Recent trends in diabetes treatments show an increasing interest in traditional systems of medicine. Ayurveda, a traditional Indian system medicine, advocates a wide range of medicinal plants to treat diabetes. Although there have been numerous studies on extracts from these medicinal plants that demonstrate antidiabetic activity, scientific studies directed to the isolation, purification and identification of active ingredients responsible for the hypoglycemic activity and also the modes of action of these extracts/active ingredient(s) on glucose homeostasis have been often inconclusive or lacking except for a few cases. The aim of this present study was to identify and isolate a potent antidiabetic compound(s) from some extensively advocated Ayurvedic antidiabetic plants such as 'Trigonella foenum-graecum' Linn (TFG), 'Pterocarpus marsupium' Roxb (PM), 'Gymnema sylvestre' R.Br (GS) and 'Curcuma longa' Linn (CL). An in-house developed 'in vitro' tissue culture-based bioassay method was employed in the present study to determine the effects of plant extracts on insulin secretion from mouse pancreas tissues and on glucose uptake by mouse skeletal muscle tissues under both normoglycemic (5mM glucose) and hyperglycemic (12mM glucose) culture conditions. The results from our preliminary study indicated that all these plant extracts have beneficial effects on glucose homeostasis either by stimulating insulin or enhancing glucose uptake or activating both. In terms of their comparative effects on tissues that regulate glucose metabolism, the aqueous extracts of plants, PM and CL, were found to be more potent when compared with other studied aqueous extracts of plants TFG and and GS, within culture conditions.

Essential oils from the Australian Aboriginal medicinal plant 'Eremophila longifolia' (emu bush) were characterised using GC/MS and NMR, and antimicrobial capacity investigated using disc diffusion and broth dilution. Leaves were collected from various locations within New South Wales (NSW, Australia) and hydro-distilled for volatile leaf oils. Overall yield and oil constitution differed markedly according to the geographical region from which the plants were collected. 'E. longifolia' demonstrated a variety of chemotypes not yet recognised. Four further chemotypes are now recognised within NSW, in addition to the two previously characterised from other regions of Australia; the Northern Territory (NT) and the Murchison district in Western Australia (WA). Characterisation of NSW chemotypes revealed that here 'E. longifolia' does not produce the carcinogenic volatile compound, safrole, as previously described in the leaf oil from Murchison specimens (WA). Two separate chemotypes within NSW yielded oil as high as 7% w/w and 3.5% w/w consisting mostly of iso-menthone (70-90%) and karahanaenone (≈80%) respectively; marking these as the most abundant natural sources of these compounds so far described [3,4,5]. The two remaining chemotypes had a much lower yield, 0.2 and 0.7%, and were more similar to the chemotype found in the NT; leaf oils consisting of limonene (≈20%) and borneol (20-30%) respectively. Antimicrobial assays of volatile oils from the four chemotypes revealed a moderate to high antimicrobial capacity, varying with species and chemotype. Traditional (location specific) indigenous applications of the oils are consistent with these results. The essential oil from 'E. longifolia' may thus be a likely candidate for further investigation into cosmeceutical use addressing a similar market niche to that already successfully occupied by the essential oil of 'Melaleuca alternifolia' (tea tree oil) and more recently 'Backhousia citriodora' (lemon myrtle oil). Further investigations (wound healing, anti-inflammatory and cultivar chemotype requirements) are in progress.

X-Ray data for two N-acyloxy-N-alkoxyamides, a class of direct-acting mutagens, indicate extreme pyramidalisationat the amide nitrogen in keeping with spectroscopic and theoretically determined properties of amides with bisoxosubstitutionat nitrogen. The combined electronegativity of two oxygens leads to average angles at nitrogen of 107.8and 108.1° and |χN| of 66° and 65°. The sp³ nature of nitrogen results in negligible amide resonance as evidencedby long N–C(O) bonds, high IR carbonyl stretch frequencies, carbonyl ¹³C NMR data and very low amideisomerisation barriers. In addition, conformations in the solid state support a strong n₀–σ*[NOAc] anomeric interactionas predicted by molecular orbital theory. HF/6-31G* calculations on formamide, N-methoxyformamide andN-formyloxy-N-methoxyformamide support these findings.

Principal component analysis of ¹H NMR spectra of dichloromethane extracts taken from grapevine leaves reveals that phylloxera infestation of the root system causes metabolic changes in the leaves of infested grapevines, both in the field and in the glasshouse. A number of potential markers of phylloxera infestation were detected but their presence is transient and varies with the stage of the growing season. The changes in the metabolic profile caused by phylloxera infestation more closely resemble those caused by nitrogen deficiency than those induced by water stress. A reduction in the ratio of linoleic acid to linolenic acid in the triglyceride component of the leaf extract may provide an indicator of phylloxera infestation.

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.

'Eremophila longifolia' is a woody shrub, endemic to arid and semi-arid regions of Australia, where it is employed in traditional indigenous medicine to treat a wide variety of conditions. An early report examining 'E. longifolia' leaf essential oil composition had indicated high levels of the hepatotoxic and carcinogenic phenylpropanoid safrole, and as a result, authors have urged caution in the use of traditional preparations derived from this species. The present study was initiated after noting significant variations in morphology and odor profiles of wild 'E. longifolia' specimens in the state of New South Wales, (NSW) Australia. Leaves from several specimens were collected across a range of biogeographic regions in NSW. Essential oils were obtained by hydrodistillation and analysed using GCMS and NMR spectroscopy. Thirty-five compounds were identified with comparison of retention data and mass spectra with that of published values. Considerable variation was found among specimens in essential oil yield and composition, resulting in identification of three distinct types (here designated A, B and C). Type A specimens produced oils at relatively high yields (3.1% - 5.7 %) with major constituents isomenthone (61.1% - 86.7%), menthone (8.8% - 22.6%) and α-terpineol (8.4% - 11.0%). Type B specimens produced oils of relatively moderate yield (0.5% - 1.9% g/g) with major constituents karahanaenone (81.0% - 82.2%) and α -terpineol (4.1% - 11.7%). One specimen (designated type C) produced essential oil at relatively low yield (0.4% g/g fresh leaves) with major constituents identified as borneol (31.7%), fenchol (19.7%) and limonene (9.9%). No phenylpropanoids, including safrole, were detected in any of the specimens examined here. The relatively uncommon monoterpenoid karahanaenone is valued as a precursor in the fragrance industry and to the best of our knowledge the leaves of type B specimens described here represent the richest known natural source of this compound.

Can Phylloxera infestation cause detectable metabolic changes in grape leaves? We are investigating the existence of chemical fingerprints of Phylloxera in extracts taken from grapevine leaves and their possible use as a method of early detection of Phylloxera infestation.

Lepidozenal and isobicyclogermacrenal were isolated from the leaves of 'Eucalyptus dawsonii' and a complete assignment of their ¹H and ¹³C NMR spectra was carried out using 2D NMR methods.