Evaluation of the anti-inflammatory properties of Dodonaea polyandra, a Kaanju traditional medicine

Pharmaceutical Potential of Remedial Plants and Helminths for Treating Inflammatory Bowel Disease

Research is increasingly revealing that inflammation significantly contributes to various diseases, particularly inflammatory bowel disease (IBD). IBD is a major medical challenge due to its chronic nature, affecting at least one in a thousand individuals in many Western countries, with rising incidence in developing nations. Historically, indigenous people have used natural products to treat ailments, including IBD. Ethnobotanically guided studies have shown that plant-derived extracts and compounds effectively modulate immune responses and reduce inflammation. Similarly, helminths and their products offer unique mechanisms to modulate host immunity and alleviate inflammatory responses. This review explored the pharmaceutical potential of Aboriginal remedial plants and helminths for treating IBD, emphasizing recent advances in discovering anti-inflammatory small-molecule drug leads. The literature from Scopus, MEDLINE Ovid, PubMed, Google Scholar, and Web of Science was retrieved using keywords such as natural product, small molecule, cytokines, remedial plants, and helminths. This review identified 55 important Aboriginal medicinal plants and 9 helminth species that have been studied for their anti-inflammatory properties using animal models and in vitro cell assays. For example, curcumin, berberine, and triptolide, which have been isolated from plants; and the excretory-secretory products and their protein, which have been collected from helminths, have demonstrated anti-inflammatory activity with lower toxicity and fewer side effects. High-throughput screening, molecular docking, artificial intelligence, and machine learning have been engaged in compound identification, while clustered regularly interspaced short palindromic repeats (CRISPR) gene editing and RNA sequencing have been employed to understand molecular interactions and regulations. While there is potential for pharmaceutical application of Aboriginal medicinal plants and gastrointestinal parasites in treating IBD, there is an urgent need to qualify these plant and helminth therapies through reproducible clinical and mechanistic studies.

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

The Australian rainforest is a rich source of medicinal plants that have evolved in the face of dramatic environmental challenges over a million years due to its prolonged geographical isolation from other continents. The rainforest consists of an inherent richness of plant secondary metabolites that are the most intense in the rainforest. The search for more potent and more bioavailable compounds from other plant sources is ongoing, and our short review will outline the pathways from the discovery of bioactive plants to the structural identification of active compounds, testing for potency, and then neuroprotection in a triculture system, and finally, the validation in an appropriate neuro-inflammatory mouse model, using some examples from our current research. We will focus on neuroinflammation as a potential treatment target for neurodegenerative diseases including multiple sclerosis (MS), Parkinson's (PD), and Alzheimer's disease (AD) for these plant-derived, anti-inflammatory molecules and highlight cytokine suppressive anti-inflammatory drugs (CSAIDs) as a better alternative to conventional nonsteroidal anti-inflammatory drugs (NSAIDs) to treat neuroinflammatory disorders.

Indigenous Uses, Phytochemical Analysis, and Anti-Inflammatory Properties of Australian Tropical Medicinal Plants

Australian tropical plants have been a rich source of food (bush food) and medicine to the first Australians (Aboriginal people), who are believed to have lived for more than 50,000 years. Plants such as spreading sneezeweed (Centipeda minima), goat’s foot (Ipomoea pes-caprae), and hop bush (Dodonaea viscosa and D. polyandra) are a few popular Aboriginal medicinal plants. Thus far, more than 900 medicinal plants have been recorded in the tropical region alone, and many of them are associated with diverse ethnomedicinal uses that belong to the traditional owners of Aboriginal people. In our effort to find anti-inflammatory lead compounds in collaboration with Aboriginal communities from their medicinal plants, we reviewed 78 medicinal plants used against various inflammation and inflammatory-related conditions by Aboriginal people. Out of those 78 species, we have included only 45 species whose crude extracts or isolated pure compounds showed anti-inflammatory properties. Upon investigating compounds isolated from 40 species (for five species, only crude extracts were studied), 83 compounds were associated with various anti-inflammatory properties. Alphitolic acid, Betulinic acid, Malabaric acid, and Hispidulin reduced proinflammatory cytokines and cyclooxygenase enzymes (COX-1 and 2) with IC₅₀ values ranging from 11.5 to 46.9 uM. Other promising anti-inflammatory compounds are Brevilin A (from Centipeda minima), Eupalestin, and 5′-methoxy nobiletin (from Ageratum conyzoides), Calophyllolide (from Calophyllum inophyllum), and Brusatol (from Brucea javanica). D. polyandra is one example of an Aboriginal medicinal plant from which a novel anti-inflammatory benzoyl ester clerodane diterpenoid compound was obtained (compound name not disclosed), and it is in the development of topical medicines for inflammatory skin diseases. Medicinal plants in the tropics and those associated with indigenous knowledge of Aboriginal people could be a potential alternative source of novel anti-inflammatory therapeutics.

