Centranthus ruber (L.) DC. and Tropaeolum majus L.: Phytochemical Profile, In Vitro Anti-Denaturation Effects and Lipase Inhibitory Activity of Two Ornamental Plants Traditionally Used as Herbal Remedies

Ornamental plants often gain relevance not only for their decorative use, but also as a source of phytochemicals with interesting healing properties. Herein, spontaneous Centranthus ruber (L.) DC. and Tropaeolum majus L., mainly used as ornamental species but also traditionally consumed and used in popular medicine, were investigated. The aerial parts were extracted with methanol trough maceration, and resultant crude extracts were partitioned using solvents with increasing polarity. As previous studies mostly dealt with the phenolic content of these species, the phytochemical investigation mainly focused on nonpolar constituents, detected with GC-MS. The total phenolic and flavonoid content was also verified, and HPTLC analyses were performed. In order to explore the potential antiarthritic and anti-obesity properties, extracts and their fractions were evaluated for their anti-denaturation effects, with the use of the BSA assay, and for their ability to inhibit pancreatic lipase. The antioxidant properties and the inhibitory activity on the NO production were verified, as well. Almost all the extracts and fractions demonstrated good inhibitory effects on NO production. The n-hexane and dichloromethane fractions from T. majus, as well as the n-hexane fraction from C. ruber, were effective in protecting the protein from heat-induced denaturation (IC50 = 154.0 ± 1.9, 270.8 ± 2.3 and 450.1 ± 15.5 μg/mL, respectively). The dichloromethane fractions from both raw extracts were also effective in inhibiting pancreatic lipase, with IC50 values equal to 2.23 ± 0.02 mg/mL (for C. ruber sample), and 2.05 ± 0.02 mg/mL (T. majus). Obtained results support the traditional use of these species for their beneficial health properties and suggest that investigated plant species could be potential sources of novel antiarthritic and anti-obesity agents.