β-Cyclodextrin/Isopentyl Caffeate Inclusion Complex: Synthesis, Characterization and Antileishmanial Activity

Formulation of Silymarin-β Cyclodextrin-TPGS Inclusion Complex: Physicochemical Characterization, Molecular Docking, and Cell Viability Assessment against Breast Cancer Cell Lines

Silymarin (SIL) is a poorly water-soluble flavonoid reported for different pharmacological properties. Its therapeutic applications are limited due to poor water solubility. In this study, the solubility of silymarin has been enhanced by preparing freeze-dried binary and ternary complexes using beta cyclodextrin (βCD) and d-α-tocopherol polyethylene glycol 1000 succinate (TPGS). The stoichiometry of the drug and the carrier was selected from the phase solubility study. The dissolution study was performed to assess the effect of complexation on the release pattern of SIL. The formation of inclusion complexes was confirmed by different physicochemical studies. Finally, a cell viability assay (MCF 7; breast cancer cell line) was performed to compare the activity with free SIL. The phase solubilization results revealed the formation of a stable complex (binary) with a stability constant and complexation efficiency (CE) value of 288 mol L-1 and 0.045%. The ternary sample depicted a significantly enhanced stability constant and CE value (890 mol L-1 and 0.14%). The release study results showed a marked increase in the release pattern after addition of βCD (alone) in the binary mixture (49.4 ± 3.1%) as well as inclusion complex (66.2 ± 3.2%) compared to free SIL (32.7 ± 1.85%). Furthermore, with the addition of TPGS in SIL-βCD (ternary), the SIL release was found to be significantly enhanced from the SIL ternary mixture (79.2 ± 2.13%) in 120 min. However, fast SIL release was achieved with 99.2 ± 1.7% in 45 min for the SIL ternary complex. IR and NMR spectral analysis results revealed the formation of a stable complex with no drug-polymer interaction. The formation of complexes was also confirmed by the molecular docking study (docking scores of 4.1 and -6.4 kcal/mol). The in vitro cell viability result showed a concentration-dependent activity. The IC50 value of the SIL ternary complex was found to be significantly lower than that of free SIL. The findings of the study concluded that the prepared SIL inclusion complex can be used as an alternative oral delivery system to enhance solubility, dissolution, and biological activity against the tested cancer cell line.

Cutaneous/Mucocutaneous Leishmaniasis Treatment for Wound Healing: Classical versus New Treatment Approaches

Cutaneous leishmaniasis (CL) and mucocutaneous leishmaniasis (ML) show clinical spectra that can range from a localized lesion (with a spontaneous healing process) to cases that progress to a generalized systemic disease with a risk of death. The treatment of leishmaniasis is complex since most of the available drugs show high toxicity. The development of an effective topical drug formulation for CL and ML treatment offers advantages as it will improve patient’s compliance to the therapy given the possibility for self-administration, as well as overcoming the first pass metabolism and the high costs of currently available alternatives. The most common dosage forms include solid formulations, such as membranes and semi-solid formulations (e.g., ointments, creams, gels, and pastes). Topical treatment has been used as a new route of administration for conventional drugs against leishmaniasis and its combinations, as well as to exploit new substances. In this review, we discuss the advantages and limitations of using topical drug delivery for the treatment of these two forms of leishmaniasis and the relevance of combining this approach with other pharmaceutical dosage forms. Emphasis will also be given to the use of nanomaterials for site-specific delivery.

Preparation, Optimization, and Characterization of Inclusion Complexes of Cinnamomum longepaniculatum Essential Oil in β-Cyclodextrin

Cinnamomum longepaniculatum essential oil (CLEO) possesses antibacterial, anti-inflammatory, and antioxidant activities. However, CLEO shows volatilization and poor solubility, which limits its application field. In this research, inclusion complexes of β-cyclodextrin (β-CD) with CLEO were produced, and its physicochemical properties were characterized. Response surface methodology was used to obtain optimum preparation conditions. A statistical model was generated to define the interactions among the selected variables. Results show that the optimal conditions were an H2O/β-CD ratio of 9.6:1 and a β-CD/CLEO ratio of 8:1, with the stirring temperature of 20 °C for the maximal encapsulation efficiency values. The physicochemical properties of CLEO/β-CD inclusion complexes (CLEO/β-CD-IC) were investigated. Fourier transform infrared spectroscopy showed that correlative characteristic bands of CLEO disappeared in the inclusion complex. X-ray diffraction presented different sharp peaks at the diffraction angle of CLEO/β-CD-IC. The thermogravimetric analysis demonstrated the thermal stability of CLEO was enhanced after encapsulation. Tiny aggregates with a smaller size of CLEO/β-CD-IC particles were observed by scanning electron microscopy. The comparison of β-CD, CLEO, and physical mixtures with CLEO/β-CD-IC confirmed the formation of inclusion complexes.

Application of molecular docking in elaborating molecular mechanisms and interactions of supramolecular cyclodextrin

The cyclodextrin (CD)-based supramolecular nanomedicines have attracted growing interest because of their superior characteristics, including desirable biocompatibility, low toxicity, unique molecular structure and easy functionalization. The smart structures of CD impart host-guest interaction for meeting the multifunctional needs of disease therapy. However, it faces challenges in formulation design and inclusion mechanism clarification of the functional supramolecular assemblies owing to the complicated structures and mechanisms. Fortunately, molecular docking helps the researchers to comprehend the interaction between the drug and the target molecule for achieving high-through screening from the database. In this review, we summarized the category and characteristics of molecular docking along with the properties and applications of CD. Significantly, we highlighted the application of molecular docking in elaborating molecular mechanisms and simulating complex structures at molecular levels. The issues and development of CD and molecular docking were also presented to provide beneficial reference and new insights for supramolecular nano-systems.

