Phenolics and Polyphenolics from Melastomataceae Species

The Melastomataceae family, the seventh largest flowering plants, has been studied in several fronts of natural product chemistry, including terpenoids, simple phenolics, flavonoids, quinones, lignans and their glycosides, as well as a vast range of tannins or polyphenols. This review concerns the phenolic and polyphenolic metabolites described in the literature for several genera of this family, the mode of isolation and purification, and the structure elucidation of these new natural products that has been achieved by extensive spectral analyses, including ESI-MS, 1H-, 13C-NMR spectra and two-dimensional experiments, COSY, TOCSY, J-resolved, NOESY, HMQC, DEPT, and HMBC, as well as chemical and enzymatic degradations and the chemotaxonomic meaning. Finally, a general biogenetic pathway map for ellagitannins is proposed on the bases of the most plausible free radical C-O oxidative coupling.

Jussieu (1789) first recognized the melastomataceae as a natural unit; however, David Don (1823) was who put structure into the family. Triana, a Colombian native with extensive knowledge in the field, published his system in 1865 and slightly modified it in 1871. Triana's system grouped the melastomataceae in three subfamilies, melastomatoideae, astronioideae and memecyloideae; which include thirteen tribes. Owing to the size of this family, the internal classification has been reviewed several times. A recent systematic analysis of melastomataceous plants re-structured and placed them into two subfamilies, kibesioideae and melastomatoideae, which contains only nine tribes (see Table S1) and separated memecyloideae and crypteronioideae to upgrade them to the family status, memecylaceae and crypteroniaceae respectively [2].

Folk Medicinal Uses of Melastomataceous Plants
Melastomataceous plants have been long used as traditional medicines, especially in Asia and Latin America. In Indonesia, Malaysia and China, some species of this family, such as Melastoma, Medinilla and Osbeckia species, have been used as remedies for diarrhea, dysentery, leukorrhea, and various skin diseases, as well as astringents or hemostatics [8]. The tannins and the presence of alkylated derivatives of ellagic acid in various plants of this group may be responsible for these medicinal applications [9]. Various phytochemical studies have revealed ellagitannins as the main constituents.
In China, a decoction of the leaves of Melastoma dodecandrum Lour. is suggested to be effective as a wash for scrofula, hemorrhoids, dermatitis, leprosy, scabies, athlete's foot, and snakebites, as well as to prevent abortion. The root juice is taken as a remedy for post parturient abdominal pains and dysentery [8]. The whole plant has been used as a traditional antipyretic, antitoxic, diuretic, hemostatic and anti-rheumatic medicine. An 80% aqueous acetone extract of the whole plant exhibited anti-allergic activity in the passive cutaneous anaphylaxis test and toward histamine release from rat peritoneal mast cells with an antigen antibody reaction in vitro [10]. The leaves of Melastoma malabathricum Linn., which is known as "daunharendong" in Indonesia and Malaysia, have been used as a crude drug for the treatment of diarrhea, dysentery and leucorrhea [11][12][13].
In Chiapas Mexico, people eat the leaves of Arthrostema ciliatum Pavón ex Don. In another parts of Central America, the decoction of the whole plant is used as diuretic, purgative and as refreshment [14]. A syrup prepared from flowers of Rhychanthera grandiflora (Aubl.) DC. has been cited as a natural medicine against respiratory illnesses in French Guyana [15].
Arthrostema volubile (Bompl. Ex Naudin) Triana and A. macrodesmum Gleason are used in Colombia in decoction of their stems or whole aerial part of the plant as a febrifuge, especially in the treatment of malaria. The stems are chewed or in the form of sap to quench the thirst and to cure the gum irritations. The decoction of the whole plant of Brachyotum strigosum (L.f.) Triana is used against the calculus of the bladder and other ailments of genitourinary tract; whereas the decoction of Chaetolepis microphylla (Bompl.) Miq. is used as diuretic [16].
Bellucia dichotoma Cogn. is one of various plant species used in folk medicine in the west of the state of Pará, Brazil, to treat snake bites. The extract inhibits the local effects of Bothrops atroxvenomas as suggested by the inhibition of phospholipase A2, hemorrhagic and edematogenic activities [17].
In Colombia, some species of the family have been used as folk medicine for the treatment of malaria, infections, skin injuries, respiratory diseases, bladder calculus and other genitourinary ailments, as diuretic and as a topical remedy for gum irritations. Verbal information submitted by settlers from Caldas, Colombia indicates that Tibouchina ciliaris Vent.) Cogn. and Monochaetum multiflorum (Bonpl.) Naudin are traditionally used for treatment of skin infections and injuries.
A recent and concise review on melatomataceous plants medicinal uses has been published [18], and another review correlating the chemical structure and gastric anti-ulcer activity of tannins [19].     Table S4. Anthocyanins isolated from melastomataceous plants.