Evaluation of biological activities of raw and cooked Brassica oleracea sprout extracts rich in bioactive compound Sulforaphane

Abstract

Background and Aims: Broccoli sprout extract (Brassica oleracea) has extensive biological activities that are mainly attributed to the presence of bioactive compounds, such as sulforaphane. This study aimed to investigate the antioxidant and antibacterial activities of cooked and raw extracts of broccoli sprouts. Materials and Methods: The amount of sulforaphane in broccoli sprout extract was evaluated by high-performance liquid chromatography (HPLC). Moreover, the amount of phenolic and flavonoid compounds and antioxidant capacity were investigated by the DPPH free radical scavenging method. In addition, the antibacterial activity of raw and cooked sprout extracts on some bacteria was explored using disk diffusion assay and minimum inhibitory concentration (MIC) by macro dilution method. Significant differences were analyzed by one-way analysis of variance (ANOVA) through Duncan's multiple range test. Results: Based on the results obtained by HPLC, the amount of sulforaphane in the raw broccoli sprout extract was determined to be 787.46 μg/mL. Moreover, the antioxidant activity of raw and cooked sprout extracts depicted a higher antioxidant activity with an increase in concentration. Furthermore, the antibacterial study showed that cooked sprout extract had higher antimicrobial activity, compared to the raw sprout extract (at a significance level of 0.05). The highest growth inhibition zone was found against Gram-positive Bacillus cereus strain with a diameter of 18±0.6 mm; moreover, the lowest amounts of MIC and MBC were obtained at 0.39 and 0.78 mg/mL, respectively. Conclusion: In general, the results show that cooked broccoli sprout extract has significant antioxidant and antibacterial activities, compared to the raw sprout. Accordingly, it can be utilized in food, health, and medical products as a highly promising source. However, further studies are required to be conducted in this regard.