Activity of crude extracts from Brazilian cerrado plants against clinically relevant Candida species

Prospecting Plant Extracts and Bioactive Molecules with Antimicrobial Activity in Brazilian Biomes: A Review

Antimicrobial resistance is currently one of the greatest threats to global health, food security, and development. In this aspect, medicinal plants have been studied to support the development of viable alternatives to prevent and treat infectious diseases. This study aimed to perform a review of the literature comprising the antimicrobial activity of vegetable species from Brazilian biomes. We selected 67 original scientific publications about extracts, fractions, or isolated molecules from plants in the Brazilian biomes, published between 2016 and 2020 in Pubmed, ScienceDirect, and Scielo. Data demonstrated that 98 plant species, especially collected in the Cerrado, Atlantic Forest, and Caatinga biomes, were tested against 40 fungi and 78 bacterial strains. Bioactive fractions of Eucalyptus globulus methanolic stump wood extract were active against Candida albicans and C. tropicalis (MIC 2.50 µg/mL). The catechin purified from Banisteriopsis argyrophylla leaves had activity against C. glabrata (MIC 2.83 µg/mL) and ethanolic extract obtained from Caryocar coriaceum bark and fruit pulp exhibited MIC of 4.1 µg/mL on Microsporum canis. For bacteria, compounds isolated from the dichloromethane extract of Peritassa campestris, lectin extracted from a saline extract of Portulaca elatior and essential oils of Myrciaria pilosa exhibited significant effect against Bacillus megaterium (MIC 0.78 µg/mL), Pseudomonas aeruginosa (MIC 4.06 µg/mL) and Staphylococcus aureus strains (MIC 5.0 µg/mL), respectively. The findings support the antimicrobial and bioeconomic potential of plants from Brazilian biodiversity and their promising health applications.

"Cow's Hoof" (Bauhinia L., Leguminosae): A Review on Pharmacological Properties of Austral South American Species

The genus Bauhinia s.l. (Leguminosae), known as cow's hoof, unha de boi or pata de vaca, has been used in traditional medicine worldwide. The aim of the present review is to summarize the studies published on the biological activity of the main native medicinal species reported in austral South America. Of the 14 species present in the region, 10 are consumed as leaf infusions to regulate glucose and lipid metabolism, as well as used for their anti-inflammatory and analgesic effects and to treat various diseases. Pharmacological properties have been recorded in seven species. Antioxidant, anticoagulant, antihypertensive, diuretic, antimicrobial and antitumor properties have been reported in B. forficata. Together with B. holophylla, they are important for their antidiabetic properties, since several studies indicate their effectiveness as a hypoglycemic agent. B. bauhinioides is distinguished for its anti-inflammatory and antithrombotic activities and S. microstachya for its analgesic properties. Anti-ulcer and wound healing activities recorded in B. holophylla and B. ungulata, respectively, are of particular interest. Most of the species possess antitumor activity. The antioxidant capacity of flavonoids and other bioactive compounds make these plants good candidates to assist or treat various alterations related with oxidative stress, such as diabetic complications. Thus, these species constitute promising targets for new bioactive substance research and phytotherapy.

Non-albicans Candida Species: Immune Response, Evasion Mechanisms, and New Plant-Derived Alternative Therapies

Fungal infections caused by Candida species have become a constant threat to public health, especially for immunocompromised patients, who are considered susceptible to this type of opportunistic infections. Candida albicans is known as the most common etiological agent of candidiasis; however, other species, such as Candida tropicalis, Candida parapsilosis, Nakaseomyces glabrata (previously known as Candida glabrata), Candida auris, Candida guilliermondii, and Pichia kudriavzevii (previously named as Candida krusei), have also gained great importance in recent years. The increasing frequency of the isolation of this non-albicans Candida species is associated with different factors, such as constant exposure to antifungal drugs, the use of catheters in hospitalized patients, cancer, age, and geographic distribution. The main concerns for the control of these pathogens include their ability to evade the mechanisms of action of different drugs, thus developing resistance to antifungal drugs, and it has also been shown that some of these species also manage to evade the host's immunity. These biological traits make candidiasis treatment a challenging task. In this review manuscript, a detailed update of the recent literature on the six most relevant non-albicans Candida species is provided, focusing on the immune response, evasion mechanisms, and new plant-derived compounds with antifungal properties.

