Risk assessment of in vitro cytotoxicity, antioxidant and antimicrobial activities of Mentha piperita L. essential oil.

The objective of this study was to determine the chemical composition as well as antioxidant, antibacterial, and cytotoxic properties of the essential oil of Mentha piperita L. (peppermint). Fifteen chemical constituents were identified in the essential oil, for a total of 99.99% of the compounds. The essential oil exhibited antimicrobial activity against two Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes. The minimum inhibitory concentration (MIC) of essential oil of Mentha piperita L. for Staphylococcus aureus and Listeria monocytogenes was 1.84 µg/ml, whereas the minimum bactericidal concentration (MBC) values were 3.7 and 7.43 µg/ml, respectively. The oil displayed potent antioxidant activity inhibiting up to approximately73% of 2,2'-azinothiobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. In the cytotoxicity assay, the highest essential oil concentration (100 µg/ml) resulted in viability of approximately 90% human epidermal keratinocyte (HaCaT) cells. With respect to antitumor activity in C6 rat glioma cells, there was significant reduction in cell viability: 56-74% in 24 hr, and 71-77% in 48 hr. Data suggest that in presence of the essential oil of Mentha piperita L. antioxidant, antibacterial, antitumor and non-cytotoxic properties were noted.

Peppermint and its respective active component in diets of broiler chickens: growth performance, viability, economics, meat physicochemical properties, and carcass characteristics.

This study was conducted to investigate effects of dietary peppermint leaves and menthol supplementations on performance, survivability rate, cost economics, meat physicochemical properties, and carcass characteristics of broiler chicks. A total of 384 1-day-old, unsexed Ross 308 broiler chicks, were divided into 2 experiments. Each experiment included 192 birds that were assigned to 4 dietary treatments that included peppermint leaves at concentrations of 0, 5, 10, or 15 g/kg in the first experiment or menthol at concentrations of 0, 26, 52, or 78 mg/kg in the second experiment. Each treatment had 6 replicate pens with 8 birds. The experiments lasted for 35 D. The peppermint leaves contained 1.48% essential oil that contained 35.1% menthol, and the levels of menthol were selected based on the concentrations in peppermint leaf levels. Body weight and body-weight gain increased with the increase in dietary peppermint leaves (linear, P < 0.01) and menthol concentrations (linear, quadratic, P < 0.01) during the trial periods. In addition, the feed intake linearly increased (P < 0.01) with increasing peppermint leaves or menthol levels and, in turn, caused linear improvements (P < 0.01) in feed conversion values. Interestingly, a lower mortality rate was recorded in the supplementation groups and, therefore, a higher net return was observed. However, pH values and drip loss percentage of breast and leg muscles were not affected by either dietary peppermint levels or menthol levels. Increasing peppermint or menthol levels decreased (P < 0.001) cook-loss percentage of breast and leg muscles. On the other hand, dietary supplementation of peppermint leaves or menthol had no effect (P ≥ 0.05) on the relative weights of dressing, breast, leg, liver, heart, gizzard, spleen, or pancreas. Interestingly, abdominal fat percentage was decreased by either supplemental peppermint or menthol. Hence, the present investigation demonstrates that peppermint leaves can be used as an effective novel nutritional bio-agent up to 15 g/kg to improve the performance of broiler chicks, mainly due to its active component.

Comparative Chemical Analysis of Mentha piperita and M. spicata and a Fast Assessment of Commercial Peppermint Teas.

The hydrodistilled essential oils and volatile compounds (by static headspaces technique) of Mentha piperita L. and M spicata L. were characterized by GC-MS. Headspace analysis of Mentha piperita revealed the existence of menthone (25.4%), 1,8-cineole (17.7%) and menthol (12.1%) as the main components, while the essential oil contained high amounts of menthol (46.8%) and menthone (25.6%). By contrast, headspace analysis of M. spicata showed a high content of limonene (37.0%) together with carvone (13.0%), ß-pinene (10.4%) and α-pinene (9.8%), while the essential oil was reach in carvone (51.7%), dihydrocarveol (11.5%) and cis-dihydrocarvone (9.1%). Eleven samples of peppermint tea available on the Romanian market were analysed by headspace GC-MS. The volatile profile of the tea samples was compared with that of Mentha piperita L. and certain differences were emphasized and discussed.

Assessment of vacuum-dried peppermint (Mentha piperita L.) as a source of natural antioxidants.

The purpose of this study was to investigate the effect of temperature in the vacuum drying process of Mentha piperita L. (50 to 90 °C). Generally, drying processes affect the quality of product, however, vacuum drying works under sub-atmospheric pressures. In order to investigate how temperature affects this herb, as to color, chlorophyll, total phenolic (TPC), total flavonoid (TFC) contents, antioxidant activity by DPPH and ORAC methods. Mineral, vitamin C and sugar contents were also evaluated. A slight change in color and chlorophyll content was observed in the samples. The highest values for TPC, TFC and antioxidant activity methods were obtained at 50 and 70 °C however, a decrease in the vitamin C content was observed. Minerals such as K, Ca, Mg and Na were found. Sucrose showed the highest sugar content. This work suggests that M. piperita L. can be used as a natural antioxidant, whether fresh or dried.