ABSTRACT
ObjectiveTo investigate the quality variation of Lonicera japonica flower from different harvesting periods by ultraviolet visible（UV-Vis） fingerprint combined with chemometrics. MethodTwenty-five L. japonica flower samples from five harvesting periods， including young bud stage，green bud stage，white bud stage，silver and golden flower stages， were collected， with five samples for each stage. UV-Vis fingerprints of L. japonica flower from different harvesting periods were established in the context of the optimum extraction method based on the single factor experiment. The results showed that the absorption values at 209，216，226，250，280，303，318， and 350 nm were significantly different. Moreover，after data pretreatment and normalization，multivariate statistical analyses， such as principal component analysis （PCA），partial least squares discriminant analysis （PLS-DA），and orthogonal PLS-DA （OPLS-DA）were performed by SIMCA-P+ to establish the quality variation model of L. japonicas flower from harvesting periods. ResultAs revealed by PCA and PLS-DA， L. japonicas flower samples from five harvesting periods were clustered separately and closely in a harvesting time-dependent manner， suggesting that the content of components contained in samples from different harvesting periods was highly distinct and correlated with harvesting periods. The pairwise comparison of OPLS-DA indicated that triterpenoids or volatile oils were the main components causing the changes from the young bud stage to the green bud stage，and the content of them decreased. The main components from the green bud stage to the white bud stage were triterpenoids （or iridoids），volatile oils，phenolic acids， or flavonoids，and the content of them decreased， which was consistent with the HPLC result of chlorogenic acid. From the white bud stage to the silver flower stage， the main components were iridoids （increasing in content） and triterpenoids （or volatile oils） （decreasing in content）. The main altered components from the silver flower stage to the golden flower stage were triterpenoids （or volatile oils） whose content increased. ConclusionThis method is simple and feasible， which can provide references for the quality control of Chinese medicine.
ABSTRACT
A method was established for content determination of two kinds of phenolic acids, including rosmarinic acid)(RA) and caffeic acid(CA), and six kinds of flavonoids including scutellarein-7-O-diglucuronide(SDG), luteolin-7-O-diglucuronide(LDG), apigenin-7-O-diglucuronide(ADG), scutellarin-7-O-glucuronide(SG), luteolin-7-O-glucuronide(LG), and apigenin-7-O-glucuronide(AG) in Perilla frutescens leaves. The content of eight chemical components was measured based on ten P. frutescens germplasms of different chemotypes of volatile oil, different cultivated years, and different harvesting periods. The results showed that there was a great difference between the two kinds of constituents of different germplasms. The total content of the two phenolic acids was 2.24-34.44 mg·g~(-1), and the total content of the six flavonoids was 11.55-34.71 mg·g~(-1). Then according to content from most to least, the order of each component was RA(2.13-33.97 mg·g~(-1)), LDG(1.31-14.80 mg·g~(-1)), SG(1.97-8.45 mg·g~(-1)), ADG(2.68-7.60 mg·g~(-1)), SDG(1.16-5.87 mg·g~(-1)), LG(0.78-1.91 mg·g~(-1)), AG(0.56-1.00 mg·g~(-1)), and CA(0.11-0.68 mg·g~(-1)). The chemical contents of the 5 PA-type germplasms in 2017 were mostly higher than those in 2018 showing a large variation with the cultivation years. These contents of two kinds of phenolic acids of 9 germplasms fluctuated with the harvesting time. The content decreased before early flower spike(the 3~(rd) to 18~(th) in August) at first and began to increase in flowering and fruiting period(the 18~(th) in August to 2~(nd) in September). However, these contents had slowly decreasing trend after 2~(nd) in September till 17~(th) in the same month. Interestingly, the content raised again in the maturity of fruits. The variation tendency of contents in six kinds of flavonoids components was inconsistent in different germplasms with the variation of harvesting time. The content of flavonoids in part of germplasms was negatively correlated with the fluctuation of phenolic acids. There was no correlation between phenolic acids and chemical type of the volatile oil. This paper may provide a reference for the high-quality germplasm of P. frutescens cultivation.