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Chemopreventive Agents
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
The monoterpenoids (also called monoterpenes) are a diverse C10-subclass of the terpenoids consisting of two isoprene units. These compounds are often highly volatile, and so are often used as components of plant-based essential oils. Many are known for their antimicrobial activity which is attributed to their ability to disrupt membranes. Certain monoterpenoids are also reported to have cancer chemoprevention activity, examples of which include limonene and thymoquinone (Figure 12.28), which are described in more detail below. Structures of the monoterpenoids limonene and thymoquinone.
Essential Oils and Volatiles in Bryophytes
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Agnieszka Ludwiczuk, Yoshinori Asakawa
Monoterpenoids are compounds found in the essential oils obtained from many aromatic plants. These compounds contribute to the flavor and aroma of the plant from which they are extracted. However, this group of terpenoids is not dominant in terms of liverworts components. The available literature data show that monoterpenoids are usually present in complex thalloid liverworts. These terpenes are the major volatile components found in the liverworts belonging to genera of Asterella, Conocephalum, and Wiesnerella, and the most characteristic compounds are sabinene (11), α-pinene (12), limonene (13), and acetate derivatives of borneol (14), myrtenol, nerol (15), and geraniol (Ludwiczuk et al., 2008; Ludwiczuk and Asakawa, 2015). Selected fragrant components found in liverworts are presented in Figure 21.3.
Types of Raw Incense
Published in Kerry Hughes, The Incense Bible, 2014
Alpha-pinene is thought to be one of the main compounds contributing to frankincense’s characteristic fresh and balsamic odor, with gamma-butyrolactones lending strong coumarinic odors. The volatile components of Boswellia serrata essential oil have been found to be about thirty-five different chemical constituents of which alpha-pinene (73 percent) was the predominant constituent. Other monoterpenoids include beta-pinene (2.05 percent), cis-verbenol (1.97 percent), trans-pinocarveol (1.80 percent), borneol (1.78 percent), myrcene (1.71 percent), verbenone (1.71 percent), limonene (1.42 percent), thuja-2,4(10)-diene (1.18 percent) and p-cymene (1.0 percent). One sesquiterpene, alpha-copaene (0.13 percent), has been identified in the essential oil (Kasali et al., 2002).
Research progress on antiviral constituents in traditional Chinese medicines and their mechanisms of action
Published in Pharmaceutical Biology, 2022
Volatile oils, with monoterpenoids and sesquiterpenoids as the major components, refer to a class of aromatic oily liquids, which are volatile at room temperature and can be distilled with water vapour (Edris 2007). Volatile oils possess a broad spectrum of physiological activities, which are the main active constituents of many common antiviral traditional Chinese medicines such as Nepeta cataria Linn. (Labiatae) whole herb (Jingjie), Houttuynia cordata Thunb. (Saururaceae) overgroud part (Yuxingcao) and Lianqiao (Yuan et al. 2017; Lee, Wang et al. 2018; Řebíčková et al. 2020). A large number of studies have shown that volatile oils have antioxidant, antibacterial, antifungal and antiviral effects (Zhang, Huo, et al. 2020; Darwish et al. 2020; El-Alam et al. 2020). Because of the lipophile nature of the volatile oils, they are advocated to penetrate the viral membrane easily leading to membrane rupture. Volatiles oils contain a variety of active chemical components that synergize multiple stages of viral replication and have positive effects on the host respiratory system, including bronchiectasis and mucolysis (Youssef et al. 2020).
Synergistic antimicrobial combination of carvacrol and thymol impairs single and mixed-species biofilms of Candida albicans and Staphylococcus epidermidis
Published in Biofouling, 2020
Thirukannamangai Krishnan Swetha, Arumugam Vikraman, Chari Nithya, Nagaiah Hari Prasath, Shunmugiah Karutha Pandian
The C + T combination displayed potent antimicrobial activity against both planktonic and sessile cells of C. albicans and S. epidermidis, indicating this combination to be a potential alternative to manage mixed-species infections. The use of C + T as an antimicrobial coating on implants could impede single- and mixed-species biofilms, and reduce the rate of implant infections. Concerning toxicity, these monoterpenoids are categorized as generally recognized as safe compounds by the Food and Drug Administration. In addition, administration of feed containing 100mg kg−1 of C + T reduces weaning associated intestinal oxidative stress in pigs (Wei et al. 2017). Furthermore, Azizi et al. (2012) reported lethal dosage (LD50) values of 471mg kg−1 for C and 566mg kg1 for T, and described their efficacy in improving cognition in rat models of dementia. Another study reported mild to moderate genotoxic effects of C and T in vitro and insignificant toxicity in vivo (Stammati et al. 1999). Thus, identification of a safe dose range and profiling the toxicity and side effects of the C + T combination in various eukaryotic models are essential before clinical applications can be realized.
Chemical composition, enantiomeric analysis and anticholinesterase activity of Lepechinia betonicifolia essential oil from Ecuador
Published in Pharmaceutical Biology, 2022
James Calva, Luis Cartuche, Salomé González, José Vinicio Montesinos, Vladimir Morocho
Few studies of Lepechinia species showing cholinesterase activity have been conducted, among them, L. paniculata showed IC50 values of 28.2 ± 1.8 2 µg/mL (Panamito et al. 2021). According to the study conducted by Miyazawa and Yamafuji (2005) analysing the inhibitory potency of 17 kinds of bicyclic monoterpenoids, the (+) and (–)-α-pinene enantiomers showed moderate inhibitory activity against AChE with an IC50 value of 0.4 and 0.44 mM, respectively, meanwhile, the (–)-β-pinene isomer exerted a low inhibition (48.5%) at 1.0 mM dose. For sabinene, an IC50 value of 176.5 µg/mL against AChE was determined by Bonesi et al. (2010). In our work, sabinene and β-pinene account for more than 57% of the chemical composition of the EO, and from the enantiomeric analysis we can determine that the main enantiomers are (–)-β-pinene with >96% e.e. and (+) sabinene with 93.56% e.e. which can explain the fact that the EO exert a good inhibitory activity against AChE. Further studies should be conducted to determine the inhibitory profile of the enantiomers found in this study against AChE as well as their kinetics mechanisms. Monoterpenoids should be assessed as individual compounds or as a mixture as presented in the essential oil to characterise completely the inhibitory effect observed over AChE. Despite the low yield obtained for the EO, the identification of the inhibitory profile of the compounds or the mixture as they are occurring in this EO could provide the information to propose a formulation as adjuvant therapy in the treatment of neurodegenerative diseases such as Alzheimer’s disease.