Stachytarpheta cayennensis extract inhibits promastigote and amastigote growth in Leishmania amazonensis via parasite arginase inhibition

HPLC method for quantifying verbascoside in Stizophyllum perforatum and assessment of verbascoside acute toxicity and antileishmanial activity

We report the chemical composition of the crude leaf extracts obtained from Stizophyllum perforatum (Cham.) Miers (Bignoniaceae), a simple high-performance liquid chromatography-diode array detection (HPLC-DAD) method based on mangiferin as an internal standard to quantify verbascoside, and the verbascoside acute oral toxicity and antileishmanial activity. HPLC-high-resolution mass spectrometry-DAD (HPLC-HRMS-DAD) analyses of the crude ethanol S. perforatum leaf extracts (CE-1 and CE-2) revealed that verbascoside was the major constituent in both extracts. CE-1 was purified, and verbascoside and casticin, among other compounds, were isolated. The developed HPLC-DAD method was validated and met the required standards. Investigation of the CE-2 acute toxicity indicated a lethal dose (LD50) greater than 2,000 mg/kg of body weight. Both CE-1 and CE-2 exhibited antileishmanial activity. The isolated compounds, verbascoside and casticin, also displayed antileishmanial activity with effective concentrations (IC50) of 6.23 and 24.20 µM against promastigote forms and 3.71 and 18.97 µM against amastigote forms of Leishmania amazonensis, respectively, but they were not cytotoxic to J774A.1 macrophages. Scanning electron microscopy of the L. amazonensis promastigotes showed that the parasites became more rounded and that their plasma membrane was altered in the presence of verbascoside. Additionally, transmission electron microscopy demonstrated that vacuoles emerged, lipids accumulated, kinetoplast size increased, and interstitial extravasation occurred in L. amazonensis promastigotes exposed to verbascoside. These findings suggest that S. perforatum is a promising candidate for further in vivo investigations against L. amazonensis.

Anti-asthmatic activity of standardized hydro-ethanolic and aqueous extracts of Stachytarpheta cayennensis (Rich.) Vahl in a murine model

ETHNOPHARMACOLOGICAL RELEVANCE

Stachytarpheta cayennensis (Verbenaceae) has been used in Brazilian traditional medicine to treat asthma and other respiratory diseases.

AIMS OF THE STUDY

To investigate the effects of different doses of standardized hydro-ethanolic (SCH) and aqueous (SCA) extracts of aerial parts of S. cayennensis using a murine ovalbumin (OVA)-induced asthma model.

MATERIALS AND METHODS

The major constituents of the plant extracts were identified and standardized by ultra-performance liquid chromatography coupled with mass spectrometry. Balb/c mice were challenged with OVA solution and treated concomitantly by intraperitoneal injection of standardized SCH or SCA extracts at 50, 100, and 200 mg/kg concentrations. OVA-challenged control animals were treated with either dexamethasone (OVA-DEX) or saline solution (OVA-SAL). After challenge, we assessed in vivo bronchial hyperresponsiveness, airway inflammation (number of cells), peribronchial inflammation (histological analysis) and production of OVA-specific IgE and interleukin (IL)-4, IL-5, and IL-13 (ELISA).

RESULTS

Acteoside, isoacteoside, and ipolamiide were the major constituents of SCH and SCA. The respective concentrations of acteoside in SCH and SCA were 78 and 98 μg/mL, while those of ipolamiide were 30 and 19 μg/mL. Treatment with 200 mg/kg of SCH or SCA decreased IL-4, IL-5, and IL-13 in lung homogenates. These reductions were accompanied by a lower influx of inflammatory cells (eosinophils, lymphocytes, and macrophages) to the airways and lungs. In addition to the anti-inflammatory effects, administration of SCA, but not SCH, ameliorated the parameters of bronchial hyperresponsiveness and decreased levels of circulating OVA-specific IgE.

CONCLUSION

The results presented herein demonstrate for the first time the anti-asthmatic activity of S. cayennensis extracts in a murine model, thereby supporting the ethnopharmacological uses of the plant.

Antibacterial and Anti-inflammatory Activity of Extracts and Major Constituents Derived from Stachytarpheta indica Linn. Leaves and Their Potential Implications for Wound Healing

