An assessment of solvent residue contaminants related to cannabis-based products in the South African market.

Organic solvents are used for manufacturing herbal medicines and can be detected as residues of such processing in the final products. It is important for the safety of consumers to control these solvent residues. South African cannabis-based product samples were analysed for solvent residue contaminants as classified by the United States Pharmacopeia (USP), chapter 467. The origin of these samples ranged anywhere from crude extract, product development samples, and market ready final products. Samples were submitted to a contract laboratory over a period of 2 years from 2019 to 2021. To date, no data of this kind exist in South Africa specifically relating to cannabis-based medicinal, recreational, or complementary products. A total of 279 samples were analysed in duplicate by full evaporation headspace gas-chromatography mass-spectrometry and the results are reported in an anonymised format. The results showed an alarming 37% sample solvent residue failure rate with respect to adherence to USP 467 specification. It is important to ensure regulation is enforced to control product quality. The South African public need to be educated about the risks associated with cannabis-based products.

An assessment of the potency related to Cannabis-based products in the South African market.

It was the aim of this study to analyse a portion of the South African cannabis-based products market and provide a detailed overview of their THC and CBD profiles. To date, no data of this kind exists in South Africa. Samples were submitted to a contract laboratory. A total of 840 samples were analysed in duplicate (1680 datapoints in total) and reported in an anonymous format. Samples were categorised into 7 different types: Edible, Extract, Infusion, Liquid, Other, Plant material, and Solid. Each category was divided into the following weight by percentage concentration levels:<0.1 wt.-%, 0.1 wt.-% to 1 wt.-% and finally>1 wt.-%. Both HPLC-UV, as well as, GC-MS was employed for analysis with the datasets combined. The results indicated that high amounts of THC are present in most of the cannabis-based products in South Africa. This is of concern due to the health implications of these products, and the current South African legislation related to CBD and THC. Medicines and controlled substance regulators as well as the South African public will be informed about the current state of cannabis-based products in South Africa.

Monoamine Oxidase Inhibition by Kavalactones from Kava (Piper Methysticum).

Monoamine oxidases (MAOs) are key metabolic enzymes for neurotransmitter and dietary amines and are targets for the treatment of neuropsychiatric and neurodegenerative disorders. This study examined the MAO inhibition potential of kavain and other kavalactones from the roots of kava (Piper methysticum), a plant that has been used for its anxiolytic properties. (±)-Kavain was found to be a good potency in vitro inhibitor of human MAO-B with an IC50 of 5.34 µM. (±)-Kavain is a weaker MAO-A inhibitor with an IC50 of 19.0 µM. Under the same experimental conditions, the reference MAO inhibitor, curcumin, displays IC50 values of 5.01 µM and 2.55 µM for the inhibition of MAO-A and MAO-B, respectively. It was further established that (±)-kavain interacts reversibly and competitively with MAO-A and MAO-B with enzyme-inhibitor dissociation constants (Ki) of 7.72 and 5.10 µM, respectively. Curcumin in turn, displays a Ki value of 3.08 µM for the inhibition of MAO-A. Based on these findings, other kavalactones (dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin) were also evaluated as MAO inhibitors in this study. Yangonin proved to be the most potent MAO inhibitor with IC50 values of 1.29 and 0.085 µM for MAO-A and MAO-B, respectively. It may be concluded that some of the central effects (e.g., anxiolytic) of kava may be mediated by MAO inhibition.

1,3,4-Oxadiazol-2-ylbenzenesulfonamides as privileged structures for the inhibition of monoamine oxidase B.

