Based on the Benzoflex (Vesicol Chemical Co.) as PVC plasticizer substituents for Di-n-octyl phthalate (DOP), a series of new aromatic carboxylic acid ester compounds were designed as plasticizers, synthesized, and screened for the endocrine disrupting activity. 2-Hydroxybenzoic acid (1) and 2-methoxybenzoic acid (2) as the commercially available starting materials were reacted with diethylene glycol (3) in the presence of p-toluenesulfonic acid using Dean-Stark column to give diethylene glycol di-(2-hydroxy)benzoate (4, KH01) and diethylene glycol di-(2-methoxy)benzoate (5, KH02), respectively. And diethylene glycol di-(3-pyridinyl) ester (7, KH03) and dipropylene glycol di-(3-pyridinyl) ester (9, KH04) were obtained in high yields by treatment of nicotinoyl chloride (6) with diethylene glycol (3) and dipropylene glycol (8) in the presence of triethylamine as a base. To determine the estrogenic disrupting effect of new synthetic phthalate analogues, E-screen assay method was used. Of these compounds, 4 (KH01) was found to be compound without endocrine disrupting effect.

As alternatives of phthalate plasticizers harmful as endocrine disruptors, citrate esters have been considered for plasticizer in the production of cosmetics, PVC plastics, and pharmaceuticals. Though considered to be low toxic in mammals in vivo and in vitro toxicological information for citrate esters in aquatic lives remained poorly understood. In an effort to find alternative plasticizers we examined the developmental toxicity of tributyl O-acetylcitrate (ATBC), triethyl 2-acetylcitrate (ATEC) and trihexyl O-acetylcitrate (ATHC) together with dibutyl phthalate (DBP) as the positive control in Xenopus laevis embryos based on Frog Embryo Teratogenesis Assay Xenopus (FETAX). In X. laevis embryos LC50 and EC50 values of ATBC at 96 hours were calculated to be 12.7 ppm (13.3 mg/L) and 11.6 ppm (12.2 mg/L). The LC50 and EC50 values of ATEC at 96 hours were calculated to be 360.6 ppm (409.6 mg/L) and 364.3 ppm (413.8 mg/L), respectively. The LC50 values of ATHC at 96 hours were calculated to be 97.5 ppm (98.0 mg/L). The LC50 and EC50 values of dibutyl phthalate (DBP) at 96 hours were calculated to be 12.7 ppm (13.2 mg/L) and 7.1 ppm (7.4 mg/L), respectively. Developmental abnormality such as head malformation, gut malformation, bent trunk, ventral blister, abnormal tail and myotome were significantly increased by DBP at 8.9 ppm, and which was observed by citrate esters at much higher concentration (ATEC, 320 ppm; ATHC, > 75 ppm; ATBC, 15 ppm). In DBP treated embryos, overgrowth of nostrils was frequently observed and growth was inhibited at 6 ppm. ATEC and ATBC inhibited growth at 80 and 15 ppm, respectively. In ATHC treated embryos, the head and tail length were significantly increased at 14.8 ppm. Lipid peroxidation in tadpoles was significantly increased by DBP (10 ppm) but not by ATEC, ATBC, and ATHC. In tadpoles pro-apoptotic bad, bax and bak mRNA levels and DNA fragmentation were significantly increased by DBP (10 ppm) but not by citrate esters. Together, citrate esters could be considered as substitution for phthalate esters as plastic plasticizers.