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1.
Mol Plant ; 17(7): 1129-1150, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38835170

ABSTRACT

Mescaline, among the earliest identified natural hallucinogens, holds great potential in psychotherapy treatment. Nonetheless, despite the existence of a postulated biosynthetic pathway for more than half a century, the specific enzymes involved in this process are yet to be identified. In this study, we investigated the cactus Lophophora williamsii (Peyote), the largest known natural producer of the phenethylamine mescaline. We employed a multi-faceted approach, combining de novo whole-genome and transcriptome sequencing with comprehensive chemical profiling, enzymatic assays, molecular modeling, and pathway engineering for pathway elucidation. We identified four groups of enzymes responsible for the six catalytic steps in the mescaline biosynthetic pathway, and an N-methyltransferase enzyme that N-methylates all phenethylamine intermediates, likely modulating mescaline levels in Peyote. Finally, we reconstructed the mescaline biosynthetic pathway in both Nicotiana benthamiana plants and yeast cells, providing novel insights into several challenges hindering complete heterologous mescaline production. Taken together, our study opens up avenues for exploration of sustainable production approaches and responsible utilization of mescaline, safeguarding this valuable natural resource for future generations.


Subject(s)
Biosynthetic Pathways , Hallucinogens , Mescaline , Hallucinogens/metabolism , Mescaline/metabolism , Nicotiana/metabolism , Nicotiana/genetics , Plant Proteins/metabolism , Plant Proteins/genetics
3.
Nat Plants ; 9(5): 817-831, 2023 05.
Article in English | MEDLINE | ID: mdl-37127748

ABSTRACT

Modulation of the endocannabinoid system is projected to have therapeutic potential in almost all human diseases. Accordingly, the high demand for novel cannabinoids stimulates the discovery of untapped sources and efficient manufacturing technologies. Here we explored Helichrysum umbraculigerum, an Asteraceae species unrelated to Cannabis sativa that produces Cannabis-type cannabinoids (for example, 4.3% cannabigerolic acid). In contrast to Cannabis, cannabinoids in H. umbraculigerum accumulate in leaves' glandular trichomes rather than in flowers. The integration of de novo whole-genome sequencing data with unambiguous chemical structure annotation, enzymatic assays and pathway reconstitution in Nicotiana benthamiana and in Saccharomyces cerevisiae has uncovered the molecular and chemical features of this plant. Apart from core biosynthetic enzymes, we reveal tailoring ones producing previously unknown cannabinoid metabolites. Orthology analyses demonstrate that cannabinoid synthesis evolved in parallel in H. umbraculigerum and Cannabis. Our discovery provides a currently unexploited source of cannabinoids and tools for engineering in heterologous hosts.


Subject(s)
Cannabinoids , Cannabis , Humans , Cannabinoids/metabolism , Cannabis/genetics , Flowers/metabolism , Plant Leaves/metabolism
5.
Front Pharmacol ; 13: 894960, 2022.
Article in English | MEDLINE | ID: mdl-35548332

ABSTRACT

Medical Cannabis and its major cannabinoids (-)-trans-Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are gaining momentum for various medical purposes as their therapeutic qualities are becoming better established. However, studies regarding their efficacy are oftentimes inconclusive. This is chiefly because Cannabis is a versatile plant rather than a single drug and its effects do not depend only on the amount of THC and CBD. Hundreds of Cannabis cultivars and hybrids exist worldwide, each with a unique and distinct chemical profile. Most studies focus on THC and CBD, but these are just two of over 140 phytocannabinoids found in the plant in addition to a milieu of terpenoids, flavonoids and other compounds with potential therapeutic activities. Different plants contain a very different array of these metabolites in varying relative ratios, and it is the interplay between these molecules from the plant and the endocannabinoid system in the body that determines the ultimate therapeutic response and associated adverse effects. Here, we discuss how phytocannabinoid profiles differ between plants depending on the chemovar types, review the major factors that affect secondary metabolite accumulation in the plant including the genotype, growth conditions, processing, storage and the delivery route; and highlight how these factors make Cannabis treatment highly complex.

