgE levels of a mouse model of atopic dermatitis (AD). Mice were sensitized and challenged with 2,4-dinitrochlorobenzene and treated afterwards for 10 consecutive days with the gels of either A. ferox or A. vera applied topically to the affected areas. A placebo gel was used for the control mice. Blood was collected at the beginning and end of the treatment period to measure serum IgE levels. Although the gels of both the Aloe species inhibited the cutaneous inflammatory response as well as serum IgE levels in the rats, the extracts of A. ferox were superior to that of A. vera in reducing IgE levels. The gels of A. ferox and A. vera, applied topically, may be a safe and useful alternative to antihistamines and topical corticosteroids, for the treatment of patients suffering from recurring chronic AD.

The anti-tumour properties and biodistribution (as determined by the radiolabeled equivalent) of Au-compounds intended as potential chemotherapeutics.

The anti-tumour activity of the Au (I) phosphine complex [Au(dppe(2)]Cl was first discovered in the mid 1980s although promising results were obtained it did not pass clinical studies because of its toxicity to organs such as the liver and heart. The aim of this study was to determine whether the two novel gold compounds (MM5 and MM6), selected for this study, have higher selectivity for cancer cells with less toxicity towards normal cells than [Au(dppe)(2)]Cl, and also to determine whether they have improved bio distribution compared to [Au(dppe)(2)]Cl. The Au-compounds as potential chemotherapeutic drugs were evaluated by using radioactive tracers in the in vitro and in vivo studies. Results obtained from these experiments showed that the uptake of these experimental compounds was dependent on their octanol/water partition coefficient. However; the inhibition of cell growth did not correlate with the uptake of these compounds by the cells that were tested. In terms of the total uptake it was found that the compounds that were less lipophilic (MM5, MM6) were taken up less efficiently in cells than those that are more lipophilic. Therefore hydrophilic drugs are expected to have a limited biodistribution compared to lipophilic drugs. This might imply a more selective tumour uptake.

Brown coal derived humate inhibits contact hypersensitivity; an efficacy, toxicity and teratogenicity study in rats.

OBJECTIVES: The effects of two humate products were compared to that of prednisolone on a contact hypersensitivity rat model. METHODS: Rats, sensitized with dinitrofluorobenzene (DNFB), were placed on a daily oral treatment of 61 mg/kg BW of humate derived from either leonardite or bituminous coal or on prednisolone at one mg/kg BW and challenged 6 days later with a topical application of DNFB to the right ear. The inflamed ears were measured daily. In a toxicity study rats were exposed to daily oral treatment of leonardite humate at 1,000 mg/kg BW for 1 month. A teratogenicity study was done where pregnant rats were treated with 500 mg/kg BW on days 5 to 17 of pregnancy. RESULTS: Only the leonardite humate compared favourably with prednisolone in suppressing contact hypersensitivity. No signs of toxicity were observed and weight gain was normal during the 6-day and 1 month treatments and during the teratogenicity study with the leonardite humate. However, the rats on the other two products experienced slower weight gain. CONCLUSION: The identification of a naturally occurring nontoxic compound with anti-inflammatory activity is exciting and merits further evaluation in the treatment of patients suffering from inflammatory conditions.

In vitro and in vivo assessment of humic acid as an aflatoxin binder in broiler chickens.

