ABSTRACT
The secondary metabolite composition, antioxidant activities, and microbial inhibition properties of leaves of two Cistus species; C. monspeliensis and C. salvifolius were investigated using three solvent extracts (ethanol, hexane and distilled water). Ethanol extracts were most efficient at extracting phenolics, flavonoids and condensed tannins compared to hexane and distilled water for both Cistus species. A total antioxidant test (TAA) and two radical scavenging tests (DPPH and ABTS) indicated that the 70% ethanolic extract from C. salvifolius leaves had stronger antioxidant activity compared to the C. monspeliensis 70% ethanol extract, while the aqueous extract of C. monspeliensis was much stronger than the aqueous extract or the 70% ethanol extract of C. salvifolius. Overall, the polar extracts were more active in both species than the non-polar extracts. Thus aqueous ethanol extracts of the leaves of each Cistus species were tested for their ability to inhibit seven pathogenic microbial strains, including Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, and Candida albicans. Leaf ethanol extracts from both species were active against each microbial species, but the C. monspeliensis leaf ethanolic extract was much more active against several microbial species than that of C. salvifolius. For example, the C. salvifolius 70% ethanol extract showed its highest antimicrobial activity against P. aeruginosa and A. niger (MIC 3.1 mg/ml and MBC 6.3 mg/ml for both), while the C. monspeliensis extract showed much higher overall activity against E. coli, P. aeruginosa and C. albicana. (MIC 6.25 mg/ml and MBC 12.5 mg/ml for all three). In conclusion, maceration with 70% ethanol was the most efficient method for extracting total polyphenols, flavonoids, and condensed tannins from the two Cistus species, and the aqueous-ethanol extracts displayed the highest antioxidant and antimicrobial activities. Hence, the aqueousethanolic extracts of both species may be considered as potential sources of natural antioxidants and antimicrobial agents.
A composição de metabólitos secundários, atividade antioxidante e propriedades de inibição microbiana de extratos das folhas de duas espécies de Cistus; C. monspeliensis e C. salvifolius foram investigados utilizando-se três solventes de extração (etanol, hexano e água destilada). A extração com etanol foi a mais eficiente na extração de compostos fenólicos, flavonóides e taninos condensados em comparação com hexano e água destilada para ambas as espécies de Cistus. Um teste antioxidante total (TAA) e dois testes de eliminação de radicais (DPPH e ABTS) indicaram que o extrato em etanol 70% das folhas de C. salvifolius teve maior atividade antioxidante em comparação com o extrato etanólico de C. monspeliensis, enquanto o extrato aquoso de C. monspeliensis teve maior atividade antioxidante que o respectivo extrato aquoso ou o extrato etanólico de C. salvifolius. Em geral, os extratos polares foram mais ativos em ambas as espécies do que os extratos não-polares. Assim, extratos etanólico e aquoso das folhas de cada uma das espécies de Cistus foram testados quanto à sua capacidade de inibir sete cepas microbianas patogênicas, incluindo Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Enterococcus faecalis, Aspergillus niger, e Candida albicans. Extratos etanólicos da folha de ambas as
Subject(s)
Cistus , Antifungal Agents , AntioxidantsABSTRACT
The effects of dry-heat and seed soaking in distilled water or in gibberellic acid on germination performance of Cistus creticus L. and C. laurifolius L. were studied in the present study Germination percentages of two Cistus species were low due to dormancy Soaking in distilled water for 24 hr resulted in 28% germination in C. creticus and 43% in C. laurifolius. Gibberellic acid applications (20, 100 and 250 mg l(-1)) for 24 hr gave 32, 30 and 23% germination, respectively in Cistus creticus and 33, 37 and 28% germination, respectively in C. laurifolius. Dry-heat pretreatments at 50, 80 and 100 degrees C for several times (1-60 min) also significantly increased germination percentage in two species. The highest germination in C. creticus was obtained with dry-heat at 100 degrees C for 1 or 5 min (80% and 83%, respectively) and in C. laurifolius at 100 degrees C for 5 min (87%). A significant increase in germination rate was also achieved under different pretreatments. The physiological dormancy caused by an impermeable seed coat can be overcome by dry-heat pretreatments in two Cistus species.