PLANTAS MEDICINAIS A UTILIZAR EM FITOTERAPIA COMO ANTI-FÚNGICOS: EFEITO DE COMPOSTOS FENÓLICOS NO CRESCIMENTO DE ESPÉCIES DE CANDIDA EM SUSPENSÃO E EM BIOFILMES

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Decoction, infusion and hydroalcoholic extract of cultivated thyme: Antioxidant and antibacterial activities, and phenolic characterization

Publication . Martins, Natália; Barros, Lillian; Santos-Buelga, Celestino; Silva, Sónia; Henriques, Mariana; Ferreira, Isabel C.F.R.

Bioactivity of thyme has been described, but mostly related to its essential oils, while studies with aqueous extracts are scarce. Herein, the antioxidant and antibacterial properties of decoction, infusion and hydroalcoholic extract, as also their phenolic compounds, were evaluated and compared. Decoction showed the highest concentration of phenolic compounds (either phenolic acids or flavonoids), followed by infusion and hydroalcoholic extract. In general, the samples were effective against gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and gram-negative (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Enterococcus aerogenes, Proteus vulgaris and Enterobacter sakazakii) bacteria, with decoction presenting the most pronounced effect. This sample also displayed the highest radical scavenging activity and reducing power. Data obtained support the idea that compounds with strong antioxidant and antibacterial activities are also water-soluble. Furthermore, the use of thyme infusion and decoction, by both internal and external use, at recommended doses, is safe and no adverse reactions have been described.

2015Journal article

Open access

Lamiaceae extracts as a source of phytochemicals with promissory antioxidant properties

Publication . Martins, Natália; Heleno, Sandrina A.; Barros, Lillian; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.

Plant extracts have been used over years due to their marked healing properties. Primitive societies used them not only as botanical preparations for therapeutic uses, but also as prophylaxis and for psychological effects. Despite the recognized millenary health evidences, numerous phytochemicals responsible for those benefits remain unknown. Among the heterogeneous group of secondary metabolites, phenolic compounds have been pointed out as relevant bioactive phytochemicals [1-3]. Furthermore, the culinary uses of different plant species associated to their biological activities highlight them as potential functional foods. The aim of the present work was to evaluate the antioxidant potential of aqueous (infusion and decoction) and methanol/water (80:20, v/v) extracts of three Lamiaceae plant species used with culinary and medicinal purposes, Origanum vulgare L. (oregano), Thymus vulgaris L. (thyme) and Salvia officinalis L. (sage), and to relate it with the phenolic profile assessed by HPLC-DADESI/ MS. In general, aqueous extracts evidenced the highest antioxidant potential (lipid peroxidation inhibition free radicals scavenging activity and reducing power). This potential seems to be related with the abundance in phenolic compounds, once sage that showed the highest antioxidant activity, also gave the highest concentration both in phenolic acid derivatives and flavonoids, followed by thyme and oregano. In all the studied samples, rosmarinic acid and luteolin derivatives (especially luteolin 7-Oglucuronide and luteolin 7-O-glucoside) were the most abundant phenolic acid derivatives and flavonoids, respectively. Other abundant phenolic compounds present in these matrices were apigenin derivatives (in oregano and sage), hesperetin and eriodictyol derivatives (in thyme), hispidulin glucuronide (in sage), caffeic acid dimers, trimers and tetramers (in sage), and lithospermic acid A (a caffeic acid tetramer), quercetin and kaempferol derivatives (in oregano and thyme). Overall, flavonoids followed by phenolic acid derivatives were the classes involved in the antioxidant potential of the tested Lamiaceae extracts. These species might be used as functional foods, but more studies are necessary in order to elucidate the mechanisms of action involved, as well as the bioavailability of the different phenolic compounds and related metabolic pathways.

2015Conference object

Open access

New approaches to the treatment of candidiasis regarding alternative and complementary medicine

Publication . Martins, Natália; Ferreira, Isabel C.F.R.; Barros, Lillian; Silva, Sónia; Henriques, Mariana

Candidiasis is considered one of the most common opportunistic fungal infections, but in the last years, hás reached epidemic leveis. Despite being Cândida albicans considered the most frequent, other non-Candida albicans Cândida species have also been involved [1]. Accordingly, and also due to the overuse of antimicrobial agents, the number of microorganisms with acquired drug-resistance is increasing, which difficult the success of the treatment [2]. Thus, other efficient and new alternatives are required, and the present work aims to provide new insides towards an effective treatment of candidiasis, according to our recent revision of the related literature [1]. A wide variety of factors are involved and favors the occurrence of this complicated fungal infection. Prevention is the most effective treatment, which includes for example, a good personal hygiene, to avoid some dietary risk factors and also to ensure a healthy intestinal flora. But, in face of an active infection, a rapid and effective inten/ention is necessary. Antifungal drugs should be prescribed only if necessary. Plants are extremely rich sources of phytochemicals with antimicrobial potential, such as phenolic compounds, wtiich are able not only to reduce Cândida species to a normal and controllable levei, but also to promote correct metabolic and immunologic functions, among other health benefits. For example, phenolic extracta of Juglans regia L., Eucalyptus globulus L., Rtfóus ulmifolius Schott, Pterospartum tridentatum (L.) Willk. [3] as well as Sa/wa officinalis L. [4] have shown to be promissory antifungal agents, being those effects mainly related with the presence of phenolic acids and flavonoids. Notwithstanding, their mechanisms of action remain unknown, which still encourage the research in this área.

