Dioxygenated metabolites of cannabidiol formed by rat liver

Characterizing the degradation of cannabidiol in an e-liquid formulation

The reported characteristics of cannabidiol (CBD) have encouraged significant growth in commercial CBD products. There is limited information on the stability of CBD and some researchers have noted significant reductions of CBD in products. In this study, the chemical profiles of plant-based and chemically synthesized CBD in a prototype e-liquid formulation were assessed during 4 weeks of storage under varying conditions. Samples were analysed on days 1, 8, 15, 22, and 29 by untargeted analysis using ultra-high performance liquid chromatography-trapped ion mobility-time-of-flight mass spectrometry (UHPLC-TIMS-TOF-MS). On day 1, analysis of plant-based and synthetic CBD formulations showed small differences in their composition, with plant-based CBD e-liquid containing trace levels of a higher number of phytocannabinoid-related impurities. Storage for 4 weeks under stress (40 °C, 75% relative humidity, dark) and ambient (25 °C, 60% relative humidity, daylight) conditions led to increases in the number and abundance of cannabinoid-related degradation products, including cannabielsoin (CBE) and CBD-hydroxyquinone (HU-331), which are products of the oxidation of CBD, and other unidentified cannabinoid-related compounds. The unidentified cannabinoid-related compounds were probed by accurate mass measurement and MS² fragmentation but could not be matched using a mass spectral library derived from 39 commercially available cannabinoid reference standards. Based on elemental composition and MS² fragmentation patterns, the unidentified cannabinoid-related compounds were classified as hydroxy-CBE, hydroxy-CBD, and dihydroxy-CBD. The analysis of e-liquid formulations protected from light and stored at 4 °C for 4 weeks indicated only very small increases in CBD oxidation products. The results indicate that CBD degrades in e-liquid solution at ambient temperature in dark and light to form potentially undesirable products, including cannabielsoin and cannabidiol hydroxyquinone.

Does cannabidiol have a role in the treatment of schizophrenia?

Schizophrenia is a debilitating psychiatric disorder which places a significant emotional and economic strain on the individual and society-at-large. Unfortunately, currently available therapeutic strategies do not provide adequate relief and some patients are treatment-resistant. In this regard, cannabidiol (CBD), a non-psychoactive constituent of Cannabis sativa, has shown significant promise as a potential antipsychotic for the treatment of schizophrenia. However, there is still considerable uncertainty about the mechanism of action of CBD as well as the brain regions which are thought to mediate its putative antipsychotic effects. We argue that further research on CBD is required to fast-track its progress to the clinic and in doing so, we may generate novel insights into the neurobiology of schizophrenia.

Metabolism of 20(S)-Ginsenoside Rg₂ by Rat Liver Microsomes: Bioactivation to SIRT1-Activating Metabolites

20(S)-Ginsenoside Rg₂ (1) has recently become a hot research topic due to its potent bioactivities and abundance in natural sources such as the roots, rhizomes and stems-leaves of Panaxginseng. However, due to the lack of studies on systematic metabolic profiles, the prospects for new drug development of 1 are still difficult to predict, which has become a huge obstacle for its safe clinical use. To solve this problem, investigation of the metabolic profiles of 1 in rat liver microsomes was first carried out. To identify metabolites, a strategy of combined analyses based on prepared metabolites by column chromatography and ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) was performed. As a result, four metabolites M1–M4, including a rare new compound named ginsenotransmetin A (M1), were isolated and the structures were confirmed by spectroscopic analyses. A series of metabolites of 1, M_A–M_G, were also tentatively identified by UPLC-Q-TOF/MS in rat liver microsomal incubate of 1. Partial metabolic pathways were proposed. Among them, 1 and its metabolites M1, M3 and M4 were discovered for the first time to be activators of SIRT1. The SIRT1 activating effects of the metabolite M1 was comparable to those of 1, while the most interesting SIRT1 activatory effects of M3 and M4 were higher than that of 1 and comparable with that of resveratrol, a positive SIRT1 activator. These results indicate that microsome-dependent metabolism may represent a bioactivation pathway for 1. This study is the first to report the metabolic profiles of 1invitro, and the results provide an experimental foundation to better understand the in vivo metabolic fate of 1.

