Acaricidal and Insecticidal Activities of Essential Oils and Constituents of Tasmannia lanceolata (Poir.) A.C.Sm. (Canellales: Winteraceae) Against Tetranychus urticae Koch (Trombidiformes: Tetranychidae) and Myzus persicae Sulzer (Hemiptera: Aphididae)

The negative side effects of synthetic pesticides have drawn attention to the need for environmentally friendly agents to control arthropod pests. To identify promising candidates as botanical pesticides, we investigated the acaricidal and insecticidal activities of 44 plant-derived essential oils (EOs) against Tetranychus urticae Koch and Myzus persicae Sulzer. Among the tested EOs, Tasmannia lanceolata (Poir.) A.C.Sm. (Tasmanian pepper) essential oil (TPEO) exhibited strong acaricidal and insecticidal activity. Mortality rates of 100% and 71.4% against T. urticae and M. persicae, respectively, were observed with TPEO at a concentration of 2 mg/ml. Polygodial was determined to be the primary active component after bioassay-guided isolation of TPEO using silica gel open-column chromatography, gas chromatography, and gas chromatography-mass spectrometry. Polygodial demonstrated acaricidal activity against T. urticae with mortality rates of 100%, 100%, 61.9%, and 61.6% at concentrations of 1, 0.5, 0.25, and 0.125 mg/ml, respectively. Insecticidal activity against M. persicae was also evident, with mortality rates of 88.5%, 85.0%, 46.7%, and 43.3% at respective concentrations of 1, 0.5, 0.25, and 0.125 mg/ml. Insecticidal and acaricidal activities of TPEO were greater than those of Eungjinssag, a commercially available organic agricultural material for controlling mites and aphids in the Republic of Korea. These findings suggest that TPEO is a promising candidate for mites and aphids control.

Valorisation of Three Underutilised Native Australian Plants: Phenolic and Organic Acid Profiles and In Vitro Antimicrobial Activity

Tasmannia lanceolata, Diploglottis bracteata and Syzygium aqueum are understudied native Australian plants. This study aimed to characterise the non-anthocyanin phenolic and organic acid profiles of the aqueous extracts obtained from the leaves of T. lanceolata and fruits of D. bracteata and S. aqueum by UHPLC-Q-Orbitrap-MS/MS and UHPLC-TQ-MS/MS. A total of 39, 22, and 27 non-anthocyanin polyphenols were tentatively identified in T. lanceolata, D. bracteata, and S. aqueum extracts, respectively. Furthermore, sugars and ascorbic acid contents as well as in vitro antioxidant and antimicrobial activities of the extracts were determined. Response surface methodology was applied to achieve an extract blend with a strong inhibitory effect against Pseudomonas viridiflava, the main cause of soft rot in vegetables, Bacillus subtilis, Rhodotorula diobovata and Alternaria alternata. The identified compounds including organic acids (e.g., quinic, citric and malic acids) and polyphenols (e.g., catechin, procyanidins, and ellagitannins) might contribute to the observed antimicrobial activity. Furthermore, this study provides the most comprehensive phenolic profiles of these three underutilised native Australian plants to date.

Phytochemical and Safety Evaluations of Finger Lime, Mountain Pepper, and Tamarind in Zebrafish Embryos

Plants play a pivotal role in drug discovery, constituting 50% of modern pharmacopeia. Many human diseases, including age-related degenerative diseases, converge onto common cellular oxidative stress pathways. This provides an opportunity to develop broad treatments to treat a wide range of diseases in the ageing population. Here, we characterize and assess the toxicological effects of finger lime (Citrus australasica), mountain pepper (Tasmannia lanceolata), and small-leaved tamarind (Diploglottis australis) extracts. The characterization demonstrates that these Australian native plants have antioxidant potential and, importantly, they have high concentrations of distinct combinations of different antioxidant classes. Using zebrafish larvae as a high-throughput pre-clinical in vivo toxicology screening model, our experiment effectively discriminates which of these extracts (and at what exposure levels) are suitable for development towards future therapies. The LC50-96h for finger lime and tamarind were >480 mg/L, and 1.70 mg/L for mountain pepper. Critically, this work shows that adverse effects are not correlated to the properties of these antioxidants, thus highlighting the need for combining characterization and in vivo screening to identify the most promising plant extracts for further development. Thus, we present a high-throughput pre-clinical screening that robustly tests natural plant products to utilize the diversity of antioxidant compounds for drug development.

