Flavonoid enriched extract of Alternanthera brasiliana with photoprotective effect: Formulation development and evaluation of quality

Abstract Alternanthera brasiliana is popularly known as "penicillin" and has been used as an anti-inflammatory and for wound healing in folk medicine, been the flavonoids the main chemical markers with pharmacological activity in this species. The objective of this work was to perform the pharmacognostic characterization of the powder of Alternanthera brasiliana, the optimization of the extraction of total flavonoids and the preparation of a gel with photoprotective effect from the addition of this extract enriched of flavonoids. The pharmacognostic characterization, the preparation of fluid enriched extract of flavonoids and quality control of the gel were carried out according to the Brazilian Pharmacopeia, and the evaluation of photoprotective activity was carried out according to the Mansur method. Regarding pharmacognostic characterization, some data are being published for the first time, such as acid insoluble ash (10.02 ± 0.22 %), sulfated ash (12.77 ± 0.01 %), extractable substances by ethanol (4.75 ± 0.07 %) and the foam index (0). In the optimization of extraction, the condition that provided the extract with the highest concentration of total flavonoids was Ab-EFE-3, with solvent hydration at low level, powder:solvent ratio at low level and magnetic stirring at high level. The highest total flavonoid content was 503.7 ± 14.01 mg of rutin equivalents/g. A gel was manipulated with Alternanthera brasiliana enriched flavonoid extract and had its quality control attested by the tests performed. The spectrophotometric SPF of the prepared gel was analyzed at the beginning (T0) and at the end (T12) of the stability study, presenting statistically different initial and final values. The final SPF-UVB of formulation was 21.33 ± 1.25 for the sample submitted to freezing/defrosting cycle, and 19.57 ± 0.74 for the sample maintained at room temperature.