Novel Green Biosynthesis of 5-Fluorouracil Chromium Nanoparticles Using Harpullia pendula Extract for Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third highest major cause of morbidity and mortality worldwide. Hence, many strategies and approaches have been widely developed for cancer treatment. This work prepared and evaluated the antitumor activity of 5-Fluorouracil (5-Fu) loaded chromium nanoparticles (5-FuCrNPs). The green biosynthesis approach using Harpullia (H) pendula aqueous extract was used for CrNPs preparation, which was further loaded with 5-Fu. The prepared NPs were characterized for morphology using scanning and transmission electron microscopes (SEM and TEM). The results revealed the formation of uniform, mono-dispersive, and highly stable CrNPs with a mean size of 23 nm. Encapsulation of 5-Fu over CrNPs, with a higher drug loading efficiency, was successful with a mean size of 29 nm being produced. In addition, Fourier transform infrared (FTIR) and X-ray diffraction pattern (XRD) were also used for the investigation. The drug 5-Fu was adsorbed on the surface of biosynthesized CrNPs in order to overcome its clinical resistance and increase its activity against CRC cells. Box–Behnken Design (BBD) and response surface methodology (RSM) were used to characterize and optimize the formulation factors (5-Fu concentration, CrNP weight, and temperature). Furthermore, the antitumor activity of the prepared 5-FuCrNPs was tested against CRC cells (CACO-2). This in vitro antitumor study demonstrated that 5-Fu-loaded CrNPs markedly decreased the IC50 of 5-Fu and exerted more cytotoxicity at nearly all concentrations than 5-Fu alone. In conclusion, 5-FuCrNPs is a promising drug delivery system for the effective treatment of CRC.

Potential anti-neuroinflammatory compounds from Australian plants - A review

Neuroinflammation is a complex response to brain injury involving the activation of glia, release of inflammatory mediators, such as cytokines and chemokines, and generation of reactive oxygen and nitrogen species. Even though it is considered an event secondary to neuronal death or dysfunction, neuro-inflammation comprises a majority of the non-neuronal contributors to the cause and progression of neurodegenerative diseases like Alzheimer's Disease (AD), Parkinson's Disease (PD), Multiple Sclerosis (MS), Chronic Traumatic Encephalopathy (CTE) and others. As a result of the lack of effectiveness of current treatments for neurodegenerative diseases, neuroinflammation has become a legitimate therapeutic target for drug discovery, leading to the study of various in vivo and in vitro models of neuroinflammation. Several molecules sourced from plants have displayed anti-inflammatory properties in the study of neurodegenerative diseases. A group of these anti-inflammatory compounds has been classified as cytokine-suppressive anti-inflammatory drugs (CSAIDs), which target the pro-inflammatory AP1 and nuclear factor-κB signaling pathways and inhibit the expression of many pro-inflammatory cytokines, such as interleukin IL-1, IL-6, TNF-α, or nitric oxide. Australian plants, thriving amid the driest inhabited continent of the world, are an untapped source of chemical diversity in the form of secondary metabolites. These compounds are produced in response to biotic and abiotic stresses that the plants are exposed to in the highly biodiverse environment. This review is an attempt to highlight anti-inflammatory compounds isolated from Australian plants.

Anti-Inflammatory Activity of a Polymeric Proanthocyanidin from Serjania schiedeana

