Screening of acute and sub-chronic dermal toxicity of Calendula officinalis L essential oil.

The objective of the study is to access the safety of Calendula essential oil by studying acute and sub-chronic dermal toxicity. The dermal toxicities of Calendula essential oil were evaluated in accordance with OECD guidelines number 402 and 411 respectively. The animals were exposed to Calendula officinalis (CO) essential oil dose of 20 mL/kg body weight for acute dermal toxicity, whereas for dermal sub-chronic toxicity study, rats were exposed to CO oil 2.5, 5 and 10 mL/kg body weight, respectively, for 7 times in a week for 90 days. The parameters studies included CNS stimulation, depression, hematological parameters (RBC, WBC, Hb, Lymphocyte % etc), biochemical parameters (total protein, albumin, total bilirubin, ALP, AST, etc), relative organ weight, necropsy and histopathology. In toxicity studies, all animals exhibited normal behavior without any change in hematology, blood biochemistry, necroscopical and histopathology. The no observed effect level (NOEL) and no observed adverse effect level (NOAEL) of CO oil were 2.5 and 10 mg/kg/day, respectively. CO oil is under the herbal medicinal product according to the European Medicines Agency with the claim of an LD50 value of 20 mL/kg body weight. The result indicates that CO essential oil did not produce any significant toxic effects.