The present study investigates the monoamine oxidase (MAO) inhibition properties of a series of ten 5-aryl-1,3,4-oxadiazol-2-ylbenzenesulfonamides. The target compounds were synthesized by dehydration of the corresponding N,N'-diacylhydrazines with phosphorus oxychloride to yield the 1,3,4-oxadiazole cycle with concomitant transformation of the sulfonamide to the sulfonyl chloride group. Treatment with aqueous ammonia in acetonitrile regenerated the target sulfonamides. The results of the enzymology document that these compounds are potent and specific MAO-B inhibitors with the most potent compound exhibiting an IC50 value of 0.0027 µM. An analysis of the structure-activity relationships shows that the 4-benzenesulfonamides are significantly more potent MAO-B inhibitors than the corresponding 3-benzenesulfonamides, and that the corresponding N,N'-diacylhydrazine synthetic precursors are weak MAO inhibitors. Although MAO inhibition by oxadiazole compounds are known, this is the first report of nanomolar MAO inhibition potencies recorded for sulfonamide derivatives. MAO-B specific inhibitors such as those discovered here may be of interest in the treatment of neurodegenerative disorders such as Parkinson's disease.

Evaluation of Selected Natural Compounds as Dual Inhibitors of Catechol-O-Methyltransferase and Monoamine Oxidase.

BACKGROUND: The most effective symptomatic treatment of Parkinson's disease remains the metabolic precursor of dopamine, L-dopa. To enhance the efficacy of L-dopa, it is often combined with inhibitors of the enzymes, catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) B, key metabolic enzymes of L-dopa and dopamine. OBJECTIVE: This study attempted to discover compounds that exhibit dual inhibition of COMT and MAO-B among a library of 40 structurally diverse natural compounds. Such dual acting inhibitors may be effective as adjuncts to L-dopa and offer enhanced value in the management of Parkinson's disease. METHODS: Selected natural compounds were evaluated as in vitro inhibitors of rat liver COMT and recombinant human MAO. Reversibility of MAO inhibition was investigated by dialysis. RESULTS: Among the natural compounds morin (IC50 = 1.32 µM), chlorogenic acid (IC50 = 6.17 µM), (+)-catechin (IC50 = 0.86 µM), alizarin (IC50 = 0.88 µM), fisetin (IC50 = 5.78 µM) and rutin (IC50 = 25.3 µM) exhibited COMT inhibition. Among these active COMT inhibitors only morin (IC50 = 16.2 µM), alizarin (IC50 = 8.16 µM) and fisetin (IC50 = 7.33 µM) were noteworthy MAO inhibitors, with specificity for MAO-A. CONCLUSION: None of the natural products investigated here are dual COMT/MAO-B inhibitors. However, good potency COMT inhibitors have been identified, which may serve as leads for future development of COMT inhibitors.

Synthesis and Evaluation of 2-benzylidene-1-tetralone Derivatives for Monoamine Oxidase Inhibitory Activity.

BACKGROUND: Chalcone has been identified as a promising lead for the design of Monoamine Oxidase (MAO) inhibitors. This study attempted to discover potent and selective chalcone-derived MAO inhibitors by synthesising a series consisting of various cyclic chalcone derivatives. The cyclic chalcones were selected based on the possibility that their restricted structures would confer a higher degree of MAO isoform selectivity, and included the following chemical classes: 1-indanone, 1- tetralone, 1-benzosuberone, chromone, thiochromone, 4-chromanone and 4-thiochromanone. METHODS: The cyclic chalcone derivatives were synthesised via a one-pot Claisen-Schmidt condensation reaction. The MAO inhibitory properties of the chalcone derivatives were evaluated with the recombinant human MAO-A and MAO-B enzymes and the potencies were expressed as the IC50 values. A selected inhibitor was docked into an active site model of MAO-B. RESULTS: The results showed that the cyclic chalcones are in general good potency, and in most instances specific inhibitors of the MAO-B isoform. Among these compounds, the 4-chromanone derivative was the most potent MAO-B inhibitor with an IC50 value of 0.156 µM. To further investigate the MAO inhibition of cyclic chalcones, a series of twenty-three 2-benzylidene-1-tetralone derivatives were synthesised and evaluated as MAO inhibitors. Most 2-benzylidene-1-tetralones possess good inhibitory activity and specificity for MAO-B with the most potent inhibitor displaying an IC50 value of 0.0064 µM, while the most potent MAO-A inhibitor possessed an IC50 value of 0.754 µM. CONCLUSION: This study thus shows that certain cyclic chalcones are human MAO-B inhibitors, compounds that could be suitable for the treatment of neurodegenerative disorders such as Parkinson's disease.