Comparative metabolism of cannabidiol in dog, rat and man

Urinary metabolites of cannabidiol (CBD) were extracted from human, dog and rat urine, concentrated by chromatography on Sephadex LH-20, and identified by GC/MS. Over 50 metabolites were identified with considerable species variation. CBD was excreted in substantial concentration from human urine, both in the free state and as its glucuronide. In dog, unusual glucoside conjugates of three metabolites (4''- and 5''-hydroxy and 6-oxo-CBD), not excreted in the unconjugated state, were found as the major metabolites at early times after drug administration. Other metabolites in all three species were mainly acids. Side-chain hydroxylated derivatives of CBD-7-oic acid were particularly abundant in human urine but much less so in dog. In the latter species the major oxidized metabolites were the products of beta-oxidation with further hydroxylation at C-6. A related, but undefined pathway, resulted in loss of three carbon atoms from the side-chain of CBD in man with the production of 2''-hydroxy-tris,nor-CBD-7-oic acid. Previous experiments indicate that 3'-hydroxy-metabolites are the precursors of compounds having this side-chain. Metabolism by the epoxide-diol pathway, resulting in dihydro-diol formation from the delta-8-double bond, gave metabolites in both dog and human urine. It was concluded that CBD could be used as a probe of the mechanism of several types of biotransformation, particularly those related to carboxylic acid metabolism, as intermediates of the type not usually seen with endogenous compounds were excreted in substantial concentration.

Comparative in vitro metabolism of the cannabinoids

The metabolism of delta-9-tetrahydrocannabinol (delta-9-THC), delta-8-THC, delta-11-THC, cannabidiol (CBD), cannabinol (CBN), cannabichromene (CBC), cannabigerol (CBG) and the equatorial-isomer of hexahydrocannabinol (HHC) was studied in microsomal preparations obtained from rats, mice, guinea pigs, rabbits, hamsters, gerbils and a cat. Identification of metabolites was by GC/MS and quantification by gas chromatography. Major metabolites were monohydroxylated compounds but the pattern of hydroxylation varied considerably between the species, no doubt reflecting the variable nature of the cytochrome P-450 mixed-function oxidases. Although the primary carbon allylic to the endocyclic double bond of tricyclic cannabinoids was usually the major site of attack, the 4' (side-chain, omega-1 position) and the terpene ring were usually favoured by the cat and hamster respectively. The guinea pig generally produced more metabolites hydroxylated in the side-chain (all positions) than did the other species. The results from HHC were very similar to those from THC, namely hydroxylation at C-11 in most species, and the production of high concentrations of 8 alpha-hydroxy-HHC in the mouse and 8 beta-hydroxy-HHC in the hamster. As this molecule lacks the double bond of the THCs and, hence, the allylic nature of C-11 and C-8, the results suggest that it is the orientation of the molecule to the active site of the cytochrome P-450 mixed-function oxidase rather than the reactivity of the C-H bond that governs the position of hydroxylation.

Cannabielsoin as a new metabolite of cannabidiol in mammals

Cannabielsoin (CBE) was identified as a novel metabolite of cannabidiol (CBD) in the guinea pig in vivo and in vitro. Its formation by liver microsomes of guinea pigs needed NADPH and molecular oxygen, and was inhibited with SKF 525-A, metyrapone and alpha-naphthoflavone, indicating participation of cytochrome P-450 (P-450). The CBE-forming activity was highest in guinea pigs, followed by mice, rabbits and rats. In the rat, sex difference was found in the CBE formation (male greater than female). CBD monomethylether (CBDM) was also biotransformed to CBE monomethylether (CBEM) in the guinea pig in vivo and in vitro. When CBD dimethylether (CBDD) was employed as substrate, 1S,2R-epoxy-CBDD was identified. The results suggest that CBD and CBDM are biotransformed by P-450 to CBE-type metabolites via 1S,2R-epoxides. In pharmacological studies using mice, CBDD and 1S,2R-epoxy-CBD-2',6'-diacetate produced hypothermia, and CBD, CBDM and CBEM prolonged pentobarbital-induced sleep. Moreover, 1S,2R-epoxy-CBD-2',6'-diacetate was examined in the Ames test, but had no mutagenicity.

