Historical perspectives and contribution of Aboriginal medicines

To put this review into overall Australian ethnomedical context, we analysed the literature to see what was the contribution of Aboriginal health system in Australia and worldwide. Historical studies and records of Aboriginal medicinal plants, e.g. [23,24,25,26,27,28,29], reveal their extensive use across Australia. While the medical practices of Aboriginal communities in Australia involve the use of plants [30, 31], there is little documentation of European use of this knowledge in early botanical texts. Stack [32] writes that 200 years ago, Aboriginal traditional medicine played no part in the lives of the European immigrants since they brought their own diseases and used their own traditional remedies. However, there are records, which show that during the early years of European settlement, some medical practitioners and botanists interacted with Aboriginal healers and experimented with native flora for medicinal purposes. For example, Denis Considen (1788–1794) (first assistant surgeon to Surgeon-General John White in the first fleet) claimed to be the first European medical practitioner to discover Indigenous medicinal plants; however, his methods of discovery are unknown and it is unclear if he involved Indigenous informants [33]. Considen documented some Indigenous medicinal plant efficacy including myrtle (possibly Eugenia australis) and yellow gum (possibly Xanthorrhoea hastilis) for dysentery, and native sarsaparilla (Smilax glycyphylla) as an antiscorbutic [33]. MacPherson [33] further suggested that native sarsaparilla was not only therapeutic but was considered more pleasant than Jamaican or Central American sarsaparilla. He also stated that prior to 1927 it had been a common article of trade among Sydney herbalists. One of the widely traded plants by both the Aboriginal people and the European settlers was macadamia nuts (Macadamia sp.).

Despite disruption of Aboriginal medical practices by Europeans, there have been some major contributions by Aboriginal Peoples to world medicinal knowledge. For example, Pearn [13] suggests that Aboriginal child care ethnomedicinal knowledge represents the ‘The world’s longest surviving paediatric practices’ [13]. Even today, Aboriginal ethnomedical practices form a living treasure trove of many Aboriginal communities. The use of medicinal plants by different communities across Australia is determined by the vegetation and environment they live in [14]. For example, the fruits of the native shrubs Solanum laciniatum are used in southern Australia, while Solanum aviculare (Kangaroo Apple) was used in the eastern parts of Australia [32]. Both species were used as poultices for joint swellings [32]. Both of these Solanum species contain an alkaloid solasodine, which is the precursor of cortisone and other steroids used in production of oral contraceptives (i.e. 'the pill') [34]. These plants have been imported into Russia and Eastern Europe where they are now cultivated at large scale, due to their capacity to biosynthesise this valuable phytochemical [32]. Similarly, the native Aboriginal narcotic shrub, pituri (Duboisia hopwoodii) of the arid interior region of Australia led to the research of congeneric, Duboisia myoporoides, which proved to be highly beneficial. Joseph Banks, the first European botanist to visit the east coast of Australia (in 1770), observed ‘pituri’ being chewed by Aboriginals similarly to tobacco or East Indian betele [35]. A century later (in 1872), Ferdinand von Mueller, the Victorian Government botanist, identified the plant as Duboisia hopwoodii [36]. Von Mueller suggested that the related Duboisia myoporoides should be researched, and it was found to produce hyoscine, currently known as scopolamine, an alkaloid that is a highly effective treatment for motion sickness [37].

Queensland Aboriginal medicinal plants

Of all Australian States, Queensland, located in the north-east, encompasses the widest variety of landscapes, vegetation types, and climatic zones—temperate, wet and dry tropics, and semiarid to arid—across its 1.73 million square kilometres. The vegetation includes temperate, subtropical, and tropical rainforests, eucalypt woodlands, coastal communities and heath, a variety of grasslands and wetlands, and mangroves and marshes (Fig. 2) [38]. Queensland’s Aboriginal communities have lived in harmony within these landscapes for thousands of years. Their customary knowledge is shaped by the rich and diverse vegetation communities that are home to a diverse range of medicinal plant species, including that are endemic to the state. Some of the earliest records of medicinal plant knowledge in Queensland were made by botanists, chief protectors, anthropologists, pastoralists, and chemists [39]. For example, a pastoralist, amateur anthropologist, and politician Edward Palmer writes that Aboriginal people possess a considerable amount of knowledge of native plants and their uses [40].

