Australian animals might kill you, but the plants could cure you…

Phytochemistry of Australia’s Tropical Rainforest: Medicinal potential of ancient plants by Cheryll J Williams, 2021. CSIRO Publishing/CABI.

It is often remarked that Australia is one of the most venomous countries on the planet (e.g. Carly Williams; Jude Dinely). Which perception is usually down to the weird and wonderful animals that live upon that land (Meg Matthias), or in its coastal waters (Louise Gentle). Understandably, the Australians aren’t that keen on this ‘mythinformation’* being all that most people know about their homeland’s amazing wildlife (and, anyway, Mexico – apparently – has more animals that are venomous…). So, I won’t be banging on about Australia’s fauna here. Instead, I’ll concentrate on that country’s flora, and take a look at Cheryll Williams’ Phytochemistry of Australia’s Tropical Rainforest [hereafter PATR] (which book is here appraised).

Although some of Australia’s plants can be as dangerous as its animals,** the focus of PATR is much more on the healing properties of its benign rainforest botanics, i.e. concentrating upon the plants’ life-giving potential rather than any life-shortening propensity. But, featuring some plants whose poisonous nature are well-known – e.g. the aptly-named Australian poison walnut tree (Cryptocarya pleurosperma) (which contains a curare-like ‘principle’), and no doubt many more plants whose toxicity are as yet unassessed – Williams’ Australian pharmacological journey reminded me of two famous quotes. First is one attributed to Paracelsus (anuka*** Philippus Aureolus Theophrastus Bombastus von Hohenheim) (Spyros Michaleas et al., Toxicology Reports 8: 411-414, 2021; https://doi.org/10.1016/j.toxrep.2021.02.012), “the dose makes the poison” (Philippe Grandjean, Basic Clin Pharmacol Toxicol. 119(2): 126–132, 2016; doi: 10.1111/bcpt.12622). Second is Friedrich Nietzsche’s “what does not kill me makes me stronger”. Both capture not only the potential dangers in discovering and testing new plant-derived treatments for human conditions but also the empowerment that can come from a successful outcome.

Whilst any life-limiting potential of the rainforest flora is reason to proceed with caution in attempts to harness its power to do good, it’s not a reason to ignore it: There are many stories of the benefits that have come from appropriate use and exploitation of botanics elsewhere in the world. Although well-documented, and probably familiar to many readers, several of those tales are included in PATR. As a good example of that it’s worth highlighting the case of nutmeg. Fragrant nutmeg (Myristica fragrans), originally sourced from the Spice Islands (now a part of Indonesia), has a very long history of use as a medicinal plant by humans. That compendium of accomplishments is comprehensively catalogued in PATR‘s Table 7.0 “Medicinal uses of fragrant nutmeg”. Occupying six pages, that data display is just a small part of the 40+ pages of Chapter 7 that are devoted to nutmeg and mace. Why are so many pages of PATR taken up by a species that Williams informs us is not native to Australia? In the absence of context or justification, it would be easy to dismiss their inclusion as some sort of text-padding. But, that is not the case; those success stories are presented as inspiration and justification to take more interest in the Australian flora, particularly species that are closely related to sources of plant-produced pharmaceuticals of proven value from other countries. The rationale for that view lies within the concept of chemical taxonomy [where evolutionarily-related species are likely to contain similar cocktails of chemical compounds, which may have medicinal value, e.g. Ram Singh, 2016 (J Med Plants Stud 2016;4(3):90-93)], which is an important theme throughout the book. In the particular case of nutmeg, although fragrant nutmeg is not an Australian native, three other Myristica species are…

Although it takes a lot of time and money to prove the pharmaceutical worth of just a single plant-derived product [and Williams provides ample evidence of the long and winding road that leads to the door of successful drug discovery], it’s a journey that should be taken. After all, in humanity’s battle against the dreaded dual demons of disease and debilitation (and untimely death), we need as wide an arsenal of effective drugs and medicines as possible. Fortunately, that task has become a lot easier with Williams having already done a lot of the hard work in highlighting species that are worthy of further investigation. And now that PATR has been released into the community it is surely indefensible to continue to ignore the pharmaceutical possibilities of indigenous Australian plants.

However, with a depressingly long list of factors that threaten the survival of rainforest plants – covered in-depth and breadth by Williams – it’s a desperate race against time to make the necessary progress that’s sorely-needed progress that’s essential to identify, catalogue, and assess each species’ pharmaceutical properties. But, as Williams also reminds us, any exploitation of that resource should be carried out in a way that respects nature and conserves the rainforest habitat for the future. Books such as PATR are therefore very important, and should also serve as a ‘wake-up’ call to everybody who values our so-called ‘natural capital’. Although the land of Australia was once known as terra australis incognita, thanks to PATR there is now no longer a need for the formidable pharmaceutical potential of its rainforest vegetation to be ‘flora incognita’.

