What is a chemotype & what are kava chemotypes?

Dear Kava Guru,

What is a chemotype and what are kava chemotypes?

Time and time again on my guru database here at Kava.Guru, I have used the word “chemotype” with reference to the Piper methysticum plant. But, I feel terrible because I don’t think I’ve once really explained what a chemotype is or more specifically what kava chemotypes are. So, it’s now time for me to break down this more scientifically based term so that you – my lovingly dedicated audience – can have a better understanding of kava right down to its scientific makeup.

A chemotype is used to distinguish varieties of plants within the same species – meaning that the members of a species can share the same basic genome and often the same phenotype (physical appearance) and yet have significant differences in their chemical composition. Another word that you might see tossed around in reference to the chemical composition of a plant is “chemovar”, which is just a way of denoting the chemically different variety of the plant [7].   We can break the word down into its etymological bits to get an even better understanding. Chemo is quite simply a prefix that turns the word in to something relating to chemicals, so when it is added to the front of “type” to become “chemotype” it essentially just means chemical type. Likewise, with chemovar, -var is just a suffix added to words to mean “variety” – so, “chemovar” just means chemical variety [2].

You will notice the word “cultivar” used frequently here on Kava.Guru and also, as an extended example of the etymological significance of –var, I’ll just point out that culti- is a prefix referencing cultivation – so, cultivar just means the cultivated variety of a particular plant species. All varieties of the Piper methysticum plant are cultivars because Piper methysticum is itself the cultivar of Piper wichmannii – the wild sister of Piper methysticum. In fact Piper methysticum is unable to self propagate, therefore making it dependent upon cultivation by humans [5].

The fun thing about the chemical composition of a plant is that you could have two plants that are botanically identical – two kava plants for example that cannot be told apart – and yet each could have a very different chemical composition. You could have two plants that have the same leaf structure and root anatomy and yet hold entirely different properties with regard to their chemical makeup. As a result these plants might look the same but actually have completely different effects with regard to chemical interactions in the human system. So you may have one cultivar of Piper methysticum that is essentially useless in terms of its sedative effect because it has a very low kavalactone index, whereas another variety that looks botanically identical might have a very pleasurable and noticeable effect.  This is why it’s always extremely important to know the variety of kava a vendor is offering – you certainly don’t want to endanger your system, but of course you do want to have kava that instills the benefits you desire.

So how is it possible for two plants of the same species that look botanically identical to have such varied chemical compositions?

Well, there are many upon many things that affect the chemical constituents of a plant and their interactions. The major variables are soil conditions and the climate, which is why the South Pacific Islands and Hawaii are so well-suited to the cultivation of excellent kava.   But, something as seemingly benign as the direction of the wind could have an impact on the chemical composition as well – for example, by carrying in particles from neighbouring regions that might change the soil composition, which could then change the chemical make up of the plant itself.  So, weather and the time of year of course have a lot to do with it as well [4]. Think of it like wine varietals. Vineyards are known for their wines because they have mastered a particular growing situation that yields a very desirable and specific type of wine. Two grapes of the same varietal could yield almost entirely different wines – just because of something as seemingly simple as one having been grown in the mountains and the other having been grown near the sea.

So, if the chemical composition of a plant is so flexible how on earth can one know what exactly they are growing and whether or not it will be the chemotype they desire?

Fortunately, the primary factor in the chemical composition of kava is its genetics. A particular variety of a plant can be cultivated over and over again because botanical geneticists have become skilled in producing a particular genetic structure – or plant cultivar. Furthermore, it’s actually possible to determine the chemical composition with respect to kavalactone quantities using near-infrared reflectance spectroscopy (NIRS) [4]. Spectroscopy is a field of study that looks at the interactions between matter and radiated energy and NIRS is a technique specific to the near-infrared region of the electromagnetic spectrum [10]. Breaking it down further, NIRS is a technique that measures the molecular overtones and the vibrations that happen through different molecular combinations and their interactions that create measurable radiant energy [8, 10].  While it’s difficult to determine which chemical components are responsible for certain features or results [10], two studies have nonetheless proven that it is possible to determine the kavalactone makeup of dried kava by using NIRS technologies [4]. This sort of technique is necessary for kava regulation because certain aspects of the chemical composition of kava – specifically the kavalactone quantity – can be affected by growing conditions, such as the climate or the use of particular agricultural techniques [4].