Wounds of various types continue to have a severe socioeconomic impact on the cost of health care. Globally, there has been increased interest surrounding the identification of bioactive compounds that promote or modulate the wound healing process. Stachytarpheta indica Linn. is traditionally used to heal wounds and relieve inflammation; however, the theorised pharmacological properties have not yet been scientifically validated. In this study, dried and ground plant leaves were extracted with water and methanol, which were then subjected to various analyses. The antimicrobial activity of the plant extracts and isolated compounds was determined using well diffusion assays, while the minimum inhibitory concentrations were determined with a colorimetric assay. Morphological changes of human keratinocytes in response to plant extracts were observed with differential interference contrast microscope imaging. Cell viability, proliferation, and migratory effects post-treatment with the plant extracts were also evaluated via colorimetric cytotoxicity assays and a real-time cell analyser protocol. Anti-inflammatory effects of plant extracts and isolated compounds were evaluated by flow cytometry and cyclooxygenase and lipoxygenase enzyme inhibition assays. Three active compounds, i.e. ipolamiide, verbascoside and iso-verbascoside, were isolated from S. indica leaves. Verbascoside demonstrated broad-range antibacterial activity and imposed strong inhibition at 9.77 μg/mL against Staphylococci spp. S. indica extracts (0.1-0.2 mg/mL) were shown to improve human keratinocyte proliferation up to 60% and induce morphological changes by producing cytoplasmic projections at concentrations higher than 0.4 mg/mL. Plant extracts (6.25-100 μg/mL) and individual compounds (3.125-50 μg/mL) elicited strong anti-inflammatory effects by suppressing the expression of interleukin-8 and inhibiting cyclooxygenase-1 and 5-lipoxygenase enzymes. Collectively, these results indicate that plant extracts and isolated compounds derived from S. indica have the potential to inhibit bacterial growth, promote tissue regeneration and reduce inflammation, hence, potentially providing the basis for a novel therapeutic for the treatment of wounds.

Natural Products That Target the Arginase in Leishmania Parasites Hold Therapeutic Promise

Parasites of the genus Leishmania cause a variety of devastating and often fatal diseases in humans worldwide. Because a vaccine is not available and the currently small number of existing drugs are less than ideal due to lack of specificity and emerging drug resistance, the need for new therapeutic strategies is urgent. Natural products and their derivatives are being used and explored as therapeutics and interest in developing such products as antileishmanials is high. The enzyme arginase, the first enzyme of the polyamine biosynthetic pathway in Leishmania, has emerged as a potential therapeutic target. The flavonols quercetin and fisetin, green tea flavanols such as catechin (C), epicatechin (EC), epicatechin gallate (ECG), and epigallocatechin-3-gallate (EGCG), and cinnamic acid derivates such as caffeic acid inhibit the leishmanial enzyme and modulate the host’s immune response toward parasite defense while showing little toxicity to the host. Quercetin, EGCG, gallic acid, caffeic acid, and rosmarinic acid have proven to be effective against Leishmania in rodent infectivity studies. Here, we review research on these natural products with a focus on their promise for the development of treatment strategies as well as unique structural and pharmacokinetic/pharmacodynamic features of the most promising agents.

Ethnopharmacology Study of Plants from Atlantic Forest with Leishmanicidal Activity

Leishmaniasis is an infectious disease caused by a protozoan belonging to Leishmania genus. Different clinical outcomes can be observed depending on the parasite species and patient's health condition. The outcomes can range from single cutaneous lesions to lethal visceral form. The treatment of all forms of leishmaniasis is based on pentavalent antimonials, and, in some cases, the second-line drug, amphotericin B, is used. Beside the toxicity of both classes of drugs, in some areas of the world, parasites are resistant to antimonial. These detrimental features make fundamental the discovery and characterization of new drugs or plant extracts with leishmanicidal effects. Brazil is a well-known country for its biodiversity. Additionally, the common knowledge inherited for generations in small villages makes Brazil a source of new information and resources for the discovery and development of new drugs. Based on ethnopharmacology, elderlies were interviewed about plants they commonly used for skin diseases and infections. Five native plants from Atlantic forest were indicated; EtOH and n-hexane extracts were prepared with the vegetative organs of the plants and assayed against promastigote and amastigote forms of L. (L.) amazonensis. The major molecules of each extract were detected using qualitative nuclear magnetic resonance. Among all tested extracts, the n-hexane extract from the leave of Eugenia uniflora (Myrtaceae), enriched in myricitrin and quercitrin flavonoids, was the most effective against L. (L.) amazonensis amastigotes. This data supports the ethnopharmacology approach as a successful tool for the discovery of new drugs with leishmanicidal effects.

Cinnamic acids derived compounds with antileishmanial activity target Leishmania amazonensis arginase

This study describes the activity of five natural hydroxycinnamic acids and derived compound: caffeic (1), rosmarinic (2), chlorogenic (3), and cryptochlorogenic (4), acids and isoverbascoside (5). All compounds inhibited Leishmania amazonensis arginase with IC₅₀ -in range of 1.5-11 μM. Compounds 2 and 5 also showed activity against promastigotes of L. amazonensis with IC₅₀  = 61 (28-133) μM and IC₅₀  = 14 (9-24) μM, respectively. Further computational studies applying molecular docking simulations were performed on the competitive inhibitors to gain insight into the molecular basis for arginase inhibition and could be exploited to the development of new antileishmanials drug targeting parasite arginase.