Herbal Extracts with Antifungal Activity against Candida albicans: A Systematic Review

In the era of antimicrobial resistance, fungal pathogens are not an exception. Several strategies, including antimicrobial stewardship programs and high throughput screening of new drugs, are being implemented. Several recent studies have demonstrated the effectiveness of plant compounds with antifungal activity. In this systematic review, we examine the use of natural compounds as a possible avenue to fight fungal infections produced by Candida albicans, the most common human fungal pathogen. Electronic literature searches were conducted through PubMed/MEDLINE, Cochrane, and Science Direct limited to the 5 years. A total of 131 articles were included, with 186 plants extracts evaluated. Although the majority of the natural extracts exhibited antifungal activities against C. albicans (both in vivo and in vitro), the strongest antifungal activity was obtained from Lawsonia inermis, Pelargonium graveolens, Camellia sinensis, Mentha piperita, and Citrus latifolia. The main components with proven antifungal activities were phenolic compounds such as gallic acid, thymol, and flavonoids (especially catechin), polyphenols such as tannins, terpenoids and saponins. The incorporation of nanotechnology greatly enhances the antifungal properties of these natural compounds. Further research is needed to fully characterize the composition of all herbal extracts with antifungal activity as well as the mechanisms of action of the active compounds.

Ethanolic Extract of Dried Leaves from the Cerrado Biome Increases the Cryotolerance of Bovine Embryos Produced In Vitro

In vitro embryo production (IVP) induces excessive production of reactive oxygen species (ROS), which affects blastocyst quality. Therefore, the supplementation of culture media with antioxidants is an alternative to overcome oxidative stress damage. However, there is a growing demand for the use of antioxidant compounds that are more natural and less toxic in cell cultures. The present study is aimed at evaluating the effect of ethanolic extracts from cerrado leaves on IVP. First, the antioxidant capacity and the amount of phenolic compounds of the leaves were evaluated. Then, the best ethanolic extract concentration composed of cagaita (Eugenia dysenterica) and murici (Byrsonima crassifolia) to be used during the in vitro culture of in vitro-produced embryos was determined. Afterward, we evaluated the influence of the extract of both plants on ROS and glutathione (GSH) production, while also evaluating the apoptosis and ROS metabolism gene expression. In a subsequent step, the effect of the ethanolic extracts of dried cagaita and murici leaves during embryonic cultivation on the cryotolerance of expanded blastocysts was studied. The results showed a significant reduction in the proportion of apoptotic cells from embryos cultivated with 0.01 mg/mL of the cagaita ethanolic extract, besides inducing an increase in the GPX4 and PRDX3 transcription levels. The murici ethanolic extract induced an increase in the transcription abundance of these genes but did not reduce the proportion of apoptotic cells. In addition, expanded blastocysts cultivated with extracts at a concentration of 0.01 mg/mL and cryopreserved had higher hatching rates and lower degeneration rates when compared to the frozen group previously supplemented with the extracts. Moreover, the apoptosis rate of embryos cultured for 12 h after cryopreservation was lower in groups previously exposed to extracts during in vitro cultivation. Such extracts may be used as alternatives to increase the cryotolerance of in vitro-produced embryos.

Anti-Fungal Efficacy and Mechanisms of Flavonoids

The prevalence of fungal infections is growing at an alarming pace and the pathogenesis is still not clearly understood. Recurrence of these fungal diseases is often due to their evolutionary avoidance of antifungal resistance. The development of suitable novel antimicrobial agents for fungal diseases continues to be a major problem in the current clinical field. Hence, it is urgently necessary to develop surrogate agents that are more effective than conventional available drugs. Among the remarkable innovations from earlier investigations on natural-drugs, flavonoids are a group of plant-derived substances capable of promoting many valuable effects on humans. The identification of flavonoids with possible antifungal effects at small concentrations or in synergistic combinations could help to overcome this problem. A combination of flavonoids with available drugs is an excellent approach to reduce the side effects and toxicity. This review focuses on various naturally occurring flavonoids and their antifungal activities, modes of action, and synergetic use in combination with conventional drugs.

