Toxicity Test Using Brine Shrimp Lethality Test (BSLT) and Antioxidant Assay of Ricinoleic Acid-Based Ester Conjugate Synthesized by Steglich Esterification

Ricinoleic acid has been known to have therapeutic activities such as antimicrobial, anti-inflammatory, antiproliferative, and anticancer. In this research, synthesis of ricinoleic acid-based ester conjugate compound with tocopherol was carried out by coupling reaction of Steglich esterification using DCC as coupling reagent and DMAP as the catalyst. Thin-layer chromatography was performed to identify the product and showed Rf values of 0.40 for ricinoleic acid, 0.53 for ricinoleic acid ester, and 0.73 for tocopherol. The product was purified using silica gel column chromatography with petroleum ether: ethyl acetate (9:1, v/v) as the eluent. Characterization by FT-IR showed new absorption of the C-O ester functional group at wavenumbers at 1760 cm^-1 - 1690 cm^-1 and a sharper absorption peak for the aromatic C-H functional group at 870 cm^-1 - 675 cm^-1. Antioxidant activity assay of the ester conjugate produced and tocopherol as control gave IC50 values of 4.152 ppm and 0.625 ppm, respectively. Toxicity assay using Brine Shrimp Lethality Test (BSLT) showed LC50 value of this ester product compound was 58.344 ppm. Based on this value, the ricinoleic acid-based ester conjugated showed toxic properties and potential as a bioactive compound.