Recent progress in drug targets and inhibitors towards combating leishmaniasis

Lesihmaniasis is one of the major neglected tropical disease caused by the parasite of the genus Leishmania. The disease has more than one clinical forms and the visceral form is considered fatal. With the lack of potential vaccine, chemotherapy is the major treatment source considered for the control of the disease in the infected people. Drugs including amphotericin B and miltefosine are widely used for the treatment, however, development of resistance by the parasite towards the administered drug and high-toxicity of the drug are of major concern. Hence, more attention has been shown on identifying new targets, effective inhibitors, and better drug delivery system against the disease. This review deals with recent studies on drug targets and exploring their essentiality for the survival of Leishmania. Further, new inhibitors for those targets, novel anti-leishmanial peptides and vaccines against leishmaniasis were discussed. We believe that this pool of information will ease the researchers to gain knowledge and help in choosing right targets and design of new inhibitors against Leishmaniasis.

Leishmanicidal and cytotoxic activity from plants used in Tacana traditional medicine (Bolivia)

ETNOPHARMACOLOGICAL RELEVANCE

Thirty-eight Tacana medicinal plant species used to treat skin problems, including leishmania ulcers, skin infections, inflammation and wound healing, were collected in the community of Buena Vista, Bolivia, with the Tacana people. Twenty two species are documented for the first time as medicinal plants for this ethnic group living in the northern area of the Department of La Paz.

AIM OF THE STUDY

To evaluate the leishmanicidal effect (IC₅₀) and cytotoxicity (LD₅₀) of the selected plants. To carry out bioguided studies on the active extracts. To assess the potential of Bolivian plant biodiversity associated with traditional knowledge in the discovery of alternative sources to fight leishmaniasis.

MATERIALS AND METHODS

Seventy three ethanol extracts were prepared from 38 species by maceration and were evaluated in vitro against promastigotes of Leishmania amazonensis and L. braziliensis. Active extracts (IC₅₀ ≤ 50 μg/mL) were fractionated by chromatography on Silica gel column and the fractions were assessed against the two Leishmania strains. The most active fractions and the crude extracts were evaluated against reference strains of L. amazonensis, L. braziliensis, L. aethiopica, two native strains (L. Lainsoni and L. braziliensis) and for cytotoxicity against HeLa cells. The chromatographic profile of the active fractions was obtained by reverse phase chromatography using HPLC.

RESULTS

From the 73 extracts, 39 extracts (53.4%) were inactive and 34 showed activity. Thirteen species were sselected for bioguided studies. The crude extracts and their 36 fractions were evaluated against two Leishmania strains. The most active fraction were tested in a panel of five leishmania strains and for cytotoxicity. The Selective Index (SI = LD₅₀/IC₅₀) was calculated, and were generally low. Retention time and UV spectra were recorded for the active fractions by HPLC-DAD using a reverse phase column. Profiles were very different from each other, showing the presence of different compounds.

CONCLUSION

Bolivian traditional knowledge from the Tacanba was useful to identify plants with effect on Leishmania promastigotes. Chromatographic bioguided studies showed stronger leishmanicidal and cytotoxic activity for the medium polar fraction. HPLC analysis showed different chromatographic profiles of the active fractions.

Antiprotozoal activity of medicinal plants used by Iquitos-Nauta road communities in Loreto (Peru)

ETHNOPHARMACOLOGICAL RELEVANCE

In the Peruvian Amazon, the use of medicinal plants is a common practice. However, there is few documented information about the practical aspects of their use and few scientific validation. The starting point for this work was a set of interviews of people living in rural communities from the Peruvian Amazon about their uses of plants. Protozoan diseases are a public health issue in the Amazonian communities, who partly cope with it by using traditional remedies. Validation of these traditional practices contributes to public health care efficiency and may help identify new antiprotozoal compounds.

AIMS OF STUDY

to inventory and validate the use of medicinal plants by rural people of Loreto region.

MATERIALS AND METHODS

Rural mestizos were interviewed about traditional medication of parasite infections with medicinal plants. Ethnopharmacological surveys were undertaken in two villages along Iquitos-Nauta road (Loreto region, Peru), namely 13 de Febrero and El Dorado communities. Forty-six plants were collected according to their traditional use for the treatment of parasitic diseases, 50 ethanolic extracts (different parts for some of the plants) were tested in vitro on Plasmodium falciparum (3D7 sensitive strain and W2 chloroquine resistant strain), Leishmania donovani LV9 strain and Trypanosoma brucei gambiense. Cytotoxic assessment (HUVEC cells) of the active extracts was performed. Two of the most active plants were submitted to preliminary bioguided fractionation to ascertain and explore their activities.

RESULTS

From the initial plants list, 10 were found to be active on P. falciparum, 15 on L. donovani and 2 on the three parasites. The ethanolic extract from Costus curvibracteatus (Costaceae) leaves and Grias neuberthii (Lecythidaceae) bark showed strong in vitro activity on P. falciparum (sensitive and resistant strain) and L. donovani and moderate activity on T. brucei gambiense.

CONCLUSIONS

The Amazonian forest communities in Peru represents a source of knowledge on the use of medicinal plants. In this work, several extracts with antiprotozoal activity were identified. This work contributes to validate some traditional uses and opens subsequent investigations on active compounds isolation and identification.