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Mangrove forests are one of the most special forest ecosystems as a hub for marine biotope, yet they are also one of the most threatened and vulnerable ecosystems. Field investigations showed that many populations of Myoporum bontioides (Myoporaceae), a mangrove associate species recorded in southern China, southern Japan and northern Vietnam, have disappeared in China during the recent decades. For the conservation of this species and other related coastal mangrove species, we here report the genetic diversity and population structure of M. bontioides using amplified fragment length polymorphism (AFLP). The analysis produced 1557 polymorphic bands across all the 143 investigated individuals. Our results revealed a relatively high level of genetic diversity (species level: P = 98.90%, He = 0.233, I = 0.451; population level: P = 59.61%, He = 0.171, I = 0.265) and a high level of genetic differentiation (GST = 0.238 and ΦST = 0.316) in M. bontioides. No correlation was observed between genetic distances and geographic distances. A mixed mating system and limited long-distance dispersal ability may partially account for the genetic differentiation. UPGMA dendrogram, PCoA and STRUCTURE analysis revealed a distinct structure of M. bontioides populations. These findings underline that populations of M. bontioides should be preserved in situ, and the Gaoqiao and Taiwan populations should be prioritized for conservation.

The aerial parts of the endemic Australian plant Eremophila debilis (Myoporaceae) contain 3% dry weight of the biologically active 5,6,7,3',4',5'-hexamethoxyflavone, which had its structured confirmed using X-ray crystal crystallography. The presence of significant levels of the polypharmacologically active 5,6,7,3',4',5'-hexamethoxyflavone in the edible parts of the plant has potential implications for its use as a food and bush medicine.

Volatile oils of Eremophila longifolia F. Muell. (Myoporaceae) leaves were obtained by hydrodistillation and analysed using GC-MS. A total of 33 compounds were identified in the oils examined and a high degree of intraspecific variability in chemical composition between specimens occurring in separate geographic localities was found. Multivariate statistical analysis of chemical composition of volatile oils enabled classification of three chemotypes in this species.

A detailed investigation of the wood, leaf, branch and root oil of Eremophila mitchellii (Benth.) was carried out by a combination of GC-FID, GC-MS and NMR. The wood oil was composed predominantly of eremophilanes, a rare class of biologically active, bicyclic sesquiterpenoids. The root oil was also found to contain the eremophilanes together with the zizaene sesquiterpene, sesquithuriferone. 9-Hydroxy-1,7(11),9-eremophilatrien-8-one and the known 1(10),11-eremophiladien-9-one (eremophilone), 9-hydroxy-7(11),9-eremophiladien-8-one (2-hydroxyeremophilone), 8-hydroxy-11-eremophilen-9-one (santalcamphor), 8-hydroxy-10,11-eremophiladien-9-one, sesquithuriferone and 8-hydroxy-1,11-eremophiladien-9-one were purified and elucidated by NMR. Three approaches to the purification of the major eremophilanes from the wood oil are described. (+) Spathulenol, α-pinene, globulol, viridiflorene were the major constituents of the leaf oil. All of the essential oils and the eremophilanes exhibited cytotoxicity against P388D(1) mouse lymphoblast cells in-vitro.

This paper reports on the isolation and identification of antibacterial constituents from the indigenous Australian medicinal plant Eremophila duttonii F. Muell. (Myoporaceae). Preparations derived from this plant are used by indigenous populations in the topical treatment of minor wounds, otitis and ocular complaints, and as a gargle for sore throat. Several authors have reported extracts of this plant to effect rapid bacteriolysis and inhibit growth of a wide range of Gram-positive micro-organisms. In other studies involving screening of native medicinal plants for antibacterial activity, extracts of Eremophila duttonii have been reported to consistently exhibit the highest potency amongst all species included. From a hexane extract, we identified two diterpenes of the serrulatane class, the principal constituents responsible for antibacterial activity and present as major constituents of the resinous leaf cuticle: serrulat-14-en-7,8,20-triol (1) and serrulat-14-en-3,7,8,20-tetraol (2). In addition, a hydroxylated furanosesquiterpene with mild antibacterial activity which appeared to be a novel compound was isolated from the extract and tentatively identified as 4-hydroxy-4-methyl-1-(2,3,4,5-tetrahydro-5-methyl[2,3'-bifuran]-5-yl) pentan-2-one. Minimum inhibitory concentrations for each of the compounds against three Gram-positive bacteria: Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (ATCC 12228) and Streptococcus pneumoniae (ARL 10582), were determined using a micro-titre plate broth dilution assay.