Study On The Chemical Constituents Of Two Medicinal Plants

This thesis consists of three chapters.Chapter 1 is a review on the constituents and pharmacological activities of Maca(Lepidium meyenii Walp.).Chapter 2 discusses the chemical constituents from the root of Maca.Chapter 3 deals with the chemical constituents from the fruits of Syzygium malaccense.By means of modern chromatography and spectroscopic technology,47 compounds were isolated and identified from the above plants.They covers macamides,alkaloids,triterpenoids,sterides,flavonids,and flavonoid glycosides,etc.Among them,2 compounds,quinoline alkaloids,were new,2 compounds were new natural products,and 31 ones were isolated from the two plants for the first time.The constituents and pharmacological activities of maca were summarized in Chapter 1.Lepidium meyenii Walp.,commonly known as Maca,is a small Brassicaceae crop and native to the Andes.Nowadays,it has been planted successfully in Yunnan Province and Xinjiang Autonomous Region of China.Two centuries ago,the natives of Peru have used Maca as food and folk medicine.Maca has many pharmaceutical effects,such as enhancing energy,alleviating fatigue,improving fertility,strengthening sexual desire,controlling rheumatism,relieving the menopausal discomfort and menopausal symptoms.The chemical constituents of Maca may regulate human hormones,promote metabolism,improve memory,treat depression and combat AIDS.31 compounds were isolated from the ethyl acetate and chloroform part of the 95% ethanol extract of the root of Maca in the second Chapter.These compounds were identified as 3-hydroxy-5-methoxy-2-ethyoxylquinoline(1),3-cyano-5-methoxydihydroquinoline(2),3-benzyl-1,2-dihydro-N-hydroxypyridine-4-carbaldehyde(3),tetrahydro-2-(phenylmethyl)-1Hpyrrolo[1,2-c]imidazole-1,3(2H)-dione(4),N-(phenylmethyl)-formamide(5),1,3-dibenzylurea(6),N-[(3-methoxyphenyl)methyl]-N’-(phenylmethyl)-ethanediamide(7),1-O-α-D-glucopyranosyl-(2S,3R,4E,8Z)-2-N-(2′-hydroxypalmitoyl)octadecasp hinga-4,8-dienine(8),N-benzylhexadecanamide(9),N-(3-methoxbenzyl)hexade canamide(10),N-benzyl-(9Z)-octadecenamide(11),N-benzyl-(9E)-octadecenamide(12),N-benzyl-9Z,12Z-octadecadienamide(13),N-benzyl-13-oxo-9E,11E-octadeca dienamide(14),N-benzyl-9-oxo-12Z-octadecenamide(15),menadione cyclopenta diene(16),cyclolaudanol(17),ursolic acid(18),daucosterol(19),β-sitosterol(20),benzyl alcohol(21),2-phenylacetonitrile(22),p-hydroxybenzoic acid(23),2-(3-hydroxyphenyl)acetonitrile(24),2-(3-methoxyphenyl)acetonitrile(25),4-hydroxybenzyl cyanide(26),(8Z)-heptadecenoic acid(27),hexadecanoic acid(28),octadecane(29),sucrose(30),and glycerol(31).Among them,compounds 5 and 6 were new quinoline alkaloids,compounds 4 and 7 were new natural compounds,compounds 5,6,8,16-18,21,23-25,27-29,and 31 were isolated from L.meyenii Walp for the first time.Syzygium malaccense,distributed mainly in Taiwan and Xishuang Banna of China,is an evergreen tree in the Myrtle family and native to Malaysia.It is a kind of medical and edible plants.16 compounds were isolated from the ethyl acetate extracts of the 95% ethanol extract of the fruit of S.malaccense in chapter 3.These compounds were identified as 3-O-methy-lellagic acid 3′-O-α-L-rhamnopyranoside(32),isorhamnetin(33),kaempferol 3-O-α-L-rhamnoside(34),quercetin 3-O-α-L-rhamnopyranoside(35),5,7,4′-trihydroxy-3′-methoxyflavon ol-3-O-α-L-rhamnopyranoside(36),5,7,3′,5′-tetrahydroxy-4′-methoxyflavonol-3-O-α-L-Rhamnopyranoside(37),kaempferol 3-O-β-D-galuctopyranoside(38),quercet in-3-O-β-D-glucopyranoside(39),quercetin-3-O-β-D-xylopyranoside(40),2’-Oglucopyranosyl-4,4’,6’-trihydroxydihydrochalcone(41),pinocembrin-7-O-β-D-gluco pyranoside(42),daucosterol(43),4,5-dihydroxy-6-methy-α-pyrone(44),5,7-dihy droxy-2-methyl chromone(45),transcinnamic acid(46)and dimethyl malate(47).All of compounds were isolated from S.malaccense for the first time.