*2.6.* β*-Caryophyllene Toxicity*

BCP is classified according to OECD (Organization for Economic Co-operation and Development) guideline 423 as a category five substance (toxic at doses greater than 2000 mg/kg) [65].

Studies about acute toxicity have been carried out. The oral administration of 2000 mg/kg of the molecule in female Swiss mice induces no toxic e ffects [10], whereas in rats an LD50 greater than 5000 mg/kg has been calculated [62].

Subchronic toxicity (90 days) has been assessed in studies in Wistar rats, which do not show toxicity at the dose of 700 mg/kg/die [62], and in female Swiss mice, which are not altered in terms of locomotion and muscle tone with both single and repeated doses [10].

In rodents, overall absence of neurotoxicity at the dosages used to study pharmacological e ffects (20 to 100 mg/kg) has been found [10,41]. Moreover, in various studies, no damage to the gastric mucosa has been observed, nor changes in other internal organs (brain, heart, liver, lungs, spleen, kidneys) or in haematological parameters have been reported both in female Swiss mice and in Wistar rats [10,62]. Moreover, an Ames test has shown no mutagenicity [63].

Body weight has resulted decreased by 5% in female Swiss mice, even if this variation is not significant [10]. Nevertheless, even though this molecule is safe, at least in animal studies, greater consideration is needed of the possible interactions of the sesquiterpene with drugs and other molecules contained in the food. In fact, a research conducted on subcellular fractions of hepatic tissue of rats and humans, demonstrates a significant inhibition by BCP and its derivatives BCPO and α-humulene against enzymes involved in metabolism and xenobiotic detoxification. Xenobiotics undergo metabolic biotransformations, followed by degradation and subsequent elimination. It is evident that the inhibitory e ffects exerted by BCP on drug metabolizing enzymes considerably increases the levels of drugs in the organism, with prolonged duration of action and increased toxicity. This makes absolutely necessary a variation of the posology of drugs taken at the same time of enzymatic inhibitors. The extent of the inhibition of cytochrome P450 isoform CYP1A2 (Cytochrome P450 Family 1 Subfamily A Member 2) is greater in rat microsomes than in human ones and, above all, BCPO is able to competitively inhibit the enzyme in rats and humans through a non-competitive mechanism. However, BCP and α-humulene result less powerful than BCPO [64].

Furthermore, they have a fair capability to inhibit CYP3A4, involved in the metabolism of many xenobiotics, such as ciclosporin, paclitaxel, ketoconazole, verapamil, nifedipine, omeprazole, statins, various sexual hormones and drugs. The inhibition causes the increase of medicine levels, which could determine severe side e ffects. Finally, the three terpenes exert a weak inhibition against the isoforms CYP2A6 (Cytochrome P450 Family 2 Subfamily A Member 6), CYP2B6 (Cytochrome P450 Family 2 Subfamily B Member 6), CYP2C9 (Cytochrome P450 Family 2 Subfamily C Member 9), CYP2C19 (Cytochrome P450 Family 2 Subfamily C Member 19), CYP2D6 (Cytochrome P450 Family 2 Subfamily D Member 6), CYP2E1 (Cytochrome P450 Family 2 Subfamily E Member 1) [64].