Fig. 2

Representative vegetation of Queensland. a Desert. b Grassland. c Savannah. d Wet Tropics (Photo courtesy: Phurpa Wangchuk and Gerry Turpin)

Joseph Henry Maiden, who was the Curator of the Australian Museum at that time, wrote that Queensland is by far the richest of the colonies concerning recorded plants with medicinal properties [41]. However, he did not consult local Aboriginal people for medicinal plant knowledge stating that ‘In fairness to ourselves we must confess ourselves very little indebted to the Australian aboriginal for information as to the medical (or in fact any other) properties of our plants’ (Maiden, 1889). He also suggested that the great majority of these will be common to India and the Archipelago and have been employed by the natives of those countries [41]. Based on the little available literature and the oral medical traditions still practised by the rural Aboriginal elders and traditional knowledge holders of Queensland, it is fair to say that Maiden’s information on Aboriginal medical knowledge was limited and his perceptions were grossly misleading. Walter E. Roth, as Northern Protector of Aboriginals on Cape York Peninsula, recorded extensive information on Aboriginal customs, languages, and knowledge [42]. Similarly, Sandyl Kyriazis and Nai Beguta Agama Aboriginal Corporation have listed many medicinal plants in their book ‘Bush Medicine of the Northern Peninsula area of Cape York’ [43]. Leonard James Webb accompanied a team of anthropologists and Aboriginal people to document Indigenous plant uses at Lockhart River in northern Queensland between 1952 and 1977. He recognized the value of collaboration between scientists, anthropologists, and Indigenous peoples, combining the collection of scientific data with cultural perspectives in the study of plant uses [26, 44]. The inventory list (Table 1) supports the view that Queensland is rich in Aboriginal medicinal knowledge and plant diversity.

Table 1 List of Queensland medicinal plants and their uses [24, 25, 27, 32, 44,45,46]Inventory of Queensland Aboriginal medicinal plants

Based on the archival information from the TIEC database (maintained by an Indigenous ethnobotanist Mr. Gerry Turpin, Fig. 3) and the online information, we have identified a total of 135 species of medicinal plants used by Queensland Aboriginal people. The archival information is presented in Table 1, including botanical name, plant family, habit, plant part used, and diseases/conditions treated.

Fig. 3

An Indigenous ethnobotanist Gerry Turpin collecting herbarium specimens of Aboriginal medicinal plants (Photo courtesy—Gerry Turpin, first author of this manuscript)

Diversity of medicinal plants

Table 1 lists the botanical names of 135 species of plants used customarily as medicines by Aboriginal people of Queensland. These plants belong to three plant groups—angiosperms, gymnosperms, and pteridophytes—and represent a total of 53 families and 103 genera. Plant families with most species with recorded medicinal properties were Myrtaceae (14), Fabaceae (11), Lamiaceae (8), and Apocynaceae, Asteraceae, and Euphorbiaceae (7 each). It is no surprise that Myrtaceae is recorded as having the most medicinal uses of any plant family as it is one of the most common but largely tropical families worldwide, estimated to include about 5,950 species in about 132 genera [47]. Queensland has 60 genera and 746 species of Myrtaceae [48]. Many plants within the Myrtaceae family contain oils in the leaves, and oil is one of the best solvents for medicinal compounds. Within the Myrtaceae family, there are five genera used medicinally in Queensland: Eucalyptus (seven species used medicinally), Melaleuca (four species), Corymbia (two species), Syzygium (one species) and the introduced Psidium guajava. Corymbia and Eucalyptus are two of the three genera (the other being Angophora) that comprise the ‘eucalypts’, a group of iconic Australian forest trees including more than 800 species that together dominate 77% of Australia’s native forests [49]. While fungi, seaweed, and bryophytes (liverworts, hornworts, and mosses) were commonly used globally as foods and medicines, the record of use, particularly in Queensland, is very poor [45, 50]. Lichens were also not recorded.

