Atividade antioxidante, anti-inflamatória e estudo de estabilidade de Rubus idaeus e Rubus fruticosus em monodroga e combinadas

Abstract

Rubus fruticosus and Rubus idaeus are species whose fruits, blackberry and raspberry, respectively, have remarkable bioactive properties. These fruits are widely consumed in the form of infusions, often marketed in Brazil as “red fruit tea” and promoted with claims of high antioxidant potential. However, most studies that prove their bioactive activities are based on the use of the leaves as monodrugs. This study aimed to evaluate the antioxidant, anti-inflammatory and cancer chemopreventive activity of infusions of R. idaeus and R. fruticosus, both alone (monodrugs) and in combinations, as well as the chemical and biological equality of the infusions when subjecting their plant drugs to accelerated stability, to evaluate the shelf life of the dried drugs for the preparation of the infusions. This is a pioneering study in the analysis of infusions of combined species.The samples were purchased from a qualified supplier and moisture, antioxidant (DPPH) and anthocyanin content analyses were performed to define the ideal drying time for the experiments (24, 48 and 96h). After this step, the centesimal composition of the dried fruits was determined and then infusions were prepared at a concentration of 13.33 mg/mL with an infusion time of 5 minutes. Individual infusions of R. ideaus and R. fruticosus were tested as monodrugs and three combinations of these. Chemical analyses included the determination of total anthocynins, flavonoids, polyphenols and tannins by spectrophotometric methods. The determination of phenolic compounds and flavonoids was also performed by ighPerformance Liquid Chromatography (HPLC). The antioxidant capacity was evaluated by chemical assays using the ABTS, DPPH and FRAP methods. In addition, biological activity was investigated in vitro by means of cytotoxicity, reduction of nitric oxide and superoxide anion, reduction of inflammatory cytokines, protective effect against hydrogen peroxide and induction of quinone reductase. For the stability study, the herbal drugs were incubated at 40ºC and 70% of humidity for six months, with analyses being performed every 45 days, both herbal drugs and their infusions. The analyses that covered the scope of the stability study were the determination of moisture, antioxidant evaluation (DPPH), determination of phenolic compounds and flavonoids (HPLC), microbiological safety and sensory examination. The results indicated that all infusions presented antioxidant and anti-inflammatory activities, with more expressive effects for the monodrugs in certain parameters, such as R. ideaus, which presented greater inhibition of superoxide anion, while R. fruticosus was the only sample to present a protective effect against hydrogen peroxide. Greater anti-inflammatory activities were also observed for the infusions of isolated species, namely, Rubus fruticosus being able to reduce the expression of IL-1 cytokines by 43% and R. ideaus as the sample that most reduced nitric oxide. Regarding the stability study, it was possible to observe different behaviors of the phenolic compounds throughout the stability study, while gallic acid and tannic acid increased at the end of the stability study, chlorogenic acid was degraded, inferring in the antioxidant activity found, which increased for all samples. Regarding microbiological safety, the results were satisfactory and regarding the sensory examination, despite presenting changes throughout the study, it was considered viable for consumption. The stability study was conclusive as satisfactory, which indicates that the dried plant drugs of blackberry and raspberry fruits, by the methods used, can be stored at room temperature for up to one year, as long as they are sealed and protected from sunlight, for the purpose of making infusions with antioxidant benefits. The findings of this study reinforce the bioactive potential of infusions of R. idaeus and R. fruticosus, especially in the modulation of oxidative stress and inflammation, with their infusions being more active as monodrugs. The relevance of the observed effects, particularly for monodrugs, suggests the need for further studies to explore their therapeutic applicability, including investigations in vivo models and clinical trials. Furthermore, considering the popular use of these infusions and their functional potential, future research could evaluate the inclusion of these species in the National Policy for Medicinal Plants and Phytotherapeutics, as well as assess the bioavailability of bioactive compounds and the stability of these substances in the long term and during industrial processing.