Australian native fruits and vegetables: Chemical composition, nutritional profile, bioactivity and potential valorization by industries

Australian native plants have adapted themselves to harsh climatic conditions enabling them to produce unique and high levels of secondary metabolites. Native fruits and vegetables have been an integral part of the Indigenous Australian diet and Bush medicine for centuries. They have recently gained popularity owing to their rich dietary fiber, minerals, polyphenolic and antioxidant contents. This review presents a comprehensive summary and critical assessment of the studies performed in the last few decades to understand the phytochemical and nutritional profiles and therapeutic properties of Australian native fruits and vegetables. Furthermore, the potential of these fruits and vegetables as functional food ingredients and in the prevention and treatment of different diseases is discussed. Research on the nutritional and phytochemical profiles and therapeutic activity of Australian vegetables is limited with most studies focused on native fruits. These fruits have demonstrated promising antioxidant, anticancer, anti-inflammatory and antimicrobial activities mostly in in vitro models. More research to a) identify novel bioactive compounds, b) define optimal post-harvest and extraction methods, and c) understand molecular mechanisms of pharmacological activity through preclinical and clinical studies is prudent for the prospective and wider use of Australian native fruits and vegetables by the food, pharmaceutical, and nutraceutical industries.

Comparison of the antibacterial activity of Australian Terminalia spp. extracts against Klebsiella pneumoniae: a potential treatment for ankylosing spondylitis

Traditional medicines prepared using Terminalia species have been used globally to treat inflammation and pathogenic infections. Recent studies have demonstrated that multiple Asian and African Terminalia spp. inhibit bacterial triggers of some autoimmune inflammatory diseases, including ankylosing spondylitis. Despite this, the effects of Australian Terminalia spp. on a bacterial trigger of ankylosing spondylitis (K. pneumoniae) remain unexplored. Fifty-five extracts from five Australian Terminalia spp. were investigated for K. pneumoniae growth inhibitory activity. Methanolic, aqueous and ethyl acetate extracts of most species and plant parts inhibited K. pneumoniae growth, with varying potencies. Methanolic leaf extracts were generally the most potent bacterial growth inhibitors, with minimum inhibitory concentration (MIC) values of 66 μg/mL (T. ferdinandiana), 128 μg/mL (T. carpenteriae) and 83 μg/mL (T. petiolares). However, the aqueous leaf extract was the most potent T. grandiflora extract (MIC = 87 μg/mL). All T. catappa extracts displayed low growth inhibitory activity. The Terminalia spp. methanolic leaf extracts were examined by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). All contained a relative abundance of simple gallotannins (particularly gallic and chebulic acids), the flavonoid luteolin, as well as the monoterpenoids cineole and terpineol. Notably, all Terminalia spp. were non-toxic or of low toxicity in ALA and HDF toxicity assays, highlighting their potential for preventing the onset of ankylosing spondylitis and treating its symptoms once the disease is established, although this needs to be verified in in vivo systems.

The Therapeutic Properties of Plants Used Traditionally to Treat Gastrointestinal Disorders on Groote Eylandt, Australia

The First Australians had well-developed healing systems. Groote Eylandt inhabitants used a variety of plant species to treat diarrhoea and other gastrointestinal illnesses. This study was undertaken to test, identify, and evaluate traditional medicines to treat these conditions against gastrointestinal bacterial, protozoal, and viral pathogens, as well as against cancer cell proliferation. Six plant species (Buchanania obovata Engl., Casuarina equisetifolia L., Eucalyptus tetrodonta F. Muell., Planchonia careya (F. Muell.) R. Knuth, Terminalia carpentariae C. T. White, and Vigna vexillata (L.) A. Rich.) were selected from a survey of a panel of elders from the Warnindhilyagwa tribe and compared with the published literature. Decoctions prepared according to traditional methods were screened for growth inhibitory activity of a panel of diarrhoea-causing bacterial pathogens by disc diffusion and liquid dilution MIC assays. Inhibitory activity against the gastrointestinal protozoal parasite Giardia duodenalis and antiproliferative activity against human colorectal (Caco2) and cervical (HeLa) cancer cell lines were evaluated using MTS-based colorimetric cell proliferation assays. Preliminary antiviral screening was accomplished using an MS2 bacteriophage plaque reduction assay. Toxicity was evaluated using Artemia franciscana nauplii mortality and HDF cell viability bioassays. All traditional medicines tested inhibited bacterial growth, often with MIC values substantially <1000 μg/mL. T. carpentariae was particularly noteworthy, with MIC values of 230-350 μg/mL against Citrobacter freundii, Salmonella newport, Shigella sonnei, Staphylococcus aureus, and Staphylococcus epidermidis. This species also had MICs 450-950 μg/mL against all other bacterial pathogens. B. obovata Engl. and E. tetrodonta were also good inhibitors of bacterial growth, albeit with substantially higher MIC values than determined for T. carpentariae. The T. carpentariae decoction was also the best inhibitor of MS2 phage replication (IC50 = 427 μg/mL) and Caco2 and HeLa proliferation (IC50 values of 885 and 85 μg/mL, respectively). None of the extracts were particularly strong inhibitors of Giardia duodenalis growth. All decoctions were nontoxic in the Artemia nauplii and HDF cell viability bioassays, indicating their suitability for therapeutic use.