Volatile Nitrogenous Compounds from Bacteria: Source of Novel Bioactive Compounds

Bacteria can produce nitrogenous compounds via both primary and secondary metabolic processes. Many bacterial volatile nitrogenous compounds produced during the secondary metabolism have been identified and reported for their antioxidant, antibacterial, antifungal, algicidal and antitumor activities. The production of these nitrogenous compounds depends on several factors, including the composition of culture media, growth conditions, and even the organic solvent used for their extraction, thus requiring their identification in specific conditions. In this review, we describe the volatile nitrogenous compounds produced by bacteria especially focusing on their antimicrobial activity. We concentrate on azo-compounds mainly pyrazines and pyrrolo-pyridines reported for their activity against several microorganisms. Whenever significant, extraction and identification methods of these compounds are also mentioned and discussed. To the best of our knowledge, this is first review describing volatile nitrogenous compounds from bacteria focusing on their biological activity.

Anti-leishmanial compounds from microbial metabolites: a promising source

Leishmania is a complex disease caused by the protozoan parasites and transmitted by female phlebotomine sandfly. The disease affects some of the poorest people on earth with an estimated 700,000 to 1 million new cases annually. The current treatment for leishmaniasis is toxic, long, and limited, in view of the high resistance rate presented by the parasite, necessitating new perspectives for treatment. The discovery of new compounds with different targets can be a hope to make the treatment more efficient. Microbial metabolites and their structural analogues with enormous scaffold diversity and structural complexity have historically played a key role in drug discovery. We found thirty-nine research articles published between 1999 and 2021 in the scientific database (PubMed, Science Direct) describing microbes and their metabolites with activity against leishmanial parasites which is the focus of this review. KEY POINTS: • Leishmania affects the poorest regions of the globe • Current treatments for leishmaniasis are toxic and of limited efficacy • Microbial metabolites are potential sources of antileishmania drugs.

Exploring Innovative Leishmaniasis Treatment: Drug Targets from Pre-Clinical to Clinical Findings

Leishmaniasis is a group of tropical diseases caused by parasitic protozoa belonging to the genus Leishmania. The disease is categorized in cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and visceral leishmaniasis (VL). The conventional treatment is complex and can present high toxicity and therapeutic failures. Thus, there is a continuing need to develop new treatments. In this review, we focus on the novel molecules described in the literature with potential leishmanicidal activity, categorizing them in pre-clinical (in vitro, in vivo), drug repurposing and clinical research.

Analysis of the mechanisms of action of isopentenyl caffeate against Leishmania

Leishmaniasis is a neglected parasitic disease for which the conventional treatment can be considered inefficient and extremely aggressive, generating several and severe side effects. Therefore, the discovery of new drug candidates is important for the improvement in the quality of life of patients. Previously, we reported the promising results of isopentyl caffeate (ICaf) against Leishmania chagasi (agent of visceral leishmaniasis) and Leishmania amazonensis (agent of cutaneous leishmaniasis) promastigotes, displaying IC₅₀ of 1.56 and 1.71 μM, respectively. Herein, we aimed to decipher the mechanisms of anti-Leishmania action of ICaf. Light and scanning electron microscopy assays showed relevant morphological changes in promastigotes when treated with ICaf, including rounding of the parasite body, shortening of the flagellum, blebs on the plasma membrane and cellular aggregation. The parasite mitochondrion was targeted by ICaf, resulting in a significant reduction in its metabolic activity and electric membrane potential followed by an increase in the production of reactive oxygen species, which culminated in the loss of plasma membrane integrity and parasite death. Relevantly, ICaf also had a potent anti-amastigote action. The IC₅₀ values calculated for intracellular amastigotes of L. amazonensis were 3.27, 1.60 and 1.52 μM, while for L. chagasi the values were 2.48, 1.84 and 1.60 μM, respectively, after treating the infected macrophages with ICaf for 24, 48 and 72 h. ICaf was well tolerated by THP-1 macrophages, which gave rise to excellent selectivity indexes considering both Leishmania species. The current results suggest that ICaf may emerge as a chemotherapeutic alternative for the treatment of leishmaniasis.

Anti-Tumor Efficiency of Perillylalcohol/β-Cyclodextrin Inclusion Complexes in a Sarcoma S180-Induced Mice Model

The low solubility and high volatility of perillyl alcohol (POH) compromise its bioavailability and potential use as chemotherapeutic drug. In this work, we have evaluated the anticancer activity of POH complexed with β-cyclodextrin (β-CD) using three complexation approaches. Molecular docking suggests the hydrogen-bond between POH and β-cyclodextrin in molar proportion was 1:1. Thermal analysis and Fourier-transform infrared spectroscopy (FTIR) confirmed that the POH was enclosed in the β-CD cavity. Also, there was a significant reduction of particle size thereof, indicating a modification of the β-cyclodextrin crystals. The complexes were tested against human L929 fibroblasts after 24 h of incubation showing no signs of cytotoxicity. Concerning the histopathological results, the treatment with POH/β-CD at a dose of 50 mg/kg promoted approximately 60% inhibition of tumor growth in a sarcoma S180-induced mice model and the reduction of nuclear immunoexpression of the Ki67 antigen compared to the control group. Obtained data suggest a significant reduction of cycling cells and tumor proliferation. Our results confirm that complexation of POH/β-CD not only solves the problem related to the volatility of the monoterpene but also increases its efficiency as an antitumor agent.