Today we have the pleasure to share a post from our friends and collaborators at Vanuatu’s Root and Pestle The post was written John McGowan, the chief scientist and lab wizard at Root and Pestle’s state of the art kava processing facility. This blog was partly inspired by long conversations about kava chemotypes a d the frequent questions about kava’s chemistry/chemotypes we all get from both new and seasoned kava drinkers. It is primarily informed by Root and Pestle’s analytical work and relevant published research, including Dr Vincent Lebot’s famous books and papers. It is a fairly loooong read, but very rich in information and will be appreciated by anyone who really wants to understand what kava’s chemotypes are about and, more broadly, how chemical analysis can help us understand kava’s composition, properties and differences between cultivars.

Introduction

First, a bit about the depth and level of writing to expect in this article: 

Like most things, this topic could easily wander off track into the dark and murky waters of technical rabbit holes, and when it comes to chemistry, even staying on topic can present a few complexities which we feel are better off simplified, glossed over, or even ignored, perhaps to the chagrin of those of you with advanced postgraduate degrees in the sciences. We apologise for this. We know that our readers are brilliant people, capable of absorbing every detail, but for the sake of relative brevity, accessibility, and ease of digestibility, we’ll err on the side of simplistic generalisations at a few places here and there within these blogs, including this one, at the sacrifice of supreme correctness, just so we don’t have to spend all week writing and you won’t have to spend all day reading, and so that neither of us needs to go back to school just for a little edification. 

On the other hand, at more than one place we might start meandering along a technical pathway that some would prefer not to walk down in its entirety. If you find yourself caught in one of these shadowy zones of techno-babble, fear not. You can feel free to skip ahead a few paragraphs and you’ll still get the gist of what we’re trying to convey. It isn’t always easy writing a well-rounded article suitable to all our readers when the subject is a bit tech-heavy at its foundation, but we’ll give it a shot – feel free to give us some feedback to help us improve the way we communicate in upcoming articles. We’ve been in the kava game for a long time and employ experts in their fields with many years of experience, but we’re a bit new on the blog scene. Thank you for sticking by us while we learn the ropes. We appreciate your support.

We hope and believe though, that we may be able to convey a better level of understanding without getting into the gritty depths of secondary metabolites, lactones, kavalactones, flavokavains, chalcones, chalconoids, flavonoids, oligomerisation, isomerisation, solute precipitation, limits of detection and quantitation, and the like, but we might touch on these, and we’ll try to compile a bit of a reference list or bibliography of sorts, with a few links to further information, for those who seek it. We’ll direct you to a few “easy access” sources, such as Wikipedia, so that you can get a mostly correct, generalised run-down, if there are a few gaps in your knowledge, as well as to a few (perhaps) more robust sources, for some deeper dives. If these links are useful to you – great. If not – no worries. We hope you will get what you can out of this article (and our references) and leave the rest behind; If it all gets a bit much, just go chill out with a shell of kava.

Let’s get into it

Like many other herbs and plants, kava has an abundance of phytochemicals, many of which have psychoactive properties. Principle among these are the major kavalactones desmethoxyangonin, dihydrokavain, yangonin, kavain, dihydromethysticin, and methysticin, also referred to as 1, 2, 3, 4, 5, and 6, respectively, under the widely adopted chemotype naming conventions for P. methysticum, in use now for over 3 decades. By the way, The Kava Society recently interviewed one of the co-authors of the original kava chemotyping paper – you can check it out here.

So, what’s a chemotype?

Chemotypes essentially refer to the unique fingerprint-like chemical compositions of different biological organisms – In the case of kava, sometimes plants which have little difference in morphology (i.e., they look the same) can contain widely varying amounts and ratios of organic chemical compounds. Understanding the importance of chemotypes, and how to interpret them, can help you to distinguish which particular cultivar of kava you might prefer the most, especially once you have a bit of experience in the kava drinking arena.