Metabolism of cannabidiol by the rat

Metabolites of CBD excreted into the bile and perfusion fluid were examined in a rat liver perfusion preparation. Metabolites were extracted with ethyl acetate and identified by GC/MS as TMS derivatives. Four mono- and five di-hydroxy metabolites were identified with major sites of metabolic attack being at C-7 and C-4". A hydroxy-ketone was detected but not fully identified. All biliary metabolites were conjugated with glucuronic acid. Urinary metabolites were studied in rats with samples taken at times to 25 h after drug administration. Unmetabolized CBD and 13 metabolites were identified by GC/MS. Major metabolites were acids with beta-oxidation being a prominent pathway. The 6- and 7-hydroxy derivatives of 4",5"-bis,nor-CBD-3"-oic acid were the most abundant compounds but substantial concentrations of the di-acids, CBD-5",7-dioic acid and 4",5"-bis,nor-CBD-3",7-dioic acid were present. Concentrations of the more highly oxidized metabolites increased with time.

Urinary metabolites of cannabidiol in dog, rat and man and their identification by gas chromatography-mass spectrometry

Urinary metabolites of cannabidiol (CBD), a non-psychoactive cannabinoid of potential therapeutic interest, were extracted from dog, rat and human urine, concentrated by chromatography on Sephadex LH-20 and examined by gas chromatography-mass spectrometry as trimethylsilyl (TMS), [2H9]TMS, methyl ester-TMS and methyloxime-TMS derivatives. Fragmentation of the metabolites under electron-impact gave structurally informative fragment ions; computer-generated single-ion plots of these diagnostic ions were used extensively to aid metabolite identification. Over fifty metabolites were identified with considerable species variation. CBD was excreted in substantial concentration in human urine, both in the free state and as its glucuronide. In dog, unusual glucoside conjugates of three metabolites (4"- and 5"-hydroxy- and 6-oxo-CBD), not excreted in the unconjugated state, were found as the major metabolites at early times after drug administration. Other metabolites in all three species were mainly acids. Side-chain hydroxylated derivatives of CBD-7-oic acid were particularly abundant in human urine but much less so in dog. In the latter species the major oxidized metabolites were the products of beta-oxidation with further hydroxylation at C-6. A related, but undefined pathway resulted in loss of three carbon atoms from the side-chain of CBD in man with production of 2"-hydroxy-tris,nor-CBD-7-oic acid. Metabolism by the epoxide-diol pathway, resulting in dihydro-diol formation from the delta-8 double bond, gave metabolites in both dog and human urine. It was concluded that CBD could be used as a probe of the mechanism of several types of biotransformation; particularly those related to carboxylic acid metabolism as intermediates of the type not usually seen with endogenous compounds were excreted in substantial concentration.

In vitro metabolism of cannabidiol in the rabbit: identification of seventeen new metabolites including thirteen dihydroxylated in the isopropenyl chain

The metabolism of cannabidiol (CBD) was studied in liver microsomes from the female New Zealand white rabbit. Metabolites were extracted with ethyl acetate, concentrated by chromatography on Sephadex LH-20 and examined as trimethylsilyl (TMS), methyl ester/TMS and (2H9)TMS derivatives by gas chromatography/mass spectrometry. Thirty-nine metabolites, mainly mono-, di- and tri-hydroxy compounds, were identified; 17 of these have not been reported before. New metabolites included 8,9-dihydroxy-8,9-dihydro-CBD (two isomers) and seven monohydroxy derivatives of each of these two compounds. The mass spectra of the TMS derivatives of metabolites not hydroxylated in the isopropenyl group were generally dominated by the ion produced by retro-Diels-Alder cleavage of the terpene ring. Other structurally informative ions included the tropylium ion and fragments diagnostic of hydroxylation at C-1", C-2", C-3", C-4" and C-7. The spectra of the TMS derivatives of metabolites hydroxylated in the isopropenyl group were generally dominated by the ion at m/z 143. This involved loss of CH2OTMS and a retro-Diels-Alder fragmentation analogous to that seen in the other metabolites, but with charge retention by the other (smaller) fragment. Other, related fragment ions also characterized these metabolites.