The in vitro affinity and adsorption capacity of a humic acid, oxihumate, for aflatoxin B1 (AFB1) was evaluated, utilizing Langmuir and Freundlich adsorption isotherms. Oxihumate showed a high in vitro affinity for AFB1. The Freundlich isotherm fitted the data better than the Langmuir isotherm, and binding capacities of 10.3, 7.4, and 11.9 mg of AFB1/g of oxihumate at pH 3, 5, and 7, respectively, were calculated. The in vivo efficacy of oxihumate as an aflatoxin binder in male broiler chickens exposed to aflatoxin-contaminated feed from 7 to 42 d of age was also assessed. The efficacy of oxihumate was compared with a commercially available product with a brewers dried yeast (BDY) and brewers fermentation solubles as main active ingredients. A total of 420 birds were assigned to 28 pens, with 15 birds per pen. The following treatments were applied: 1) 0 mg of AFB1 + 0 additives, 2) 1 mg of AFB1/kg of feed + 0 additives, 3) 1 mg of AFB1/kg of feed + 3.5 g of oxihumate/kg of feed, 4) 1 mg of AFB1/kg of feed + 3.5 g of BDY/kg of feed, 5) 2 mg of AFB1/kg of feed + 0 additives, 6) 2 mg of AFB1/kg of feed + 3.5 g of oxihumate/kg of feed, and 7) 2 mg of AFB1/kg of feed + 3.5 g of BDY/kg of feed. Each treatment consisted of 4 replicates. Oxihumate was effective in diminishing the adverse effects caused by aflatoxin on BW of broilers (P < 0.05). Oxihumate also showed protective effects against liver damage, stomach and heart enlargement, as well as some of the hematological and serum biochemical changes associated with aflatoxin toxicity (P < 0.05). Results indicated that oxihumate, but not BDY, could alleviate some of the toxic effects of aflatoxin in growing broilers. Oxihumate might, therefore, prove to be beneficial in the management of aflatoxin-contaminated feedstuffs for poultry when used in combination with other mycotoxin management practices. Additional studies are warranted to assess its efficacy under a wide variety of circumstances.

Activity of 7-methyljuglone in combination with antituberculous drugs against Mycobacterium tuberculosis.

The recent increase in the incidence of tuberculosis with the emergence of multidrug-resistant (MDR) cases has lead to the search for new drugs that are effective against MDR strains of Mycobacterium tuberculosis and can augment the potential of existing drugs against tuberculosis. In the present study, we investigated the activities of a naphthoquinone, 7-methyljuglone, isolated from the roots of Euclea natalensis alone and in combination with other antituberculous drugs against extracellular and intracellular M. tuberculosis. Combinations of 7-methyljuglone with isoniazid or rifampicin resulted in a four to six-fold reduction in the minimum inhibitory concentration of each compound. Fractional inhibitory concentration (FIC) indexes obtained were 0.2 and 0.5, respectively, for rifampicin and isoniazid, suggesting a synergistic interaction between 7-methyljuglone and these anti-TB drugs. The ability of 7-methyljuglone to enhance the activity of isoniazid and rifampicin against both extracellular and intracellular organisms suggests that 7-methyljuglone may serve as a promising compound for development as an anti-tuberculous agent.

Influence of irinotecan and SN-38 on the irradiation response of WHO3 human oesophageal tumour cells under hypoxic conditions.

Irinotecan and its metabolite SN38 were evaluated for their cytotoxicity and influence on radiosensitivity in WHO3 human oesophageal cells under hypoxic conditions. The IC50's of Irinotecan and SN-38 were found to be 0.8 and 0.04 microM, repectively, with SN-38 emerging as the more potent drug. The toxicities were similar under anoxic conditions. Given in conjunction with irradiation under hypoxic conditions, the two drugs restored the radiosensitivity of WHO3 cells in a dose-dependent manner by factors of 1.5-2.1 as compared to a control oxygen enhancement ratio (OER) of 2.1 in this cell system. In the subtoxic concentration range of 10(-2) microM SN-38 still generated a marked sensitisation of hypoxic tumour cells by factors of 1.2-1.6. It is concluded that the topoisomerase inhibitor Irinotecan and in particular the metabolite SN-38 may be clinically useful for radiotherapy of notoriously hypoxic tumour pathologies.

Evaluation of cisplatin and a novel platinum polymer conjugate for drug toxicity and drug distribution in mice.