7.
Pain ; 163(5): 975-983, 2022 05 01.
Article in English | MEDLINE | ID: mdl-34538843

ABSTRACT

ABSTRACT: Studies have shown that women are more susceptible to adverse effects (AEs) from conventional drugs. This study aimed to investigate the differences of medical cannabis (MC)-related AEs between women and men in patients with chronic noncancer pain (CNCP). This is a cross-sectional study of adult patients licensed for MC treatment who were also diagnosed as patients with CNCP by a physician. Data included self-reported questionnaires and comprehensive MC treatment information. Simultaneously, identification and quantification of phytocannabinoids and terpenoids from the MC cultivars were performed. Comparative statistics were used to evaluate differences between men and women. Four hundred twenty-nine patients with CNCP (64% males) reported fully on their MC treatment. Subgrouping by sex demonstrated that the weight-adjusted doses were similar between men and women (0.48 [0.33-0.6] gr for men and 0.47 [0.34-0.66] gr for women). Nonetheless, women reported more than men on MC-related AEs. Further analysis revealed that women consumed different MC cultivar combinations than men, with significantly higher monthly doses of the phytocannabinoids CBD and CBC and significantly lower monthly doses of the phytocannabinoid 373-15c and the terpenoid linalool. Our findings demonstrate sex differences in MC-related AEs among patients with CNCP. Women are more susceptible to MC-related AEs, presumably because of both the inherent sex effect and the consumption of specific phytocannabinoid compositions in the MC cultivar(s). The understanding of these differences may be crucial for planning MC treatments with safer phytocannabinoid and terpenoid compositions and to better inform patients of expected AEs.


Subject(s)
Chronic Pain , Medical Marijuana , Adult , Analgesics, Opioid/therapeutic use , Chronic Pain/drug therapy , Cross-Sectional Studies , Female , Humans , Male , Medical Marijuana/adverse effects , Sex Characteristics , Terpenes/therapeutic use
8.
Front Plant Sci ; 12: 753847, 2021.
Article in English | MEDLINE | ID: mdl-34804093

ABSTRACT

In the last decades, growing evidence showed the therapeutic capabilities of Cannabis plants. These capabilities were attributed to the specialized secondary metabolites stored in the glandular trichomes of female inflorescences, mainly phytocannabinoids and terpenoids. The accumulation of the metabolites in the flower is versatile and influenced by a largely unknown regulation system, attributed to genetic, developmental and environmental factors. As Cannabis is a dioecious plant, one main factor is fertilization after successful pollination. Fertilized flowers are considerably less potent, likely due to changes in the contents of phytocannabinoids and terpenoids; therefore, this study examined the effect of fertilization on metabolite composition by crossbreeding (-)-Δ9-trans-tetrahydrocannabinol (THC)- or cannabidiol (CBD)-rich female plants with different male plants: THC-rich, CBD-rich, or the original female plant induced to develop male pollen sacs. We used advanced analytical methods to assess the phytocannabinoids and terpenoids content, including a newly developed semi-quantitative analysis for terpenoids without analytical standards. We found that fertilization significantly decreased phytocannabinoids content. For terpenoids, the subgroup of monoterpenoids had similar trends to the phytocannabinoids, proposing both are commonly regulated in the plant. The sesquiterpenoids remained unchanged in the THC-rich female and had a trend of decrease in the CBD-rich female. Additionally, specific phytocannabinoids and terpenoids showed an uncommon increase in concentration followed by fertilization with particular male plants. Our results demonstrate that although the profile of phytocannabinoids and their relative ratios were kept, fertilization substantially decreased the concentration of nearly all phytocannabinoids in the plant regardless of the type of fertilizing male. Our findings may point to the functional roles of secondary metabolites in Cannabis.

