Antiprotozoal effect of crude extracts and flavonoids isolated from Chromolaena hirsuta (asteraceae)

Quercetin as a Promising Antiprotozoan Phytochemical: Current Knowledge and Future Research Avenues

Despite tremendous advances in the prevention and treatment of infectious diseases, only few antiparasitic drugs have been developed to date. Protozoan infections such as malaria, leishmaniasis, and trypanosomiasis continue to exact an enormous toll on public health worldwide, underscoring the need to discover novel antiprotozoan drugs. Recently, there has been an explosion of research into the antiprotozoan properties of quercetin, one of the most abundant flavonoids in the human diet. In this review, we tried to consolidate the current knowledge on the antiprotozoal effects of quercetin and to provide the most fruitful avenues for future research. Quercetin exerts potent antiprotozoan activity against a broad spectrum of pathogens such as Leishmania spp., Trypanosoma spp., Plasmodium spp., Cryptosporidium spp., Trichomonas spp., and Toxoplasma gondii. In addition to its immunomodulatory roles, quercetin disrupts mitochondrial function, induces apoptotic/necrotic cell death, impairs iron uptake, inhibits multiple enzymes involved in fatty acid synthesis and the glycolytic pathways, suppresses the activity of DNA topoisomerases, and downregulates the expression of various heat shock proteins in these pathogens. In vivo studies also show that quercetin is effective in reducing parasitic loads, histopathological damage, and mortality in animals. Future research should focus on designing effective drug delivery systems to increase the oral bioavailability of quercetin. Incorporating quercetin into various nanocarrier systems would be a promising approach to manage localized cutaneous infections. Nevertheless, clinical trials are needed to validate the efficacy of quercetin in treating various protozoan infections.

Two New Cytotoxic Sesquiterpene-Amino Acid Conjugates and a Coumarin-Glucoside from Crossostephium chinense

The Asteraceae family is a promising source of bioactive compounds, such as the famous Asteraceae plants Tanacetum cinerariifolium (pyrethrin) and Artemisia annua (artemisinin). As a result of our series of phytochemical studies of the subtropical plants, two novel sesquiterpenes, named crossoseamines A and B in this study (1 and 2, respectively), one undescribed coumarin-glucoside (3), and eighteen known compounds (4-21) were isolated from the aerial part of Crossostephium chinense (Asteraceae). The structures of isolated compounds were elucidated by spectroscopic methods, including 1D and 2D NMR experiments (¹H, ¹³C, DEPT, COSY, HSQC, HMBC, and NOESY), IR spectrum, circular dichroism spectrum (CD), and high-resolution electrospray ionization-mass spectrometry (HR-ESI-MS). All isolated compounds were evaluated for their cytotoxic activities against Leishmania major, Plasmodium falciparum, Trypanosoma brucei (gambiense and rhodesiense), and human lung cancer cell line A549 because of the high demand for the discovery of new drug leads to overcome the present side effects and emerging drug-resistant strains. As a result, the new compounds (1 and 2) showed significant activities against A549 (IC₅₀, 1: 3.3 ± 0.3; 2: 12.3 ± 1.0 μg/mL), L. major (IC₅₀, 1: 6.9 ± 0.6; 2: 24.9 ± 2.2 μg/mL), and P. falciparum (IC₅₀, 1: 12.1 ± 1.1; 2: 15.6 ± 1.2 μg/mL).

From wandering weeds to pharmacy: An insight into traditional uses, phytochemicals and pharmacology of genus Chromolaena (Asteraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Chromolaena species, of the Asteraceae family, are distributed across the tropical and the temperate regions of Africa, the Americas, southern Asia, and Australia. Despite "falling out of favour" among the people because of their "weedy" nature, Chromolaena species have indisputable long medicinal history in the treatment of malaria, nasal congestion, inflammation, eye disorders, asthma, cough, flu, headache, and cold.

AIM OF THE REVIEW

The aim of this review is to systematically summarize the current knowledge on ethnopharmacology, phytochemistry, pharmacology, toxicology, and real-time scientific applications of the genus Chromolaena after its re-classification from genus Eupatorium, as well as to proffer integrated approaches in maximizing their therapeutic values despite their "weedy" nature.

MATERIALS AND METHODS

First, the current species in the genus were verified by "The Plant List" (http://www.theplantlist.org) and "Royal Botanic Gardens, Kew/Missouri Botanical Garden" (http://mpns.kew.org/mpns-portal/). Second, the relevant information on each of the identified species was gathered from following databases: Google Scholar, Online Wiley library, ScienceDirect, SciFinder, Scopus, PubMed. Scientific literature was searched from inception till August 2021.