An efficient method for total RNA extraction from leaves of arboreal species from the Brazilian Cerrado

Abstract Considering the lack of information on RNA extraction from arboreal species, specially from the Brazilian Cerrado, the aim of this study was to test RNA extraction methods for a wide variety of native plant species from this biome. The methods tested consisted of: (i) TRIzol® reagent, (ii) TRIzol® reagent with modifications, (iii) CTAB buffer, and (iv) Modified CTAB buffer, initially for leaf samples of Xylopia aromatica and Piper arboreum. Later the procedure with the best results was used to obtain purified RNA from 17 other native species. Based on A260/A280 absorbance ratio the Modified CTAB method was the best for total RNA extraction for those woody species. Ten out of eleven species tested through RT-PCR generated fragments of the expected size from the total RNA extracted by the selected method, confirming it as the best option to obtain high-quality RNA for molecular analyses and for use in the detection of viruses infecting these tree species.

In vitro evaluation of Eugenia dysenterica in primary culture of human gingival fibroblast cells

Eugenia dysenterica is a Brazilian tree investigated for its properties and bioactive compounds, which are believed to have both pharmacological and phytochemical therapeutic effects. The leaves of this tree contain tannins, flavonoids, terpenes, and saponins, with reportedly beneficial effects to the human body. Despite these therapeutic applications, its effects have never been tested on oral tissues. Therefore, the aim of the present study was to evaluate the cytotoxic and antioxidant effects and the anti-inflammatory and repair properties of the acetone fraction of E. dysenterica on primary culture of human gingival fibroblasts and on the immortalized murine macrophage cell line (RAW 264.7). For this purpose, a metabolic activity assay, a wound healing assay, a nitric oxide assay, and RT-qPCR were performed. The assays revealed a cytoprotective effect of this plant, suggested by the increase in the expression of SOD1 and NRF2. An antioxidant potential effect was observed in the DPPH• assay. However, the fraction of E. dysenterica did not show anti-inflammatory activity. In conclusion, Eugenia dysenterica may promote cytoprotection when associated with chlorhexidine digluconate because of its antioxidant effect. However, additional studies are necessary on other human dental tissues using other parts of the plant in order to develop a possible mouthwash to assist patients with oral disorders.

Phenolic Composition and Antifungal Effect of Costus cf. arabicus L Against Yeast of the Candida Genus

Background:

The emergence of fungal resistance to commercial drugs has been observed, and because of that, research with natural products have been performed with the aim of obtaining bioactive compounds.

Objective:

Evaluate the chemical composition and antifungal activity of the ethanolic extract of Costus cf. arabicus L leaves (EECAL) over strains of the genus Candida, as well as its inhibitory potential over yeast virulence.

Methods:

The composition of EECAL was analyzed through High Performance Liquid Chromatography (HPLC). The Minimum Inhibitory Concentration (MIC) was determined by broth microdilution using spectrophotometer readings and the Minimal Fungicidal Concentration (MFC) was investigated. The reading data of the MIC was used to trace a cellular growth curve and calculate the Inhibitory Concentration for 50% of the cells (IC50) of the extract and fluconazole. The effect over the yeast morphology was verified using wet-chamber microculture and visualized through optical microscopy (40x).

Results:

HPLC detected the presence of flavonoids and phenolic acids. The extract presented fungistatic effect (MIC of 8.192 µg/mL). The IC50 of the extract and fluconazole varied between 4,008.7 to 5,116.8 µg/mL and 44.0 to 83.1 µg/mL, respectively. The extract inhibited the formation of hyphae at MICx2 against CA LM 77. For the CA INCQS 40006, the inhibition was verified at MIC/2. In the CT LM 23 and CT INCQS 40042 strains the presence of hyphae was considered absent at the MIC.

Conclusion:

The extract presented antifungal action on cell growth at elevated concentrations and an inhibitory effect of dimorphism in the tested Candida species.

