Características químicas e microbiológicas do açafrão-da-terra (Curcuma longa)

Abstract

In order to use medicinal plants in a safe, efficient and quality way, the Ministry of Health has published the list of RENISUS. The aim of it is that research with these species are carried out and strengthened. Among the seventy-one names of plants in the list, the interest of this study is Curcuma longa, also known as turmeric. The objectives were to analyze the contents of bioactive compounds and the antioxidant capacity of turmeric rhizomes from their antimicrobial activity. The rhizomes were dehydrated at temperatures of 40, 60 and 80ºC. The extracts were prepared using 1.0 g of the rhizomes with 100 mL of the solvents: ethanol / water (70:30), ethanol / water (95:5), methanol / water (70:30) and methanol / water (95:5). Analyzing the data, turmeric presented as a low source of ascorbic acid, being 1.70±0.07 mg 100 g-1, 1.59±0.04 mg 100 g-1 and 1.85±0.04 mg 100 g-1 for the temperatures of 40, 60 and 80ºC respectively. For the total phenols determined using the Folin-Ciocalteau reagent, the highest values for the solvent were EtOH 70% at 40°C and MeOH 95% at 60°C, showing no significant difference between them, being 1158.33±83.88 and 1318.67±74.03 mg EAG 100 g-1, respectively. There was a decrease in phenol contents when the drying temperature was increased to 80°C. The anthocyanins, total and yellow flavonoids, as well as the antioxidant capacity (DPPH and ABTS methods) of turmeric dehydrated rhizomes were determined. With the exception of anthocyanins and phenols, which degraded as the drying temperature increased, the remaining compounds were stable. High values were observed for total flavonoids, with extracts being EtOH 70% and MeOH 95% at 40ºC and EtOH 95% at 80ºC in less than five minutes, being the most efficient in the extraction of these compounds. For yellow flavonoids, all temperatures presented high values, when compared with other studies, and did not differ significantly between them. The antioxidant activity by the DPPH free radical sequestration method was performed at concentrations of 10.000 and 1.000 μg mL-1. For the highest concentration, all the extracts had a potential of inhibition of the radical with more than 80%, being high and being able to be compared with the ascorbic acid standard values. For the lower concentration, the percentages of inhibition presented values between 28-45% in the time of 30 minutes, the extracts being more active the MeOH 95% of the dryings at 40 and 80ºC. By the ABTS method, the conditions that presented the best radical inhibition potentials were MeOH 95% extracts at temperatures of 40 and 80°C, with 80% and 75% of inhibition respectively. The antimicrobial activity was very efficient for S. aureus, reaching a CBM of 60.000 g mL-1, with the extracts EtOH 70% and EtOH 95% at the temperature of 80ºC, while for E. coli, CBM was 120.000 g mL-1 with EtOH 95% extract at 60°C. By analyzing the results, the best conditions for turmeric are drying at 40 or 80°C and extraction with MeOH 95%.