As with other psychoactive compounds, the amount and ratio of the psychoactive constituents of kava can contribute greatly to both the physiological effects and subjective experience of the person consuming them. Although there are a multitude of naturally occurring chemicals in kava,16,17,18,19,20 the quantity and ratio of the 6 major kavalactones listed above are likely what will affect the kava drinker’s experience the most, with each kavalactone influencing the overall effect in its own way.

Psychoactive compounds are tricky though; There can be synergistic effects, whereby the effect induced by one molecular interaction in the brain is enhanced (or altered) by another compound acting at the same site (or even via an entirely different mechanism), leading to potentiation or enhancement of a particular physiological or subjective response. In other words, some psychoactive compounds, in addition to whatever effect they confer on their own, also increase (or otherwise alter) the effect induced by another psychoactive compound such that the resultant effect of the 2 compounds administered in combination with each other is greater than would be their individual effects added together. Because of the potential for synergism in kava,,  it is not only the quantity of a particular kavalactone that is important in regard to its ultimate effect on the human mind and body, but also its ratio to other kavalactones, and let’s not forget that the unique physiology of the person who imbibes this incredible elixir will play a major role too. 

There are a whole host of other pharmacological factors that have the potential to influence how kavalactones and their ratios to each other might work to affect a person’s state of mind while under their influence. Some of these have been relatively well studied, but as with most psychoactive substances, there is plenty yet to learn about kava too. We won’t get into it in great detail here, but the potential for things like competitive partial or inverse agonism, competitive antagonism, allosteric modulation, variability in accumulation, differing absorption or clearance rates, among other factors, may be applicable to kava and its constituents; The point is, it isn’t as simple as saying more of this one particular kavalactone will induce exactly this one particular physiological or psychological response.

That said, if you drink enough kava, you will get to appreciate how different chemotypes make you feel, and which feeling would be most desirable for you to experience at any given time, and therefore, which kava you would optimally like to get into your shell. It is always nice to have a few varieties on hand, with some people preferring to drink very similar kavas with only subtle differences between them, and other people opting for more extremes in the chemotypes of the kavas they elect to imbibe. To many people, variety is the spice of life, as it were.

Ok, so how do you interpret the chemotype assigned to your kava?

The simplified kava chemotype lists the 6 major kavalactones, by number, in order of their abundance in relation to each other within the plant. For example, a batch of Kelai kava might have a chemotype of 243156, informing us that of the 6 kavalactones listed, dihydrokavain (2) is most abundant, followed by kavain (4), then yangonin (3), desmethoxyyangonin (1), dihydromethysticin (5), and least of all, methysticin (6).

Although the kava buzz can be a very subjective thing, and each of the kavalactones (or kavalactone combinations) might affect one individual differently than another, many people find that kavain (4) is most responsible for the heady or uplifting part of the experience, whilst dihydromethysticin (5) is widely regarded as the major player at the other end of the spectrum, with it contributing more of the heaviness

that some people describe as making them melt into the couch. Dihydrokavain (2) is often regarded as contributing an effect somewhere between kavain and dihydromethysticin – you’ll have to experiment and find out which chemotype is perfect for you, but even without experimentation, knowing the chemotype can help you to avoid certain effects that you know you don’t want to deal with; Tudei kava, for example, usually has a chemotype beginning with “25” or “52”, and the majority of people will likely do well to avoid it and instead opt for something beginning with a “24” or “42”.

Chemotype Limitations

Invaluable as an indicator of what it is that you are consuming, chemotyping your kava is an incredibly helpful tool which enables our customers to know and understand more about what they are drinking, but the chemotype can’t convey all there is to know about what you might expect a particular kava to taste like or how it might make you feel.

How is it possible that two different batches with the same chemotype, for example 243156, might offer substantial differences in the subjective experience they confer to the person fortunate enough to consume them? 