9.
Front Pharmacol ; 12: 613805, 2021.
Article in English | MEDLINE | ID: mdl-34093173

ABSTRACT

Introduction: Chronic non-cancer pain (CNCP) is one of the most prevalent indications for medical cannabis (MC) treatment globally. In this study, we investigated CNCP parameters in patients during prolonged MC treatment, and assessed the interrelation between CNCP parameters and the chemical composition of MC chemovar used. Methods: A cross-sectional questionnaire-based study was performed in one-month intervals for the duration of six months. Subjects were adult patients licensed for MC treatment who also reported a diagnosis of CNCP by a physician. Data included self-reported questionnaires. MC treatment features included administration route, cultivator, cultivar name and monthly dose. Comparison statistics were used to evaluate differences between the abovementioned parameters and the monthly MC chemovar doses at each time point. Results: 429, 150, 98, 71, 77 and 82 patients reported fully on their MC treatment regimens at six one-month intervals, respectively. Although pain intensities did not change during the study period, analgesic medication consumption rates decreased from 46 to 28% (p < 0.005) and good Quality of Life (QoL) rates increased from 49 to 62% (p < 0.05). These changes overlapped with increase in rates of (-)-Δ9-trans-tetrahydrocannabinol (THC) and α-pinene high dose consumption. Conclusion: Even though we observed that pain intensities did not improve during the study, QoL did improve and the rate of analgesic medication consumption decreased alongside with increasing rates of high dose THC and α-pinene consumption. Understanding MC treatment composition may shed light on its long-term effects.

10.
Pharmacol Res ; 169: 105651, 2021 07.
Article in English | MEDLINE | ID: mdl-34000362

ABSTRACT

Medical cannabis (MC) treatment for chronic pain is increasing, but evidence regarding short- and long-term efficacy and associated adverse effects (AEs) of the different cannabis plant components is limited. Most reports focus on two phytocannabinoids, (-)-Δ9-trans-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). This study, aimed to identify patterns of phytocannabinoid compositions associated with MC treatment response and with related AEs. Participants in this multicenter prospective cohort were patients with chronic non-cancer pain that were prescribed MC by physicians. Data was collected before MC treatment, at one month (short-term) and at 12 months (long-term). Simultaneously, liquid chromatography mass spectrometry identification and quantification of phytocannabinoids from the cultivars were performed. The monthly dose of each phytocannabinoid for each patient was z-scaled and clustered into ten groups to assess the difference in analgesic treatment response (≥30%/50% pain intensity reduction) and AEs rates. We identified ten clusters that had similar analgesic treatment response rates. However, there were significant differences in AEs rates both at short- and long-term. We identified specific phytocannabinoid compositions that were associated with overall AEs rates (5% compared to 53% at short-term and 44% at long-term) and with specific AEs rates such as MC related central nervous system, gastrointestinal and psychological AEs. To conclude, Evaluating only Δ9-THC or CBD is insufficient to find associations with MC related AEs. Therefore, comprehensive profiling of phytocannabinoids is needed to discover associations to related AEs and help physicians prescribe safer cannabis with less AEs while still relieving pain.


Subject(s)
Cannabinoids/therapeutic use , Chronic Pain/drug therapy , Medical Marijuana/therapeutic use , Adult , Cannabinoids/analysis , Cannabinoids/pharmacology , Female , Humans , Male , Medical Marijuana/adverse effects , Medical Marijuana/chemistry , Middle Aged , Prospective Studies , Surveys and Questionnaires , Treatment Outcome
11.
Front Plant Sci ; 11: 583605, 2020.
Article in English | MEDLINE | ID: mdl-33178249

ABSTRACT

The therapeutic use of medical Cannabis is growing, and so is the need for standardized and therapeutically stable Cannabis products for patients. The therapeutic effects of Cannabis largely depend on the content of its pharmacologically active secondary metabolites and their interactions, mainly terpenoids and phytocannabinoids. Once harvested and during storage, these natural compounds may decarboxylate, oxidize, isomerize, react photochemically, evaporate and more. Despite its widespread and increasing use, however, data on the stability of most of the plant's terpenoids and phytocannabinoids during storage is scarce. In this study, we therefore aimed to determine postharvest optimal storage conditions for preserving the composition of naturally biosynthesized secondary metabolites in Cannabis inflorescences and Cannabis extracts. To this end, Cannabis inflorescences (whole versus ground samples) and Cannabis extracts (dissolved in different solvents) from (-)-Δ9-trans-tetrahydrocannabinol- or cannabidiol-rich chemovars, were stored in the dark at various temperatures (25, 4, -30 and -80°C), and their phytocannabinoid and terpenoid profiles were analyzed over the course of 1 year. We found that in both Cannabis inflorescences and extracts, a storage temperature of 25°C led to the largest changes in the concentrations of the natural phytocannabinoids over time, making this the most unfavorable temperature compared with all others examined here. Olive oil was found to be the best vehicle for preserving the natural phytocannabinoid composition of the extracts. Terpenoid concentrations were found to decrease rapidly under all storage conditions, but temperatures lower than -20°C and grinding of the inflorescences were the least favorable conditions. Overall, our conclusions point that storage of whole inflorescences and extracts dissolved in olive oil, at 4°C, were the optimal postharvest conditions for Cannabis.

