Plant 101

Aglaia odorata Lour. (Meliaceae)


Mizilan ('fragment of rice flower')

Aglaia odorata was described in 1790. This is the earliest use of the name Aglaia, now known to be the largest genus in the Mahogany family. Aglaia odorata is a small tree native to China, Vietnam, Cambodia and Thailand. Flowering throughout the year, it is grown as an ornamental in China, Indo-China, Peninsular Malaysia, Singapore and Java. The leaves are divided into five, dark green, shiny leaflets. Individual flowers are tiny, yellow and strongly citronella scented. They are used in China for scenting tea and in Java for perfuming clothes.

Many of the remaining 120 species in the genus are common trees of Indo-Australasian tropical forests. Aglaia taxonomy, reproductive ecology, phylogeny, biogeography and evolution have been investigated in Oxford for almost forty years. A monograph of the entire genus, throughout its range, was published in 1992, becoming the foundation for interpretation of Aglaia research and a model for other genera and families of woody plants. During this research, two Aglaia species in the Botanic Garden's palm house were grown from seeds collected off wild trees growing in primary tropical rain forest.

Aglaia's fruits contain seeds surrounded by an edible flesh. If the fruit opens to expose its brightly-coloured seeds, birds remove, swallow and carry the seeds away from the tree. In species where it remains closed, primates and other mammals remove the outer, inedible fruit wall and swallow the fleshy seeds. Viable seeds are usually expelled undamaged from the animal's gut.

Aglaia's range extends eastwards far beyond the limit of most placental mammals. Endemic birds, including birds of paradise and flightless cassowaries in New Guinea and Australia and large, island-dwelling pigeons in the Pacific islands, seem to be the dispersers of the numerous recently evolved Aglaia species in the eastern part of the generic range.

Aglaia is the only source of a unique group of natural products featuring a cyclopenta[b] benzofuran skeleton, discovered in 1982 and known as flavaglines. Discovery of an entirely new, structurally distinct, class of secondary metabolites in higher plants is a rare event. More than fifty derivatives of these compounds have now been isolated. Most have potent insecticidal properties and antifungal, antiviral, antibacterial or antihelmintic bioactivity. Several exhibit cytotoxic activity against a range of human cancers. These are reported to act as direct inhibitors of translation initiation, a rare target among anticancer agents of natural origin. At least one is undergoing trials for its medicinal value.

Further reading

Grudinski M et al. 2014. An evaluation of taxonomic concepts of the widespread plant genus Aglaia and its allies across Wallace's Line (tribe Aglaieae, Meliaceae). Molecular Phylogenetics and Evolution 73: 65-76.

Grudinski M et al. 2014. West to east dispersal in a widespread animal-dispersed woody angiosperm genus (Aglaia, Meliaceae) across the Indo-Australian Archipelago. Journal of Biogeography 41: 1149-1159.

Pan L et al. 2014. Rocaglamide, silvestrol and structurally related bioactive compounds from Aglaia species. Natural Products Reports 31: 924-939.

Pannell CM 1992. A taxonomic monograph of the genus Aglaia Lour. (Meliaceae). HMSO.

Pannell CM 2007. Aglaia (Meliaceae). In Soepadmo E et al. (eds) Tree Flora of Sabah and Sarawak 6: 24-107.

Caroline Pannell