The pharmacology of kavalactones is complex, as hinted at earlier, and despite a multitude of peer reviewed scientific journal articles being written about the constituents of kava, scientists don’t yet have the complete picture of exactly how every molecule interacts in the human body. It is possible that while one compound may serve to increase or decrease signalling of a particular receptor in the brain, another seemingly similar compound may have the opposite effect.

The net result is that sometimes subtle differences in chemotype are experienced in different ways, and these differences cannot always be conveyed by the 6-digit code:

Kava chemotype numbers tell you the order of relative abundance of each of the 6 major kavalactones, but taking a look at a kava with a chemotype of 243156 doesn’t tell you if there is twice or three times as much kavain (4) as dihydrokavain (2), or if they are nearly identical in quantity – differences that we see all time in the analytical and research & development labs at Root and Pestle; Even with the ability to detect and report less than 1 part per million (ppm), sometimes the quantitative difference between 2 (or even 3) kavalactones overlap within the margins of error and limitations of technology, leading to the identical batch of kava being able to be reported with different chemotypes.

We regularly analyse kavas that have nearly identical amounts of 2 or 3 different kavalactones, desmothoxyyangonin (1), dihydromethysticin (5), and methysticin (6), for example, which (assuming they are the least abundant of the 6 major kavalactones in that batch, and the relative abundance of the first 3 kavalactones is distinct from one another) could still lead to the same kava being reported with up to 6 different combinations of the last 3 digits in the chemotype (xxx156, xxx165, xxx516, xxx561, xxx615, and xxx651). 

It happens the other way around too – rather than the same batch having the potential for different chemotype labelling, wildly different plants with significantly different compositions might be accurately published with identical chemotype codes. Take for example a kava where there is only a few percent less relative abundance of each kavalactone in the 6-digit sequence than the kavalactone before it (the relative abundance of each kavalactone would be fairly similar across the board), compared to a kava which has perhaps only 30% as much of each kavalactone as the one before it (the relative abundance of the first kavalactone could be more than 10-fold that of the least abundant kavalactones). You can imagine how different the subjective experience might be if you compared the composition of these entirely different kavas – the ratios of kavalactones would be wildly different, and yet these 2 distinctly different kavas could have the same correctly-published 6-digit chemotype; There is only so much information that can be conveyed by simple arrangement of 6 numerals… This could be one reason why some connoisseurs are more interested in the ratio of kavain to dihydromethysticin (the K/DHM ratio), for example, than the standard 6-digit chemotype, assuming they’re dealing with a cultivar of known nobility.

The standard 6-digit chemotype is a quick and easy way to get an idea of what effects a particular kava will induce in the person who drinks it, but in many cases it won’t tell the whole story. Not only is there plenty of opportunity for similar kavas to have very different published chemotypes, and very different kavas to have very similar (or identical) published chemotypes, but that is still under the assumption that the analysis itself was perfect. Despite the hugely informative power of analytical chemistry, and its incredibly reliable and repeatable ability to make accurate predictions based on the collection and analysis of data, there are many reasons why this valuable tool in the scientific arsenal is imperfect. To read more about why many published chemotypes (and even some certificates of analysis) are inaccurate and cannot be relied upon, expand the box below [it’s a fairly long and technical read, hence we’ve placed it in a separate box to make it easier for those who might want to skip to a slightly less technical discussion].

Further Challenges with Chemotypes

Because the margins of error are compounded at multiple steps throughout the analytical process, anytime you have cultivars or blends with kavalactones of similar relative content (which is frequently the case), there exists the potential for different labs to publish different chemotypes for the exact same product, or even the same lab to publish different chemotypes for a product that was analysed on more than one occasion.

