Pterodon pubescens oil nanoemulsions: physiochemical and microbiological characterization and in vivo anti-inflammatory efficacy studies

Stability Studies and the In Vitro Leishmanicidal Activity of Hyaluronic Acid-Based Nanoemulsion Containing Pterodon pubescens Benth. Oil

The physicochemical and microbiological stability of a hyaluronic acid-based nanostructured topical delivery system containing P. pubescens fruit oil was evaluated, and the in vitro antileishmanial activity of the nanoemulsion against Leishmania amazonensis and the cytotoxicity on macrophages was investigated. The formulation stored at 5 ± 2 °C, compared with the formulation stored at 30 and 40 ± 2 °C, showed a higher chemical and physical stability during the period analyzed and in the accelerated physical stability study. The formulation stored at 40 °C presented a significant change in droplet diameter, polydispersity index, zeta potential, pH, active compound, and consistency index and was considered unstable. The microbiological stability of the formulations was confirmed. The leishmanicidal activity of the selected system against intracellular amastigotes was significantly superior to that observed for the free oil. However, further research is needed to explore the use of the hyaluronic acid-based nanostructured system containing P. pubescens fruit oil for the treatment of cutaneous leishmaniasis.

Current Applications of Plant-Based Drug Delivery Nano Systems for Leishmaniasis Treatment

Leishmania is a trypanosomatid that causes leishmaniasis. It is transmitted to vertebrate hosts during the blood meal of phlebotomine sandflies. The clinical manifestations of the disease are associated with several factors, such as the Leishmania species, virulence and pathogenicity, the host-parasite relationship, and the host's immune system. Although its causative agents have been known and studied for decades, there have been few advances in the chemotherapy of leishmaniasis. The urgency of more selective and less toxic alternatives for the treatment of leishmaniasis leads to research focused on the study of new pharmaceuticals, improvement of existing drugs, and new routes of drug administration. Natural resources of plant origin are promising sources of bioactive substances, and the use of ethnopharmacology and folk medicine leads to interest in studying new medications from phytocomplexes. However, the intrinsic low water solubility of plant derivatives is an obstacle to developing a therapeutic product. Nanotechnology could help overcome these obstacles by improving the availability of common substances in water. To contribute to this scenario, this article provides a review of nanocarriers developed for delivering plant-extracted compounds to treat clinical forms of leishmaniasis and critically analyzing them and pointing out the future perspectives for their application.

Recent progress in micro and nano-encapsulation of bioactive derivatives of the Brazilian genus Pterodon

In the last few decades, utilization of medicinal plants by the pharmaceutical industry has led to the identification of many new bioactive compounds. The genus Pterodon, native of the Brazilian Flora, is known for the therapeutic properties attributed to its species, which are widely used in popular medicine for their anti-inflammatory, anti-rheumatic, tonic, and depurative properties. The intrinsic low water solubility of the plant derivatives from the genus, including diterpenes with vouacapane skeletons that are partially associated with the pharmacological activities, impairs the bioavailability of these bioactive compounds. Recent studies have aimed to encapsulate Pterodon products to improve their water solubility, achieve stability, increase their efficacy, and allow clinical applications. The purpose of this paper is to review recent research on the use of nanotechnology for the development of new products from plant derivatives of the Pterodon genus in different types of micro- and nanocarriers. Therapeutic properties of their different products are also presented. Finally, an update about the current and future applications of encapsulated formulations is provided.

Efficacy of nanoemulsion with Pterodon emarginatus Vogel oleoresin for topical treatment of cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a neglected tropical skin disease caused by the protozoan genus Leishmania. The treatment is restricted to a handful number of drugs that exhibit toxic effects, limited efficacy, and drug resistance. Additionally, developing an effective topical treatment is still an enormous unmet medical challenge. Natural oils, e.g. the oleoresin from P. emarginatus fruits (SO), contain various bioactive molecules, especially terpenoid compounds such as diterpenes and sesquiterpenes. However, its use in topical formulations can be impaired due to the natural barrier of the skin for low water solubility compounds. Nanoemulsions (NE) are drug delivery systems able to increase penetration of lipophilic compounds throughout the skin, improving their topical effect. In this context, we propose the use of SO-containing NE (SO-NE) for CL treatment. The SO-NE was produced by a low energy method and presented suitable physicochemical characteristic: average diameter and polydispersity index lower than 180 nm and 0.2, respectively. Leishmania (Leishmania) amazonensis-infected BALB/c mice were given topical doses of SO or SO-NE. The topical use of a combination of SO-NE and intraperitoneal meglumine antimoniate reduced lesion size by 41 % and tissue regeneration was proven by histopathological analyses. In addition, a reduction in the parasitic load and decreased in the level of IFN-γ in the lesion may be associated, as well as a lower level of the cytokine IL-10 may be associated with a less intense inflammatory process. The present study suggests that SO-NE in combination meglumine antimoniate represents a promising alternative for the topical treatment of CL caused by L. (L.) amazonensis.

Oil from the fruits of Pterodon emarginatus Vog.: A traditional anti-inflammatory. Study combining in vivo and in silico

ETHNOBOTANICAL RELEVANCE

The oil obtained from the fruits of Pterodon emarginatus Vog. (OPe) is used orally and topically, in traditional medicine for some purposes, such as acute and chronic inflammatory states as rheumatoid arthritis.

MATERIALS AND METHODS

In this work, the anti-inflammatory activity of the OPe was demonstrated based on several animal models and presented an in silico study based on the 6α,7β-dihydroxy-vouacapan-17β-oic acid (DHVA) majority compound of the OPe to evaluate the interaction this compound, with cyclooxygenase-2 (COX-2) in 4COX (Mus musculus) and 5KIR (Homo sapiens) and molecular dynamics simulation.

RESULTS

The OPe (498 mg/kg, p.o) significantly inhibited (p < 0.05, Student t-test) the primary and secondary reactions of arthritis by Freund's Complete Adjuvant (FCA) and in dermatitis induced by croton oil in mice, OPe inhibited peak of edema. In vascular permeability test in rats, the treatment with OPe was able to block the response to PGE₂, serotonin, and bradykinin (p < 0.05, Student t-test). In the writhing test in mice, the OPe at doses of 498 and 980 mg/kg (p.o) produced inhibition of 73% and 92%, respectively, and was not significantly effective in the hot plate test. In the evaluation of the potency in relation to gastric injury (gastric ulcer induced by stress) and combined assay in the assessment of anti-inflammatory potency and gastric damage, it was observed that indomethacin (10 mg/kg, p.o.) inhibited carrageenan edema by 51% and produced a higher number of gastric lesions when compared to the group treated with OPe, where only areas of hyperemia were observed, without the occurrence of ulcerative lesion, and which inhibited the edema by 47%. In the in silico study, it was found that the DHVA is capable of binding to two organisms (4COX - Mus musculus and 5KIR - Homo sapiens), however, with higher binding affinity to the organism Homo sapiens.

CONCLUSIONS

As expected, all tested ligands were capable of forming hydrogen interactions with residues at their respective binding sites, but the DHVA ligand was capable of creating slightly more hydrogen bonds when docked to either 4COX or 5KIR than the other tested ligands, thus demonstrating the participation of this compound in the anti-inflammatory and antialgic responses observed in the in vivo assays as a COX-2 inhibitor. Therefore, the results obtained support the traditional use of OPe for inflammatory and gastric problems.