For correspondence:-  Jin-He Jiang   Email: jinhejiang@126.com   Tel:+868715941089

Received: 7 July 2015        Accepted: 1 November 2015        Published: 27 December 2015

Citation: Jiang J, Zhang W, Chen Y. Phytochemical and pharmacological properties of the Genus Melodinus - A review. Trop J Pharm Res 2015; 14(12):2325-2344 doi: 10.4314/tjpr.v14i12.25

© 2015 The authors.
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Melodinus is a genus of ca. 53 species in the family Apocynaceae, mainly distributed in tropical and subtropical Asia and from Oceania to the Pacific coast. Among them, ca. 11 species occur in South China, Southwest China and Taiwan [1]. Some species, such as M. suaveolens and M. henyri have been used in Chinese folk medicine for the treatment of meningitis in children, rheumatic heart diseases, diuresis, bone fracture and so on [2,3]. M. scandens is used as a decongestive, against migraines, sinusitis and otitis [4]. figure 10 In Australia, an aq extract of M. australis, when injected into a dog, produced a sharp drop in blood pressure, accompanied by an increase in the depth of respiration and decrease in rate [5]. 1 Current crude alkaloid mixtures and purified alkaloids from some Melodinus species have demonstrated antitumor and antibacterial activities [6,7]. Many characteristic melodinus alkaloids, such as meloscine, epimeloscine, scandine and vincadifformine, had for a long time attracted great interest of synthetic organic chemists as challenging targets due to their marked diversity and complicated architectures [8,9,10] And more than twenty alkaloids were reviewed from the genus Melodinus by Sevenet et al [11]. About 14 alkaloids can be classified into the melodan skeleton and its rearranged version and derived from 18, 19-didehydrotabersonine as parent compound in the plant family Apocynaceae [12] Recently, much attention has been paid to Melodinus plants to search active melodinus alkaloids. Extensive studies of the Melodinus genus have led to the identification of several novel alkaloids. Only 22 species of the genus have been chemically investigated and provided an array of structurally interesting indole alkaloids, quinoline alkaloids, dimeric indole alkaloids, diterpenoids, triterpenes and others compounds over the past few decades. Some compounds show cytotoxic and anti-inflammatory activities. In this paper, we summarize phytochemistry and pharmacological activities of the Melodinus species so as to collate the existent information on this plant.

Phytochemical Constituents

By the deadline of MAY 2015, phytochemical studies on this genus led to the isolation of 263 compounds. Their structures are shown below and their names, the corresponding plant sources are collected. As can be seen, indole alkaloids are the dominant constituents within this genus. Alkaloids Plants of the genus Melodinus (Apocynaceae) have been proven to be good sources of alkaloids. This genus has been regarded as a rich source of monoterpenoid indole alkaloids, which originated from the condensation of tryptophan with secologanin. We now list 252 alkaloids which were obtained from the genus Melodinus. The structural characters and relationships of the major Melodinus alkaloid groups are discussed. Monoterpenoid indole alkaloids Kopsinine-type In this paper, indole alkaloids could be classified into ten groups from some Melodinus plants. This first type included nineteen alkaloids (1-19) (, ) [13-35]. The common characteristic compounds, venalstonine (3) and venalstonine (7) were produced by more than fifteen Melodinus species. Three aspidofractinine oxo-derivatives (9-11) were obtained from M. reticulates and M. guillauminii [13,14]. Melodinine L (12) was new alkaloid identified as venalstonine-N (4)-oxide from M. tenuicaudatus and M. yunnanensis [27,34]. Methoxyl substitution at C (15), a rare phenomenon, were present in pyrifoline (13) and refractidine (14) obtained from M. australis [33]. Melodinine Q (17) was venalstonine derivative with a CH3W22;COW22;CHW22;unit [29]. 14, 15-Seco-3-oxo-kopsinal (16) originated a further oxidation of bond C (14)-C (15) of venalstonine was identified by comparison of their spectral and physical properties from M. guillauminii [14]. 10, 22 - Dioxokopsane was a known alkaloids but was isolated obtained from this genus for the first time [35].