Unfortunately, there aren’t many “original” sources of high-quality determinations of published kava chemotypes corresponding to the multitude of cultivars, especially outside of the less-accessible peer-reviewed journal articles; Vincent Lebot, Mark Merlin, and Lamont Lindstrom’s excellent book, “Kava, The Pacific Elixir” possibly containing the most noteworthy list of this kind. Despite the high quality of the work, and its invaluable contribution, the chemotyping information published therein is relevant to consumers primarily for distinguishing between noble and ignoble kavas. This was incredibly important work at the time, and it remains important for the most part to only purchase noble varieties as drinking kavas, but with the introduction of single cultivars to the Western palate, and with the discovery that there is plenty of scope to enjoy the differences even between similar (but distinct) noble kavas, dialling up the resolution and improving accuracy in regard to correctly differentiating between closely chemotypically related cultivars has become more important. 

There are a few limitations with the chemotypes as published by Lebot et al. Namely, the same part of the plant was consistently used for analysis (as described in,“Buveurs de Kava”, by Patricia Siméoni and Vincent Lebot), which is important for science because comparing different parts wouldn’t make sense due the variation in chemotype and kavalactone content throughout the plant, however, the ground kava powder that ends up in homes across the world for consumption is virtually always a blend of parts, such as some ratio of lateral roots, root bark, and basal roots or rhizome, and even if it is just lateral roots (as sampled by Lebot et al.), some variation can exist even between certain roots of the same plant, particularly between the fine hair-like roots, and the much thicker sausage-sized roots, and more significant variation can exist between individual specimens. As the plants age, the ratio of those roots change, with the small roots being in great abundance early in the plant’s life, and the larger, harder, and less numerous “thick” roots dominating the root-ball mass as the plant’s age progresses. Even plants of the same cultivar, grown at the same farm, and harvested in the same way on the same day, can have slight differences in relative kavalactone ratios, and fairly significant differences in total kavalactone content. Unless you are analysing the finished product (which is almost always composed of roots from more than one plant), the chemotype of a representative plant sample is almost certainly not going to be identical to what’s in your shell.

Further, at the outset of the chromatography work performed by Lebot et al., it was not immediately known that yangonin and desmethoxyyangonin were better off being measured at considerably longer wavelengths than what worked best for the other kavalactones, and few corrections seem to have made their way into the mainstream knowledge sphere. Add to these complications the fact that compounds like yangonin can undergo isomerisation (a kind of change to the molecular structure) when exposed to light or alcohols, and methysticin can decompose in the high-temperature injection port of gas chromatography systems. These sorts of molecular degradations can lead to misquantification, and many people conducting kavalactone analysis are apparently either not aware of these kinds of problems or take inadequate steps to minimise them. 

Compounding the analysis problems caused by molecular degradation, there are numerous extraction techniques available to the analyst, and a whole host of solvents available to be used with each of those methods, many of which have their own inherent advantages or disadvantages. Be it Soxhlet extraction in ethanol or dichloromethane, maceration and sonication in water or organic solvents, high pressure Accelerated Solvent Extraction (ASE) with acetone or acetonitrile, or any combination of dozens of possible solvents in entirely different methods, the amount and ratio of kavalactones extracted will not be identical from method to method, yielding different reportable chemotypes. Again, this isn’t a problem when it comes to determining a kava’s nobility – the differences are typically easily determined by almost any modern method – but when it comes to distinguishing the differences between chemotypically similar cultivars or plants, extraction methods can make a difference. Truly the best way to report a kava’s chemotype as far as the end consumer is concerned might be to analyse exactly the ratio and quantity of kavalactones which would be ingested after following the manufacturer’s preparation instructions for that particular batch, although no producer currently does this.  Watch this space…

Growing conditions may also influence the final morphology and chemical composition of a plant – check out our article on what can influence the difference between Vanuatu kavas and Fiji kavas for a glimpse here but in any case, the final blend of ground kava root powder that you end up drinking is very likely going to have a different chemotype to the particular root sample as collected, analysed, and published in “Kava, The Pacific Elixir” (or scientific journal articles where root blending was not incorporated into the analytical process) because what’s in your bowl is almost certainly the result of a combination of more than one root, and more than likely, roots from more than one plant. Those differences in variation won’t likely result in changes drastic enough to result in a noble kava being identified as a non-noble kava (or vice versa), but they could definitely mean that the particular Kelai you’re drinking, for example, might really have a chemotype that matches more closely to what’s been published for a Borogoru, or another noble cultivar.

