Evaluation of the bioactivity of hibiscus extracts (Hibiscus sabdariffa and H. rosa-sinensis) and anti-inflammatory potential.

• Autor(a) principal: Matheus Thomaz Nogueira Silva Lima
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/52908; https://orcid.org/0000-0002-2817-5641
• topic: Hibiscus sabdariffa; Hibiscus rosa-sinensis; Bioatividade; Neuroprotetor; Anti-inflamatório; RAGE

Hibiscus, commonly known as roselle, is a plant with worldwide distribution and is greatly used as food, in the preparation of teas, food dyes, and fermented products. Red hibiscus flowers are commonly commercialized and studied around the world due to their nutritional benefits and therapeutic uses. However, other color variations occur naturally and may present potential applications in the food industry. The formulation of hibiscus-based functional foods would be of great value once nutraceutical effects have been implied to this plant. At first, this work aimed to characterize the total phenolic (TPC) and total flavonoid contents (TFC), the antioxidant, the anti-glycoxidation, and neuroprotective effects of hibiscus floral extracts. Secondly, we approached the applicability of gamma radiation as a tool in the hibiscus supply chain, by characterizing the effects of this ionizing radiation on hibiscus bioactivity. Lastly, on the way to investigate the pro-inflammatory/oxidative stress of dietary compounds as advanced glycation end-products, we evaluated the use of endothelial cells (HUVECs) as a functional model for RAGE-mediated inflammation screening. The red hibiscus variety (Hibiscus sabdariffa) is a well-known source of phenolic and flavonoids. However, here we demonstrated that the pink variety of H. rosa-sinensis presented the highest TPC (31.28±1.24 mg GAE/100 g) and TFC (469.20±3.24 mg QE/100 g) in aqueous extracts which is the most common solvent in hibiscus preparation as food. Antioxidant activity remained over 60% and 80% of DPPH and ABTS radical scavenging, respectively for all samples. Grater variation resulted from iron reducing power activity of ethanolic extracts of pink and red varieties (> 50 %). Hibiscus red variety also showed consistent anti-glycation (55 %), anti-acetylcholinesterase (> 95 %), and neuroprotective effect in vivo (D. melanogaster). The use of gamma radiation did not present extensive effects on hibiscus bioactivity. Doses of 10 kGy to 30 kGy allowed high microbial loads decontamination but 30 kGy had effects on TFC. Finally, the induction of inflammation was made possible on HUVEC culture, with increased expression of TNFα, IL6, and VCAM1 gene under TNFα (10 ng/mL) effects. However, HMGB1, a well-known inflammation activator, did not induce inflammation under the experimental conditions here applied. In a conclusion, the biodiversity within Hibiscus influences the variation in the phenolic content and bioactivity of these plants, and new varieties have been demonstrated to hold antioxidants, TPC, and TFC, comparable to the commonly consumed red hibiscus and deserve attention. Moreover, gamma radiation showed efficacy in microbial contamination reduction, while maintaining bioactive potential in the different hibiscus samples. Lastly, results from HUVECS suggested that inflammation activation is independent of variations of RAGE expression both at the transcriptional and translational levels. However, further investigation is required to delineate the precise participation of RAGE in inflammation activation on HUVEC cultures.