RESULTS

More than 190 phytochemicals have been isolated and identified from 27 species of the genus, including flavonoids, alkaloids, triterpenoids, diterpenoids, sesquiterpenoids, steroids, fatty acids, and coumarins among others. Pharmacological investigations, both in vitro and in vivo, have shown that the extracts and the compounds have antimicrobial, anticancer, antioxidant, insecticidal, anti-inflammatory, and anti-diabetic activities among others.

CONCLUSIONS

Many species of genus have potential therapeutic values, and hence they are more than "wandering" weeds. In addition, there is growing interest in the real-time scientific applications of the genus in the production of pharmacological polyherbal products, and this should serve as a stimulus to strategically develop integrated control approaches for preserving these species, with a view of maximizing their therapeutic values and reducing their cost of eradication.

The Role of Macronutrients, Micronutrients and Flavonoid Polyphenols in the Prevention and Treatment of Osteoporosis

Osteoporosis is considered an age-related disorder of the skeletal system, characterized primarily by decreased bone mineral density (BMD), microstructural quality and an elevated risk of fragility fractures. This silent disease is increasingly becoming a global epidemic due to an aging population and longer life expectancy. It is known that nutrition and physical activity play an important role in skeletal health, both in achieving the highest BMD and in maintaining bone health. In this review, the role of macronutrients (proteins, lipids, carbohydrates), micronutrients (minerals—calcium, phosphorus, magnesium, as well as vitamins—D, C, K) and flavonoid polyphenols (quercetin, rutin, luteolin, kaempferol, naringin) which appear to be essential for the prevention and treatment of osteoporosis, are characterized. Moreover, the importance of various naturally available nutrients, whether in the diet or in food supplements, is emphasized. In addition to pharmacotherapy, the basis of osteoporosis prevention is a healthy diet rich mainly in fruits, vegetables, seafood and fish oil supplements, specific dairy products, containing a sufficient amount of all aforementioned nutritional substances along with regular physical activity. The effect of diet alone in this context may depend on an individual’s genotype, gene-diet interactions or the composition and function of the gut microbiota.

Phytoprostane and phenolic compounds from Chromolaena palmaris

The chemical investigation of Chromolaena palmaris (Sch.Bip. ex Baker) R.M. King & H. Rob. expands the phytochemical composition knowledge of Chromolaena genus, since this is the first chemical investigation of this species. Twenty-five compounds were identified, including a phytoprostane, 17 flavonoids, 6 phenolic acids, and a caffeoyl-glucoside derivative obtained by classical chromatography and UHPLC-HRMS/MS analysis. Moreover, anti-Mycobacterium tuberculosis and antiproliferative activities of C. palmaris were evaluated. Dichloromethane fraction showed cytotoxicity towards human cancer cell lines, presenting TGI values on glioma (U251) of 27.8 μg mL^-1. Furthermore, compounds 1 and 2 exhibited antimicrobial activity against Mycobacterium tuberculosis with MIC of 62.5 and 15.6 μg mL^-1, respectively.

Prohexadione calcium is herbicidal to the sunflower root parasite Orobanche cumana

BACKGROUND

The obligatory sunflower root parasite Orobanche cumana Wallr. deprives its host of essential nutrients, resulting in a dramatic reduction in yield and biomass. A post-emergence application with an imidazolinone herbicide on an imidazolinone-tolerant sunflower is highly effective against O. cumana. The herbicide inhibits the enzyme acetohydroxy acid synthase and consequently, growth of the parasite is inhibited, although the sunflower survives the treatment through mutations in the target enzyme. Interestingly, field studies have shown that a combined application of an imidazolinone herbicide with prohexadione resulted in reduced emergence of O. cumana compared with the sole application of the herbicide. The aim of this study was to investigate whether prohexadione is herbicidal to O. cumana.

RESULTS

Prohexadione was rapidly distributed within the sunflower, reaching the roots, the site of O. cumana attack, as early as 6 h after application (HAA) on sunflower leaves. A direct impact of prohexadione on O. cumana germination was investigated and a half-maximal inhibitory concentration (IC₅₀ ) of 84 μm prohexadione was found. In addition, the inhibition of germination by prohexadione was terminal, meaning that O. cumana seeds died after prohexadione contact as soon as they were primed for germination. Additionally, excretion studies showed that a small proportion of the applied prohexadione was excreted by sunflower roots.

CONCLUSION

We show that prohexadione is an inhibitor of O. cumana germination and that the growth regulator is found in sunflower roots shortly after application. We hypothesize that prohexadione is excreted in sufficient amounts from the sunflower roots, therefore having a direct impact on O. cumana germination. © 2020 Society of Chemical Industry.