Identification of metabolites of the 1",1"-dimethylheptyl analogue of cannabidiol in rat and dog in vivo

1. Metabolism of the 1",1"-dimethylheptyl analogue of cannabidiol (DMH-CBD) was studied using an isolated perfused rat liver preparation and in rat and dog urine. 2. Metabolites were identified using g.l.c.-mass spectrometry of the trimethylsilyl (TMS), methyl ester/TMS and [2H9]TMS derivatives. 3. In contrast with the metabolism of cannabidiol, the dimethylheptyl analogue gave low concentrations of metabolites in all media examined. 4. Four metabolites were found in the perfusion fluid. Two were identified as 6- and 7-hydroxy-DMH-CBD and the other two were found to be hydroxylated in the dimethylheptyl chain but at undetermined positions. 5. Five metabolites were identified in dog urine; these were the 6- and 7-mono-hydroxy and 6,7-dihydroxy derivatives of acids formed by one stage of beta-oxidation of the dimethylheptyl chain, and the 6- and 7-hydroxy derivatives of corresponding acids formed by loss of three carbon atoms from the chain. 6. Metabolic routes were very similar to those found earlier for cannabidiol.

Metabolites of cannabidiol identified in human urine

1. Urine from a dystonic patient treated with cannabidiol (CBD) was examined by g.l.c.-mass spectrometry for CBD metabolites. Metabolites were identified as their trimethylsilyl (TMS), [2H9]TMS, and methyl ester/TMS derivatives and as the TMS derivatives of the product of lithium aluminium deuteride reduction. 2. Thirty-three metabolites were identified in addition to unmetabolized CBD, and a further four metabolites were partially characterized. 3. The major metabolic route was hydroxylation and oxidation at C-7 followed by further hydroxylation in the pentyl and propenyl groups to give 1"-, 2"-, 3"-, 4"- and 10-hydroxy derivatives of CBD-7-oic acid. Other metabolites, mainly acids, were formed by beta-oxidation and related biotransformations from the pentyl side-chain and these were also hydroxylated at C-6 or C-7. The major oxidized metabolite was CBD-7-oic acid containing a hydroxyethyl side-chain. 4. Two 8,9-dihydroxy compounds, presumably derived from the corresponding epoxide were identified. 5. Also present were several cyclized cannabinoids including delta-6- and delta-1-tetrahydrocannabinol and cannabinol. 6. This is the first metabolic study of CBD in humans; most observed metabolic routes were typical of those found for CBD and related cannabinoids in other species.

Identification of in vivo liver metabolites of delta 1-tetra-hydrocannabinol, cannabidiol, and cannabinol produced by the guninea-pig

The metabolites of delta 1-tetrahydroannabinol (delta 1-THC), cannabidiol (CBD), and cannabinol (CBN) produced in vivo by the guinea-pig have been studed by combined gas-liquid chromatography-mass spectrometry, 45 metabolites of delta 1-THC were identified of which 12 have not been reported before. Several other metabolites were detected but not identified. The major metabolic routes involved allylic and aliphatic hydroxylations, oxidations to ketones and acids, oxidative degradation of the side-chain presumably by the beta-oxidation pathway, and formation of glucuronide conjugates. Di- and tri-substituted metabolites were abundant. The metabolism differed considerably from that observed in mouse and rat in that 1''- and 6 beta-hydroxylation and oxidation degradation of the side-chain were major metabolic pathways. 1''-Hydroxy-delta 1-THC was found as a pair of diasteroisomers. Similar metabolic pathways were observed with CBD; twenty metabolites were identified of which two were new. Only 6 metabolites of CBN were identified. These mainly mono-substituted in the same positions as were observed with delta 1-THC and CBD.