12.
Cancers (Basel) ; 12(9)2020 Aug 28.
Article in English | MEDLINE | ID: mdl-32872248

ABSTRACT

Cannabis or its derivatives are widely used by patients with cancer to help with cancer symptoms and treatment side effects. However, cannabis has potent immunomodulatory properties. To determine if cannabis consumption during immunotherapy affects therapy outcomes, we conducted a prospective observatory study including 102 (68 immunotherapy and 34 immunotherapy plus cannabis) consecutive patients with advanced cancers who initiated immunotherapy. Cannabis consumption correlated with a significant decrease in time to tumor progression and overall survival. On the other hand, the use of cannabis reduced therapy-related immune-related adverse events. We also tested the possibility that cannabis may affect the immune system or the tumor microenvironment through the alteration of the endocannabinoid system. We analyzed a panel of serum endocannabinoids (eCBs) and eCB-like lipids, measuring their levels before and after immunotherapy in both groups. Levels of serum eCBs and eCB-like lipids, before immunotherapy, showed no significant differences between cannabis users to nonusers. Nevertheless, the levels of four eCB and eCB-like compounds were associated with patients' overall survival time. Collectively, cannabis consumption has considerable immunomodulatory effects, and its use among cancer patients needs to be carefully considered due to its potential effects on the immune system, especially during treatment with immunotherapy.

13.
Talanta ; 219: 121336, 2020 Nov 01.
Article in English | MEDLINE | ID: mdl-32887067

ABSTRACT

Increasing evidence for the therapeutic potential of Cannabis in numerous pathological and physiological conditions has led to a surge of studies investigating the active compounds in different chemovars and their mechanisms of action, as well as their efficacy and safety. The biological effects of Cannabis have been attributed to phytocannabinoid modulation of the endocannabinoid system. In-vitro and in-vivo studies have shown that pure phytocannabinoids can alter the levels of endocannabinoids and other cannabimimetic lipids. However, it is not yet understood whether whole Cannabis extracts exert variable effects on the endocannabinoid metabolome, and whether these effects vary between tissues. To address these challenges, we have developed and validated a novel analytical approach, termed "cannabinoidomics," for the simultaneous extraction and analysis of both endogenous and plant cannabinoids from different biological matrices. In the methodological development liquid chromatography high resolution tandem mass spectrometry (LC/HRMS/MS) was used to identify 57 phytocannabinoids, 15 major phytocannabinoid metabolites, and 78 endocannabinoids and cannabimimetic lipids in different biological matrices, most of which have no analytical standards. In the validation process, spiked cannabinoids were quantified with acceptable selectivity, repeatability, reproducibility, sensitivity, and accuracy. The power of this analytical method is demonstrated by analysis of serum and four different sections of mouse brains challenged with three different cannabidiol (CBD)-rich extracts. The results demonstrate that variations in the minor phytocannabinoid contents of the different extracts may lead to varied effects on endocannabinoid concentrations, and on the CBD metabolite profile in the peripheral and central systems. We also show that the Cannabis challenge significantly decreases the levels of several endocannabinoids in specific brain sections compared to the control group. This effect is extract-specific and suggests the importance of minor, other-than CBD, phytocannabinoid or non-phytocannabinoid compounds.