Kavalactones are the active component within kava cultivars and are the factor used for chemotyping different kava varieties. While the early pioneers have identified and classified eighteen different kavalactones, only the six most major or active kavalactones are used to determine or classify a particular kava chemotype: kavain (K), dihydrokavain (DHK), methysticin (M), dihydromethysticin (DHM), yangonin (Y), and desmethoxyyangonin (DMY) [6].

Different kava cultivars have more desirable chemotypes than others and some cultivars are actually potentially dangerous. In Vanuatu only strains of noble kava are legally sold and imported – “The Kava Act” prohibits the sale of all other varieties of Kava. The Kava Act was enacted by the Vanuatu parliament back in 2002 after misinformed accusations about kava causing hepatotoxicity – it is an act that regulates the sales and cultivation of kava [4]. It is now known that certain cultivars were likely responsible for the inconclusive hepatotoxicity studies and furthermore that it was likely prepared in a way that goes against traditional preparation norms. For example, Tudei Kava has been implicated as a possible cultivar that had been used during these studies and this particular cultivar carries a high quantity of flavokavain B, a chemical known to compromise liver functioning [3].

Well my friends – there you have it: a very thorough exposition of “chemotype” with relation to kava kava, or more specifically, the Piper methysticum plant. As you may have picked up from reading this – kava gurus like myself would only ever recommend drinking kava made from regulated strains and cultivars of noble kava and would warn against using the ignoble (Tudei) cultivars as these are likely the source of the hepatotoxicity scares of 2002. So, now you can kick back and enjoy your noble kava, knowing that it has been named appropriately!

To make things a little bit easier for you I’ve thrown together a small list of the most common and desirable noble kava cultivars [1, 9]:

  • Borogu
  • Fu’u
  • Mahakea
  • Boronggoru
  • Melomelo or “sese”
  • Palarasui

Mahalo,

Kava Guru

Sources:

1. “Buy Kava Online”. Kava Dot Com. Accessed July 7th, 2014. http://www.kava.com/?p=512.

2. Douglas Harper. “Online Etymology Dictionary”: http://www.etymonline.com/index.php?term=chemo-

3. INSIDER T.V. “New Science May Boost Kava Market”. Online: http://www.naturalproductsinsider.com/videos/2014/05/insider-tv-new-science-may-boost-kava-market.aspxI

4. Lebot and Patricia Simeoni. “Identification of factors determining kavalactone content and chemotype in Kava (Piper methysticum)”. Journal of Agricultural and Food Chemistry, Vol. 56: 2008, p. 4976-4981

5. Lynch, John. “Potent Roots and the Origin of Kava”. Oceanic Linguistics, Vol. 41 (2): December, 2002, p. 493-518

6. Teschke, Rolf. March 2011. “Special Report: Kava and the Risk of Liver Toxicity: Past, Current, and Future”. American Herbal Products Association Report 26 (3): 9-17.

7. Wikipedia. “Chemotype”. Last Modified on June 17, 2013: http://en.wikipedia.org/wiki/Chemotype

8. Wikipedia. “Infrared”. Last Modified on July 6, 2014: http://en.wikipedia.org/wiki/Infrared

9. Wikipedia. “Kava”. Last modified on July 1, 2014: http://en.wikipedia.org/wiki/Kava

10. Wikipedia. “Near-Infrared Spectroscopy”. Last Modified on May 18, 2014: http://en.wikipedia.org/wiki/Near-infrared_spectroscopy

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