Study On Alkaloids And Labdane Diterpenoids From Forsythia Suspensa Collected From Hubei Province And Their Bioactivities

Forsythia suspensa（Thunb.）Vahl is a deciduous shrub plant of the genus Forsythia in the Oleaceae family.Forsythia suspensa is a dried fruit of the traditional Chinese medicine.It was included in the 2020 edition of the Chinese Pharmacopoeia.Forsythia suspensa is cold in nature and bitter in taste.It has the effects of clearing away heat and detoxifying,reducing swelling and dispelling wind-heat.It also has anti-bacterial,strengthening heart,diuretic,antiemetic and other pharmacological effects.Traditional Chinese medicine is known as the"sacred medicine for sores".Clinically,it is mainly used for the treatment of acute wind-heat cold,carbuncle and sore toxin,lymphatic tuberculosis,urinary tract infection and other diseases.Forsythia suspensa has good anti-inflammatory and anti-viral activities.Lianhua Qingwen Capsules and Shuanghuanglian Oral Liquid,which have a preventive effect on the new coronavirus,contain Forsythia suspensa.The plant is mainly produced in Shandong,Hebei,Sichuan,Hubei and other places.Forsythia suspensa is mainly from wild sources,which is greatly affected by growth environment,variety,climate,etc.The chemical active components of Forsythia suspensa from different producing areas are different.The research group conducted research on Forsythia suspensa collected from Shandong in the early stage,and obtained a variety of monomer compounds with good biological activity from it.Based on this,we conducted chemical and biological activity research on Forsythia suspensa collected from Hubei province.Using silica gel column chromatography,Sephadex LH-20 column chromatography and high-efficiency preparative thin-layer chromatography and other separation methods,from the 95%ethanol extract of Forsythia suspensa fruits,9 alkaloids,14 labdane diterpenoids and 12 other types of compounds were separated.Among them,4 are new compounds,and their structures were identified by MS,HR-MS,UV,IR,1D-NMR,2D-NMR,single crystal x-ray diffraction and ECD calculations.The structures were characterized as Forsyshiyanine A（1）,Forsyshiyanine B（2）,cyclo（L-Leu-L-Tyr）（3）,xylopinine（4）,terahyropalmatine（5）,（-）-bicuculline（6）,（-）-egenine（7）,（-）-7’-O-methylegenine（8）,suspansine A（9）,Forsyshiyanin A（10）,Forsyshiyanin B（11）,18-hydroxy-7-oxolabda-8（9）,13（E）-dien-15-oic acid（12）,19-hydroxy-ent-labda-8（17）,13（E）-dien-oic acid（13）,ent-Labda-8（17）,13（Z）-dien-15,19-dioic acid（14）,ent-labda-8（17）,13（E）-dien-15,19-dioic acid（15）,3β-hydroxy-8（17）,13（Z）-labdadien-15-oic acid（16）,enantio-Labda-8（20）,13（E）-dien-15,18-dioic acid（17）,12,18-dihydroxy-labda-8（17）,13（E）-diene-15-oic acid（18）,3,18-dihydroxy-labda-8（17）,13（E）-diene-15-oic acid（19）,7-hydroxy-labda-8（17）,13（E）-diene-15,19-dioic acid（20）,19-hydroxy-7-oxolabda-8（9）,13（E）-diene-15-oic acid（21）,7-oxolabda-8（9）,13（Z）-diene-15,18-dioic acid（22）,3-hydroxy-8（17）,13（E）-labdadien-15-oic acid（23）,phillygenol（24）,pnoresinoldimethyl ether（25）,epipinoresinol（26）,pinoresinol monomethyl ether（27）,epieudesmin（28）,isolariciresinol（29）,3,3’-dimethoxy-4,4’,9-trihydroxy-7,9’-epoxylignan-7’-one（30）,alphitolic acid（31）,betulinic acid（32）,oleanic acid（33）,vanillic acid（34）,caffeic acid（35）.Among them,4 new compounds were isolated,namely compounds 1-2,10-11,and compound 7 was isolated from Forsythia suspensa for the first time.The results of activity screening about alkaloids and labdane diterpenoids isolated from Forsythia suspensa show that,when the alkaloid is 10μM,the inhibitory rate of the alkaloid on glucuronidase ranges from 47.9%to 56.0%.Among them,the IC₅₀ value of the anti-H1N1 virus ranges from 7.3μM to 32.5μM,and the EC₅₀ value of the anti-RSV virus ranges from 3.7μM to 14.1μM.The results showed that at a concentration of 10μM,the inhibitory rate of labdane diterpenoids on glucuronidase ranged from 46.8%to 51.0%,and the anti-viral（H1N1 and RSV）activity studies showed that the IC₅₀ value of the anti-H1N1 virus range is 18.4μM～26.2μM,and the EC₅₀ value of anti-RSV virus ranges from 10.5μM to13.2μM.The results show that the alkaloids and labdane diterpenoids have good anti-inflammatory and anti-viral activities.