Chemical Constituents Of Forsythia Suspensa And Bioactivity Study

Forsythia suspensa (F. suspensa), the air-dried fruit of Forsythia suspensa (Thunb.) Vahl( Oleaceae ) is a common traditional Chinese medicine recorded in ChinesePharmacopeia. ShaanxiProvince is one of the main habitats of this plant. This research mainlyintroduced the chemical constituents and bioactivity of F. suspensa, and it included thefollowing four sections.Part one isolated four compounds from the EtOH extraction of air-dried fruits of F. suspensa, using the polyamide column chromatography, silica gel column chromatography and preparative HPLC methods. Campared with the reference substances, three of them were demonstrated to be forsythiaside; rutin and forsythin. The last one was an unknown novel compound, and it was named as isoforsythiaside.Second part, the chemical structure of isoforsythiaside was elucidated by the means of spectroscopy, UV,IR,MS and NMR. This compound is a glycoside isomer of forsythiaside, the conformation of rhamnose in the molecule of isoforsythiaside isβ-rhamnose, notα-rhamnose.The third part studied on the content of forsythiaside; rutin and forsythin from different parts of F. suspensa using the HPLC and HPLC-MS methods. The quantitative analyses showed that there was much more forsythiaside from barks, leaves, flowers, fruits and seeds than from roots, branches and fruit shells. The leave and flower were the main sources of existing rutin. The content of forsythin from leaves was much higher than that from the other parts. Determination of forsythiaside and forsythin from fruits of F. suspensa and Forsythia viridissima (F. viridissima) Lindl collected in different periods showed that the content of forsythiaside from fruits of F. suspensa was much higher than it from fruits of F. viridissima. And there was no forsythin from fruits of F. viridissima. So F. viridissima should not be used as Forsythia suspensa. All the quantitative analyses provided groundwork for the revision of China Pharmacopoeia (Edition 2010).Part four were mainly correlated with the antioxidant and antibacterial activities of isoforsythiaside, forsythiaside and forsythin. Both antioxidant activities and antibacterial effects of the three isolated compounds showed that isoforsythiaside and forsythiaside had strong activities. The activities of forsythin were much weaker. Owing to these properties, the study can be further extended to exploit for the possible application of isoforsythiaside and forsythiaside as the alternative antioxidants and antibacterial agents from natural origin.In a conclusion, forsythiaside, among a number of compounds isolated from F. suspensa, is mainly responsible for the antioxidant and antibacterial activities of this plant. And it is the main and marker compound of this plant. The use of forsythin as unique marker component of quality control for F. suspensa is not enough , and sometimes leads to a biased assessment. Quantification of forsythiaside in F. suspensa would be of great significance for the evaluation of the quality of this herb and its Chinese medicinal preparations. China Pharmacopoeia (vol.1 , Edition 2010) have decided to add forsythiaside as a marking composition of F. suspensa.