Isolation and Biological Properties of the Natural Flavonoids Pectolinarin and Pectolinarigenin-A Review

Flavonoids are metabolites widely distributed in plants and commonly present in foods, such as fruits and vegetables. Pectolinarin, which belongs to the flavone subclass, has attracted considerable attention due to its presence in many medicinal plants. It has turned out to be a good biological agent especially due to its antioxidant, anti-inflammatory, antidiabetic, and antitumor activities, evaluated both in vitro and in vivo. Its aglycone, the metabolite pectolinarigenin, is also known for a series of biological properties including anti-inflammatory and antidiabetic effects. In the first overview on the two metabolites here presented, their collection, isolation and the results of their biological evaluation are reported.

Bioactive compounds sourced from Terminalia spp. in bacterial malodour prevention: an effective alternative to chemical additives

OBJECTIVE

Recently, our group reported that extracts prepared from the Australian native plant Terminalia ferdinandiana Exell. are potent inhibitors of the growth malodorous bacteria with similar efficacy to triclosan and through these results, we highlighted a potential biological alternative to the current chemical additives. Other members of the genus Terminalia are also well documented for their antibacterial potential and tannin contents and thus were investigated as potential deodorant additives.

METHODS

Solvent extractions prepared from of selected Indian, Australian and South African Terminalia spp. were screened by disc diffusion and liquid dilution assays against C. jeikeium, S. epidermidis, P. acnes and B. linens. The antibacterial activity was quantified by liquid dilution MIC assays. The extracts were screened for toxicity using Atremia franciscana nauplii and HDF cell viability bioassays. High-resolution time-of-flight (TOF) LC-MS and GC-MS headspace fingerprint analysis was used to detect tannin, flavonoid and terpenoid components in the extracts.

RESULTS

Bacterial growth inhibition was observed in all Terminalia extracts with the methanolic T. chebula, T. carpenteriae and T. sericea extracts the most promising bacterial growth inhibitors, yielding MIC values as low as 200 µg mL^-1 . Toxicity analyses of the extracts were favourable, and we determined that the methanolic T. chebula, T. carpenteriae and T. sericea extracts were all non-toxic. Using previously detected T. ferdinandiana antimicrobials as benchmarks, LC-MS and GC-MS fingerprint analyses revealed similar compounds in the methanolic T. chebula, T. carpenteriae and T. sericea extracts.

CONCLUSION

Through these results, we propose that Terminalia spp. extracts may be useful deodorant additives to inhibit the growth of axillary and plantar malodorous bacteria, offering a biological alternative to their chemically synthesized counterparts.