It should be noted, too, that the average chemotype of the plant’s roots as they grow in the ground are not necessarily reflected perfectly by the chemotype of the finished powdered product, even if the relative root composition is maintained and extraction and analysis methods are consistently employed; Perhaps surprisingly, certain steps in the production process may asymmetrically favour the concentration or degradation of some kavalactones more than others, even perhaps due just to the intensity of a particular mechanical processes. Indeed, anyone who’s spent some time in the kava world knows that the technique used to squeeze your kava can influence the quality of the beverage in your shell, but few consider the possibility that some kavalactones might be “squeezed” out of the roots differently in the production process too. Our instant kavas and our traditional blends come from the same premium plant source, and yet there we observe some chemotype differentiation between the resultant finished powders, which is sometimes enough to warrant changing the order of a digit or 2 in the published chemotype of a particular batch; Many people report that instant kavas actually feel different to traditional blends of the same cultivar, and perhaps chemotypical variation is a contributing factor to these subjective differences

[For the Root and Pestle/Kava Society Single Cultivar Range], we normally blend the entire root section in the ratio as Mother Nature provided it, so what you end up drinking is representative of the net total of all kavalactones from all of the various lateral and basal roots as harvested, and we opt to purchase only kavas that we believe are the perfect age and in perfect condition for drinking. However, different roots are best prepared in different ways, depending on their size, firmness, and other factors, and then recombined in their natural ratio before the finished product is packaged and shipped to our customers. We have the capability to analyse any part of any plant at every stage in our process, using the latest techniques in Ultra High Performance Liquid Chromatography (or UHPLC, which is a big step up from High Pressure Liquid Chromatography, or HPLC), among others, and from time to time we might make adjustments to the ratios to optimise the quality of a particular finished product. The chemotype resulting from adjustments to root ratios must be carefully calculated in advance, and confirmed after the production process through careful measurement to ensure that our customers get nothing but the best. Our experience in this area has shown us that it is sometimes very easy to end up with different chemotypes by only subtly changing the blending ratios. No other producer has ever claimed that they take this kind of care, and we are aware of none that have the kind of capability required to incorporate chemotype measurement of all relevant root sections and of each finished powder into their routine methods of production.

You really need to consult the Certificate of Analysis (COA) of your particular batch of kava (or send it to a reputable lab for analysis) if you want to know the chemotype of the powder you’re drinking, and it would really be best if you sent a sample to multiple labs and compared and questioned the differences, and took an average of the most reliable reports. We have seen numerous published chemotype lists online, and a disturbingly high percentage of them are riddled with errors; Simply not being based on finished ground powders is exceedingly common, as is copying and pasting results from elsewhere, which perpetuates inaccuracies – the more places people see the same information, the more likely they are to believe it, regardless of its validity, and the more likely they are to throw away true information which looks like an outlier in the face of their experience. In fact, there seems to be a bit of an echo-chamber in the kava world which has permeated a high number of kava forums, social media groups, distributors, retailers, and even producers, whereby many people possess the same misinformation and are confident in its validity, regardless of its true correctness. 

Without intending to muddy the waters too much, there is a little more to the story than just the reported chemotype as well: The 6 major kavalactones contribute largely to the subjective psychological and physiological experience, to be sure, however, there are a number of other alkaloids such as minor lactones and flavokavains which have the potential to alter the experience too. These are not reported by the standard 6-digit chemotype used to identify the primary kavalactones, and they can vary in concentration from plant to plant and from batch to batch. This means that even if you had perfect instrumentation and technique, two batches with the same reported chemotype might be experienced differently by some of our customers because of these other constituents – particularly amongst afficionados and connoisseurs who more easily notice and appreciate the differences, and of course depending upon their sensitivity to any of the compounds – which varies from person to person.