Re-appraising the potential of naringin for natural, novel orthopedic biotherapies

Naringin is a naturally occurring flavonoid found in plants of the Citrus genus that has historically been used in traditional Chinese medical regimens for the treatment of osteoporosis. Naringin modulates signaling through numerous molecular pathways critical to musculoskeletal development, cellular differentiation, and inflammation. Administration of naringin increases in vitro expression of bone morphogenetic proteins (BMPs) and activation of the Wnt/β-catenin and extracellular signal-related kinase (Erk) pathways, thereby promoting osteoblastic proliferation and differentiation from stem cell precursors for bone formation. Naringin also inhibits osteoclastogenesis by both modifying RANK/RANKL interactions and inducing apoptosis in osteoclasts in vitro. In addition, naringin acts on the estrogen receptor in bone to mimic the native bone-preserving effects of estrogen, with few systemic side effects on other estrogen-sensitive tissues. The efficacy of naringin therapy in reducing the osteolysis characteristic of common musculoskeletal pathologies such as osteoporosis, degenerative joint disease, and osteomyelitis, as well as inflammatory conditions affecting bone such as diabetes mellitus, has been extensively demonstrated in vitro and in animal models. Naringin thus represents a naturally abundant, cost-efficient agent whose potential for use in novel musculoskeletal biotherapies warrants re-visiting and further exploration through human studies. Here, we review the cellular mechanisms of action that have been elucidated regarding the action of naringin on bone resident cells and the bone microenvironment, in vivo evidence of naringin’s osteostimulative and chondroprotective properties in the setting of osteolytic bone disease, and current limitations in the development of naringin-containing translational therapies for common musculoskeletal conditions.

Phytochemical Study of Tanacetum Sonbolii Aerial Parts and the Antiprotozoal Activity of its Components

The genus Tanacetum includes some popular endemic species of the flora of Iran, with important medicinal properties. In a project, directed at structurally interesting bioactive metabolites from Iranian endemic species, we studied Tanacetum sonbolii Mozaff. Eight compounds comprising six phenolic and two terpenoidal compounds were isolated from the ethyl acetate extract of the aerial parts of the plant by normal and reverse phase chromatography. Their structures were established mainly by 1D and 2D NMR spectroscopic techniques, including ¹H-¹H COSY, HSQC and HMBC methods and confirmed by comparing their NMR data with those reported in the literature. The compounds namely: 2,4-dihydroxy-6-methoxyacetophenone (1), apigenin (2), 5-desmethylsinensetin (3), 5-desmethylnobiletin (4), 8-methoxycirsilineol (5), scopoletin (6), ursolic acid (7), and β-sitosterol (8). In-vitro antiprotozoal activity of compounds 1, 3, and 5 were evaluated against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum parasites and also toxicity against rat myoblast (L6) cells. Compound 5 showed promising activity against T. b. rhodesiense.

Phytochemical Analysis and Trypanocidal Activity of Marrubium incanum Desr

The rationale inspiring the discovery of lead compounds for the treatment of human parasitic protozoan diseases from natural sources is the well-established use of medicinal plants in various systems of traditional medicine. On this basis, we decided to select an overlooked medicinal plant growing in central Italy, Marrubium incanum Desr. (Lamiaceae), which has been used as a traditional remedy against protozoan diseases, and to investigate its potential against Human African trypanosomiasis (HAT). For this purpose, we assayed three extracts of different polarities obtained from the aerial parts of M. incanum—namely, water (MarrInc-H₂O), ethanol (MarrInc-EtOH) and dichloromethane (MarrInc-CH₂Cl₂)—against Trypanosoma brucei (TC221), with the aim to discover lead compounds for the development of antitrypanosomal drugs. Their selectivity index (SI) was determined on mammalian cells (BALB/3T3 mouse fibroblasts) as a counter-screen for toxicity. The preliminary screening selected the MarrInc-CH₂Cl₂ extract as the most promising candidate against HAT, showing an IC₅₀ value of 28 μg/mL. On this basis, column chromatography coupled with the NMR spectroscopy of a MarrInc-CH₂Cl₂ extract led to the isolation and identification of five compounds i.e. 1-α-linolenoyl-2-palmitoyl-3-stearoyl-sn- glycerol (1), 1-linoleoyl-2-palmitoyl-3-stearoyl-sn-glycerol (2), stigmasterol (3), palmitic acid (4), and salvigenin (5). Notably, compounds 3 and 5 were tested on T. brucei, with the latter being five-fold more active than the MarrInc-CH₂Cl₂ extract (IC₅₀ = 5.41 ± 0.85 and 28 ± 1.4 μg/mL, respectively). Furthermore, the SI for salvigenin was >18.5, showing a preferential effect on target cells compared with the dichloromethane extract (>3.6). Conversely, stigmasterol was found to be inactive. To complete the work, also the more polar MarrInc-EtOH extract was analyzed, giving evidence for the presence of 2″-O-allopyranosyl-cosmosiin (6), verbascoside (7), and samioside (8). Our findings shed light on the phytochemistry of this overlooked species and its antiprotozoal potential, providing evidence for the promising role of flavonoids such as salvigenin for the treatment of protozoal diseases.