Habits of Queensland medicinal plants

Of the 135 species of Queensland medicinal plants (Table 1), 62 species are trees, followed by herbs (26 species), shrubs (22 species), climbers (16 species), epiphytes and grasses (4 species each), and palm-like (3 species) (Fig. 4). The epiphyte category includes orchids and hemiparasitic mistletoes; shrubs include small erect, woody plants, and succulent shrubberies; and trees include mangroves and tree ferns.

Fig. 4

Category of habits of medicinal plants. a Bar graph showing number of species in each habit category

Plant parts used for treating diseases

Over millennia, Aboriginal people have determined which plant parts are useful medicinally. Table 1 shows different parts of 135 medicinal plants grouped into 10 major categories: ‘Branch & Twig’, ‘Bark’, ‘Charcoal & Ash’, ‘Flower’, ‘Fruit & Seed’, ‘Leaf’, ‘Plant exudate’, ‘Root’, ‘Whole plant’ and ‘Wood’ (Fig. 5). The category ‘Bark’ includes outer bark, inner cambium, and root bark; ‘Fruit & Seed’ comprises fruit, seed, and kernel; ‘Leaf’ includes young leaf, leaf stalk, leaf tip, and young shoot; ‘Plant exudate’ includes oil, sap, gum, resin, kino, and latex; and ‘Root’ includes tap root, tuber, and bulb. The category ‘Whole plant’ is mostly smaller herbaceous plants and vines where it was more productive and easier to collect the roots, stems, and leaves together rather than separating plant parts. Of 10 major plant part categories, ‘Leaf’ ranked first in terms of percentage use with 24%, followed by bark (20.6%), root (14.9%), whole plant (13.1%), plant exudate (11.4%), fruit & seed (9.1%), branch & twig (2.9%), wood (2.3%), charcoal & ash (1.1%), and flower (0.6%), for example, the leaves of Aegiceras corniculatum, the barks of Acacia melanoxylon, the roots of Flueggea virosa, Alphitonia excelsa as whole plant, Corymbia polycarpa for kino (plant exudate), the fruits of Morinda citrifolia, branches and twigs of Cassytha filiformis, the wood of Clerodendrum floribundum, and the flowers of Euphorbia mitchelliana. It is to be expected that leaves show the highest amount of usage in Aboriginal medicine, given that leaves are in abundance, easily accessed and processed. Leaves are also readily harvested typically without much damage to the plant and readily replenished, making their use sustainable. Leaves are an easy target not only for humans but also for herbivores.

Fig. 5

Category of medicinal plants parts and their percentage of uses citation

Types of diseases treated by medicinal plants

A total of 62 types of diseases are treated by 135 medicinal plants listed in Table 1. Most medicinal plants are used for treating disease of the nervous system, integumentary system, respiratory system, and digestive system. Over 17% of these medicinal plants have been reported to be used for treating ‘Skin sores and infections’ (integumentary system), followed by ‘Cuts and wounds’ (12.6%), ‘Stomach disorders’ (digestive system) and ‘Pain’ (nervous system) (8.5% each), ‘Fever’ (7.9%), ‘Cough and cold’ (respiratory system) (7.6%), ‘Headache’ (6.3%), ‘Toothache’ (3.8%), ‘Eyesore’ (3.8%), and ‘Sexually transmitted disease’ (1.9%). Interestingly, 3.2% of plants were recorded for their use as tonics. For example, Cassytha filiformis and Barringtonia racemosa are described as good health tonics for the body. The biggest disease category ‘Skin sores and infections’ includes sores, boils, ringworm, hives, skin irritation, and other fungal and bacterial infections. Similarly, the category ‘Stomach disorders’ comprises stomach ache, gastritis, constipation, diarrhoea, and dysentery. The disease category ‘Pain’ includes body ache/pain, earache, muscle pain, labour pain, and chest pain; the ‘Sexually transmitted diseases’ consist of gonorrhoea, syphilis, and other infections.

