Marques Samara de Paula Pinheiro Menezes, Pinheiro Rafaela Oliveira, Nascimento Rafael Alves do, Andrade Eloísa Helena de Aguiar, Faria Lênio José Guerreiro de
Programa de Pós-Graduação em Engenharia dos Recursos Naturais da Amazônia, Universidade Federal do Pará, Belém 66075-110, Pará, Brazil.
Faculdade de Engenharia Química, Universidade Federal do Pará, Belém 66075-110, Pará, Brazil.
Molecules. 2023 Nov 14;28(22):7583. doi: 10.3390/molecules28227583.
In this study, we assessed the effects of different harvest times (9 a.m., 1 p.m., and 5 p.m.) and hydrodistillation times (60, 90, and 120 min) on the yield, chemical composition, and antioxidant activity of the spearmint ( L.) essential oil (EO) sourced from the Amazon region. EO yield was ≥1.55% and was not significantly influenced ( ≥ 0.05) by the different harvest times and hydrodistillation times. Thirty-one different organic compounds were identified, of which menthol (91.56-95.68%), menthone (0.6-2.72%), and isomenthone (0.55-1.46%) were the major constituents. The highest menthol content in the EO was obtained from samples collected at 9 a.m., with a hydrodistillation time of 60-90 min, compared to other harvest and hydrodistillation times. This suggests that exposure to sun and light, which is greater at harvest times of 1 p.m. and 5 p.m., decreased the menthol content and altered the chemical composition of Mentha EO. Furthermore, the sample harvested at 9 a.m. and hydrodistilled for 60 min showed the highest antioxidant activity (61.67 equivalent mg of Trolox per g of EO), indicating that antioxidant activity is strongly affected by light exposure and the contact duration of the sample with boiling water during hydrodistillation.
在本研究中，我们评估了不同采收时间（上午9点、下午1点和下午5点）和水蒸馏时间（60、90和120分钟）对源自亚马逊地区的留兰香（唇萼薄荷）精油（EO）的产量、化学成分和抗氧化活性的影响。EO产量≥1.55%，且不同采收时间和水蒸馏时间对其无显著影响（P≥0.05）。共鉴定出31种不同的有机化合物，其中薄荷醇（91.56 - 95.68%）、薄荷酮（0.6 - 2.72%）和异薄荷酮（0.55 - 1.46%）为主要成分。与其他采收和水蒸馏时间相比，上午9点采收、水蒸馏时间为60 - 90分钟的样品中EO的薄荷醇含量最高。这表明，下午1点和下午5点采收时，样品受到的阳光和光照更多，从而降低了薄荷醇含量并改变了留兰香EO的化学成分。此外，上午9点采收并水蒸馏60分钟的样品表现出最高的抗氧化活性（每克EO相当于61.67毫克Trolox），这表明抗氧化活性受光照以及水蒸馏过程中样品与沸水的接触时间的强烈影响。