Efficacy of Ageratum conyzoides extracts against Giardia duodenalis trophozoites: an experimental study

Background

Giardia duodenalis causes giardiasis in humans, particularly in developing countries. Despite the availability of treatments, resistance to some of the commercial anti-Giardia drugs has been reported in addition to their harmful side effects. Therefore, novel treatments for giardiasis are required. In this study, we aimed to assess the in vitro activity of crude extracts of Ageratum conyzoides against G. duodenalis trophozoites.

Methods

Plants were classified into three groups based on their flower colors: white (W), purple (P), and white–purple (W–P). Plants were separately cut into leaf (L) and flower (F) parts. Changes in internal organelle morphology of trophozoites following exposure to crude extracts were assessed using transmission electron microscopy (TEM). In subsequent experiments, efficacy of the most active essential oils from crude extracts [half maximal inhibitory concentrations (IC₅₀) ≤ 100 μg/mL] against G. duodenalis trophozoites was tested. In vitro anti-Giardia assays using essential oils were performed in the same way as those performed using crude extracts.

Results

LW–P and FP extracts showed high activity (IC₅₀ ≤ 100 μg/mL) against G. duodenalis trophozoites, with IC₅₀ ± SD values of 45.67 ± 0.51 and 96.00 ± 0.46 μg/mL, respectively. In subsequent experiments, IC₅₀ ± SD values of LW–P and FP essential oils were 35.00 ± 0.50 and 89.33 ± 0.41 μg/mL, respectively. TEM revealed the degeneration of flagella and ventral discs of G. duodenalis trophozoites following exposure to crude extracts.

Conclusion

Crude LW–P and FP extracts of A. conyzoides showed the highest activity against G. duodenalis. Exposure to crude extract induced changes in the flagella and ventral discs of G. duodenalis trophozoites, which play important roles in attachment to the surface of mucosal cells. Our results suggest that the tested extracts warrant further research in terms of their efficacy and safety as giardiasis treatment.

Biochemical characterization and chemical validation of Leishmania MAP Kinase-3 as a potential drug target

Protozoan parasites of the Leishmania genus have evolved unique signaling pathways that can sense various environmental changes and trigger stage differentiation for survival and host infectivity. MAP kinase (MAPK) plays a critical role in various cellular activities like cell differentiation, proliferation, stress regulation, and apoptosis. The Leishmania donovani MAPK3 (LdMAPK3) is involved in the regulation of flagella length and hence plays an important role in disease transmission. Here, we reported the gene cloning, protein expression, biochemical characterizations, inhibition studies and cell proliferation assay of LdMAPK3. The recombinant purified LdMAPK3 enzyme obeys the Michaelis-Menten equation with K_m and V_max of LdMAPK3 was found to be 20.23 nM and 38.77 ± 0.71 nmoles ATP consumed/mg LdMAPK3/min respectively. The maximum kinase activity of LdMAPK3 was recorded at 35 °C and pH 7. The in-vitro inhibition studies with two natural inhibitors genistein (GEN) and chrysin (CHY) was evaluated against LdMAPK3. The K_i value for GEN and CHY were found to be 3.76 ± 0.28 µM and K_i = 8.75 ± 0.11 µM respectively. The IC₅₀ value for the compounds, GEN and CHY against L. donovani promastigotes were calculated as 9.9 µg/mL and 13 µg/mL respectively. Our study, therefore, reports LdMAPK3 as a new target for therapeutic approach against leishmaniasis.

Immunomodulatory and Antileishmanial Activity of Phenylpropanoid Dimers Isolated from Nectandra leucantha

Three phenylpropanoid dimers (1-3) including two new metabolites were isolated from the extract of the twigs of Nectandra leucantha using antileishmanial bioassay-guided fractionation. The in vitro antiparasitic activity of the isolated compounds against Leishmania donovani parasites and mammalian cytotoxicity and immunomodulatory effects were evaluated. Compounds 1-3 were effective against the intracellular amastigotes within macrophages, with IC50 values of 26.7, 17.8, and 101.9 μM, respectively. The mammalian cytotoxicity, given by the 50% cytotoxic concentration (CC50), was evaluated against peritoneal macrophages. Compounds 1 and 3 were not toxic up to 290 μM, whereas compound 2 demonstrated a CC50 value of 111.2 μM. Compounds 1-3 also suppressed production of disease exacerbatory cytokines IL-6 and IL-10 but had minimal effect on nitric oxide production in L. donovani-infected macrophages, indicating that antileishmanial activity of these compounds is mediated via an NO-independent mechanism. Therefore, these new natural products could represent promising scaffolds for drug design studies for leishmaniasis.