More acidic metabolites of delta1-tetrahydrocannabinol isolated from rabbit urine

The in vivo metabolism of delta1-tetrahydrocannabinol (delta1-THC) was further investigated in the rabbit after i.v. administration. Nine acidic metabolites were isolated from a previously not investigated fraction of the urine and identified by gas chromatography-mass spectrometry and by proton magnetic resonance spectroscopy. The major metabolites were side-chain hydroxylated monocarboxylic acids. Three side-chains monocarboxylic acids hydroxylated in allylic positions in the isoprene moiety were also characterized. The metabolites 4''-hydroxy-delta1-THC-7-oic acid and 7-hydroxy-4'',5''-bisnor-delta1-THC-3''-oic acid were hitherto not identified. An earlier described dicarboxylic metabolite was present in high concentration. Further, the identity of an O-glucuronide as an in vivo urinary metabolite of delta1-THC was here for the first time unambiguously established by m.s. and p.m.r.

Microbiological oxidation of the pentyl side chain of cannabinoids

Syncephalastrum racemosum ATCC 18192 and Mycobacterium rhodochrous ATCC 19067 partially degrade the n-pentyl side chain of cannabidiol, cannabinol, delta8-tetrahydrocannabinol and delta9-tetrahydrocannabinol. Carboxylic acid and alcohol side chain derivatives are major metabolites.

In vivo metabolism of cannabinol by the mouse and rat and a comparison with a metabolism of delta 1-tetrahydrocannabinol and cannabidiol

The in vivo liver metabolism of cannabinol has been studied in the mouse and rat by combined gas chromatography and mass spectrometry. Cannabinol glucuronide was the major metabolite of cannabinol in the mouse and was accompanied by relatively large amounts of 7-hydroxycannabinol, cannabinol-7-oic acid and their corresponding glucuronide conjugates. Lower concentrations of glucuronides were found in the rat. Two series of disubstituted metabolites were found containing either a 7-hydroxyl or a 7-carboxylic acid group and a second hydroxyl group in the 1 inch-4 inch positions of the sidechain. These were of low concentration in the mouse but higher in the rat; 1 inch-hydroxy metabolites were particularly abundant in the latter species. Also found in the rat livers were small amounts of sidechain monohydroxy metabolites and larger quantities of 4 inches, 5 inches-bisnorcannabinol-3 inches-oic acid; these were absent in the mouse. The metabolites were identified using the trimethylsilyl (TMS), [2H9] TMS and methyl ester-TMS derivatives, and by reduction of acid metabolites with lithium aluminium deuteride to the corresponding alcohols.

Identification of di- and tri-substituted hydroxy and ketone metabolites of delta1-tetrahydrocannabinol in mouse liver

In vivo liver metabolites of delta1-tetrahydrocannabinol (delta1-THC) were examined with a gas chromatograph--mass spectrometer--computer system as trimethylsilyl (TMS), [2H9]TMS and methyloxime-TMS derivatives. In addition to the reported monohydroxy, acid, and hydroxyacid metabolites, the following multiply substituted metabolites were identified: 2'',7-, 3'', 7-, and 6beta,7-dihydroxy-delta1-THC; 2'',6alpha,7-, and 3'',6alpha,7-trihydroxy-delta1-THC; 2''-, 3''-, and 7-hydroxy-6-oxo-delta1-THC, and 2'',7- and 3'',7-dihydroxy-6-oxo-delta1-THC. The ketones and hydroxyacids were reduced to common alcohols with lithium aluminium deuteride and the number of deuterium atoms in the product was used to distinguish the metabolic alcohols from those produced by reduction.

Dihydroxylated metabolites of cannabinol formed by rat liver in vitro

Cannabinol (CBN) was metabolized in vitro by a 10,000 g supernatant from rat liver. After removal of unchanged CBN and its monohydroxylated metabolites four dihydroxylated metabolites were isolated. By nuclear magnetic resonance and mass spectrometry the compounds were identified as 1'',7-dihydroxy-CBN. Side chain hydroxylation occurred predominantly at C-4'' anc C-3''.