Biodiversity and the discovery of plant-based medicines

Nature is essential to life in more ways than we know. As regards the discovery of new medicines, or the rediscovery of some that have been used for a long time, biodiversity never ceases to give us the best it has to offer. The loss of biodiversity should cause, among others, this major impact: loss of essential raw materials for the health and well-being of societies.

We will never know the exact moment when our ancestors realised that, in addition to feeding us fruits could have other beneficial effects on the human body, or that placing crushed herbs, leaves and flowers on some parts of the body could improve assorted ailments. In traditional Chinese medicine, the benefits of herbs have been known for thousands of years; a little later, in 1550 BC, the Egyptians listed 877 herbal medicines in the first known medical treatise.

After , other pharma products began to emerge in modern history and based also by the daily uses of plants in society, focusing on the study of their compounds and thus changing the way we look at nature forever. And so, with the emergence of synthesised medicines, in the twentieth century, traditionally used plants were replaced by drugs.

The first of these drugs were morphine and aspirin. Inspired by the effects of opium, extracted from the poppy (Papaver somniferum), the German pharmacist Friedrich Wilhelm Sertürner (1783 – 1841) managed to isolate a crystalline substance – the principium somniferum, or morphine, thus nicknamed by the creator as a tribute to the Greek god of dreams, Morpheus. It was 1803 and only in 1826 it began to be sold by Merck. The first semi-synthetic compound to be sold was salicin, isolated from willow (Salix alba) leading to acetylsalicylic acid and aspirin, placed on the market in 1899 by Bayer.

Proof of the importance of biodiversity in treatments of yesteryear and medicines developed today, the branch of ethnopharmacology focuses on the study and systematisation of products of natural origin that have been used as medicines by peoples, gathering knowledge from areas such as botany, pharmacognosy, pharmacology and sociology. A 2001 study states that, in 122 plant-derived compounds, 80% were linked to their ethnopharmacological origins, among them important anticancer drugs such as paclitaxel or camptothecin. In total and between 1981 and 2006, 155 anticancer drugs were authorised, almost half of these drugs originating from plants.

Does this mean that taking a closer look at the ingredients societies have used for centuries, is a good starting point for the discovery of new and revolutionary medicines? Studies that revisit some of the species previously analysed indicate that it is very likely.

Meanwhile, new herbal medicines – a distinct class, which refers to medicine that exclusively includes herbal active substances – continue to be created and, to be marketed, follow their own procedures until they are allowed to be placed on the market.

And drugs whose compounds originate in biodiversity must also go through several stages to reach the market. After being first isolated or synthesised, drugs must be tested to prove their safety and efficacy through several studies, including pharmacological studies focused on the effects of chemicals on the human body. At the end of this procedure is regulatory approval by national or international entities.

Origin of medicines made from plants

From the root to the flower and from the bark to the fruit interesting ingredients can be found in various parts of the same plant and used for medical purposes. Even more interesting is to realise that, in the same plant, one of the identified ingredients can be toxic to humans while another, taken from another element, can store an active ingredient with the potential to save many lives.

Among the several components of trees and plants from which active ingredients useful in the manufacture of medicines can be derived are:

Root

From the several types of root, from woody, to herbaceous or fleshy, benefits can be obtained: ginseng (Panax ginseng), in the image, is an example of a root with acknowledged benefits for human health.

Rhizome

Rhizome is an elongated stem, equally subterranean, that usually germinates horizontally in the soil. Ginger (Zingiber officinale), in the image, is a rhizome and gingerol and its active compound offers benefits duly identified by the scientific community.

Tuber

A tuber is an underground, fleshy structure full of nutrients. A good example is the meadow turmeric (Colchicum autumnale), in the image, currently studied for its anticancer potential.

Tree bark

The protective cover of the tree also has bioactive ingredients. A good example is cinchona (Cinchona officinalis), in the image, from whose bark quinine is removed, with antimalarial, antipyretic and analgesic properties.

Wood

From the wood itself, components with important properties are also extracted. From sandalwood (Santalum album), in the image, the α-santalol property  is extracted, with antipyretic, antiseptic and diuretic properties.

