Microscopic investigations and pharmacognostic techniques for the standardization of the fruits of Rosa laxa Retz.

Rosa laxa Retz., a shrub belonging to the family Rosaceae, is widely distributed in the northern foothills of the Tianshan Mountains in Xinjiang, China. The fruits of R. laxa (FRL) has antibacterial, hypolipidemic, and antioxidant effects. In this study, FRL was subjected to pharmacognostic identification of its source, morphology, microscopic characteristics, and physicochemical properties. The microscope showed that the cross-sectional features of FRL were obvious, and the FRL powder contained vessel, parenchyma cells, exocarp cells, pollen grains, and cluster crystals. Scanning electron microscopy (SEM) analysis results show that numerous villi and many small particles (particle size of 5-50 μm) were observed in the FRL powder, and there are many gullies on the surface of the particles. In addition, the secondary metabolites of FRL were characterized via ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thin-layer chromatography (TLC). Results showed that FRL contains various secondary metabolites, including flavonoids, phenolic acids, glycosides, and tannins. Water as the extraction solvent had the highest extraction rate and the contented of total flavonoids was 2.88 mg/g, and the contented of total polyphenols was 54.89 mg/g. Moreover, TLC identification revealed that it contains catechin and tiliroside. These parameters of FRL, which are reported herein, are important to the development of the pharmacognostic standards, as well as in the identification and quality control of FRL.