Why protecting our rainforests is good for your blood pressure
The relationship between human health and the environment is indivisible and indisputable yet it seems the allure of conceptualising modern medicine as an exclusively sophisticated scientific enterprise involving labcoats, latex gloves, and laptops is leading us into damaging neglect of the natural world. As commonplace as this hyper-stylised mythos may be, it misrepresents the erratic, winding real-world road of pharmacological development from its gritty origin stories of trial-and-error, serendipitous discovery, and intrepid experimentation into the unknown (1).In arguing for the necessity of protecting this planet’s biodiversity from a medical perspective alone, we must appreciate the humbling roots of modern day biochemistry; steeped in a rich history of tribal witchcraft, indigenous herbalism, and traditional medicines; spurred forwards by a fascination with the bizarre, extraordinary, and unique flora and fauna scattered across all four corners of the earth.
Despite great advances in medical science and the phenomenal rate of growth in knowledge (at current estimated doubling-times of around 3.5 years (2)) modern medicine remains dependent on both the compounds isolated from the traditional medicinal and herbal preparations used for centuries by indigenous cultures, as well as those discovered through trailblazing field research undertaken in paddocks, jungles, rainforests, and deserts. In what is perhaps surprising reality, a tremendous proportion of the drugs that have revolutionised modern medicine were not discovered and synthesised in high-tech laboratories by international research teams who set out with the express prior intention of creating a targeted therapy to treat a particular condition (23). Rather, our present understanding of medicine, physiology, and pharmacology owes an astonishing debt to nature in its exemplar provision of biological ingenuity, novel chemical compounds, and evolutionary extravagance (29). If you look closely enough, these biological underpinnings can be readily appreciated today at the pharmacy or doctors office, with estimations that around a quarter of prescription drugs in the USA include active ingredients of plant origin (3). Without detailing the fascinating histories of each example, it can be appreciated that modern medicines hail from many diverse sub-fields of chemistry, biology, toxicology, and botany; though I would wholeheartedly encourage reading into the incredible journeys of discovery related to any of the following tales of drug discovery:
Incretins or Glucagon-Like Peptide 1 [GLP-1] agonists used in management of type 2 diabetes with additional benefits for weight loss – beginning with initial observations of anglerfish (4) and research of the different proteins in the saliva of Gila monster lizards (5).
Protamine is a peptide used to control coagulation by reversing the effects of heparin – originally synthesised in the cytoplasm of rainbow trout sperm cells (6).
Aspirin; indicated for everything from migrainous headaches to acute myocardial infarctions, prevention of stroke, and to reduce fevers – used by ancient Sumerian, Egyptian, and Greek civilisations; derived from the bark and leaves of a willow tree (7).
Atropine as used in anaesthesia, cardiac, ophthalmic, respiratory, and intensive care medicine for a range of applications from treating dysrhythmias to organophosphate poisoning – originally used in herbal medicine preparations dating back to the fourth century BCE and even in cosmetic use as a mydriatic to dilate women’s pupils; distilled from mandrake, belladonna, or deadly nightshade plants (8).
Digoxin (or digitalis if you rather) also an example of an incredibly useful cardiac anti-arrhythmic agent – originally applied as an apothecary’s treatment for dropsy; first purified from the beautiful and toxic wildflower, foxglove (9).
Curare poison and the drugs Pancuronium and Rocuronium used as muscle relaxants in routine anaesthetic practice – with a truly fascinating history beginning with an ancient Venezuelan poison used to lace sardines and catch birds like herons and cranes; derived from the Malouetia bequaertiana shrub and related plant species (10).
And…
Angiotensin Converting Enzyme [ACE] inhibitors; fist line treatment for hypertension (high blood pressure) with due credit to the unfathomable and unparalleled benefits for cardiovascular health on a truly global scale that these medications have yielded – first isolated from the venom of the South American pit viper Bothrops jararaca (11). Its venom was known to cause severe intestinal contractions and due to experimental effects in stimulating slow contractions of the smooth muscle of the gut, Sergio Ferreira and colleagues, building on the extensive earlier work of Sir John Vane, were led to suspect that this snake venom might augment the actions of bradykinin and inhibit the enzyme responsible for its breakdown, ACE (12, 13).
Although this selection presents some memorable examples, there is no shortage of instances in which careful scientific observation, research-for-research’s-sake, cross-discipline curiosity, and reverence for the natural world have yielded incredible paradigm-changing discoveries for medicine.
- The chance discovery of warfarin from investigation of a haemorrhagic disease affecting the cattle and sheep which grazed on sweet clover hay (17)
- Modern xanthines such as theophylline in airway disease - discovered as the mechanism underlying consumption of strong coffee and teas in ancient times as an asthma remedy (16)
- Colchicine’s use as a mainstay for gout treatment as derived from the autumn crocus plant (22)
- The remarkably serendipitous discovery of penicillin through incidental mould contamination of a petri dish (19), spurring this frankly under-appreciated age of antibiotics in which we now live.
- Discovery of heparin through early studies of the canine liver (17) and in curious current affairs, serious threats to heparin’s supply due to spread of African Swine Fever virus among pigs in China (18)
- Present day use of horses, sheep, and mammals in the synthesis of antivenom (20), with an unfortunate state of preventable death arising from antivenom shortages due to poor regulatory frameworks, substandard products, and weakened health systems (21).
We depend on the weird and wonderful in nature as both an inspiration and starting point for an enormous portion of medical and scientific research – plants and animals are truly indispensable in the quest for improving the health and wellbeing of populations, and preservation of biodiversity is key (14). In further defence of all manner of miscellaneous, mischievous, and accidental research, a beautifully forgotten article by Comroe and Dripps (1976) reported that an estimated 41-percent of work that was crucial for clinical advances in cardiovascular and pulmonary medicine was not clinically oriented at the time of research (23). This is to say that in these instances the researchers sought knowledge for the sake of knowledge or made their breakthroughs in work towards otherwise medically-unrelated enterprises. Without prior knowledge of where it is that research will lead us, or the ways in which seemingly unrelated and inadvertent findings may connect in years to come, we cannot know what it is we are potentially losing when our most bio-diverse ecosystems are destroyed.
Though this article has focused on pharmacology, pharmacognosy, and scientific serendipity, it can be easily seen that biodiversity is not only an environmental issue but has implications for domains as diverse as food, water, climate regulation, and energy security (15). As a society we need to encourage, value, and take pride in preservation of the natural world we are part of, and appreciate the empirically central role it has (and continues to) play in human health and scientific advancement. The unfortunate truth is that such delineations of the intimate connections between nature and health are not new, nor are the grave concerns that have been raised about the probable catastrophic effects of global environmental change (28). It was this particularly prescient warning so thoroughly expounded by Grifo and Rosenthal 23 years ago that seems to have been forgotten (28) - a saddening indictment of the obstinate and ongoing political and societal torpor pushing humanity ever closer toward collapse.
With the frightening rates of land clearing and global habitat loss currently seen (25, 26, 27) it seems the message to protect biodiversity is falling on stony ground, painting a bleak picture for the future (24). Conservation of nature for health in this sense is not about acai berries and turmeric lattes; in losing the natural world we risk losing that which is, and that which could become, the very foundations of modern medicine.
T Michniewicz, 03/10/19
Reference
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