Aims: To study how the antimicrobial and antioxidant activities of Lippia graveolens essential oils with different composition are affected after the microencapsulation process with β‐cyclodextrin (βCD).
Methods and results: Three Mexican oregano essential oils (EOs) with different carvacrol/thymol/p‐cymene ratios (38 : 3 : 32, 23 : 2 : 42, 7 : 19 : 35) were used in this study. Microencapsulation was carried out by spray‐drying. Antimicrobial activities were measured as MBC (minimal bactericidal concentration) using 0·05%/0·10%/0·20% (w/v) dilutions of EOs against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538. Antioxidant activities were determined by the 2,2′‐diphenyl‐1‐picrylhydrazil (DPPH) method. EOs showed antimicrobial and antioxidant activity, but microencapsulation preserved the antimicrobial activity in all cases and increased the antioxidant activity from four‐ to eightfold.
Conclusions: Although the Lippia essential oils were from the same species, their composition affects the biological activities before and after the microencapsulation process, as well as encapsulation efficiency. Our study supports the fact that microencapsulation of EOs in β‐cyclodextrin preserves the antimicrobial activity, improves the antioxidant activity and acts as a protection for EOs main compounds.
Significance and Impact of the Study: Microencapsulation affects positively EOs main compounds, improves antioxidant activity and retains antimicrobial activity, enhancing the quality of the oils.
ABSTRACT-The aim of this study was to obtain extracts from soursop pulp that were obtained with different solvents (chloroform, methanol, ethyl acetate and water) and different extraction methods (soxhlet, sonication and microwave), and analysed their extractable polyphenol content, antioxidant capacity and qualitative presence of acetogenins. The most efficient extraction method to obtain extractable polyphenols with high values of scavenging capacity by DPPH was sonication followed by microwave when methanol was used. The acetogenins were detected only in chloroform and ethyl acetate extracts obtained by the three extraction methods. Sonication or microwave was effective to obtain acetogenins or phenolic extracts in greater quantity than reported in soursop pulp, in a short time and few solvent. Index terms: Annona muricata, emerging extraction methods, bioactive compounds.
AVALIAÇÃO DE MÉTODOS EMERGENTES SOBRE O CONTEÚDO DE POLIFENÓIS, CAPACIDADE ANTIOXIDANTE E PRESENÇA QUALITATIVA DE ACETIOGENINAS EM PULPA DE SOURSOP(Annona muricata L.) RESUMO-O objetivo deste estudo foi avaliar os extratos do polpa da graviola obtidos com diferentes solventes (clorofórmio, metanol, acetato de etilo e água) e diferentes métodos de extração (Soxhlet, sonicação e micro-ondas). Foi analisado o conteúdo de polifenóis extraíveis, capacidade antioxidante e presença qualitativa de acetogeninas. O método de extração mais eficiente para obter polifenóis extraíveis e valores elevados de capacidade antioxidante (DPPH) foi por sonicação, seguido por micro-ondas, quando o metanol foi usado. As acetogeninas foram detectadas somente em extractos com clorofórmio e acetato de etilo para todos os métodos de extração avaliados. Sonicação ou micro-ondas foi eficaz para extrair acetogeninas ou polifenóis em maior quantidade do que o relatado em polpa de graviola, em pouco tempo e pouco solvente. Termos para indexação: Annona muricata, métodos emergentes de extração, compostos bioactivos. 1 (Paper 155-15).
Laser-induced fluorescence (LIF) spectra were obtained from Maradol papaya fruits at harvested mature, harvested immature, different ripeness stages, and during the ripening. The chlorophyll fluorescence of papaya fruits showed two maxima; one in the red at 680-690 nm (F690), and the other in far-red region at 730-740 nm (F740). The fruits that were harvested immature showed a definite increase in fluorescence intensity at both maxima within the first six days. The fluorescence emission spectra and fluorescence ratios F690/F740 were analyzed. Results showed that intensity and spectral shape are characteristics of different ripeness stages and during the ripening. The values obtained from F690/F740 showed a direct relation with the fruit harvested mature, harvested immature, and fruit in the ripening process. These results demonstrated that LIF is a useful tool for nondestructive monitoring of the changes in chlorophyll content and photosynthetic activity caused by the different ripeness stages and during the ripening of papaya fruits.
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