Phenolic-rich extract from Bryophyllum pinnatum leaf cultivated under drought stress conditions modulates the antioxidant and anti-inflammatory response

Abstract

Bryophyllum pinnatum (Lam) Pers (Crassulaceae) is used in traditional medicine to treat inflammatory diseases. There is preclinical and clinical evidence that proves its anti-inflammatory effect. This species is a good source of phenolic compounds such as flavonoids, being quercetin 3-O-L-arabinopyranosyl-(1→2)-O-L-rhamnopyranoside (Bp1), the main compound. However, to ensure the reproducibility of raw material as an active pharmaceutical ingredient, it is necessary to standardize the production chain from cultivation to the final product. The aim of this study was to understand whether water stress increases the phenolic content in B. pinnatum leaves and its effect on the modulation of anti-inflammatory and antioxidant responses. B. pinnatum was submitted to drought stress, with daily watering suspended for specified periods: 0, 5, 10, 20, and 30 days, along with a cyclic regimen involving 10 days of water deprivation followed by 10 days of regular watering for recovery (denoted as T0, T5t, T10t, T20t, T30t, and T10tcyc, respectively). For each water stress treatment (n = 10), there were control plants (n = 10) that received daily watering. After treatment, dry leaf extracts from each sample were prepared. Subsequently, the total flavonoids (TFC) and total phenolics (TPC) content were performed using spectrophotometric tests. Ultrafast liquid chromatography was used to quantify the main compound (Bp1) in the extracts. Extracts under different stress conditions showed no signs of cytotoxicity (RAW 264.7 cells) and were able to donate electrons in in vitro assays (CAT, reducing power, and DPPH). Extracts with high TPC (T20t and T30t) in the ear edema model induced by croton oil at a dose of 200 mg/kg orally showed an anti-inflammatory effect when compared to positive control, dexamethasone (1 mg/kg, orally). Regarding the Bp1 content, no major differences between the groups were observed. The results demonstrate that water stress is a promising and sustainable strategy for cultivating B. pinnatum to increase the phenolic content and positively modulate its pharmacological effects. Therefore, phenolic-rich extract of B. pinnatum can be obtained with low water resource consumption and it is a good source to use as an active ingredient in herbal medicines or supplements.