The exploration of neuraminidase inhibitory activity on Fallopia denticulata, an ethnic herb in China.

This study was designed to explore the bioactive ingredients in the extracts of Fallopia denticulata (C.C. Huang) Holub, a medicinal plant grown in China, which exhibits the best neuraminidase (NA) inhibition activity. Three fractions of ethyl acetate, ethanol, and water were tested on NA inhibition assay, and the best one was conducted by ultra-performance liquid chromatography-time-of-flight mass spectrometry in the negative and positive modes to analyze the metabolic components. The results revealed the identification of the following 21 compounds: 3 organic acids, 11 flavonoids, 1 coumarin, and 6 others, such as ß-daucosterol, gallic acid, and syringic acid, of which 12 compounds were discovered for the first time in F. denticulata. In addition, we used the molecular docking technique to support the anti-NA activity of each compound in the best extract. The results confirmed that the two better bioactive compounds were (-)-epicatechin gallate and (+)-catechin. Therefore, F. denticulata could be used as a potential material for new anti-influenza drugs.

Isolation and Determination of Phenolic Glycosides and Anthraquinones from Rhizomes of Various Reynoutria Species.

Giant knotweeds of the genus Reynoutria (syn. Fallopia)-Reynoutria japonica, Reynoutria sachalinensis, and a hybrid of them, Reynoutria x bohemica-are noxious invasive plants in Europe and North America. R. japonica is a traditional East Asian (Japan and China) drug (Polygoni cuspidati rhizoma). Recently, it has been included in European Pharmacopoeia as one of the traditional Chinese medicinal herbs. In this study, a reversed-phase high performance liquid chromatography method with diode array detector and time-of-flight mass spectrometry was developed and validated for the profiling of rhizomes from European invasive populations and Polygoni cuspidati rhizoma purchased in China. Twenty-five compounds were identified, mainly stilbenes, anthraquinones, flavan-3-ols, and phenylpropanoid esters. Tatariside B, hydropiperoside, vanicoside C, a new compound (3,6-O-di-p-coumaroyl)-ß-fructofuranosyl-(2 → 1)-(2'-O-acetyl-6'-O-feruloyl)-ß-glucopyranoside) were reported for the first time in these raw materials. Six compounds from three phytochemical classes-stilbenes: piceid and resveratrol; anthraquinones: emodin and physcion; hydroxycinnamic sucrose esters: vanicosides A and B-were quantified using the validated method. R. japonica from China contained twice as many stilbenoids than samples from Poland (piceid 14.83 mg/g dm vs. 7.45 mg/g and resveratrol 1.29 mg/g vs. 0.65 mg/g). R. sachalinensis rhizomes contained lower quantities of anthraquinones and no detectable stilbenes, which together with higher amounts of hydroxycinnamic glycosides makes it easily distinguishable from the other two. The phytochemical profile of R. x bohemica was intermediate between the two parent species.

Comparative Histological and Phytochemical Study of Fallopia species.

Fallopia species which belong to the Polygonaceae family have several data related to their use in the Asian herbal medicine. In this work, some histological and phytochemical parameters of Fallopia japonica, F. sachalinensis, and F. x bohemica were analysed and compared. Rhizome and leaf samples were collected before, during, and after the flowering period at 3 habitats in Szombathely and 4 habitats in Baranya County, Hungary. The main histological characteristics of the stem, leaf and petiole were studied by light microscopy in cross section. Total tannin and anthraquinone contents were determined according to the official methods of the Hungarian Pharmacopoeia VIIIth (equal to the European Pharmacopoeia 6th). No species-specific markers were found in any plant part. In the rhizome, the highest tannin content was measured in Japanese knotweed, followed by Bohemian and giant knotweed in each period. The tannin content measured in each plant was higher in the leaves than in the rhizomes except F. japonica. The rhizome of F. japonica had the highest anthraquinone content before the flowering period, followed by F. x bohemica and F. sachalinensis. According to earlier and our preliminary data, Fallopia taxa are of great therapeutic promise in the future.