Plantago squarrosa Murray extracts inhibit the growth of some bacterial triggers of autoimmune diseases: GC-MS analysis of an inhibitory extract

Ankylosing spondylitis, multiple sclerosis, rheumatoid arthritis and rheumatic fever are autoimmune inflammatory diseases that may be triggered in genetically susceptible individuals by specific bacterial pathogens. Inhibiting the growth of these bacteria with high antioxidant plant extracts may inhibit the aetiology of these diseases, as well as inhibiting the later phase symptoms. P. squarrosa extracts were analysed for antioxidant activity using a DPPH free radical scavenging assay. Bacterial growth inhibitory activity was evaluated using disc diffusion assays and the activity was quantified by MIC determination. The extracts were screened for toxicity by A. franciscana nauplii assays. The most potent antibacterial extract (ethyl acetate) was analysed by GC-MS headspace profile analysis and compounds were identified with reference to a phytochemical database. All extracts displayed strong DPPH radical scavenging activity. The ethyl acetate extract was particularly potent (IC₅₀ 1.4 µg/mL), whilst the other extracts also had significant radical scavenging activity (IC₅₀ values between 11 and 22 µg/mL). Notably, the bacterial growth inhibitory activity of the extracts correlated with their DPPH radical scavenging activity. The ethyl acetate extract, which had the greatest DPPH scavenging activity, generally displayed the most potent bacterial growth inhibitory activity. This extract was particularly potent against P. mirabilis, P. vulgaris and A. baylyi (MIC values of 484, 575 and 880 µg/mL, respectively). It also inhibited P. aeruginosa and S. pyogenes growth, albeit with higher MICs (1600-3700 µg/mL). All other extract-bacteria combinations were either inactive or resulted in mid-low potency inhibition. All extracts were non-toxic in the A. franciscana bioassay (LC₅₀ substantially > 1000 µg/mL). In total, 89 unique mass signals were identified in the P. squarrosa ethyl acetate extract by non-biased GC-MS headspace analysis. A number of compounds which may contribute to the antibacterial activity of this extract have been highlighted.

Terminalia chebula Retz. Fruit Extracts Inhibit Bacterial Triggers of Some Autoimmune Diseases and Potentiate the Activity of Tetracycline

Terminalia chebula Retz. is a northern Indian plant species known for its anti-inflammatory and antimicrobial properties. T. chebula fruit powder was extracted with solvents of varying polarity and screened for bacterial growth inhibition by disc diffusion assay. The minimum inhibitory concentration (MIC) was quantified by both liquid dilution and disc diffusion techniques. To screen for combinatorial effects, the T. chebula fruit extracts were combined with a range of conventional antibiotics and tested against each bacteria using a liquid dilution assay. Where synergy was detected, the optimal ratios were determined using isobologram analysis. Toxicity was examined using Artemia nauplii and HDF bioassays. T. chebula fruit methanolic, aqueous and ethyl acetate extracts displayed strong antimicrobial activity against the bacterial triggers of all autoimmune inflammatory diseases except K. pneumoniae, for which only moderate inhibition was observed. Indeed, MIC values as low as 195 μg/mL were measured for the aqueous extract against a resistant strain of P. aeruginosa. Of further note, both the aqueous and ethyl acetate extracts interacted synergistically in combination with tetracycline against K. pneumoniae (Σ FIC 0.38 and 0.25 respectively). All extracts were nontoxic in the Artemia and HDF toxicity assays, further indicating their potential for medicinal use.

Inhibition of Shewanella spp. growth by Syzygium australe and Syzygium luehmannii extracts: natural methods for the prevention of fish spoilage

Syzygium australe and Syzygium luehmannii fruit and leaf were investigated for their ability to inhibit Shewanella spp. growth. Extracts of both Syzygium spp. displayed potent growth inhibitory properties against all Shewanella spp. tested in disc diffusion and liquid diffusion assays. In general, S. australe extracts were more potent inhibitors of Shewanella spp. growth, and the fruit extracts were generally better than the corresponding leaf extracts. The methanolic S. australe fruit extract was a particularly potent inhibitor of all Shewanella spp. growth, with MIC values as low as 87 µg/mL. The aqueous and ethyl acetate S. australe fruit extracts were similarly potent inhibitors of Shewanella spp. growth, albeit with slightly higher MIC values. Several other Syzygium spp. extracts also were potent bacterial growth inhibitors, albeit with MIC values generally >1000 µg/mL. The most potent S. australe fruit extracts were nontoxic in the Artemia franciscana bioassay, with LC₅₀ values substantially >1000 µg/mL. The potent bacterial growth inhibitory activity and lack of toxicity of the S. australe fruit extracts indicate their potential as natural fish and seafood preservatives.

