Phytochemical Standardization of an Extract Rich in Flavonoids from Flowers of Kalanchoe pinnata (Lam) Pers

Kalanchoe pinnata is a species widely used in traditional medicine in Latin America and southern Africa. This species has been reported to have different activities, such as antioxidant, anti-inflammatory, and cytotoxic, the latter being related to its flavonoid content. The aim of this study was to contribute to the standardization of the aqueous extract of flowers from Kalanchoe pinnata. Purification of chemical markers was carried out by centrifugal partition chromatography (CPC). Stability tests under stress conditions were conducted for the extract by using the chromatographic profiles analyzed by ultra-performance liquid chromatography coupled to photodiode array detection (UPLC-PDA) and ultra-high-performance liquid chromatography combined with quadrupole-time of flight–mass spectrometry (UHPLC-MS-QTOF), with quantification of flavonoids by a validated UPLC-PDA method. Physicochemical variables of the plant material were within the limits established by official guides. Thirteen flavonoids present in the extract were identified, the major compounds being quercetin 3-O-α-L-arabinopyranosyl-(1→2)-α-L-rhamnopyranoside and quercetin 3-O-D-glucuronide, purified by CPC. A range of total flavonoids for the extract from 8–13% was determined. Finally, through stability tests, it was observed that the extract was stable in most conditions but evidenced moderate degradations upon acid and basic hydrolysis. Through qualitative and quantitative chemical characterizations, it was possible to chemically standardize the aqueous extract of flowers from K. pinnata, with a high content of flavonoids, under parameters required by the WHO and pharmacopoeias.