The toxicity and distribution of cisplatin and two novel platinum (Pt) polymer conjugates (Pt-6 and Pt-7) were determined in serum and tissue of BALB/c mice at specific time points after i.p. administration of a drug bolus containing identical Pt concentrations. Pt concentrations were determined in serum, liver and kidney at 5 and 15 min, respectively, after drug administration by inductively coupled plasma mass spectrometry. It was found that the Pt polymer Pt-7 gave rise to a considerably lower Pt concentration in serum and considerably higher concentration in liver and kidney than cisplatin. LD25 measurements indicated that the Pt-7 polymer is considerably less toxic than cisplatin. In vitro experiments and determination of IC50 values in a variety of human tumor cell lines, normal lymphocytes and fibroblasts confirmed that Pt-6 and Pt-7 polymers are 40-500 times more toxic for tumor cells than for normal cells, perhaps reflecting preferential uptake. The toxicity of cisplatin was found to be only 1.6-40 times more effective in tumor cells. These inter-relationships are supported by the observation that the tumor enrichment factor (TEF) for cisplatin is only in the region of 6, and much lower than for Pt-6 and Pt-7, where TEFs are in the region of 40 and 150, respectively. These results demonstrate that the Pt polymer conjugates exhibit greater tumor specificity than cisplatin, killing tumor cells more effectively while being considerably less toxic for normal cells. It is concluded that the Pt polymer conjugates may be superior for cancer therapy and warrant further testing to assess their full clinical potential.

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.

Studies on antibacterial, antioxidant and fibroblast growth stimulation of wound healing remedies from South Africa.

Aqueous and methanol extracts of Urtica urens, Capparis tomentosa, Dicoma anomala, Leonotis leonorus, Xysmalobium undulatum, Helichrysum foetidum, Pterocarpus angolensis, Terminalia sericea and Gunnera perpensa, plants documented as being used for topical wound healing in the literature, were tested for antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli and Pseudomonas aeruginosa. Methanol and water extracts of two of these plants, Terminalia sericea and Gunnera perpensa, were more active compared to the other extracts against Streptococcus pyogenes and Staphylococcus aureus. The effects of the latter plants on fibroblast growth as well as oxidant production by N-formyl-methionyl-leucyl-phenylalanine were also studied. The water and methanol extracts of Terminalia sericea and Gunnera perpensa significantly decreased luciginin enhanced chemiluminescence at concentrations of 100 microg/ml and higher. However, the extracts had no effect on the growth of primary human fibroblasts.

Flow cytometric evaluation of apoptosis and cell viability as a criterion of anti-tumour drug toxicity.

BACKGROUND: Determination of the drug concentration required to kill 50% of the tumour cells (EC50) does not take into account the propensity of cells to undergo apoptosis and necrosis. These 2 parameters and the viable cells are here assessed by a flow cytometric (FC) approach using propidium iodide (PI) and FITC-Annexin V staining. MATERIALS AND METHODS: A number of carcinoma cell lines of defined p53 status were exposed to cis-PtII for 24 hours, stained with PI and FITC-Annexin V and analyzed by FC. Unstained viable cells, early apoptotic cells and necrotic cells were scored separately in dual parameter plots of green fluorescence (FITC) against red fluorescence (PI) to generate dose response curves. RESULTS: EC50 values for cell viability were found to be 1-4 times higher than survival data from colony assays resembling data obtained by MTT or Crystal Violet vital dye staining. Percentage apoptosis measured by Annexin V binding was in agreement with microscopic scoring of apoptotic cells after Acridine Orange staining. CONCLUSION: The FC assay described gives a good estimate of cell viability resembling data from vital dye staining assays and provides additional information on apoptosis and necrosis. FC data from Annexin V binding and microscopic scoring after Acridine Orange staining were in excellent agreement.

Investigation of the anti-HIV properties of oxihumate.

A unique process has been developed to convert bituminous coal by controlled wet oxidation followed by base treatment to a water-soluble humate called oxihumate. Oxihumate inhibited HIV-1 infection of MT-2 cells with an IC(50) of 12.5 microg/ml. Treatment of free and cell-attached HIV with oxihumate irreversibly reduced infectivity, while the susceptibility of target cells to the virus was not impaired by treatment prior to infection. The infectivity of the HIV particles was inhibited by interference with CD4 binding and the V3 loop-mediated step of virus entry. No viral resistance to oxihumate developed over a 12-week period in vitro. Oxihumate therefore holds promise for the treatment of HIV-infected patients.

Tetramethylpiperidine-substituted phenazines inhibit the proliferation of intrinsically multidrug resistant carcinoma cell lines.