The ethyl acetate extract (SsAcOEt) from Serjania schiedeana, select fractions (F-6, F-12, F-13, F-14), and one isolated compound, were evaluated in 12-O-tetradecanoylphorbol 13-acetate (TPA) ear edema and kaolin/carrageenan (KC)-induced monoarthritis assays. SsEtOAc induced edema inhibition of 90% (2.0 mg/ear), fractions showed activity within a range of 67–89%. Due to the fact F-14 showed the highest effect, it was separated, yielding a proanthocyanidin-type called epicatechin–(4β → 8)–epicatechin–(4β → 8, 2β → O → 7) epicatechin (ETP). This compound (2.0 mg/ear) provoked 72% of edema inhibition (ED50 = 0.25 mg/ear, Emax = 52.9%). After 9 days of treatment, joint inflammation was decreasing, and on the last day, SsEtOAc (400 mg/kg), F-14 and ETP (10 mg/kg), SsEtOAc (200 mg/kg), methotrexate (MTX) 1.0 mg/kg and meloxicam (MEL) 1.5 mg/kg, produced an inhibition articulate edema of 94, 62, 36, 21, 80, and 54%, respectively. In the joint, pro-inflammatory molecules were elevated in animals without treatment (vehicle group, VEH). Treatments from S. schiedeana induced a decrease in the concentration of interleukin (IL)-1β, IL-17, and IL-6, and SsEtOAc at a higher dose diminished tumor necrosis factor (TNF-α). IL-10 and IL-4 were fewer in the VEH group in comparison with healthy mice; the animals with treatments from S. schiedeana induced an increment in the levels of these cytokines in joint and spleen.

In vitro inhibitory activities of selected Australian medicinal plant extracts against protein glycation, angiotensin converting enzyme (ACE) and digestive enzymes linked to type II diabetes

Background

There is a need to develop potential new therapies for the management of diabetes and hypertension. Australian medicinal plants collected from the Kuuku I’yu (Northern Kaanju) homelands, Cape York Peninsula, Queensland, Australia were investigated to determine their therapeutic potential. Extracts were tested for inhibition of protein glycation and key enzymes relevant to the management of hyperglycaemia and hypertension. The inhibitory activities were further correlated with the antioxidant activities.

Methods

Extracts of five selected plant species were investigated: Petalostigma pubescens, Petalostigma banksii, Memecylon pauciflorum, Millettia pinnata and Grewia mesomischa. Enzyme inhibitory activity of the plant extracts was assessed against α-amylase, α-glucosidase and angiotensin converting enzyme (ACE). Antiglycation activity was determined using glucose-induced protein glycation models and formation of protein-bound fluorescent advanced glycation endproducts (AGEs). Antioxidant activity was determined by measuring the scavenging effect of plant extracts against 1, 1-diphenyl-2-picryl hydrazyl (DPPH) and using the ferric reducing anti-oxidant potential assay (FRAP). Total phenolic and flavonoid contents were also determined.

Results

Extracts of the leaves of Petalostigma banksii and P. pubescens showed the strongest inhibition of α-amylase with IC₅₀ values of 166.50 ± 5.50 μg/mL and 160.20 ± 27.92 μg/mL, respectively. The P. pubescens leaf extract was also the strongest inhibitor of α-glucosidase with an IC₅₀ of 167.83 ± 23.82 μg/mL. Testing for the antiglycation potential of the extracts, measured as inhibition of formation of protein-bound fluorescent AGEs, showed that P. banksii root and fruit extracts had IC₅₀ values of 34.49 ± 4.31 μg/mL and 47.72 ± 1.65 μg/mL, respectively, which were significantly lower (p < 0.05) than other extracts. The inhibitory effect on α-amylase, α-glucosidase and the antiglycation potential of the extracts did not correlate with the total phenolic, total flavonoid, FRAP or DPPH. For ACE inhibition, IC₅₀ values ranged between 266.27 ± 6.91 to 695.17 ± 15.38 μg/mL.

Conclusions

The tested Australian medicinal plant extracts inhibit glucose-induced fluorescent AGEs, α-amylase, α-glucosidase and ACE with extracts of Petalostigma species showing the most promising activity. These medicinal plants could potentially be further developed as therapeutic agents in the treatment of hyperglycaemia and hypertension.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1421-5) contains supplementary material, which is available to authorized users.

Arid awakening: new opportunities for Australian plant natural product research

The importance of plants and other natural reserves as sources for biologically important compounds, particularly for application in food and medicine, is undeniable. Herein we provide a historical context of the major scientific research programs conducted in Australia that have been aimed at discovering novel bioactive natural products from terrestrial plants. Generally speaking, the main approaches used to guide the discovery of novel bioactive compounds from natural resources have included random, ethnobotanical and chemotaxonomic strategies. Previous Australian plant natural product research campaigns appear to have lacked the use of a fourth strategy with equally high potential, namely the ecologically guided approach. In addition, many large studies have sampled plant material predominantly from tropical regions of Australia, even though arid and semi-arid zones make up 70% of mainland Australia. Therefore, plants growing in arid zone environments, which are exposed to different external stressors (e.g. low rainfall, high ultraviolet exposure) compared with tropical flora, remain an untapped reservoir of potentially novel bioactive compounds. Research of Australian arid zone plants that is ecologically guided creates a new opportunity for the discovery of novel bioactive compounds from plants (and potentially other biota) for application in health care, food and agricultural industries.