Evaluation of the in vitro trypanocidal activity of methylated flavonoid constituents of Vitex simplicifolia leaves

Background

Trypanosomiasis is a neglected tropical disease with complex clinical manifestations, tedious diagnosis, and difficult treatments. The drugs available for the treatment of this endemic disease are old, expensive, and associated with other problems including safety and drug resistant parasites. Therefore, there is an urgent need for the development of new, effective, cheap, and safe drugs for its treatment. Plants are potentially rich sources of leads for new drugs against trypanosomiasis.

Vitex simplicifolia (Verbenaceae) is used traditionally for the treatment of tooth ache, edema, skin diseases, gout and trypanosomiasis in Nigeria. In a preliminary study, the methanol extract of Vitex simplicifolia was shown to exhibit a pronounced trypanocidal activity against T. b. rhodesiense.

The present study was undertaken to investigate the active component responsible for the acclaimed activity of the leaves of Vitex simplicifolia in the traditional treatment of trypanosomiasis in Nigeria and other African countries. Our investigations aim at assessing the plant as a new source of potential trypanocidal compounds.

Methods

The crude extracts were prepared from the dried leaves using methanol, successive extraction with hexane, dichloromethane, ethylacetate and butanol was also done. The ethylacetate fraction was further fractionated and compounds isolated using preparative chromatographic technique and their structures were elucidated by NMR, mass spectrometry and comparison with literature data. Trypanocidal activities and cytotoxicity, using rat skeletal myoblast (L6) cells were investigated and their selectivity indices were determined.

Results

The chromatographic separations of the methanol extracts gave rise to seven compounds. The isolated compounds 2, 3, 6 and 7 exhibited promising trypanocidal activity with IC₅₀ values ranging from 4.7-12.3 μg/ml and cytotoxicity in the range of 1.58- 46.20 μg/ml. Compound 6, however, showed the most selective trypanocidal activity with a selectivity index of 9.8. This is the first report of trypanocidal activity of flavonoids from this plant genus.

Conclusions

The isolated compounds from Vitex simplicifolia exhibited noteworthy trypanocidal activities and hence may provide a source of new antitrypanosomal agents. These results also support the traditional use of Vitex simplicifolia in the treatment of trypanosomiasis. This is the first report of trypanocidal effect of flavonoids from this plant genus.

Phytochemical and antitrypanosomal investigation of the fractions and compounds isolated from Artemisia elegantissima

CONTEXT

Trypanosoma brucei brucei (T.b. brucei) infection causes death in cattle, while the current treatments have serious toxicity problems. However, natural products can be used to overcome the problems associated with parasitic diseases including T.b. brucei.

OBJECTIVE

Artemisia elegantissima Pamp (Asteraceae) was evaluated phytochemically for its constituents and antitrypanosomal potential against T.b. brucei for the first time. Scopoletin isolated from A. elegantissima has shown better potential then the standard drug suramin, used against T.b. brucei.

MATERIALS AND METHODS

The ethanol extract of the aerial parts of A. elegantissima was fractionated by column and preparative thin-layer chromatography into six fractions (A-F) yielding 13 compounds, these were evaluated for their antitrypanosomal activity against T.b. brucei at different concentrations.

RESULTS

Thirteen compounds were isolated from A. elegantissima: (Z)-p-hydroxy cinnamic acid, stigmasterol, β-sitosterol, betulinic acid, bis-dracunculin, dracunculin, scopoletin, apigenin, dihydroluteolin, scoparol, nepetin, bonanzin, and 3',4'-dihydroxy bonanzin. The fractions D-F were found to be active at the concentration of 20 µg/ml and three compounds isolated from these fractions, scopoletin (MIC ≤0.19 µg/ml), 3',4'-dihydroxy bonanzin (MIC = 6.25 µg/ml) and bonanzin (MIC = 20 µg/ml), were found to be highly active.

DISCUSSION AND CONCLUSION

Artemisia elegantissima was phytochemically and biologically explored for its antitrypanosomal potential against T.b. brucei. The number and orientation of phenolic hydroxyl groups play an important role in the antitrypanosomal potential of coumarins and flavonoids. The compounds 3',4'-dihydroxy bonanzin and scopoletin with low MIC values, hold potential for use as antitrypanosomal drug leads.