Inhibition of Klebsiella pneumoniae growth by selected Australian plants: natural approaches for the prevention and management of ankylosing spondylitis

A wide variety of herbal remedies are used in traditional Australian medicine to treat inflammatory disorders, including autoimmune inflammatory diseases. One hundred and six extracts from 40 native Australian plant species traditionally used for the treatment of inflammation and/or to inhibit bacterial growth were investigated for their ability to inhibit the growth of a microbial trigger for ankylosing spondylitis (K. pneumoniae). Eighty-six of the extracts (81.1%) inhibited the growth of K. pneumoniae. The D. leichardtii, Eucalyptus spp., K. flavescens, Leptospermum spp., M. quinquenervia, Petalostigma spp., P. angustifolium, S. spinescens, S. australe, S. forte and Tasmannia spp. extracts were effective K. pneumoniae growth inhibitors, with MIC values generally <1000 µg/mL. The T. lanceolata peppercorn extracts were the most potent growth inhibitors, with MIC values as low as 16 µg/mL. These extracts were examined by non-biased GC-MS headspace analysis and comparison with a compound database. A notable feature was the high relative abundance of the sesquiterpenoids polygodial, guaiol and caryophyllene oxide, and the monoterpenoids linalool, cineole and α-terpineol in the T. lanceolata peppercorn methanolic and aqueous extracts. The extracts with the most potent K. pneumoniae inhibitory activity (including the T. lanceolata peppercorn extracts) were nontoxic in the Artemia nauplii bioassay. The lack of toxicity and the growth inhibitory activity of these extracts against K. pneumoniae indicate their potential for both preventing the onset of ankylosing spondylitis and minimising its symptoms once the disease is established.

Terminalia ferdinandiana extracts as inhibitors of Giardia duodenalis proliferation: a new treatment for giardiasis

Giardisis is a debilitating disease caused by gastrointestinal parasites of the genus Giardia. High-antioxidant T. ferdinandiana fruit extracts were investigated for the ability to block Giardia duodenalis growth. Methanolic and aqueous extracts had the most potent growth inhibitory activity (IC50 values of approximately 700 and 140 μg/ml, respectively). Ethyl acetate and chloroform extracts also inhibited G. duodenalis growth, albeit with lower potency. The hexane extract was completely devoid of G. duodenalis growth inhibitory activity. All extracts were nontoxic in the Artemia fransiscana bioassay. Nontargeted HPLC-quadrupole time-of-flight (QTOF) mass spectroscopy (with screening against three compound databases) putatively identified 17 compounds in all of the inhibitory extracts but not in the inactive hexane extract. The low toxicity of the Terminalia ferdinandiana fruit extracts and their potent G. duodenalis growth inhibitory bioactivity indicate their potential as medicinal agents in the treatment and prevention of this disease.

The potential of selected South African plants with anti-Klebsiella activity for the treatment and prevention of ankylosing spondylitis

A wide variety of herbal remedies are used in traditional African medicine to treat inflammatory disorders, including some autoimmune diseases. Thirty-four extracts from 13 South African plant species traditionally used for the treatment of inflammation were investigated for their ability to control a microbial trigger for ankylosing spondylitis (Klebsiella pneumoniae). Twenty-six of the extracts (76.5%) inhibited the growth of K. pneumoniae. Methanol and water extracts of Ballota africana, Carpobrotus edulis leaves, Kigellia africana, Lippia javanica, Pelargonium fasiculata, Syzygium cordatum (including bark), Terminalia pruinoides and Terminalia sericea were effective K. pneumoniae inhibitors, with MIC values <1000 µg/ml. The roots of Tulbaghia violaceae and bark from Warburgia salutaris also demonstrated efficacy. The most potent extracts were examined by RP-HPLC and UV-Vis spectroscopy for the presence of resveratrol. Methanolic extracts of B. africana, C. edulis leaves, L. javanica, T. pruinoides and T. sericea, as well as aqueous B. africana, T. pruinoides and T. sericea extracts, displayed peaks with retention times and UV-Vis spectra consistent with the presence of resveratrol. Resveratrol was generally a minor component, indicating that resveratrol was not solely responsible for the anti-Klebsiella growth inhibitory properties. Plant extracts with K. pneumoniae inhibitory activity were either non-toxic, or of low toxicity in the Artemia (brine shrimp) nauplii bioassay. Their low toxicity and antibiotic bioactivity against K. pneumoniae indicate their potential for both preventing the onset of ankylosing spondylitis and minimising its symptoms once the disease is established.