The antibacterial activity of the crude extract of E. alternifolia and of the isolated compounds against Gram-positive bacteria provides a Western scientific explanation of the therapeutic modality of this plant species in traditional Aboriginal medicinal practice.

Plants in the Australian genus Eremophila (Scrophulariaceae) have attracted considerable recent attention for their antimicrobial compounds, which possess a wide range of chemical structures. As they are typically associated with the oily-waxy resin layer covering leaves and green branchlets, and Eremophila lucida is prominent among the species containing a pronounced sticky resin layer, this species was considered of interest for assessing its antibacterial constituents. The n-hexane fraction of the crude acetone extract of the leaves exhibited antibacterial activity against Staphylococcus aureus. Isolation led to the known compounds cembratriene, (3Z, 7E, 11Z)-15-hydroxycembra-3,7,11-trien-19-oic acid (1), the sesquiterpenoid, farnesal (2) and the viscidane diterpenoid, 5α-hydroxyviscida-3,14-dien-20-oic acid (3). The purified compounds were tested for antibacterial activity with 2 and 3 showing moderate antibacterial activity against Gram-positive bacteria.

The ethanol leaf extracts of four medicinal plants named Hibiscus mutabilis, Leucas aspera, Ixora coccinea and Polyalthia longifolia were examined for their possible regulatory effect on nitric oxide (NO) levels using sodium nitroprusside as a NO donor in vitro. Most of the extracts tested demonstrated direct scavenging of NO and exhibited significant activity and the potency of scavenging activity was in the following order: Leucas aspera > Ixora coccinea > Hibiscus mutabilis> Polyalthia longifolia. All the evaluated extracts exhibited a dose-dependent NO scavenging activity. The ethanolic leaf extract of Leucas aspera showed the greatest NO scavenging effect of 80.50% at 320 µg/ml with IC50 value of 94.15 µg/ml as compared to the positive control ascorbic acid where 74.56 % scavenging was observed at similar concentration with IC50 value of 62.48 µg/mL. The maximum NO scavenging of Ixora coccinea, Hibiscus mutabilis and Polyalthia longifolia were 79.65 %, 78.60% and 70.67 % with IC50 values of 43.72 µg/ml, 147.64 µg/ml and 167.08 µg/ml respectively. The present results suggest that these plants might be potent and novel therapeutic agents for scavenging of NO and the regulation of pathological conditions caused by excessive generation of NO and its oxidation product.

Plant metabolites that have shown activity against bacteria and/or environmental fungi represent valuable leads for the identification and development of novel drugs against clinically important human pathogenic fungi. Plants from the genus Eremophila were highly valued in traditional Australian Aboriginal medicinal practices, and E. alternifolia was the most prized among them. As antibacterial activity of extracts from E. alternifolia has been documented, this study addresses the question whether there is also activity against infectious fungal human pathogens. Compounds from leaf-extracts were purified and identified by 1- and 2-D NMR. These were then tested by disk diffusion and broth microdilution assays against ten clinically and environmentally relevant yeast and mould species. The most potent activity was observed with the diterpene compound, 8,19-dihydroxyserrulat-14-ene against Cryptococcus gattii and Cryptococcus neoformans, with minimum inhibition concentrations (MIC) comparable to those of Amphotericin B. This compound also exhibited activity against six Candida species. Combined with previous studies showing an antibacterial effect, this finding could explain a broad antimicrobial effect from Eremophila extracts in their traditional medicinal usage. The discovery of potent antifungal compounds from Eremophila extracts is a promising development in the search for desperately needed antifungal compounds particularly for Cryptococcus infections.

Preliminary phytochemical screening of the methanolic extract of the whole plant of Saccharum spontaneum Linn. (Family-Gramineae) revealed the presence of alkaloids, flavonoids, reducing sugar, tannins and saponins. The antidiarrhoeal activity of the extract (200 and 400 mg/kg) was assessed on experimental animal and a dose dependent decrease in the total number of faecal dropping was obsereved in castor oil induced diarrhoea in mice. The plant extract was also assessed for effect on the central nervous system (CNS) using a number of neuropharmacological experimental models in mice. The extract produced a dosedependent reduction of the onset and duration of pentobarbitone-induced hypnosis, reduction of locomotor and exploratory activities in the open field and hole cross tests. These results suggest that the extract possesses antidiarrhoeal and CNS depressant activity.