Ricinus communis L. (commonly known as castor plant) is a widely distributed medicinal plant traditionally used for its diverse therapeutic properties. This study aimed to isolate and identify bioactive compounds from R. communis L. through a bioassay-guided fractionation approach and evaluate their pharmacological potential. Aqueous and organic extracts were obtained from the leaves and seeds of R. communis collected in central Tunisia. The extracts were initially screened for phytochemical constituents, including alkaloids, flavonoids, saponins, phenolics, and terpenoids, using standard qualitative and quantitative methods.

Preliminary in vitro bioactivity assays—including antioxidant (DPPH, ABTS), antibacterial (MIC, disk diffusion), and anti-inflammatory (protein denaturation inhibition)—guided the selection of the most potent extract for further fractionation using chromatographic techniques (TLC, column chromatography, HPLC). Isolated fractions were tested again to confirm bioactivity, and the most active compounds were characterized using spectroscopic methods such as FTIR, NMR, and MS.

The study successfully identified several phytochemicals, with two lead compounds showing strong antioxidant and antibacterial properties comparable to standard controls (ascorbic acid and ciprofloxacin). The bioactive fractions significantly inhibited the growth of Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and demonstrated moderate activity against Gram-negative strains. Additionally, the fractions exhibited anti-inflammatory activity through the inhibition of protein denaturation and cellular nitric oxide production.