The effects of nine new tetramethylpiperidine (TMP)-substituted phenazines on the growth of a human esophageal cancer cell line (WHCO3), two human hepatocellular carcinoma cell lines (PLC and HepG2) and three human colon cancer cell lines (CaCo2, COLO 320DM and HT29) were compared to those of clofazimine, B669 and five standard chemotherapeutic agents. The three most active TMP-substituted phenazines against these cell lines were B3962, B4126 and B4125 with mean IC50 values for all the cancer cell lines tested of 0.36, 0.47 and 0.48 microg/ml respectively. B3962 and B4126, but not B4125 were also the most active against a semi-continuous human fibroblast culture (MRC5). The compound with the highest tumor specificity relative to the fibroblast culture, was B4125. Importantly, there was minimal variation in sensitivity of the different cell lines, including a multidrug resistant cell line (COLO 320DM) expressing high levels of P-glycoprotein, to the TMP-substituted phenazines. This was not the case with the standard chemotherapeutic agents. The efficacy of compounds such as B4125 against a broad spectrum of multidrug resistant cancer cell lines, together with their relatively high tumor specificity, suggests that these agents may be useful in the treatment of intrinsically resistant cancers such as colon and liver cancer.

Vitamin E attenuates the injurious effects of bioactive phospholipids on human ciliated epithelium in vitro.

Bioactive phospholipids (PL), particularly lysophosphatidylcholine (LPC), are being increasingly implicated in the pathogenesis of various acute and chronic inflammatory disorders, particularly those of the airways, while there is emerging evidence that vitamin E may function as a natural antagonist of these lipid mediators of inflammation. The aims of this study were to document the effects of vitamin E on the inhibition of ciliary beating and damage to structural integrity of human ciliated epithelium induced by the PL, platelet-activating factor (PAF), lyso-PAF and LPC in vitro in relation to the anti-oxidative and membrane-stabilizing properties of the vitamin. Ciliary beat frequency was measured by a phototransistor technique, and damage to structural integrity assessed by a visual-scoring index, while superoxide production by polymorphonuclear leukocytes and membrane-stabilizing potential were measured using lucigenin-enhanced chemiluminescence and haemolytic procedures, respectively. All three PL caused inhibition of ciliary beating and structural damage to human ciliated epithelium by membrane-directed cytotoxic mechanisms, which were potentiated by human polymorphonuclear leukocytes due to induction of oxidant-mediated injury. Both direct and phagocyte-inflicted epithelial injury was attenuated by vitamin E. In haemolytic and chemiluminescence assays, vitamin E neutralized both the membrane-destabilizing and pro-oxidative actions of all three PL, while spectrophotometric analysis of mixtures of vitamin E with PAF, lyso-PAF and LPC revealed alterations in peak intensity, as well as peak shifts, indicative of physicochemical interactions between the vitamin and the PL. Vitamin E status may be a determinant of susceptibility to phospholipid-mediated airway inflammation and damage.

Effects of tetramethylpiperidine (TMP)-substituted phenazines on membrane stability and P-glycoprotein function.

The lipophilicity and membrane-destabilizing activities of clofazimine and three tetramethyl-piperidine (TMP)-substituted phenazines were compared with the anti-tumor and multiple drug resistance (MDR) neutralizing potential of these agents using a P-glycoprotein (P-gp)-expressing small cell lung cancer cell line (H69/LX4). Partition coefficients were measured as an index of lipophilicity, while membrane-destabilizing potential was measured using a conventional hemolytic assay. The membrane-destabilizing potential of the TMP-substituted phenazines was found to correlate positively with the degree of lipophilicity, as well as with MDR reversal activity. The presence of a TMP group, as well as chlorine atoms on the phenyl and anilino rings of these agents contributed to the enhancement of anti-tumor activity by potentiating membrane-destabilizing activity. TMP-substituted phenazines may be useful in the design of novel anti-cancer and MDR reversal agents.

Tetramethylpiperidine-substitution increases the antitumor activity of the riminophenazines for an acquired multidrug-resistant cell line.