Of 135 medicinal plant species, 53 of them have been cited for the treatment of a single disease (one plant–one disease treatment category). For example, Acmella grandiflora and Euphorbia tirucalli are used for treating only toothache and skin cancer, respectively. Similarly, while Coelospermum decipiens is used as a contraceptive, Abrus precatorius is used for abortion. However, the majority of medicinal plants have been used for treating more than one disease. For example, Alphitonia petriei is used for treating headache, cough and cold, fever, stomach upset, body ache, muscle pain, snake bite, eye sore, skin lesion, cuts/wounds, toothache, diarrhoea and as a tonic. Another plant, Grewia retusifolia, is used for treating diarrhoea, dysentery, boils, swelling, toothache, stomach ache, sores, skin lesions, wounds, cuts, and cough. Four plant species are used for treating stings from marine organisms such as rays, fishes, and sea jellies.

For treating the diseases, decoctions are commonly used in herbal medicine and these are preparations from plants using water. While decoctions, especially the tonics, are frequently ingested for diseases such as gastritis, cough and cold, and fever, poultices are commonly used for external skin diseases. Some medicinal plants are chewed and swallowed. There are a few plant species that are burnt and used as fumigants. Some plant products are used as infusions.

Biodiscovery initiatives involving Queensland medicinal plants

Biodiscovery involves identification of novel drug lead compounds from various natural resources such as plants, animals, fungi, bacteria, and extremophiles. Novel and effective drugs can be developed from natural products, especially from medicinal plants using a biorational ethnobotany-guided strategy. Indeed, out of 122 current plant-derived prescription drugs, 80% were discovered from medicinal plants [3]. Well-known examples are quinine (antimalarial compound isolated from Cinchona officinalis), artemisinin (antimalarial compound isolated from Artemisia annua), paclitaxel (anticancer compound isolated from Taxus baccata), vincristine (anticancer compound isolated from Catharanthus rosea), aspirin (anti-inflammatory compound derived from salicylic acid isolated from Salix babylonica), and morphine (analgesic compound isolated from Papaver somniferum). Rainforest plants are the source of a quarter of pharmaceutical products, and more than 70% of these plant species are found exclusively in the tropical Amazon rainforest [51].

Queensland harbours the great majority of Australia’s tropical rainforest, which represents a warehouse of the continent’s medicinal treasure trove [52]. However, the biodiversity of these rainforests, along with other species-rich tropical biomes such as the Great Barrier Reef, is under threat of climate change [53,54,55]. Consequently, the changes in the environment might trigger plant physiological responses as well as adaptations in secondary metabolism to produce either higher concentrations or novel phytochemicals to cope with abiotic stress (Mounter, 2019). It is well known that such anti-stress biomolecules exhibit potent antioxidant and anti-inflammatory properties [56,57,58,59], which have potential applications in novel drug development.

The rich and diverse vegetation of Queensland has shaped the development of unique ethnobotanical knowledge of Aboriginal and Torres Strait Islander people, which has huge potential to guide biodiscovery programmes. Early investigations of Aboriginal medicinal plant knowledge in Queensland were carried out by chemists and pharmacologists in the nineteenth century. For example, Joseph Bancroft analysed properties of the pituri narcotic used by inland Aboriginal groups, which was later discovered to contain nicotine alkaloids [60, 61]. Commencing in 1944, an Australian Phytochemical Survey was established by Leonard James Webb at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Brisbane, but few Queensland medicinal plants were screened for their phytochemicals [44, 62]. In 1984, CSIRO staff based in Melbourne began publishing the results of the Phytochemical Survey [29]. However, it does not contain comprehensive information on bioactive chemical constituents of Queensland medicinal plants.

A recent review by Janice Mani and colleagues [63] reported the antioxidative and therapeutic potential of selected number of Australian plants, which included only a limited number of Queensland medicinal plants. While some medicinal plants that are distributed globally may have been studied for their phytochemical and pharmacological activities, there are hundreds of Queensland native plants that remain unexplored for therapeutic applications. Indeed, Australian medicinal plants in general remain underexplored in terms of biological, medicinal, and economic resources. Given that the globally popular natural medicines and their related products from other parts of the world (worth an estimated US$83 billion [64, 65]) has created lucrative marketplaces and that the Australian agriproducts are already enjoying an international reputation for their high-quality and clean image, there are exclusive demands for the Queensland medicinal plants. More elaborate studies are therefore required to develop quality parameters to monitor the quality of medicinal plants (both cultivated and wild type) and to identify biomarker and bioactive compounds. This will not only improve our knowledge on the phytochemistry of Queensland medicinal flora, but also generate data and ideas for developing herbal industries related to health-promoting, pharmaceutical, nutraceuticals, cosmetics, and functional food products. This has a huge scope for the development of a sustainable regional development of Queensland, Indigenous workforce development, and promotion of plant-based biotechnological innovations both locally and worldwide.