Leishmanicidal and cholinesterase inhibiting activities of phenolic compounds of Dimorphandra gardneriana and Platymiscium floribundum, native plants from Caatinga biome

In recent years, the Brazilian Health Ministry and the World Health Organization have supported research into new technologies that may contribute to the surveillance, new treatments, and control of visceral leishmaniasis within the country. In light of this, the aim of this study was to isolate compounds from plants of the Caatinga biome, and to investigate their toxicity against promastigote and amastigote forms of Leishmania infantum chagasi, the main responsible parasite for South American visceral leishmaniasis, and evaluate their ability to inhibit acetylcholinesterase enzyme (AChE). A screen assay using luciferase-expressing promastigote form and an in situ ELISA assay were used to measure the viability of promastigote and amastigote forms, respectively, after exposure to these substances. The MTT colorimetric assay was performed to determine the toxicity of these compounds in murine monocytic RAW 264.7 cell line. All compounds were tested in vitro for their anti-cholinesterase properties. A coumarin, scoparone, was isolated from Platymiscium floribundum stems, and the flavonoids rutin and quercetin were isolated from Dimorphandra gardneriana beans. These compounds were purified using silica gel column chromatography, eluted with organic solvents in mixtures of increasing polarity, and identified by spectral analysis. In the leishmanicidal assays, the compounds showed dose-dependent efficacy against the extracellular promastigote forms, with an EC50 for scoporone of 21.4µg/mL, quercetin and rutin 26 and 30.3µg/mL, respectively. The flavonoids presented comparable results to the positive control drug, amphotericin B, against the amastigote forms with EC50 for quercetin and rutin of 10.6 and 43.3µg/mL, respectively. All compounds inhibited AChE with inhibition zones varying from 0.8 to 0.6, indicating a possible mechanism of action for leishmacicidal activity.

Antimicrobial activity, cytotoxicity, and phytochemical screening of Voacanga globosa (Blanco) Merr. leaf extract (Apocynaceae)

OBJECTIVE

To determine the antibacterial, antifungal, antiprotozoal, cytotoxic, and phytochemical properties of ethanol extracts of leaves of Voacanga globosa (Blanco) Merr. (V. globosa).

METHODS

The extracts were tested against bacteria and fungus through disc diffusion assay; against protozoa through growth curve determination, antiprotozoal and cytotoxicity assays.

RESULTS

The extract revealed antibacterial activities, inhibiting the growth of Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, Micrococcus luteus, and Salmonella typhimurium. Antifungal assay showed that it inhibited Candida albicans. The antiprotozoal assay against Trichomonas vaginalis and Entamoeba histolytica showed that V. globosa can inhibit the parasites, wherein the action can be comparable to metronidazole. With the in situ cell death detection kit, Trichomonas vaginalis and Entamoeba histolytica exposed to V. globosa leaf extract was observed to fluoresce simultaneously in red and yellow signals signifying apoptotic-like changes. Preliminary phytochemical screening revealed the chemical composition of plant extract containing alkaloids, saponins, 2-deoxysugars, and hydrolysable tannins.

CONCLUSIONS

Thus, this study provides scientific evidence on the traditional use of V. globosa leaf extract in treating microbial diseases. Further, the leaf extract can possibly be used to produce alternative forms of antimicrobials.

Chemical and Biological Activity of Leaf Extracts of Chromolaena Leivensis

The flavonoids 3,5-dihydroxy-7-methoxy-flavanone, 3,5-dihydroxy-7-methoxyflavone and 3,5,7-trihydroxy-6-methoxyflavone were isolated from the leaves of C. leivensis. Preliminary observations in K562 cells (human erythroleukemia) using the trypan blue test, showed a 90% viability at a concentration of 100 μg/mL; however, further testing of the flavonoids at concentrations of 25, 50 and 100 μg/mL showed toxicity affecting the morphology of human erythroleukemia cells (K562) and human melanoma cells (A375). Induction of apoptosis was produced by 3,5-dihydroxy-7-methoxyflavone at 72 hours after treatment with arrest in the G2 / M phase of the cell cycle. The A375 cells treated with 50 μg/mL of 3,5-dihydroxy-7-methoxy-flavanone for 24, 48 and 72 hours, display effects on the behavior of the cell cycle. The flavonoid 3,5-dihydroxy-7-methoxyflavone has activity on the mitochondrial membrane at concentrations of 25, 50 and 100 μg/mL, at time intervals of 8 to 12 hours. The flavonoids 3,5-dihydroxy-7-methoxy-flavanone and 3,5-dihydroxy-7-methoxyflavone at a concentration of 25 μg/mL increased the expression of costimulatory molecules corresponding to the phenotype presented by mature dendritic cells with differentiation markers CD40, CD83, CD86 and HLA-DR. The two flavonoids at concentrations between 0.39 and 100 μg/mL slightly increased the proliferation of peripheral blood mononuclear cells in the presence and in the absence of phytohemagglutinin. These flavonoids at concentrations of 50 and 100 μg/mL slightly increased the proliferation of fibroblasts.

