Seasonal Variations in Chemical Constituents of Some European Herbs

Thymus vulgaris L. in Torà (Segarra, Catalunya, Spain), 490 m altitude. Photo by Isidre blanc, from Wikipedia. Reproduced under Creative Commons CC BY-SA 4.0 licence.

This interesting paper presents an overview of the existing literature published since the year 2000, seeks to identify some repeatedly found seasonal trends and discusses some possible explanations for these trends.

Link to full text of article

Li, Y., Zidorn, C. Seasonal variations of natural products in European herbs. Phytochem Rev (2022). https://doi.org/10.1007/s11101-021-09797-7

Coriander: Traditional Uses, Phytochemistry, Cardiovascular Benefits

Coriandrum sativum L.: Image from Wikimedia Commons. Public domain. Original book source: Prof. Dr. Otto Wilhelm Thomé Flora von Deutschland, Österreich und der Schweiz 1885, Gera, Germany.

Simple Summary

The following is a simple summary of this recent review paper:

Mahleyuddin, N.N.; Moshawih, S.; Ming, L.C.; Zulkifly, H.H.; Kifli, N.; Loy, M.J.; Sarker, M.M.R.; Al-Worafi, Y.M.; Goh, B.H.; Thuraisingam, S.; et al. Coriandrum sativum L.: A Review on Ethnopharmacology, Phytochemistry, and Cardiovascular Benefits. Molecules 2022, 27, 209. https://doi.org/10.3390/molecules27010209.

1. Traditional Uses in Various Old-World Regions

Fruits (seeds)

  • Rheumatoid arthritis, inflammation, and joint pain.
  • Some liver diseases (roasted seeds).
  • Dyspeptic complaints, as a digestive.
  • Loss of appetite, as an appetiser.
  • Convulsions.
  • Anxiety, insomnia.
  • As a diuretic.
  • “Melancholia”.
  • To lower blood glucose levels.
  • Influenza.
  • Bad breath.
  • Bad odour from genitalia.

Leaves

  • Mouth ulcer.
  • Eye redness.
  • “Melancholia”.
  • Digestive complaints, poor digestion.
  • To lower blood glucose levels.

Aerial parts

  • Viral infection.
  • Neurasthenia.

Whole plant

  • Measles.
  • Diabetes.
  • Aerophagy.
  • Gastroenteritis.
  • As a diaphoretic.
  • As a diuretic.
  • As a carminative.
  • As a stimulant.

Essential oil

  • Aa an aphrodisiac.
  • As an analgesic.
  • As an antimicrobial, mouth infections.
  • As a digestive stimulant.
  • Gastric ulcers.

Unspecified part(s)

  • As a diuretic, some renal diseases.
  • Anxiety; as a sedative and muscle relaxant.

2. Main Phytochemical Constituents

Fruits (seeds)

  • Carotenoids including β-carotene.
  • Tocols: α-, β-, γ- δ- tocopherols, and α-, γ-tocotrienols.
  • Fatty acids: Petroselinic linoleic, palmitic and oleic acids.
  • Sterols: Stigmasterol, β-sitosterol, δ-stigmasterol.
  • Volatile constituents: Linalool, camphor, geraniol.

Aerial parts

  • Carotenoids including β-carotene.
  • Phenolic acids: Ferulic, gallic and caffeic acids.
  • Benzoic acid derivative: Salicylic acid.
  • Coumarins: Esculetin, esculin, scopoletin, 4-hydroxycoumarin, umbelliferone, dicoumarin.
  • Flavonoids: hyperoside, rutin, hesperidin, vicenin, diosmin, luteolin, apigenin, orientine, dihydroquercetin, catechin, arbutin.

Essential oil

  • Linalool.
  • γ-terpenine.
  • α-pinene.

3. Physiological Effects of Phytochemicals from C. sativum

Flavonoids: A flavonoid-rich fraction was found to have hypotensive activity.

Quercetin (a flavonoid): A quercetin-rich aqueous ethanolic extract inhibits α-amylase, α-glucosidase and lipase, and thus potentially has antidiabetic and anti-obesity effects.

Polyphenols: A polyphenol-rich extract inhibits angiotensin-converting enzyme thus potentially has a antihypertensive effect.

Isocoumarins: Isocoumarin aglycones and (to a lesser degree) isocoumarin glycosides (cilantroside A and B) have been found to have neurotrophic / neuroprotective effects by stimulation of nerve growth factor. The aglycones of isocoumarins also showed anti-inflammatory effects.

Phenolic glycosides: The phenolic glycosides daphnin and benzyl-O-β-d-glucoside have also been found to stimulate nerve growth factor.

Sterols: Plant sterols have hypocholesterolaemic effects.

Essential oil: Prominent activities against diabetes, microbial infections, and inhibitory to acetylcholinterase.

Other: A linalool, ascorbyl palmitate and petroselinic acid-rich petroleum ether extract of coriander seeds reduces oxidative stress, is hypolipidaemic, hypoglycaemic, and preventative against diabetic nephropathy.

4. Cardiovascular Benefits of C. sativum

A systematic review was carried out of studies investigating the potential cardiovascular benefits of C. sativum.