Candida Infections and Therapeutic Strategies: Mechanisms of Action for Traditional and Alternative Agents

The Candida genus comprises opportunistic fungi that can become pathogenic when the immune system of the host fails. Candida albicans is the most important and prevalent species. Polyenes, fluoropyrimidines, echinocandins, and azoles are used as commercial antifungal agents to treat candidiasis. However, the presence of intrinsic and developed resistance against azole antifungals has been extensively documented among several Candida species. The advent of original and re-emergence of classical fungal diseases have occurred as a consequence of the development of the antifungal resistance phenomenon. In this way, the development of new satisfactory therapy for fungal diseases persists as a major challenge of present-day medicine. The design of original drugs from traditional medicines provides new promises in the modern clinic. The urgent need includes the development of alternative drugs that are more efficient and tolerant than those traditional already in use. The identification of new substances with potential antifungal effect at low concentrations or in combination is also a possibility. The present review briefly examines the infections caused by Candida species and focuses on the mechanisms of action associated with the traditional agents used to treat those infections, as well as the current understanding of the molecular basis of resistance development in these fungal species. In addition, this review describes some of the promising alternative molecules and/or substances that could be used as anticandidal agents, their mechanisms of action, and their use in combination with traditional drugs.

An Update on Candida tropicalis Based on Basic and Clinical Approaches

Candida tropicalis has emerged as one of the most important Candida species. It has been widely considered the second most virulent Candida species, only preceded by C. albicans. Besides, this species has been recognized as a very strong biofilm producer, surpassing C. albicans in most of the studies. In addition, it produces a wide range of other virulence factors, including: adhesion to buccal epithelial and endothelial cells; the secretion of lytic enzymes, such as proteinases, phospholipases, and hemolysins, bud-to-hyphae transition (also called morphogenesis) and the phenomenon called phenotypic switching. This is a species very closely related to C. albicans and has been easily identified with both phenotypic and molecular methods. In addition, no cryptic sibling species were yet described in the literature, what is contradictory to some other medically important Candida species. C. tropicalis is a clinically relevant species and may be the second or third etiological agent of candidemia, specifically in Latin American countries and Asia. Antifungal resistance to the azoles, polyenes, and echinocandins has already been described. Apart from all these characteristics, C. tropicalis has been considered an osmotolerant microorganism and this ability to survive to high salt concentration may be important for fungal persistence in saline environments. This physiological characteristic makes this species suitable for use in biotechnology processes. Here we describe an update of C. tropicalis, focusing on all these previously mentioned subjects.

Phytochemical Analysis and Antimicrobial Activity of Myrcia tomentosa (Aubl.) DC. Leaves

This work describes the isolation and structural elucidation of compounds from the leaves of Myrcia tomentosa (Aubl.) DC. (goiaba-brava) and evaluates the antimicrobial activity of the crude extract, fractions and isolated compounds against bacteria and fungi. Column chromatography was used to fractionate and purify the extract of the M. tomentosa leaves and the chemical structures of the compounds were determined using spectroscopic techniques. The antibacterial and antifungal activities were assessed using the broth microdilution method. The phytochemical investigation isolated 11 compounds: α-bisabolol, α-bisabolol oxide B, α-cadinol, β-sitosterol, n-pentacosane, n-tetracosane, quercetin, kaempferol, avicularin, juglanin and guaijaverin. The crude ethanolic extract and its fractions were tested against 15 bacteria and 9 yeasts. The crude extract inhibited the in vitro growth of yeasts at concentration of 4 to 32 μg/mL. The hexane, dichloromethane, ethyl acetate and aqueous fractions inhibited Candida sp. at concentrations of 4 to 256 μg/mL, whereas the Cryptococcus sp. isolates were inhibited only by the hexane and dichloromethane fractions in minimal inhibitory concentrations (MICs) at 16 to 64 μg/mL. The flavonoid quercetin-3-O-α-arabinofuranose (avicularin) was the most active compound, inhibiting Candida species in concentrations of 2 to 32 μg/mL. The MIC values suggest potential activity of this plant species against yeast.