Optimization of topical photodynamic therapy with 3,7-bis(di-n-butylamino)phenothiazin-5-ium bromide for cutaneous leishmaniasis

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) has evolved as a promising therapeutic measure for the treatment of cutaneous leishmaniasis (CL). In particular, phenothiazine compounds have demonstrated efficacy for PDT of CL. The objective of our present study is to define the use of a new specific phenothiazine photosensitizer, 3,7-bis(di-n-butylamino)phenothiazin-5-ium bromide (PPA904) applied topically as a cream to treat CL.

MATERIALS AND METHODS

To establish the optimal conditions for this treatment, we compared two different ways to improve current regimens of PDT with PPA904 cream (500 microM of PPA904 in Unguentum M) by changing the duration of topical application, and by administration of several consecutive PDT procedures. An initial regimen recommended by the manufacturer (Photopharmica Co. Ltd., Leeds, UK) was maintained as a control: the cream was applied topically for 30 minutes at a final concentration of PPA904 at 500 microM, and the designated treatment area was irradiated with a broad band light source of 665+/-15 nm at a fluence of 50 J/cm(2) (50 mW/cm(2)).

RESULTS

The best curative PPA904-PDT regimen was achieved under the conditions of a longer duration of topical application time (90 minutes) and several (three) consecutive treatments with 4-day intervals between treatments. The mechanisms responsible for such improvements (kinetics of drug penetration, depth of necrosis of the CL lesions after PDT, and daily changes in the parasitic load after PDT) are discussed in the present study.

CONCLUSION

Topical PPA904-PDT, implemented as described above, is a promising treatment for CL, and clinical studies will be initiated to establish efficacy in humans.

Antileishmaniasis activity of flavonoids from Consolida oliveriana

A set of flavonoids from Consolida oliveriana, kaempferol (1), quercetin (2), trifolin (3), and acetyl hyperoside (5) and their O-acetyl derivatives (1a, 2a, 3a), and octa-O-acetylhyperoside (4) showed leishmanicidal activity against promastigote as well as amastigote forms of Leishmania spp. The cellular proliferation, metabolic, and ultrastructural studies showed that the acetylated compounds 2a, 3a, and 4 were highly active against Leishmania (V.) peruviana, while 2a as well as 4 were effective against Leishmania (V.) braziliensis. These compounds were not cytotoxic and are effective at similar concentrations up to or lower than the reference drugs (pentostam and glucantim).

Parasiticidal effect of ?-aminolevulinic acid-based photodynamic therapy for cutaneous leishmaniasis is indirect and mediated through the killing of the host cells

Several clinical reports have shown promising, but not optimal, results from photodynamic therapy with delta-aminolevulinic acid-derived protoporphyrin IX, termed ALA-PDT, as a treatment for cutaneous leishmaniasis (CL). Therefore, understanding the basis of the phototoxic response of Leishmania parasites to ALA-PDT may be critical for optimization. We report here both in vitro and in vivo mechanistic studies of ALA-PDT against CL. Following in vitro co-incubation of Leishmania major with 0.1 microM ALA, the PpIX concentration remained at the basal level, whereas after co-incubation with 0.1 microM exogenous PpIX, the PpIX level was 100-fold higher. No differences in ALA-derived PpIX levels were detected between Leishmania-infected and non-infected J774.2 cells, and PDT did not demonstrate any parasiticidal effects on amastigotes. In contrast, in vivo topical ALA-PDT, performed on a murine CL model, resulted in significant reductions of the parasite loads and vigorous tissue destruction. After ALA-PDT, a dramatically decreased percentage of macrophages and increased levels of interleukin-6 were observed in the infected skin. The clinical outcome observed with ALA-PDT is likely the result of unspecific tissue destruction accompanied by depopulation of macrophages rather than direct killing of parasites.

Photodynamic therapy for cutaneous leishmaniasis: the effectiveness of topical phenothiaziniums in parasite eradication and Th1 immune response stimulation

