NADES-mediated folk plant extracts as novel antifungal agents against Candida albicans

https://doi.org/10.1016/j.jpba.2019.01.026Get rights and content

Highlights

  • Natural solvents showed outstanding performance as plant biocompounds vehicle.

  • Antifungal activity of Larrea extracts were higher than their individual compounds.

  • Topical formulations prepared with Larrea extracts showed satisfactory performance.

Abstract

Candida albicans is an opportunistic pathogenic yeast commonly found in mouth, gastrointestinal tract and vagina. Under certain conditions, it causes skin, mucosal and systemic infections. With growing concern over the emergence of resistant strains to conventional antifungals, the development of novel antifungal agents for the management of this pathogen is an urgent need. In the present work, novel bioextracts from folk medicinal plants were directly used as active ingredient in a topical formulation for dermal candidiasis. With the aim to replace hazardous traditional reagents, a natural solvent composed by lactic acid: glucose: water (LGH) was used as vehicle for bioactive compound extraction. Furthermore, phenolic and alkaloid composition were determined by HPLC and their individual antifungal effect was evaluated. LGH extracts of Larrea spices demonstrate a significant antimicrobial activity against C. albicans being higher than their individual bioactive constituents. Notably, the mixture of Larrea cuneifolia and L divaricata extracts in topical formulations reveal a synergistic antifungal effect highlighting their potential for candidiasis treatment.

Introduction

Candida albicans is the most prevalent fungal pathogen in humans causing candidiasis; giving rise to severe morbidity in millions of individuals world-wide [1]. This fungal infection affects predominantly superficial skin and mucosa (oral and vaginal). Also, it can lead to life-threatening systemic infections, known as invasive candidiasis [[1], [2], [3], [4]]. The conventional therapeutic treatments for candidiasis are associated with several side effects that limits the dose and dosing frequency. Moreover, the extensive use of a limited number of antifungal agents, particularly azoles, has conducted to the emergence of resistant strains, a problem of growing concern. For dermal candidiasis, the relapse is highly frequent [4,5]. In this context, the development of novel antifungal agents for the management of this pathogen represents not only a greatest challenge but also an urgent need for medicine [[4], [5], [6], [7]].

Throughout history, medicinal plants have been successfully explored for their antimicrobial properties being an interesting alternative to synthetic drugs. Bioactive compounds of plants are mainly secondary metabolites, among them phenolic compounds and alkaloids are the most relevant group [8]. Interestingly, these compounds have been reported for their therapeutic activities such as cardio-protective, anti-inflammatory and antimicrobial [9]. Traditionally the extraction of plant metabolites are carried out with solvents such as chloroform, methanol, ethanol, hexane, diethyl ether and water [10,11]. Although these extracts are obtained from natural sources, their extraction procedure presents many disadvantages for human health and for the environment [12]. Therefore, the development of natural solvents turns to be a major priority to achieve safer extracts.

Natural deep eutectic solvents (NADES) have been introduced in the last decade as promising green media. They are eutectic mixtures consisting of natural metabolites bound together by inter-molecular interactions, particularly hydrogen bonding [13].Their common components are naturally present in all types of cells and organisms such as sugars (glucose, fructose, sacarose, etc.); organic acids (lactic, malic, citric acids, etc.); urea and choline chloride [14]. NADES have gained attention in chemistry for the extraction and separation of analytes from natural sources due to their outstanding advantages including biodegradability, low toxicity, solute stabilization, sustainability and low cost [[14], [15], [16]]. Recently, plant extract mediated by NADES have been evaluated for their antimicrobial properties [17], this opens interesting possibilities for their application in phytomedicine. To best of our knowledge, NADES bio extracts have not been used in dermal formulations.

In the present work, NADES extracts of Thymus vulgaris, Origanum vulgare, Larrea divaricata and L. cuneifolia were evaluated against Candida albicans. In order to clarify what compound in folk plant extracts shows antifungal properties, phenolic and alkaloid composition were determined and their individual antimicrobial effect were compared with the extracts. Furthermore, extracts cream formulations were prepared and challenged in terms of physical parameters as well as biological activity.

Section snippets

Chemicals and standard solutions

Compounds for NADES preparation including glucose anhydrous (≥99%) and L (+) lactic acid (85–90%) were purchased from Biopack (Bs. As., Argentina). Analytical standards, apigenin 95% (Api), naringenin ≥95% (Nar), caffeic acid ≥99% (Caf), nordihydroguaiaretic acid ≥97% (NDGA) and rosmarinic acid ≥99% (Ros) were purchased from Sigma Aldrich (St. Louis, MO,USA). Quercetin dihydrate ≥97% (Quer) were obtained from Alfa Aesar (Haverhill, MA, USA); tyrosol >99,5% (Tyr) from Fluka Analytical (St.

Results and discussion

NADES have been introduced as sustainable solvents for bioactive compounds extraction from medicinal plants [21]. In this sense, a NADES composed by lactic acid: dextrose: water (LGH) was used for L. divaricata, L. cuneifolia, T. vulgaris and O. vulgare extract preparation.

In order to illustrate the potential of NADES in the extraction of phenolic and alkaloids compounds, comparisons of the extraction efficiencies with the traditional solvents methanol and water were performed (Supplementary

Conclusions

The present work represents an advancement in the knowledge of chemical composition and antifungal properties of Larrea medicinal plants. NADES bio extracts were used for the first time in dermal formulations. The extraction ability of NADES opens interesting possibilities for their use as vehicles of phenolic and alkaloid bioactive compounds for pharmaceutical applications. LGH extracts of Larrea spices demonstrate a significant antimicrobial activity against C. albicans being higher than

Acknowledgments

This work was supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Facultad de Ciencias Agrarias, Universidad Nacional de Cuyo (Mendoza, Argentina). The authors are particularly grateful to Dra. Viviana Parra from Dermatology area of Hospital Lagomaggiore (Mendoza, Argentina) for providing Candida albicans strain.

References (30)

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