Phloroglucinol Derivatives From The Leaves Of Syzygium Samarangense

The plant Syzygium samarangense?Blume?Merr.&Perry?Myrtaceae?is an evergreen tree originated from Malaysia and India,which had been commercially cultivated in China for years.In Southeast Asia,it's fleshy fruit,commonly known as pink wax apple,is an economically important fruit with excellent quality and special flavor.The leaves,roots and barks of S.samarangense could be used as folk medicine for the treatment of fever,eczema,itch,and diarrhoea,etc.Previous phytochemical investigations on this plant had led to the isolation of terpenoids,polyphenols,and volatile oil.As a part of our ongoing project to search structurally unique and biologically active phloroglucinol derivatives from plants of family Myrtaceae,our group had reported the isolation of several novel phloroglucinols from the plants of genera Eucalyptus,Callistemon,Psidium,Rhodomyrtus,and Myrtus.The blank in phloroglucinol constiturent of S.samarangense and our interest in chemistry of the special sencondary metabolites prompted us to carry out a phytochemical investigation on the leaves of S.samarangense,which led to the isolation of 27phloroglucinol derivatives.On the basis of spectroscopic analyses,their structures were indentified as samarangol A?SS-1?,samarangol B?SS-2?,samarangol C?SS-3?,samarangol D?SS-4?,samarangol E?SS-5?,samarangol F?SS-6?,samarangone A?SS-7?,samarangone B?SS-8?,samarangone C?SS-9?,samarangone D?SS-10?,samarangone E?SS-11?,samarangone F?SS-12?,samarangone G?SS-13?,symarangol A?SS-14?,crinatusin A₁?SS-15?,symarangol B?SS-16?,symarangol C?SS-17?,5,7-dihydroxy-2-pentadecylchromone?SS-18?,samarone A?SS-19?,jambone G?SS-20?,samarone B?SS-21?,samarone C?SS-22?,jambone E?SS-23?,jambone F?SS-24?,samarone D?SS-25?,samarone E?SS-26?,and jamunone B?SS-27?,respectively.Among them,SS-1^SS-6,SS-14,SS-16,and SS-17 are nine new phloroglucinol-terpene adducts.Compounds SS-7^SS-13 are identified as seven new cyclicpolyketide-terpene adducts.In addition,SS-19,SS-21,SS-22,SS-25,and SS-26 are five new acylphloroglucinol derivatives bearing a long alkyl side chain.Moreover,some isolated phloroglucinols were evaluated for their cytotoxic effects on HepG2 and MDA-MB-231 cells by using MTT assay,several of which showed potent cytotoxicity on both two cancer cell lines.