Photodynamic therapy (PDT) is emerging as a therapeutic modality in the clinical management of cutaneous leishmaniasis (CL). The efficacy of PDT against CL has been demonstrated previously with aminolevulinic acid, although the prolonged terms of therapy were less than ideal, and the search for new photosensitizers (PS) is ongoing. However, phenothiaziniums have demonstrated high parasiticidal effects in vitro. The subject of our investigation is the in vivo activity of two PS, 5-ethylamino-9-diethylaminobenzo[a]phenoselenazinium chloride (EtNBSe) and (3,7-Bis(N,N-dibutylamino) phenothiazinium bromide (PPA904). The results of our comparative analysis of the efficacy of these two phenothiazinium analogues demonstrated a high antiparasitic activity of EtNBSe in vitro, and the higher efficacy of PPA904 in a mouse model of CL. The kinetics of photodestruction are different in parasite and mammalian cells, and with both dyes, the macrophages are more susceptible to photodynamic effects than L. major parasites. As the number of parasites in the lesions undergoes a biphasic change, temporarily increasing on days 2-4 and decreasing on days 5-7, more than one treatment is required within an interval of 5 to 7 days. We have also shown that PPA904-PDT can provide an immunomodulating, dose-dependent efflux on IL-12p70 production. This mechanism could be responsible for promoting a more rapid healing in PPA904-PDT treated mice. Our initial data indicate that phenothiaziniums exhibit a high parasiticidal effect in vivo against CL; this finding may be of use in establishing curative PDT regimens for future clinical trials.

The role of photosensitizer molecular charge and structure on the efficacy of photodynamic therapy against Leishmania parasites

Photodynamic therapy (PDT) is emerging as a potential therapeutic modality in the clinical management of cutaneous leishmaniasis (CL). In order to establish a rationale for effective PDT of CL, we investigated the impact of the molecular charge and structure of photosensitizers on the parasitic phototoxic response. Two photosensitizers from the benzophenoxazine family that bear an overall cationic charge and two anionic porphyrinoid molecules were evaluated. The photodynamic activity of the photosensitizers decreases in the following order: EtNBSe > EtNBS > BpD > PpIX. The studies suggest that compared to hydrophobic anionic photosensitizers, the hydrophilic cationic benzophenoxazine analogs provide high effectiveness of PDT possibly due to (1) their strong attraction to the negatively charged parasitic membrane, (2) their hydrophilicity, (3) their high singlet oxygen quantum yield, and (4) their efficacy in targeting intracellular organelles.

Antitrypanosomal and antileishmanial activities of flavonoids and their analogues: in vitro, in vivo, structure-activity relationship, and quantitative structure-activity relationship studies

Trypanosomiasis and leishmaniasis are important parasitic diseases affecting millions of people in Africa, Asia, and South America. In a previous study, we identified several flavonoid glycosides as antiprotozoal principles from a Turkish plant. Here we surveyed a large set of flavonoid aglycones and glycosides, as well as a panel of other related compounds of phenolic and phenylpropanoid nature, for their in vitro activities against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, and Leishmania donovani. The cytotoxicities of more than 100 compounds for mammalian L6 cells were also assessed and compared to their antiparasitic activities. Several compounds were investigated in vivo for their antileishmanial and antitrypanosomal efficacies in mouse models. Overall, the best in vitro trypanocidal activity for T. brucei rhodesiense was exerted by 7,8-dihydroxyflavone (50% inhibitory concentration [IC50], 68 ng/ml), followed by 3-hydroxyflavone, rhamnetin, and 7,8,3',4'-tetrahydroxyflavone (IC50s, 0.5 microg/ml) and catechol (IC50, 0.8 microg/ml). The activity against T. cruzi was moderate, and only chrysin dimethylether and 3-hydroxydaidzein had IC50s less than 5.0 microg/ml. The majority of the metabolites tested possessed remarkable leishmanicidal potential. Fisetin, 3-hydroxyflavone, luteolin, and quercetin were the most potent, giving IC50s of 0.6, 0.7, 0.8, and 1.0 microg/ml, respectively. 7,8-Dihydroxyflavone and quercetin appeared to ameliorate parasitic infections in mouse models. Generally, the test compounds lacked cytotoxicity in vitro and in vivo. By screening a large number of flavonoids and analogues, we were able to establish some general trends with respect to the structure-activity relationship, but it was not possible to draw clear and detailed quantitative structure-activity relationships for any of the bioactivities by two different approaches. However, our results can help in directing the rational design of 7,8-dihydroxyflavone and quercetin derivatives as potent and effective antiprotozoal agents.

Immunomodulatory effects of methoxylated flavonoids from twoChromolaena species: structure-activity relationships

Excessive generation of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNL) is involved in the pathology of many inflammatory diseases. Compounds isolated from natural sources with antioxidant activity can be helpful to inhibit and/or modulate the oxidative damage associated with PMNL-derived ROS. The present study investigated the relationship between the chemical structure of five methoxylated flavonoids, isolated from Chromolaena hirsuta and Chromolaena squalida, and their inhibitory activity on ROS generation by opsonized zymosan-stimulated PMNL. The antioxidant efficacy of the studied flavonoids, assessed by luminol-dependent chemiluminescence, was dependent on the position and number of methoxy and hydroxy groups.