Background: The essential oils of Mentha species are used in pharmaceutical, cosmetic and
perfume industry and also for flavoring and preservation of several food. Moreover, Mint's essential oils
are also searched for their biological activities such as antimicrobial, antioxidant, and cytotoxic properties.
Mentha mozaffarianii is an endemic medicinal mint of Iran rich in essential oil, but not yet studied
for its cytotxic activity nor the effect of changing seasons on its chemical composition and biological
Method: We analyzed the chemical constituents of essential oils (EOs) of M. mozaffarianii at different
phenological stages (vegetative, flowering and seed set) by GC-MS and GC-FID. Also, the EOs were
evaluated for their cytotoxic potential on three human cancer cell lines namely, breast adenocarcinoma
(MCF-7), acute lymphoblastic leukemia (MOLT-4) and acute promyelocytic leukemia cells (HL-60)
using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay.
Results: Twenty seven, 26 and 25 compounds were detected in the oils at vegetative, flowering and
seed set stages, respectively. The predominant components in the oils of the plant were: piperitone oxide
(32.9±1.2, 35.3±1.2 and 51.5±0.6%), linalool (14.1±0.3, 17.1±0.6 and 8.7±016%), 1,8-cineole
(11.6±1.4, 9.5±0.3 and 8.3±0.26%) and piperitenone oxide (9.8±0.4, 8.1±0.3 and 1.7±0.05%), during
the above mentioned developmental stages, respectively. EOs of M. mozaffarianii at the different phenological
stages showed the highest cytotoxic activities against MOLT-4 (IC50s: 26.5±6.7, 26.5±2.3 and
22.3±5.4 µg/mL, respectively) followed by HL-60 and MCF-7 cell lines.
Conclusion: The results of the present study indicate that the EOs obtained from different phenological
stages of the plant showed relatively high cytotoxic activity, which can be attributed to the presence of
the oxygenated monoterpenes with highest amounts of piperitone oxide and its derivatives.