The multidrug resistance (MDR)-neutralizing and cytotoxic properties of five tetramethylpiperidine (TMP)-substituted phenazines were compared with those of their corresponding isopropyl-substituted analogues using a P-glycoprotein (P-gp)-expressing small cell lung cancer cell line (H69/LX4). All of the TMP-substituted phenazines tested outperformed their isopropyl analogues with respect to both cytotoxic and chemosensitizing properties, indicating the importance of TMP-substitution when designing novel riminophenazines with increased activity against MDR cancer cell lines. Of the TMP-substituted phenazines tested, B4112, chlorinated at position 3 of the phenyl- and anilino-rings, had the most potent anti-cancer activity in vitro, making this agent a potential candidate for evaluation in experimental and clinical oncology.

Clofazimine and B4121 sensitize an intrinsically resistant human colon cancer cell line to P-glycoprotein substrates.

The potential of B4121 to sensitize three intrinsically resistant human colon cancer cell lines (CaCo2, ATCC HTB 37; COLO 32 DM, ATCC CCL 220; HT-29, ATCC HTB 38) to vinblastine, doxorubicin, daunorubicin, paclitaxel, taxotere and cisplatin at a non-toxic, therapeutically relevant concentration of 0.25 microg/ml was compared with that of clofazimine at a similar concentration. The cell line expressing high levels of P-glycoprotein (P-gp), COLO 320 DM, was susceptible to chemosensitization by the experimental agents for the P-gp substrates (paclitaxel, taxotere, daunorubicin, vinblastine and doxorubicin) but not for cisplatin. CaCo2 cells expressed lower levels of P-gp and were only marginally susceptible to sensitization by any one of these drugs, except in the case of sensitization by B4121 for doxorubicin and taxotere, whereas the HT-29, a P-gp negative cell line, was unaffected. The riminophenazines, especially B4121, might prove useful as combination treatment in circumventing P-gp mediated resistance of colon cancers.

In vitro investigation of the antimicrobial activities of novel tetramethylpiperidine-substituted phenazines against Mycobacterium tuberculosis.

The intra- and extracellular activities of 5 novel tetramethylpiperidine (TMP)-substituted phenazines against Mycobacterium tuberculosis H37Rv (ATCC 27294) were determined and compared with those of clofazimine and rifampicin. Two of these agents, together with clofazimine, were also tested for their activities against drug-resistant strains of M. tuberculosis. Three of the TMP-substituted phenazine compounds were significantly more active than clofazimine against M. tuberculosis, including multidrug-resistant clinical strains of this microbial pathogen, demonstrating a lack of cross-resistance between the riminophenazines and standard anti-tuberculous drugs. Using M. tuberculosis-infected monocyte-derived macrophages, all of the TMP-substituted phenazines were found to possess intracellular activity which was superior to that of both clofazimine and rifampicin. In this model of intracellular bioactivity, the experimental compounds inhibited bacterial growth at concentrations which were approximately 10-fold lower than the corresponding minimal inhibitory concentration values obtained using conventional in vitro sensitivity testing procedures. These results demonstrate that the novel TMP phenazines are active against multidrug-resistant M. tuberculosis strains, and particularly effective intracellularly.

The chemosensitizing potential of GF120918 is independent of the magnitude of P-glycoprotein-mediated resistance to conventional chemotherapeutic agents in a small cell lung cancer line.

GF120918, at 250 ng/ml, increased the sensitivity of a P-glycoprotein (P-gp)-mediated multidrug resistant (MDR) small cell lung cancer cell line (H69/LX4) to the P-gp substrates, paclitaxel, taxotere, vinblastine, vinorelbine, daunorubicin and etoposide to levels which were either greater (in the case of etoposide) or close to that of the parent cell line (H69/P). This was achieved in spite of the great variation in the levels of resistance of the MDR cell line for the various anti-cancer drugs tested. These data suggest that GF120918 is a potent antagonist of P-gp mediated multidrug resistance, even in the case of high levels of resistance, as was the case with paclitaxel and taxotere (2560 and 2215 fold more than the sensitive parent cell line respectively).