The toxicity of extracts of lavender (Lavandula officinalis) leaves and flowers was evaluated. Aqueous ethanolic and acetone extracts had higher tannin content than that in the aqueous solution. Polyphenol and flavonoid contents were measured in aqueous extracts of leaves and flowers. Polyphenol concentration in aqueous leaf and flower extracts was 61.31 and 84.43 mg tannic acid/g, respectively, whereas flavonoid concentration was 194.1 and 109.9 mg quercetin/g, respectively. Saponin content was 7.85% and 6.22% in leaves and flowers extract, respectively, and alkaloids content was 0.2651% and 0.2132% for leaves and flowers extract, respectively. The EC50 (36 h) of hatching success of Artemia salina cysts was 0.301 and 0.915 mg/mL for aqueous extracts of leaves and flowers, respectively, whereas that for aqueous ethanolic extracts of leaves and flowers, it was 0.111 and 0.586 mg/mL, respectively. The EC50 (36 h) was 0.011 mg/mL for tannic acid. Additionally, the LC50 (24 h) for aqueous extracts of leaves and flowers was 0.467 and 0.724 mg/mL, respectively, whereas that of the aqueous ethanolic extracts of leaves and flowers was 0.074 and 0.126 mg/mL, respectively. The LC50 was 0.015 mg/mL for tannic acid. Although aromatherapy using lavender oils or extracts is beneficial to human health, particularly owing to its anxiolytic, analgesic, and antihyperlipidemic effects, we demonstrated that these extracts might exhibit toxicity. Hence, lavender should be used carefully by health practitioners, and lavender therapies should be closely monitored by medical staff to avoid its toxic effects.
Keywords: Artemia salina; EC; LC; Lavandula officinalis; polyphenols; toxicity.