Geographical and seasonal phytochemical variation of Artemisia afra Jacq. ex Willd

Abstract

Introduction: Artemisia afra Jacq. ex. Willd. (Asteraceae) is a popular traditional medicine in South Africa, mainly used in the form of an infusion, for the treatment of respiratory ailments. Quality control methods are limited and phytochemical variation for the infusion is not well known.Objective: To develop a sensitive quality control method for A. afra infusions by validating a liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) method and quantitatively comparing six marker compounds in A. afra samples collected from different locations and over a 12-month period.Material and methods: There was a multiple reaction monitoring method optimised and validated, according to ICH and FDA guidelines, to quantify the chemical markers present in infusions. Results:The chemistry differed significantly and interestingly, with an interchangeable trend between chlorogenic acid (CGA) and 4,5-dicaffeoylquinic acid (DCQA) observed in the samples collected monthly, elevated levels of CGA during winter and elevated levels of DCQA during summer. The remaining four markers showed a steady decrease as winter approached and a steady increase as summer approached.The ranges of the six markers were the following: CGA (0.68-14.68 μg/mg), DCQA (0.005-8.110 μg/mg), quercetin (0.01-0.65 μg/mg), luteolin (0.05-1.30 ng/mg), scopoletin (0.10-1.14 μg/mg), scopolin (0.03-1.21 μg/mg).Conclusions: A sensitive LC-ESI-MS/MS method was developed, validated, and used to quantify six marker compounds. The results indicated a large degree of phytochemical variation occurred across all samples tested, which highlights the importance of producing herbal medicine under controlled conditions and the necessity of analytical quality control methods.

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“…A. annua infusions have already been phytochemically analyzed in detail, 26,62 and those of A. afra semi-characterized only recently. 30,63 However, these data are likely not fully representative of the phytochemical content of these Artemisia spp. infusions, firstly because of the aforementioned variations, and also because additional compounds to the ones described could be expected upon deepen analysis of the plant aqueous extracts, based on the species exhaustive description in phytochemicals.…”

“…26,61,62,94,115 A. afra infusion specifically contains the aglycone quercetin although its presence seems cultivar-dependent. 30,63 This suggests that other flavonoid aglycones present in A. afra ( e.g. , kaempferol and tamarixetin, being close in structure to quercetin), as well as water-soluble heterosides other than cynaroside, might also be detected in its infusion upon deeper analysis (Table 1).…”

“…cynaroside). 30,62,63,[111][112][113][114] Infusions of A. annua show an important proportion of distinctive avonoids, minor as aglycones (e.g., eriodictyol, chrysosplenol D) and predominant as water-soluble heterosides (e.g., apigenin-6-C-b-D-glucoside, syn. isovitexin, quercetin-7-O-b-D-glucoside, syn.…”

“…chlorogenic acids, CGAs 138 ), associated in A. annua to a variable proportion of rosmarinic acid. 10,13,14,24,26,30,62,63,94 These esters are accompanied in the infusion of A. annua by their free carboxylic acid precursors (i.e., caffeic and quinic acids) although ferulic and succinic acids are generally not detected. 24,26,57,62 These free acids were never characterized in A. afra infusions, where they can be expected considering the common CGA metabolism of the two plant species (Table 2).…”

“…scopolin). 30,63,94,115 Specic coumarins in the infusion of A. annua are esculetin and eleutheroside B1, 115 which are not described in A. afra. 149 A putative trimethoxycoumarin was detected in A. annua infusion while being previously undescribed in this species, but remains unidentied regarding its substitution pattern, 62 which is known to vary between Artemisia spp.…”