Chemical constituents, anti-rheumatic potential, and anti-inflammatory properties of the aqueous extract from the aerial parts of Aristolochia esperanzae Kuntze.

Although Aristolochia plants remain controversial due to their toxicity, this group of perianth-bearing plants, which includes the medicinal species Aristolochia esperanzae, is among the most relevant from an ethnobotanical perspective. All parts of A. esperanzae are used in popular medicine in the form of infusion for the treatment of rheumatism. Thus, the anti-inflammatory properties and the chemical composition of the aqueous extract (AELS) obtained from A. esperanzae aerial parts were examined in this research. AELS was analyzed using chromatographic, hyphenated, spectrometric techniques, and a total of 35 compounds, seven alkaloids, one alkamide, seven flavonoids, four phenolic compounds, one terpene lactone, three epoxylignans, two dibenzylbutyrolactolic, five dibenzylbutyrolactone, three furofuran lignans, and two labdane diterpenes, were found in this extract. Four doses of AELS (3-300 mg/kg) were administered, by oral route (p.o.), to female Swiss mice in the carrageenan pleurisy test. The dose of 100 mg/kg was tested in Swiss mice in two models: carrageenan, complete adjuvant Freunds (CFA) and zymosan inflammatory models. The AELS extract was assayed using the methylthiazolidiphenyl-tetrazolium bromide (MTT) test to verify the leukocyte viability, and this showed no cytotoxicity in vitro. AELS significantly interfered with nitric oxide production and reduced leukocyte migration to the pleura following carrageenan stimulation. AELS significantly inhibited nitric oxide production, leukocyte migration, and mechanical hyperalgesia after zymosan-stimulated joint inflammatory process. Therefore, the present study demonstrated that AELS exhibits anti-inflammatory properties and is rich in compounds known for their anti-inflammatory potential, thereby supporting the traditional use of A. esperanzae in treating rheumatism.