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Biotransformation of Monoterpenoids by Microorganisms, Insects, and Mammals
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Yoshiaki Noma, Yoshinori Asakawa
(−)-β-Pinene (1′) was at first biotransformed by A. niger TBUYN-2 to give (+)-trans-pinocarveol (2a′) (274). (+)-trans-Pinocarveol (2a′) was further transformed by three pathways: First, (+)-trans-pinocarveol (2a′) was metabolized to (+)-pinocarvone (3′), (−)-3-isopinanone (413′), (+)-2α-hydroxy-3-pinanone (414′), and (+)-2α,5-dihydroxy-3-pinanone (415′). Second, (+)-trans-pinocarveol (2a′) was metabolized to (+)-6β-hydroxyfenchol (349ba′), and third, (+)-trans-pinocarveol (2a′) was metabolized to (−)-6β,7-dihydroxyfenchol (412ba′) via epoxide and diol as intermediates (Noma and Asakawa, 2005a) (Figure 22.160).
Metabolic conversion of β-pinene to β-ionone in rats
Published in Xenobiotica, 2021
Lujain Aloum, Mohammad H. Semreen, Taleb H. Al-Tel, Hamza Al-Hroub, Muath Mousa, Richard L. Jayaraj, Eman Alefishat, Abdu Adem, Georg A Petroianu
Overall, essential oils and their constituents are considered to have a minimum of a biphasic elimination profile. This indicates that these compounds are not confined to the blood but rather distribute to tissues which is reflected in their high volume of distribution. However, the accumulation is most likely not to occur as these compounds have short half-lives and high clearance (Kohlert et al. 2000). Indeed, the elimination half-life of the human urinary metabolites of oral α-pinene ranged from 1.4 to 1.6 hours. A secondary slower excretion phase was detected most likely due to small amount of α-pinene release from tissues; the concentration of the metabolites reached the pre-exposure level within 24 hours (Schmidt and Göen 2017). Thus, we believe that the 72 hours window of urine collection is sufficient to ensure the detection of ionone metabolite. Ishida et al. identified distinct metabolites of α-pinene and β-pinene in rabbits. The neutral metabolites of β-pinene include (+)-trans-Pinocarveol, (–)-trans-10-Pinanol, (–)-1-p-Menthene-7,8-diol, and (–)-α-terpineol, while the acidic metabolites included myrtenic acid. It was suggested that endocyclic allylic hydroxylation of β-pinene produced a trans-Pinocarveol metabolite. The β-pinene dose used in this study was almost double the maximum (–)-β-pinene dose administered to rabbits in Ishida et al. (1981) (670 mg/kg) (Ishida et al. 1981). Thus, we suggest that the transformation of β-pinene to β-ionone is an additional metabolic pathway that may occur only with higher doses of β-pinene, possibly upon saturation of other pathways.
Myrothamnus flabellifolius Welw. (Myrothamnaceae) essential oil scavenges free radicals and inhibits carbohydrate-metabolizing enzymes in vitro
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Abdulwakeel Ayokun-nun Ajao, Fatai Oladunni Balogun, Saheed Sabiu, Anofi O. Tom Ashafa
It is important to note that antioxidant and postprandial hyperglycemia control demonstrated by M. flabellifolius essential oil in this study could be attributed to either sole or synergistic bioactivities of the monoterpenoid compounds identified in the oil. α- pinene and eucalyptol (1,8-cineole) have previously been reported to reduce ferric and DPPH radicals [10,36]. The possible mechanism of antidiabetic action of MFEO could be linked to myrcene, the major component of MFEO, which has been reported to inhibit the proinflammatory cytokine (IL-6) and TNFa by stimulating NF-kB in streptozotocin-induced diabetic rats [37]. Other identified compounds in the oil, such as linalool, limonene, and camphene, have also been reported to have antioxidative properties [38,39]. However, besides linalool being an antioxidant that can mediate postprandial hyperglycemia onslaught, it can also act as a cardiovascular modulator, analgesic, and antianxiety agent with no pharmacological side effects [40]. This could be a practical approach to control oxidative stress-linked postprandial hyperglycemia. Moreover, a previous study by Talpur et al. [41] has demonstrated that administering combined essential oils, cinnamon, myrtle, fennel, cumin, oregano, etc., orally improves the sensitivity of insulin in non-insulin-dependent diabetes. There were variations in the major constituents of the essential oil from M. flabellifolius leaves reported in the present study, which were β- myrcene (37.1%) and mentha-1,5,8-triene (24.9%) compared to the previous reports. Viljoen et al. [42] reported pinocarvone (11.13%) and trans-pinocarveol (19.57%) as the major terpenoids of M. flabellifolius aerial part from South Africa, carvone and perillic acid were indicated as the major constituents of M. flabellifolius from Angola [43]. The principal components of essential oil from M. flabellifolius leaves from Zimbabwe were β-selinene (5.0–9.9%), pinocarvone (13.4–21.3%), α-pinene (tr-23.0%), trans-pinocarveol (28.7–28.8%) [44]. The variation observed in the reported major constituents of M. flabellifolius compared to the present study may be due to several factors, which include part of the plant used, age/stage of maturity, the season of harvest, method of extraction, genetic differences, geographical origin, etc [45,46].