Abstract
Reynoutria japonica Houtt. is a critical invasive alien plant in Europe and North America with a drastic impact on native flora. However, R. japonica has medicinal potential, especially as a source of stilbenes. In order to explore the potential of simple extractions of R. japonica, we conducted qualitative and quantitative analyses of fresh R. japonica rhizome infusion, decoction, and macerates with ethanol by UHPLC-DAD-ESI-MSn and UHPLC-DAD, with a focus on major constituent groups of stilbenes and anthranoids. Since R. japonica rhizome extracts showed antimicrobial potential in the past, we also evaluated the antimycobacterial effect of raw R. japonica extracts for the first time against Mycobacterium smegmatis. Of thirty-four characterized substances, six were stilbenes and twelve anthranoids. The main constituents, four trans-stilbenes and eight anthranoids, were quantified in a validated UHPLC-DAD method. The 38% ethanol macerate showed high stilbene (155.078 mg/100 g fluid extract) and low anthranoid content (5.420 mg/100 g fluid extract), while decoction showed the highest anthranoids. Antimycobacterial testing gave good results for all macerates (MIC 256 µg/mL) and trans-resveratrol (64 µg/mL). Extraction and enrichment of stilbenes from fresh plant material by simple extraction methods with food-grade solvents might encourage consideration of wild harvest of rhizomes over classic means of eradication of R. japonica.
Highlights
Since R. japonica rhizome extracts and its major constituents showed antimicrobial potential in the past, including good results for pure resveratrol against M. smegmatis achieved in our own working group [20], we evaluated the antimycobacterial effect of raw R. japonica extracts for the first time, by investigating their minimum inhibitory concentration (MIC) against Mycobacterium smegmatis mc2 155
Drug extract ratios were determined for all investigated R. japonica rhizome extracts after freeze-drying
We analysed different extraction methods of fresh R. japonica rhizome, which are reproducible without specialized instrumental equipment and using food-grade solvents, to compare yields and composition, focusing on main secondary metabolite groups of anthranoids and stilbenes
Summary
(Syn. Fallopia japonica (Houtt.) Ronse Decr., Polygonum cuspidatum Siebold and Zucc.) is an herbal perennial plant in the family of Polygonaceae [1]. It grows to heights of up to three metres in various conditions, and possesses thickened rhizomes, which may extend 4.5 m deep and up to 20 m away from parent plants [3,4]. Due to R. japonica being a fast-growing competitor early in the season, capturing space and resources, it is an invasive alien plant which can significantly diminish native flora [3,4]. In its native regions of China, R. japonica is grown and harvested for long-lasting medicinal use in traditional Chinese medicine (TCM) [5]. Dried rhizome is called “Hu Zhang” in Chinese and listed in the Pharmacopeia of the People’s Republic of
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