Subject(s)
Cannabis , Medical Marijuana , Animals , Endocannabinoids , Metabolome , Mice , Reproducibility of Results
14.
Brain Sci ; 10(6)2020 Jun 09.
Article in English | MEDLINE | ID: mdl-32526965

ABSTRACT

BACKGROUND: Medical cannabis (MC) treatment for migraine is practically emerging, although sufficient clinical data are not available for this indication. This cross-sectional questionnaire-based study aimed to investigate the associations between phytocannabinoid treatment and migraine frequency. METHODS: Participants were migraine patients licensed for MC treatment. Data included self-reported questionnaires and MC treatment features. Patients were retrospectively classified as responders vs. non-responders (≥50% vs. <50% decrease in monthly migraine attacks frequency following MC treatment initiation, respectively). Comparative statistics evaluated differences between these two subgroups. RESULTS: A total of 145 patients (97 females, 67%) with a median MC treatment duration of three years were analyzed. Compared to non-responders, responders (n = 89, 61%) reported lower current migraine disability and lower negative impact, and lower rates of opioid and triptan consumption. Subgroup analysis demonstrated that responders consumed higher doses of the phytocannabinoid ms_373_15c and lower doses of the phytocannabinoid ms_331_18d (3.40 95% CI (1.10 to 12.00); p < 0.01 and 0.22 95% CI (0.05-0.72); p < 0.05, respectively). CONCLUSIONS: These findings indicate that MC results in long-term reduction of migraine frequency in >60% of treated patients and is associated with less disability and lower antimigraine medication intake. They also point to the MC composition, which may be potentially efficacious in migraine patients.

15.
ACS Appl Mater Interfaces ; 12(21): 23707-23716, 2020 May 27.
Article in English | MEDLINE | ID: mdl-32369348

ABSTRACT

The therapeutic effect of the Cannabis plant largely depends on the presence and specific ratio of a spectrum of phytocannabinoids. Although prescription of medicinal Cannabis for various conditions constantly grows, its consumption is mostly limited to oral or respiratory pathways, impeding its duration of action, bioavailability, and efficacy. Herein, a long-acting formulation in the form of melt-printed polymeric microdepots for full-spectrum cannabidiol (CBD)-rich extract administration is described. When injected subcutaneously in mice, the microdepots facilitate sustained release of the encapsulated extract over a two-week period. The prolonged delivery results in elevated serum levels of multiple, major and minor, phytocannabinoids for over 14 days, compared to Cannabis extract injection. A direct analysis of the microdepots retrieved from the injection site gives rise to an empirical model for the release kinetics of the phytocannabinoids as a function of their physical traits. As a proof of concept, we compare the long-term efficacy of a single administration of the microdepots to a single administration of Cannabis extract in a pentylenetetrazol-induced convulsion model. One week following administration, the microdepots reduce the incidence of tonic-clonic seizures by 40%, increase the survival rate by 50%, and the latency to first tonic-clonic seizures by 170%. These results suggest that a long-term full-spectrum Cannabis delivery system may provide new form of Cannabis administration and treatments.


Subject(s)
Anticonvulsants/therapeutic use , Cannabidiol/therapeutic use , Cannabis/chemistry , Delayed-Action Preparations/therapeutic use , Plant Extracts/therapeutic use , Seizures/drug therapy , Animals , Anticonvulsants/chemistry , Anticonvulsants/pharmacokinetics , Cannabidiol/chemistry , Cannabidiol/pharmacokinetics , Delayed-Action Preparations/chemistry , Delayed-Action Preparations/pharmacokinetics , Drug Liberation , Mice , Pentylenetetrazole , Plant Extracts/chemistry , Plant Extracts/pharmacokinetics , Seizures/chemically induced
16.
Anal Chem ; 91(17): 11425-11432, 2019 09 03.
Article in English | MEDLINE | ID: mdl-31369251

ABSTRACT

The therapeutic effect of Cannabis largely depends on the content of its pharmacologically active secondary metabolites, mainly phytocannabinoids, flavonoids, and terpenoids. Recent studies suggest there are therapeutic effects of specific terpenoids as well as synergistic effects with other active compounds in the plant. Although Cannabis contains an overwhelming milieu of terpenoids, only a limited number are currently reported and used for metabolic analysis of Cannabis chemovars. In this study, we report the development and validation of a method for simultaneous quantification of 93 terpenoids in Cannabis air-dried inflorescences and extracts. This method employs the full evaporation technique via a static headspace sampler, followed by gas chromatography-mass spectrometry (SHS-GC/MS/MS). In the validation process, spiked terpenoids were quantified with acceptable repeatability, reproducibility, sensitivity, and accuracy. Three medical Cannabis chemovars were used to study the effect of sample preparation and extraction methods on terpenoid profiles. This method was further applied for studying the terpenoid profiles of 16 different chemovars acquired at different dates. Our results demonstrate that sample preparation methods may significantly impact the chemical fingerprint compared to the nontreated Cannabis. This emphasizes the importance of performing SHS extraction in order to study the natural terpenoid contents of chemovars. We also concluded that most inflorescences expressed relatively unique terpenoid profiles for the most pronounced terpenoids, even when sampled at different dates, although absolute concentrations may vary due to aging. The suggested method offers an ideal tool for terpenoid profiling of Cannabis and sets the scene for more comprehensive works in the future.