2015Conference object

Open access

Phenolic extracts of Fragaria vesca L. roots with anti-Candida potential: chemical characterization and in vitro antifungal capacity

Publication . Martins, Natália; Dias, Maria Inês; Barros, Lillian; Silva, Sónia; Henriques, Mariana; Ferreira, Isabel C.F.R.

Candida species, considered a commensal microorganism of the human flora, have caused a profound impact at public health level. Furthermore, there are alarming numbers of microorganisms with acquired drug resistance, contributing to the inefficacy of antifungal agents [1]. Thus, efficient alteratives to the current antifungal agents and without side effects need to be discovered. Plants comprise numerous bioactive compounds responsible for a wide variety of bioactive properties. Fragaria vesca L. (wild strawberry), belongs to the Rosaceae family and its fruits are commonly used for culinary purposes. Only its leaves are used for medicinal purposes, due to the astringent (hemostatic and antidiarrheal), diuretic, depurative and tonic effects [2]. A few studies have been carried out in order to evaluate the bioactive potential of its roots [3], but to the authors knowledge, no reports are available regarding its antifungal potential against Candida species. Thus, the aim of the present study was to evaluate the antifungal potential of the hydromethanolic extract obtained from F. vesca roots, against nineteen Candida strains, belonging to C. albicans, C. glabrata, C. parapsilosis and C. tropicalis species. At the tested concentration (50 mg/mL), a most pronounced inhibitory effect was observed against C. tropicalis and C. parapsilosis (inhibitory zones varying between 9-10 and 10 mm, respectively). The obtained results remained similar after 24h, 48h and even 72h. Considering the evidenced antifungal potential, and taking into account its chemical composition, the observed effects could be attributed to the presence of phenolic compounds, such as flavan-3- ols, being (epi)catechin derivatives (mainly procyanidins) the main compounds found, as also elagic acid derivatives. Further studies should be conducted in order to identify the active principle(s) responsible for the observed effects and the corresponding mechanism of action.

2015Conference object

Open access

Phenolic compounds in decoction, infusion and hydroalcoholic extract of cultivated thyme (Thymus vulgaris L.) with bioactive properties

Publication . Martins, Natália; Barros, Lillian; Santos-Buelga, Celestino; Silva, Sónia; Henriques, Mariana; Ferreira, Isabel C.F.R.

The use of medicinal plants as prevention or treatment of various conditions has, recently, sparked an increasing interest for scientific researchers that have been studying their biological properties [1]. Thymus vulgaris L. can provide a wide source of biomolecules, such phenolic compounds that have been referred to as antioxidants [2] and antimicrobials [3]. Several studies report chemical composition and antioxidant properties of thyme, but mostly of essential oils [4,5]. In the present work, the bioactive properties of decoction, infusion and hydroalcoholic extracts of cultivated thyme were evaluated, and further characterized in terms of phenolic composition. The antioxidant activity was assessed by four in vitro assays: reducing power, free radicals scavenging activity, beta-carotene bleaching inhibition and lipid peroxidation inhibition in brain cell homogenates. Antimicrobial activity was assessed against gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and gram-negative (Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Enterococcus aerogenes, Proteus vulgaris and Enterobacter sakazaki1) bacteria was also evaluated. Phenolic compounds characterization was performed by HPLC-DAD-ESI/MS. The decoction showed the highest concentration in phenolic compounds (either phenolic acids or flavonoids), followed by infusion and hydroalcoholic extract. In general, the samples were effective against gram-positive and gram-negative bacteria, although decoction presented the most pronounced effect. This sample also gave the highest radical scavenging activity and reducing power. Rosmarinic acid (in all the preparations), luteolin 7-0-glucoside (in the hydroalcoholic extract) and luteolin 7 -0-glucuronide (in the infusion and decoction) were the main phenolic acid and flavonoid, respectively. The results obtained support the idea that compounds with strong antioxidant and antibacterial activities are also water-soluble. Furthermore, the use of infusion and decoction of thyme, by both internal and external use, at recommended doses, is safe and no adverse reactions have been described.

2014Conference object

Open access