Antiproliferative Aporphine Alkaloids from Litsea glutinosa and Ethnopharmacological Relevance to Kuuku I’yu Traditional Medicine

Australian Aboriginal people have a long history of relying on plants for the treatment of various ailments and illnesses. Our ongoing collaborative research project initiated by Chuulangun Aboriginal Corporation (Cape York, Australia) has recently focussed on revealing whether Kuuku I’yu plant medicines possess anticancer-related activities and the chemistry responsible for this. Here, we present results from a study of the plant Litsea glutinosa, used traditionally for the treatment of gastrointestinal disorders. Four known aporphine alkaloids N-methylactinodaphnine (1), boldine (2), N-methyllaurotetanine (3), and isoboldine (4) were isolated by activity-guided fractionation and tested for cytotoxicity against HT29, SKMEL28, and primary human keratinocytes. Compound 1 was the most cytotoxic and this observation may be explained by the presence of a 1,2-methylenedioxy group. In silico docking revealed that a plausible mechanism for the observed cytotoxicity is the stabilization of a topoisomerase II (β) DNA–enzyme complex. The ethnopharmacological relevance of this study is discussed in the context of researching and using traditional knowledge in biomolecular discovery.

A systematic review on biological activities of prenylated flavonoids

CONTEXT

Prenylated flavonoids are a unique class of naturally occurring flavonoids that exist especially for the plant's self-defensive strategy. This special class of flavonoids increases the bioactivities of their backbone flavonoids with non-prenylation; therefore, prenylated flavonoids have more potential to be developed and utilized.

OBJECTIVE

The number, position and type of the prenyl group on the flavonoids backbone structure may have close relationships with the bioactivities of flavonoids.

METHODS

PubMed and WEB OF KNOWLEDGE® were used to search articles published in English between 1 January 2002 and 31 December 2012, which discuss the structure-activity relationship between prenylated flavonoids and their bioactivities.

RESULTS

It is proposed that the prenyl-moiety makes the backbone compound more lipophilic, which leads to its high affinity with cell membranes. The prenylation brings the flavonoids with enhancement of antibacterial, anti-inflammatory, antioxidant, cytotoxicity, larvicidal as well as estrogenic activities. However, it is reported that the prenyl-moiety decreases the bioavailability and plasma absorption of prenylated flavonoids.

CONCLUSION

The prenyl group affects the bioactivities of flavonoids in certain ways, while the action mechanisms and the structure-activity relationship as well as more in vivo studies even clinical validation trials need to be further investigated.

In Vitro Study to Evaluate Antibacterial and Non-haemolytic Activities of Four Iranian Medicinal Plants

OBJECTIVE

Aqueous extracts of four medicinal plants including Ferula gummosa, Echinophora orientalis, Nasturtium microphyllum and Verbascum thapsus were used to determine their antibacterial activities and minimum inhibitory concentration (MIC). The aim of this study was to assess antibacterial activity of extracts of four medicinal plants against a Gram-positive and a Gram-negative bacteria (Staphylococcus aureus PTCC1431, and Escherichia coli HP101BA 7601c).

METHODS

Radial diffusion assay was used to assess the antibacterial activity of extracted samples. Haemolysis assay was also used to examine their nontoxic effects on human red blood cells (RBCs).

RESULTS

This study showed that all the mentioned plants have satisfactory antibacterial effects against both Gram-positive and Gram-negative bacteria. Minimum inhibitory concentration values of these samples were less than 750 µg/mL. In addition, no significant haemolytic activity was observed at their MIC values.

CONCLUSION

The results of this study showed that all these studied plants have good potential for further studies for drug discovery.

