Mechanical Engineering and Resource Sustainability Center

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Exploring Cynara cardunculus L. by-products potential: Antioxidant and antimicrobial properties

Publication . Barbosa, Cássia H.; Duarte, Maria Paula; Andrade, Mariana A.; Mateus, Ana Rita; Vilarinho, Fernanda; Fernando, Ana Luisa; Silva, Ana Sanches

Cynara cardunculus L. (cardoon), a perennial crop indigenous to the Mediterranean region, has gained recognition for its remarkable resilience to diverse weather conditions and its multifaceted applications across various industries, which includes the use of the flower as a vegetable rennet to produce some cheeses, as a source of biomass for energy, or its seed oil for human consumption, biodiesel, and animal feed. In some applications (e.g. biomass or seed production), when crop is harvested at the end of the growth cycle, the leaves remain as the main by-products, along with the flowers. In the context of a circular economy, the aim of this work was to undergone studies to determinate their biological properties (antioxidant and antimicrobial). Methanolic and ethanolic extracts of C. cardunculus L. (globe artichoke var. scolymus (L.) Fiori) and cultivated cardoon (var. altilis DC.)) leaves and flowers were characterised in terms of their polyphenol profile (total phenolic content (TPC), total flavonoid compounds (TFC), and ultra-high performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-ToF-MS)), antioxidant capacity (free radical DPPH inhibition system, β-carotene bleaching assay), and antimicrobial capacity (minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antifungal). In addition, the cultivated cardoon leaves extracts were assessed before and after they were dried in an oven with forced air circulation to evaluate if this treatment affected their bioactive profile. Chlorogenic acid, apigenin, and luteolin were the most quantified of a total of sixteen compounds identified by UHPLC-ToF-MS. Cultivated cardoon dry leaf extract presented the best antioxidant capacity for both methanolic (EC50 = 0.8 mg/mL, antioxidant activity coefficient (AAC) = 279.67) and ethanolic (EC50 =2.1 mg/mL, AAC = 448.06) extracts, compared to the cardoon flower extracts and the globe artichoke leaf ex tracts. Dried cultivated cardoon leaf extracts presented higher antioxidant capacity than fresh cultivated cardoon leaf extracts, but a greater number of polyphenolic compounds were identified in fresh cultivated cardoon leaf extract. The Gram-positive bacteria were more sensitive to the activity of both ethanolic and methanolic extracts than the Gram-negative and cultivated cardoon dry leaf ethanolic extract presented lower MIC and MBC values (125–2000 µg/mL) for most of the tested microorganisms, thus showing higher antimicrobial activity. As for the cultivated cardoon leaf extracts, the dried leaf extracts exhibited better antimicrobial activity, with lower MIC values, than the fresh leaf extracts. The extracts only demonstrated a slight inhibition against the fungi Aspergillus fumigatus. In conclusion, studies performed indicate that dried leaves maintain their biological activities compared to fresh leaves, and that flowers present significant biological activity which suggests the great.

2024-09-10Journal article

Unknown

Identification of Marker Compounds and In Vitro Toxicity Evaluation of Two Portuguese Asphodelus Leaf Extracts

Publication . Malmir, Maryam; Lima, Katelene; Póvoas Camões, Sérgio; Manageiro, Vera; Duarte, Maria Paula; Paiva Miranda, Joana; Serrano, Rita; Moreira da Silva, Isabel; Silva Lima, Beatriz; Caniça, Manuela; Silva, Olga

The leaves of Asphodelus bento-rainhae subsp. bento-rainhae, an endemic Portuguese species, and Asphodelus macrocarpus subsp. macrocarpus have been used as food, and traditionally as medicine, for treating ulcers, urinary tract, and inflammatory disorders. The present study aims to establish the phytochemical profile of the main secondary metabolites, together with the antimicrobial, antioxidant and toxicity assessments of both Asphodelus leaf 70% ethanol extracts. Phytochemical screenings were conducted by the TLC and LC-UV/DAD-ESI/MS chromatographic technique, and quantification of the leading chemical classes was performed by spectrophotometric methods. Liquid-liquid partitions of crude extracts were obtained using ethyl ether, ethyl acetate, and water. For in vitro evaluations of antimicrobial activity, the broth microdilution method, and for the antioxidant activity, the FRAP and DPPH methods were used. Genotoxicity and cytotoxicity were assessed by Ames and MTT tests, respectively. Twelve known compounds including neochlorogenic acid, chlorogenic acid, caffeic acid, isoorientin, p-coumaric acid, isovitexin, ferulic acid, luteolin, aloe-emodin, diosmetin, chrysophanol, and β-sitosterol were identified as the main marker compounds, and terpenoids and condensed tannins were found to be the major class of secondary metabolites of both medicinal plants. The ethyl ether fractions demonstrated the highest antibacterial activity against all the Gram-positive microorganisms, (MIC value of 62 to 1000 µg/mL), with aloe-emodin as one of the main marker compounds highly active against Staphylococcus epidermidis (MIC value of 0.8 to 1.6 µg/mL). Ethyl acetate fractions exhibited the highest antioxidant activity (IC50 of 800 to 1200 µg/mL, respectively). No cytotoxicity (up to 1000 µg/mL) or genotoxicity/mutagenicity (up to 5 mg/plate, with/without metabolic activation) were detected. The obtained results contribute to the knowledge of the value and safety of the studied species as herbal medicines.

2023-03-04Journal article

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