Studies have demonstrated the cardioprotective benefits of C. sativum. These include its effect as an antioxidant, antihypertensive, anti-atherogenic, antiarrhythmic, as well as the improvement of other factors that may lead to cardiovascular disease (CVD), such as altered lipid profile, hyperglycaemia and cardiac biomarkers or enzymes.

Most of the studies included in the review were in vivo studies carried out on laboratory animals. Only two were human studies. These latter demonstrated hypolipidaemic, hypocholesterolaemic, hypotensive and antioxidant effects of coriander seed powder. As to plant parts, the majority of the studies included investigated the effects of the seeds. The two studies on the leaves showed hypolipidaemic, hypotensive, normoglycaemic and antioxidant effects.

The authors comment that more in vitro studies are needed to elucidate mechanisms of action.

Caper Leaves and Other Herbs for Cystitis in the Rif Mountains of Morocco

Capparis spinosa L. (caper). Royalty-free image from Pxfuel.com.

This study is an ethnobotanical review of herbs traditionally used to treat Cystitis in the Rif, Northern Morocco.

Mountain ranges of North Africa. From Wikimedia Commons.

Of the 60 plant species described, Capparis spinosa L. (caper) was the most commonly used – as a decoction of the leaves – followed by Apium graveolens L. (celery) – whole plant as an infusion – and Ziziphus vulgaris Lam. (jujube) – fruit, eaten.

Rif Mountains by Hamza.hayoun. From Wikimedia Commons.

A table summarising the study’s findings can be found here: https://link.springer.com/article/10.1186/s43094-021-00226-2/tables/2.

Here is a link to the whole study: https://link.springer.com/article/10.1186/s43094-021-00226-2.

Traditional Use of Medicinal Plants in Kerman Province, Iran

Roses in a flower garden, Kerman Province, Iran. Photo from Pxfuel. Public Domain.

The authors of this study surveyed the use by herbal healers of plant species found in Kerman Province, south-east Iran. They note that traditional (folk) medicine is a major component of healthcare in south-east Iran.

Kerman Province, Iran. Image from Wikipedia. Public Domain.

The study findings suggest that plants in the Asteraceae and Apiaceae families are used for the treatment of gastrointestinal disorders, Lamiaceae plants for respiratory and gastrointestinal ailments, and Apocynaceae and Euphorbiaceae plants for dermatological problems.

Photo of Rayen Citadel, Kerman Province, Iran, by Ninara, via Flickr. Creative Commons CC BY 2.0.

A full table of the medicinal plants identified and their uses by local herbal healers can be found here.

Hosseini, S.H., Bibak, H., Ghara, A.R. et al. Ethnobotany of the medicinal plants used by the ethnic communities of Kerman province, Southeast Iran. J Ethnobiology Ethnomedicine 17, 31 (2021). https://doi.org/10.1186/s13002-021-00438-z .

Copyright © Robert Hale 2021.

Why Are Dosing Recommendations So Inconsistent in Herbal Medicine?

Photo of licorice root from wallpaperflare.com. Royalty-free image.

The good news is that dosing for dried herbs taken as such (for example by chewing or as a powder in a capsule or stirred into water), or in simple water-based preparations such as infusions and decoctions, are often remarkably consistent even across cultures (e.g. traditional Chinese and traditional Western).

The perplexing thing is that with other kinds of preparations, notably tinctures and other liquid extracts, dosing recommendations differ widely between authors and between schools of thought. And yet you will not meet a practitioner who does not claim good results.

What is happening here? Here are some possibilities which we ought to consider:

  1. Many plants have a very wide therapeutic window.
  2. Herbs work in different ways when prescribed at higher, lower or minute doses, however they work to the same end. For example, some practitioners believe that in small doses herbs nudge the body towards a healing response rather than taking over parts of its physiology, which happens with larger doses: the difference between a subtle suggestion and a command. Others believe that it is some “subtle energy” conveyed by the herb, rather than the chemicals it contains, that interacts with the body’s “energy” to produce a healing response. This, they say, explains its effectiveness when used in extremely tiny doses.
  3. Practitioners’ perceptions and beliefs are subject to considerable biases and therefore are not reliable reflections of reality. The reality might be that in many cases the patient’s encounter with them and the associated treatment did not materially affect the course of the patient’s condition.
  4. The patient’s encounter with them and the associated treatment did affect the course of the patient’s condition, but this was not due in any way to the kind of herb prescribed, its dose or the nature of its preparation. It was due to other factors in the context of the interaction which we shall call “non-specific factors” e.g. the patient liked the practitioner and perceived them to be trustworthy and competent, which engendered belief in the treatment prescribed.
  5. More than one of these things are happening at the same time.

Number 5 is my best guess, with the proviso that with regard to number 2, I do not believe in “subtle energies” disembodied from the chemistry of life. But I would like to direct people’s attention to numbers 3 and 4, the importance of which I believe most practitioners vastly underestimate, and some even deny. As practitioners of a non-conventional system of medicine, there is a tendency to be defensive on these matters, which is understandable as it is a commonplace for sceptics to assume, “Well, it’s all placebo, isn’t it?” But non-specific effects along with patient and practitioner biases and are normal phenomena occurring every day in all branches of medicine, conventional and non-conventional, all over the world. Only if we admit their importance and attempt to account for them can we move to a more mature understanding of our discipline and our art as practitioners.

Copyright © Robert Hale 2021.