Some other thoughts…

The approx. 550 pages of PATR‘s main text are well-written and profusely illustrated – with almost all images in colour, and with informative legends (which is always nice to see). With at least 3600 references(!!) (which are cited in-text by numbers), it is clearly a work of great scholarship. But, not only that, it also appears to be a true labour of love that is thoughtfully-written, and probably as up-to-date as its 2021 publication date permits with mention of Australia’s devastating bush fires of 2020. Mindful of the cultural heritage associated with the Australian flora and its extensive and ancient use by the indigenous peoples of that land, there is an important cultural sensitivity warning at the front of the book. This is particularly apt in relation to some of the wording in the quoted text regarding Bunya pine feasts. Many instances are cited in PATR where modern science has vindicated traditional uses of rainforest plant remedies, further emphasising the untapped potential of these plants (and the wisdom of the Ancients).

Whilst the larger part of the book is devoted to angiosperms and gymnosperms (Regina Bailey), other members of the plant kingdom, e.g. ferns and tree ferns (Gregory Moore), whisk ferns (Matt Candeias), and lycopods (tassel ferns and clubmosses) (Joe McAuliffe) get a good mention. In keeping with the book’s title, all of the plants covered are to be found within Australia’s native rainforest, which is found in the east of the country and extends from the northern tropics (Cape York, in the northern state of Queensland) to the southern island state of Tasmania. Although we acknowledge that the present-day flora is the product of evolution, it’s nice to know that some plants haven’t changed all that much since they first appeared on the planet. In that regard, and in keeping with PATR‘s sub-title, Medicinal potential of ancient plants, it’s nice to be reminded that the Australian rainforest is home to some ancient relics of the palaeoprehistoric flora of Gondwana.

Although the book contains a wealth of information – e.g. on botany, ethnobotany, medicinal uses of plants, pharmacology, biochemistry, taxonomy, biogeography – its emphasis is the preciousness, uniqueness and rarity of the Australian rainforest flora (and the medicinal secrets they may hold). PATR ranges between hard-core biochemistry and pharmaceutical science on the one hand, and the personal narratives of traveller-explorers, naturalists and indigenous people’s ethnobotanical testimonies on the other. But, at its heart is tremendous respect for the rainforest itself and the valuable resource that its plants represent, which – if used wisely and sustainably – could help alleviate a lot of human suffering.

PATR is a book with several uses. It is certainly a phytopharmacology reference source [and therefore a tome to ‘dip into’ as-and-when; it would be extremely hard-going if you chose to read it in one single sitting as a traditional text]. It’s also something of a love story for the medicinal potential of the rainforest with plenty of lovely passages written by the author quoting other notable commentators. And, in part it’s a botanical textbook with its frequent mentions of plant biology – e.g. bioaccumulation properties of waterlilies, Lotus thermogenesis, Aristolochia pollination mechanism, and frequent background information on plant evolution and palaeoenvironments. Accordingly, many different audiences will derive value and benefit from this remarkable book. And, not just plant lovers, entomologists should also find much to interest them (e.g. the section on Butterflies of literature, legend and medicine, and the numerous butterfly pictures throughout the book).

No, PATR isn’t ‘perfect’ – e.g. it could do with more references in several places (mainly for the more general plant biological information provided), sources for some of the figures are not stated, images of flowers and fruit would greatly benefit from scale bars, in several sentences single words are bizarrely missing (which seems to be a consequence of an attempt to constrain narrative to fully fit the full-justified two columns of text per page layout the book uses), and Appendix table columns 4 and 5 appear to be erroneously identified as 3 and 4 in the text on p. 530. But, its imperfections are pleasingly minor, and far-outweighed by its positives.

By now, you may have formed the view that I like PATR. I do. So much so that there’s so much more I’d like to share with you about the book (e.g. the very particular mal-de-meric role played in the D Day landings of the Second World War by a drug derived from Australian plants, and the plant substituted for quinine during the American Civil War of 1861-1865, the identity of the plant known as Cornish pepper (because it was used as a spice in Cornwall (a county in the UK)), and the recipe for spruce beer…). But, my task here is to appraise the tome, not to give away too many of its insights and interesting facts. That’s where it is up to the reader to do his/her bit and discover their own ‘take-home messages’. And that I encourage you to do.

Summary

Lack of knowledge about the value of rainforest plants was a large part of the author’s motivation for writing the book. PATR makes it clear that there is no longer any excuse that we lack that knowledge (although we can always do with more…): The pharmaceutical potential of the Australian rainforest flora is clearly laid-out in Cheryll Williams’ Phytochemistry of Australia’s Tropical Rainforest, which is a remarkable book.

* This is a word I’d thought I’d invented. Sadly, that’s not so; it’s already in the dictionary and means what I intended ‘my’ neologism to mean: “information which is widely held to be true but which is in fact flawed or unsubstantiated; common knowledge based on hearsay rather than fact”, or “widely held and promoted but false information that has taken on a mythic quality”, or “false information, when seen as having its own mythology or being believed in like a myth would be”.

** Astute readers of this item will notice that I’ve said very little about dangerous Australian rainforest plants. To find out what they are, you’ll need to read the book(!).

*** anuka is an initialism (and maybe also an acronym (when anuka is officially defined as a word…)), which means “as not usually known as…”. And which therefore is opposed to the more familiar ‘aka’ (meaning ‘as known as’). Now, I’m pretty sure that ‘anuka’ is something I have invented…