Essential oil

Essential oils are volatile oils extracted through a distillation process. Eucalyptus oil, for example, present in small crystalline pockets in the leaves, is rich in eucalypt-oil (also called cineole), known for its antimicrobial and antiseptic properties and used in the treatment of respiratory problems. The oil extracted from the leaves of Eucalyptus globulus, in the image, is now being analysed by Portuguese scientists to confirm its potential against Alzheimer’s disease. The conclusions of the first study, published in the International Journal of Molecular Sciences, state that compounds with antioxidant characteristics, namely eucalypt, but also quercetin, ellagic acid and rutin, can offer benefits both in the prevention and reduction of brain changes characteristic of the disease, combating neuroinflammation and oxidative stress, presenting themselves as a possible ally in the creation of drugs that alter the manner how this disease progresses.

Fatty oil

On the other hand, these are non-volatile, i.e., not water-soluble, oils obtained by squeezing seeds or fruits from plants. While some of these oils have medicinal properties, others are used as conductive media for other properties. A good example of oil with properties is olive oil, antioxidant, promotes cardiovascular health, is neuroprotective and anti-inflammatory.

Leaf

It’s also possible to extract important medicinal properties from the leaves. From the neem tree (Azadirachta indica), for example, more than 60 different biochemical compounds, such as terpenoids and steroids, have so far been able to be removed, and their anticancer properties have been studied. Another recent example, a Portuguese study published in the journal Nature Communications shows the good results of genipin, a compound extracted from the white crowberry (Corema album), in the image, to treat Parkinson’s disease. This compound defends cells from the negative effects of alpha-synuclein, the protein responsible for the onset of the disease, and even stop it. Genipin is now being tested on fruit flies, a species with which humans share many genetic similarities.

Flower

Poppy (Papaver somniferum), in the image, is an excellent example of a flower with several benefits for human health: it is the natural source of opium and morphine – as mentioned above –, a strong analgesic that is synthesized from it. It was first synthesised in the early 19th century by the German pharmacist Friedrich Sertürner. The World Health Organization points out that about 11% of medicines considered “basic” and “essential” are extracted from flowering plants.

Seed Black cumin seeds (Nigella sativa), in the image, are known to be beneficial by various peoples in the world. The seeds of this species have been studied for their excellent response to various problems – as it is antioxidant, anti-inflammatory, anticancer and hypotensive –, and response to the bioactive compound thymoquinone, an oil obtained precisely from its seeds.

In addition to these origins, properties of the resin and gum and the fruit itself can still be extracted.

The future of plant-based medicines

The evolution of areas like Artificial Intelligence (AI) is stimulating and speeding up the process of discovering new drugs, responding to the demand for effective therapies but also to find new possible uses for current drugs. The revolution in the pharmaceutical industry is linked essentially to the acceleration of these processes, shortening them and making them less expensive, since there is an optimisation of resources combined with the reduction of the time required to analyse large amounts of data.

This is precisely another of AI’s great assets: being able to cross-reference information contained in databases to identify complex patterns. This new tool can also help to anticipate interactions between drugs and possible candidates so that the necessary tests can be carried out. But it can still go further: branches such as Deep Learning combined with software for molecular modelling make it possible to anticipate the effectiveness of compounds under analysis, improving them and making clinical trials, usually time-consuming, more effective.

Another field, precision medicine, where treatment is personalised according to the genetic and molecular characteristics of the patient, will also benefit from this equation, as this biomarker analysis will help in the evaluation of the best treatment, reducing the risk of side effects – a truly personalised treatment for each disease and each patient. And don’t think we’re talking about the near future: this valuable tool is already being implemented.

On the other side of the coin, challenges on the table are the cooperation between the various areas of expertise – scientists, health professionals, software engineers and AI experts – and the decoding of the information obtained, with increasing complexity and requiring validation, making sure its reliable and safe for humans. By addressing all these issues, we can create a healthier society with a higher quality of life.

It is precisely this incalculable value to humans that presents one of the greatest risks, given the excessive harvest of plants: scientists point out that a quarter of the species now existing could disappear in the next two to three decades. Overexploitation can also lead to shortages of certain species of higher medicinal value, raising their price and making them inaccessible. Agrotechnology, and genetic engineering, may provide an answer to this question.

For all this, it is safe to say that the impact of biodiversity on our health is greater than can be calculated: given the many  components of each plant and tree that can be used, but also the many responses that the same ingredient can obtain in the face of several diseases. The World Economic Forum identified biodiversity loss and ecosystem collapse as a major threat to human life over the next ten years and the need to take action now, more than ever, to protect this biodiversity and ensure that future generations have access to potential breakthrough cures. What other medicines essential to the continuation of human life are there still in nature?