Subject(s)
Cannabis/chemistry , Tandem Mass Spectrometry/methods , Terpenes/analysis , Gas Chromatography-Mass Spectrometry , Specimen Handling
17.
Oncotarget ; 10(41): 4091-4106, 2019 Jun 25.
Article in English | MEDLINE | ID: mdl-31289609

ABSTRACT

The Cannabis plant contains over 100 phytocannabinoids and hundreds of other components. The biological effects and interplay of these Cannabis compounds are not fully understood and yet influence the plant's therapeutic effects. Here we assessed the antitumor effects of whole Cannabis extracts, which contained significant amounts of differing phytocannabinoids, on different cancer lines from various tumor origins. We first utilized our novel electrospray ionization liquid chromatography mass spectrometry method to analyze the phytocannabinoid contents of 124 Cannabis extracts. We then monitored the effects of 12 chosen different Cannabis extracts on 12 cancer cell lines. Our results show that specific Cannabis extracts impaired the survival and proliferation of cancer cell lines as well as induced apoptosis. Our findings showed that pure (-)-Δ9-trans-tetrahydrocannabinol (Δ9-THC) did not produce the same effects on these cell lines as the whole Cannabis extracts. Furthermore, Cannabis extracts with similar amounts of Δ9-THC produced significantly different effects on the survival of specific cancer cells. In addition, we demonstrated that specific Cannabis extracts may selectively and differentially affect cancer cells and differing cancer cell lines from the same organ origin. We also found that cannabimimetic receptors were differentially expressed among various cancer cell lines and suggest that this receptor diversity may contribute to the heterogeneous effects produced by the differing Cannabis extracts on each cell line. Our overall findings indicate that the effect of a Cannabis extract on a specific cancer cell line relies on the extract's composition as well as on certain characteristics of the targeted cells.

18.
Sci Rep ; 8(1): 14280, 2018 09 24.
Article in English | MEDLINE | ID: mdl-30250104

ABSTRACT

Most clinical studies of Cannabis today focus on the contents of two phytocannabinoids: (-)-Δ9-trans-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD), regardless of the fact that the plant contains over 100 additional phytocannabinoids whose therapeutic effects and interplay have not yet been fully elucidated. This narrow view of a complex Cannabis plant is insufficient to comprehend the medicinal and pharmacological effects of the whole plant. In this study we suggest a new ESI-LC/MS/MS approach to identify phytocannabinoids from 10 different subclasses, and comprehensively profile the identified compounds in diverse medical Cannabis plants. Overall, 94 phytocannabinoids were identified and used for profiling 36 of the most commonly used Cannabis plants prescribed to patients in Israel. In order to demonstrate the importance of comprehensive phytocannabinoid analysis before and throughout medical Cannabis clinical trials, treatments, or experiments, we evaluated the anticonvulsant effects of several equally high-CBD Cannabis extracts (50% w/w). We found that despite the similarity in CBD contents, not all Cannabis extracts produced the same effects. This study's approach for phytocannabinoid profiling can enable researchers and physicians to analyze the effects of specific Cannabis compositions and is therefore critical when performing biological, medical and pharmacological-based research using Cannabis.


