Phytochemistry, Medicinal Properties, Bioactive Compounds, and Therapeutic Potential of the Genus Eremophila (Scrophulariaceae)

Abstract

The genus Eremophila (family Scrophulariaceae) consists of approximately 200 species that are widely distributed in the semi-arid and arid regions of Australia. Multiple Eremophila spp. are used as traditional medicines by the First Australians in the areas in which they grow. They are used for their antibacterial, antifungal, antiviral, antioxidant, anti-diabetic, anti-inflammatory, and cardiac properties. Many species of this genus are beneficial against several diseases and ailments. The antibacterial properties of the genus have been relatively well studied, with several important compounds identified and their mechanisms studied. In particular, Eremophila spp. are rich in terpenoids, and the antimicrobial bioactivities of many of these compounds have already been confirmed. The therapeutic properties of Eremophila spp. preparations and purified compounds have received substantially less attention, and much study is required to validate the traditional uses and to highlight species that warrant further investigation as drug leads. The aim of this study is to review and summarise the research into the medicinal properties, therapeutic mechanisms, and phytochemistry of Eremophila spp., with the aim of focussing future studies into the therapeutic potential of this important genus.

Chemical and Antiplasmodial Investigations on Eremophila-Derived Alkaloids and Semisynthetic Ether Analogues

“…The minor alkaloid microthecaline B (2) was purified as a clear stable gum. Comparison of the 1 H and 13 C NMR data of compound 2 and microthecaline A (1) 6 showed a high degree of homology, with the major NMR differences associated with chemical shifts for the C-2/H-2 to C-4/H-4 region of the molecule (see Tables 1, S1−S8, and S39). Furthermore, the LRESIMS of 2 (m/z 312 [M + H] + ), which was 16 Da larger than 1 (m/z 296 [M + H] + ), suggested microthecaline B contained an additional hydroxyl group compared to microthecaline A.…”

“…NMR spectra were recorded at 25 °C on a Bruker AVANCE III HD 500 or 800 MHz NMR spectrometer equipped with a cryoprobe. The 1 H and 13 (Scrophulariaceae) roots were collected on a private property at Holland Park, Queensland, Australia, during March 2020. After airdrying for 1 month, the plant material was ground into a fine powder.…”

“…1−8 Despite the fact that numerous secondary metabolites or extracts reported from Eremophila plants have been shown to exhibit novel and significant bioactivity, 9−12 only a small portion of the 287 described species have undergone detailed chemical investigation. 13 Moreover, only three of the 200+ Eremophila secondary metabolites reported to date contain nitrogen, namely, eucalyptosin A 14 and prunasin, 15 which were both isolated from Eremophila maculata, and the quinoline serrulatane microthecaline A (1), which was purified from the roots of E. microtheca and exhibited moderate antiplasmodial activity (IC 50 = 7.7 μM Plasmodium falciparum 3D7). 6 Due to the unique and rare alkaloid scaffold of microthecaline A (1) and the recent availability of significant quantities of raw E. microtheca root material from a pilot plantation crop, we decided to undertake medicinal chemistry investigations using 1 to make a unique library for drug discovery and chemical biology research.…”

“…ex Benth. (Scrophulariaceae) has been the source of both new and novel chemistry that has shown promising biological activity in a variety of biomedical-focused assays. − Despite the fact that numerous secondary metabolites or extracts reported from Eremophila plants have been shown to exhibit novel and significant bioactivity, − only a small portion of the 287 described species have undergone detailed chemical investigation . Moreover, only three of the 200+ Eremophila secondary metabolites reported to date contain nitrogen, namely, eucalyptosin A and prunasin, which were both isolated from Eremophila maculata , and the quinoline serrulatane microthecaline A ( 1 ), which was purified from the roots of E. microtheca and exhibited moderate antiplasmodial activity (IC 50 = 7.7 μM Plasmodium falciparum 3D7) …”

From the Bush to the Brain: Preclinical Stages of Ethnobotanical Anti-Inflammatory and Neuroprotective Drug Discovery—An Australian Example

“…), and hop bush ( Dodonaea viscosa and D. polyandra ), are a few popular Aboriginal medicinal plants that contributed in the biodiscovery of promising drug candidates for anti-inflammatory treatments [ 69 ]. Chemical investigations performed on the Australian plant Eremophila (Myoporaceae) is another good example of the isolation of bioactive flavonoids, phenolic compounds, and many unique and structurally diverse terpenoids, particularly sesquiterpenoids and diterpenoids with many therapeutic benefits, including antibacterial, antioxidant, and anti-inflammatory properties [ 42 , 86 ].…”