Biodiscovery frameworks, community engagement, and research approaches

In the past, especially in the 1970s–1990s, biopiracy has commonly occurred and the innovations and intellectual property rights belonging to many Indigenous peoples around the world have been exploited and compromised by the researchers, institutions, companies, and pharmaceutical industries [66]. This was partly due the lack of proper protocols, ethical rules and regulations, and biodiscovery acts. It has left Indigenous peoples dry and void of their rights, which has partly led Indigenous communities to step back from collaborating with the researchers and companies. In order to investigate the biocultural knowledge of medicinal plants used by Indigenous communities, consents and approvals from Traditional Owners/corporations must be adequately addressed [11]. At times, negotiations and signing collaborative/benefit sharing agreement with the communities can take longer, which will impede the access to plant materials and progress of research. This partly explains the relative scarcity of documented ethnomedicinal knowledge about plants used by the Australian Aboriginal and Torres Strait Islander peoples, especially in the biodiscovery space. However, if the biodiscovery research project is built upon the trust and the long-term relationship of the parties, this gap can be bridged easily.

We found that it is important to conduct any bioprospecting/biodiscovery projects in line with global ethical guidelines and intellectual property rights practices advocated by the following national and international bylaws and regulations.

World Intellectual Property Organization (relevant section on Indigenous knowledge) [67].

Nagoya Protocol on Access and Benefit-sharing and Traditional Knowledge [68].

NHMRC ethical guidelines for research with Aboriginal and Torres Strait Islander Peoples [69].

The AIATSIS Code of Ethics for Aboriginal and Torres Strait Islander Research [70].

Queensland Biodiscovery Act 2004 on using traditional knowledge for biodiscovery, which provides step-wise traditional knowledge guidelines and biodiscovery resources tool kits [71].

Relevant university’s research code of conduct such as James Cook University Aboriginal and Torres Strait Islander Research Ethics [72].

The World Health Organisation realizes the importance of traditional medicines both as the source of health care and novel drug leads for modern medicine, and therefore their long-term survival and sustainability is imperative. Australia’s Biodiversity Conservation Strategy (2010–2030) has acknowledged that preservation and sustainable maintenance of Indigenous knowledge is a priority area and therefore it is essential to actively engage Indigenous people through employment, partnership, and transfer of scientific knowledge that actively supports its sustainable use.

Building community relationships and engagement

It is important to develop collegial relationship with the Indigenous communities and propose the project to the funding bodies together as a team. The community members should be involved as a partner in shaping the research activities and the project must facilitate two-way exchange of knowledge, skills, and benefits and should provide capability building opportunities. Informed consent and ethics from the Indigenous community must be obtained prior to any information collection or documentation or product development based on traditional knowledge. It is also imperative to sign proper memorandum of understandings or collaborative agreement or benefit sharing agreement with the relevant Indigenous community. To build better trust and relationships, researchers must identify the cultural broker (Indigenous background) and provide the community with: (a) results from each aim of the project on a yearly basis, (b) study tours to research stations, (c) community researchers’ seminars where both sides present their ideas, challenges, and needs, (d) staying connected with the community, and (d) co-authorship on relevant publications. During engagement with the communities, the National Indigenous Science Education Program developed by Jamie and her group at Macquarie University can be adapted to improve the enrolment of Indigenous people in the higher education sector and guide them to become scientists, health workers, and policy changers.

Benefits to the Indigenous communities

The project design should find the needs/benefits/requirements of the Indigenous communities prior to biodiscovery grant applications. The benefits to the Indigenous community would include: (a) community development support fees to help the community in conducting administrative and legal duties relevant to the projects, (b) employment o