Subject(s)
Cannabinoids/genetics , Cannabis/genetics , Metabolome/genetics , Metabolomics , Cannabidiol/chemistry , Cannabinoids/chemistry , Cannabis/chemistry , Chromatography, Liquid , Hallucinogens/chemistry , Humans , Medical Marijuana/chemistry , Medical Marijuana/therapeutic use , Plant Extracts/chemistry , Plant Extracts/genetics , Tandem Mass Spectrometry
19.
Biotechnol Biofuels ; 8: 96, 2015.
Article in English | MEDLINE | ID: mdl-26167203

ABSTRACT

BACKGROUND: To identify and develop the best renewable and low carbon footprint biodiesel substitutes for petroleum diesel, the properties of different biodiesel candidates should be studied and characterized with respect to molecular structures versus biodiesel liquid property relationships. In our previous paper, (1)H low-field nuclear magnetic resonance (LF-NMR) relaxometry was investigated as a tool for studying the liquid-phase molecular packing interactions and morphology of fatty acid methyl esters (FAMEs). The technological potential was demonstrated with oleic acid and methyl oleate standards having similar alkyl chains but different head groups. In the present work, molecular organization versus segmental and translational movements of FAMEs in their pure liquid phase, with different alkyl chain lengths (10-20 carbons) and degrees of unsaturation (0-3 double bonds), were studied with (1)H LF-NMR relaxometry and X-ray, (1)H LF-NMR diffusiometry, and (13)C high-field NMR. RESULTS: Based on density values and X-ray measurements, it was proposed that FAMEs possess a liquid crystal-like order above their melting point, consisting of random liquid crystal aggregates with void spaces between them, whose morphological properties depend on chain length and degree of unsaturation. FAMEs were also found to exhibit different degrees of rotational and translational motions, which were rationalized by chain organization within the clusters, and the degree and type of molecular interactions and temperature effects. At equivalent fixed temperature differences from melting point, saturated FAME molecules were found to have similar translational motion regardless of chain length, expressed by viscosity, self-diffusion coefficients, and spin-spin (T 2) (1)H LF-NMR. T 2 distributions suggest increased alkyl chain rigidity, and reduced temperature response of the peaks' relative contribution with increasing unsaturation is a direct result of the alkyl chain's morphological packing and molecular interactions. CONCLUSIONS: Both the peaks' assignments for T 2 distributions of FAMEs and the model for their liquid crystal-like morphology in the liquid phase were confirmed. The study of morphological structures within liquids and their response to temperature changes by (1)H LF-NMR has a high value in the field of biodiesel and other research and applied disciplines in numerous physicochemical- and organizational-based properties, processes, and mechanisms of alkyl chains, molecular interactions, and morphologies.

20.
Biotechnol Biofuels ; 8: 12, 2015.
Article in English | MEDLINE | ID: mdl-25688289

ABSTRACT

BACKGROUND: (1)H low field nuclear magnetic resonance (LF-NMR) relaxometry has been suggested as a tool to distinguish between different molecular ensembles in complex systems with differential segmental or whole molecular motion and/or different morphologies. In biodiesel applications the molecular structure versus liquid-phase packing morphologies of fatty acid methyl esters (FAMEs) influences physico-chemical characteristics of the fuel, including flow properties, operability during cold weather, blending, and more. Still, their liquid morphological structures have scarcely been studied. It was therefore the objective of this work to explore the potential of this technology for characterizing the molecular organization of FAMEs in the liquid phase. This was accomplished by using a combination of supporting advanced technologies. RESULTS: We show that pure oleic acid (OA) and methyl oleate (MO) standards exhibited both similarities and differences in the (1)H LF-NMR relaxation times (T2s) and peak areas, for a range of temperatures. Based on X-ray measurements, both molecules were found to possess a liquid crystal-like order, although a larger fluidity was found for MO, because as the temperature is increased, MO molecules separate both longitudinally and transversely from one another. In addition, both molecules exhibited a preferred direction of diffusion based on the apparent hydrodynamic radius. The close molecular packing arrangement and interactions were found to affect the translational and segmental motions of the molecules, as a result of dimerization of the head group in OA as opposed to weaker polar interactions in MO. CONCLUSIONS: A comprehensive model for the liquid crystal-like arrangement of FAMEs in the liquid phase is suggested. The differences in translational and segmental motions of the molecules were rationalized by the differences in the (1)H LF-NMR T2 distributions of OA and MO, which was further supported by (13)C high field (HF)-NMR spectra and (1)H HF-NMR relaxation. The proposed assignment allows for material characterization based on parameters that contribute to properties in applications such as biodiesel fuels.

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