Novel indole and quinoline alkaloids from Melodinus yunnanensis

6/7-Seco rearranged spiro-indolone alkaloids,meloyunines A(1)and B(2)and a monoterpenoid quinoline alkaloid meloyunine C(3)together with its possible intermediate 14,15-dehydromelohenine B(4),and their precursorΔ14-vincamenine(5)were isolated from Melodinus yunnanensis.All structures were elucidated based on NMR,FTIR,UV,and MS spectroscopic data.The isolation of monoterpenoid indole,quinoline,and its immediate from the same plant chemically supported the biosynthesis of quinoline from indole.Compound 2 was cytotoxic against several human cancer cell lines.

TWO NEW INDOLE ALKALOIDS FROM MELODINUS MORSEI

Two new indole alkaloids named 152-hydroxy-14,15-dihydro-vindo- linine and 152-hydroxy-14,15-dihydro-16-epi-vindolinine were isolated from Melodinus morsei.Their structures were established by spectroscopic means and comparison with related compounds.

Phytochemical Analysis and Antioxidant Activity Determination on Crude Extracts of <i>Melodinus eugeniifolus</i>Barks and Leaves from Malaysia

Six different extracts of Melodinus eugeniifolus (a very rare medical plant belonging to Apocynaceae) leaves and barks were screened for their phytochemical composition, and free radical scavenging activities. Three different methods were used to test the antioxidant activity for extracts which include FRAP assay (Ferric reducing antioxidant potential), DPPH radical scavenging assay (1,1-diphenyl-2-picryl hydrazyl radical reducing power methods), and β-carotene bleaching assay. Among the different extracts tested, the ethanol extract of barks showed significant radical scavenging activities. Phytochemical analysis of the extracts revealed that the radical scavenging activities are mainly due to the presence of alkaloids, cardiac glycosides, sterols, steroids and flavonoids. The results obtained suggest that Melodinus eugeniifolus could be exploited in the management of various diseases like cancer, cardiovascular diseases and infection diseases. Highlights: Melodinus eugeniifolus, a very rare medical plant from South Asian rain forest which may be a potential drug for many diseases is first reported about its phytochemical characteristics and antioxidant activity by different methods.

The Genus Melodinus (Apocynaceae): Chemical and Pharmacological Perspectives

The plants of the genus Melodinus (Apocynaceae) are widely distributed, and have long been used in folk medicine for the treatment of various ailments such as meningitis in children and rheumatic heart diseases, hernia, infantile malnutrition, dyspepsia and testitis. Over 100 alkaloids together with flavonoids, lignans, steroids, terpenoids and coumarins have been identified in the genus, and many of these have been evaluated for biological activity. This review presents comprehensive information on the chemistry and pharmacology of the genus together with the traditional uses of many of its plants. In addition, this review discusses the structure-activity relationship of different compounds as well as recent developments and the scope for future research in this aspect.

Antibacterial constituents from Melodinus suaveolens

To investigate the non-alkaloidal chemical constituents of the stems and leaves of Melodinus suaveolens and their antibacterial activities. Compounds were isolated and purified by repeated silica gel, Sephadex LH-20, RP18, and preparative HPLC. Their structures were elucidated by comparison with published spectroscopic data, as well as on the basis of extensive spectroscopic analysis. The antibacterial screening assays were performed by the dilution method. Fourteen compounds were isolated, and identified as lycopersene(1), betulinic aldehyde(2), 3β-acetoxy-22,23,24,25,26,27-hexanordammaran-20-one(3), 3a-acetyl-2, 3, 5-trimethyl-7ahydroxy-5-(4,8,12-trimethyl-tridecanyl)-1,3a,5,6,7,7a-hexahydro-4-oxainden-1-one(4), 3β-hydroxy-28-norlup-20(29)-ene-17β-hydroperoxide(5), 3β-hydroxy-28-norlup-20(29)-ene-17α-hydroperoxide(6), β-sitosterol(7), 28-nor-urs-12-ene-3β, 17β-diol(8), α-amyrin(9), ergosta-4,6,8(14),22-tetraen-3-one(10), 3β-hydroxy-urs-11-en-28,13β-olide(11), betulin(12), obtusalin(13), and ursolic acid(14). Among the isolates, compounds 1, 2, 6, 8, 10, and 14 showed potent antibacterial activities against the four bacteria. This is the first report of the antibacterial activity of the constituents of Melodinus suaveolens.

Suadimins D—J,Monoterpenoid Indole-Quinoline and Bisindole Alkaloids from Melodinus suaveolens

Comprehensive Summary,Compounds 1—12,including seven complex monoterpenoid indole-quinoline and bisindole alkaloids,suadimins D—J(1—7)with previously unreported carbon-carbon linkages,were isolated and identified from the twigs and leaves of Melodinus suaveolens.Their structures were elucidated by a combination of diverse methods,especially the extensive spectroscopic data analysis and electric circular dichroism(ECD)calculations.The cytotoxicity of these compounds against three cancer cell lines was evaluated,some of which showed moderate activities with IC50 values ranging from 2.4 to 8.0μM.