Study On Alkaloids Of The Twigs And Leaves Of Flueggea Suffruticosa

Flueggea suffruticosa(Pall.)Baill.,a member of the genus Flueggea(Euphorbiaceae),is widely distributed in China.The flowers,twigs,and leaves of F.suffruticosa are used as folk medicine for the treatment of rheumatic disease,quadriplegia,infantile paralysis,psychical disorders,and children’s malnutrition in China.Previous phytochemical studies demonstrated that alkaloids were the characteristic components of this plant.As the representative alkaloids components,Securinega alkaloids are emerged to be hot research topic in both the chemical and biological communities due to their unique structural features and extensive pharmacological activities in recent years.Previously,our group had carried out extensive phytochemical investigations on the fruits,roots,twigs,and leaves of F.suffruticosa collected in Anhui Province of China.As a result,a series of novel Securinega alkaloids with unusual carbon skeletons were isolated,and some of which exhibited significant neuronal differentiation activity.In addition,we found that there were significant differences in the alkaloid constituents of F.suffruticosa collected from different regions.In order to search for more novel alkaloids,this thesis carried out a systematically phytochemical investigation on the twigs and leaves of F.suffruticosa collected in Heilongjiang Province.By using comprehensive chromatography method and spectroscopic analysis,a total of 34 alkaloids were isolated and identified,which are 4α-hydroxysecurinine(SA-1),4α-hydroxyallosecurinine(SA-2),4-epi-phyllanthine(SA-3),securitinine(SA-4),15α-methoxy-14,15-dihydroallosecurinine(SA-5),secu′amamine B(SA-6),securinol A(SA-7),secu′amamine E(SA-8),securinol F(SA-9),virosine B(SA-10),secu′amamine A(SA-11),phyllanthidine(SA-12),secu′amamine D(SA-13),14,15-dihydrosecurinine(SA-14),securinine(SA-15),5α-hydroxysecurinine(SA-16),(±)-allosecurinine(SA-17),niruroidine(SA-18),bubbialidine(SA-19),norsecurinine(SA-20),securidinol A(SA-21),securidinol B(SA-22),secupiperine A(SA-23),secupiperine B(SA-24),secu′amamine F(SA-25),secu′amamine G(SA-26),secupiperine C(SA-27),secupiperine D(SA-28),seculactine A(SA-29),seculactine B(SA-30),seculactine C(SA-31),3-hydroxymethyl-β-carboline(SA-32),benzamide(SA-33),and cinnamamide(SA-34),respectively.Among them,compounds SA-9,SA-16,SA-21 ～ SA-24 and SA-27 ～ SA-31 are eleven new compounds.Notably,compounds SA-21 and SA-22 are the first examples of ring B opening Securinega alkaloids.And compounds SA-29 ～ SA-31 are the first examples of quinolizidine alkaloids isolated from genus Flueggea.Furthermore,compounds SA-17,SA-25,and SA-26 were obtained as partial racemic Securinega alkaloids.The following chiral HPLC separation resulted in the obtainment of each optical pure compound.Additionally,three pairs of epimers(SA-23 and SA-24,SA-25 and SA-26,and SA-27 and SA-28)were observed to be interconvertable in methanol solvent.The influences of temperature,solvent,and p H on their interconversion were also investigated by dynamic HPLC experiments.