Anti-Inflammatory Effects and Mechanisms of Fatsia polycarpa Hayata and Its Constituents

Fatsia polycarpa, a plant endemic to Taiwan, is an herbal medicine known for treating several inflammation-related diseases, but its biological function needs scientific support. Thus, the anti-inflammatory effects and mechanisms of the methanolic crude extract (MCE) of F. polycarpa and its feature constituents, that is, brassicasterol (a phytosterol), triterpenoids 3α-hydroxyolean-11,13(18)-dien-28-oic acid (HODA), 3α-hydroxyolean-11-en-28,13β-olide (HOEO), fatsicarpain D, and fatsicarpain F, were investigated. MCE and HOEO, but not brassicasterol, dose-dependently inhibited lipopolysaccharide- (LPS-)induced expression of inducible nitric oxide synthase and cyclooxygenase-2 in RAW 264.7 macrophage line, whereas HODA, fatsicarpain D and fatsicarpain F were toxic to RAW cells. Additionally, MCE and HOEO suppressed LPS-induced production of nitric oxide, prostaglandin E₂, and interleukin-1β and interfered with LPS-promoted activation of the inhibitor kappa B kinase (IKK)/nuclear factor-κB (NF-κB) pathway, and that of the mitogen-activated protein kinases (MAPKs) extracellular signal regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38. In animal tests, MCE and HOEO effectively ameliorated 12-O-tetradecanoylphorobol-13 acetate- (TPA-)induced ear edema of mice. Thus, MCE of F. polycarpa exhibited an obvious anti-inflammatory activity in vivo and in vitro that likely involved the inhibition of the IKK/NF-κB pathway and the MAPKs, which may be attributed by triterpenoids such as HOEO.

Rare, seven-membered cyclic ether labdane diterpenoid from Dodonaea polyandra

Previous phytochemical studies on the leaf resin of dioecious plant species Dodonaea polyandra have identified the presence of furanoclerodane diterpenoids. As part of ongoing research on this species the chemical profile of an individual plant displaying male flowers was investigated. Repeated chromatographic separation of a resinous extract from the leaves of the plant yielded three labdane diterpenoids, 13,17-epoxy-13-methyl-15-oxo-labda-7-ene (1), 17-hydroxy-13-methyl-labda-7,13Z-diene-15-oic acid (2) and 13-methyl-17-oxo-labda-7,13Z-diene-15-oic acid (3) and a fourth known labdane diterpenoid (4) reported as being isolated from a natural source for the first time. Structural elucidation was carried out using conventional 1D and 2D NMR and mass spectrometry together with other complementary techniques (UV and IR). The leaf extract from this individual of D. polyandra with male flowers present displays a marked difference in the chemical composition of diterpenoids compared to previously studied extracts from the leaves of this species.

Flavonoids from the leaves and stems of Dodonaea polyandra: a Northern Kaanju medicinal plant

Three prenylated flavonoids 5,7,4'-trihydroxy-3'(3-methylbut-2-enyl)-3-methoxy flavone, 5,7-dihydroxy-3'(3-methylbut-2-enyl)-3,4'-dimethoxy flavone and 5,7,4'-trihydroxy-3',5'(3-methylbuyt-2-enyl)-3-methoxy flavone together with three other known flavonoids were isolated from the medicinal plant Dodonaea polyandra. The plant is used in the traditional medicine system of Northern Kaanju people of Cape York Peninsula, Queensland, Australia. The extracts studied have previously been found to possess anti-inflammatory activity. Successive fractionation of leaf and stem extracts by column and high performance liquid chromatography led to the isolation of these compounds. Their structures were determined using a number of spectroscopic techniques including 1D and 2D NMR and high resolution mass spectroscopy. The structural elucidation is reported herein accompanied by full ¹H and ¹³C NMR spectroscopic data. Spectroscopic data of known compounds was in agreement with that previously reported in literature.

In vivo activity of benzoyl ester clerodane diterpenoid derivatives from Dodonaea polyandra

Four new benzoyl ester clerodane diterpenoids, 15,16-epoxy-8α-(benzoyloxy)methylcleroda-3,13(16),14-trien-18-oic acid (1), 15,16-epoxy-8α-(benzoyloxy)methyl-2α-hydroxycleroda-3,13(16),14-trien-18-oic acid (2), 15,16-epoxy-8α-(benzoyloxy)methyl-2-oxocleroda-3,13(16),14-trien-18-oic acid (3), and 15,16-epoxy-2α-benzoyloxycleroda-3,13(16),14-trien-18-oic acid (4), have been isolated from the leaves and stems of Dodonaea polyandra. The anti-inflammatory activities of compounds 1, 2, and 4 were evaluated by means of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse ear edema. Compounds 2 and 4 exhibited maximum inhibition of inflammation (70-76%) at doses of 0.22 and 0.9 μmol/ear, respectively. Modest activity (~45% inhibition) was maintained at nanomole/ear doses.