So how is a chemotype helpful if the same kava could have multiple chemotypes reported, whilst completely different kavas could be reported with the same chemotypes?

Chemotypes are one piece of the beautiful kava puzzle, and a very helpful piece indeed; Don’t let the above examples of how chemotypes sometimes don’t tell the whole story give you the impression that they are useless – far from it! A 423156 is almost certainly going to be a headier experience than a 245316, which would be expected to deliver much more heaviness – we just like to be completely transparent, and to let you know that as invaluable as the science is, it is also worthwhile considering the more subjective information that’s out there – including our description of each individual cultivar, and the reviews on our website.

You can help grow the global knowledge archive when it comes to the more subjective attributes by letting us know how much you enjoyed it after you’ve tried some of the finest kava out there – our Root and Pestle/Kava Society single cultivars. If you think you’ve experienced kava, but haven’t yet tried ours, you are missing out!

References

1 https://en.wikipedia.org/wiki/Secondary_metabolite 

2 https://en.wikipedia.org/wiki/Lactone 

3 https://en.wikipedia.org/wiki/Kavalactone 

4 https://en.wikipedia.org/wiki/Flavokavain 

5 https://en.wikipedia.org/wiki/Chalcone 

6 https://en.wikipedia.org/wiki/Chalconoid 

7 https://en.wikipedia.org/wiki/Flavonoid 

8 https://en.wikipedia.org/wiki/Oligomer 

9 https://en.wikipedia.org/wiki/Isomerization 

10 https://en.wikipedia.org/wiki/Precipitation_(chemistry) 

11 https://en.wikipedia.org/wiki/Detection_limit 

12 David A Armbruster, and Terry Pry, Limit of Blank, Limit of Detection and Limit of Quantitation. Clin Biochem Rev. 2008 Aug; 29(Suppl 1): S49–S52. PMCID: PMC2556583 PMID: 18852857

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2556583/ 

13 https://en.wikipedia.org/wiki/Phytochemical 

14 https://en.wikipedia.org/wiki/Psychoactive_drug 

15 Lebot V, Lévesque J. The origin and distribution of Kava (Piper methysticum Forst. f., Piperaceae): a phytochemical approach. National Tropical Botanical Garden, Hawaii Allertonia (1989) 5:223–380 https://agris.fao.org/agris-search/search.do?recordID=FR2019113557 

16 Alexander T Shulgin. The narcotic pepper – The chemistry and pharmacology of Piper methysticum and related species. United Nations Office on Drugs and Crime. 1973/01/01 Plate 15, Pages: 59 to 74. https://www.unodc.org/unodc/en/data-and-analysis/bulletin/bulletin_1973-01-01_2_page008.html 

17Dang Xuan, Tran & Fukuta, Masakazu & Wei, Ao & Elzaawely, Abdelnaser & Khanh, Tran & Tawata, Shinkichi. Efficacy of extracting solvents to chemical compounds of kava (Piper methysticum) root. (2008).  Journal of natural medicines. 62. 188-94. 10.1007/s11418-007-0203-2.  https://www.researchgate.net/figure/Composition-of-kava-root-constituents-by-different-extracting-solvents_tbl1_5449036 

18 Young RL, Hylin JW, Plucknett DL, Kawano Y, Nakayama RT. Analysis for kawa pyrones in extracts of Piper methysticum. Phytochemistry. 1966;5:795–8.

19 Bilia AR, Scalise L, Bergonzi MC, Vincieri FF. Analysis of kavalactones from Piper methysticum (kava-kava) Journal of Chromatography B-Analytical Technologies in the Biomedical and Life Sciences. 2004 Dec; 812(1–2):203–14. https://pubmed.ncbi.nlm.nih.gov/15556499/

20 Bobeldijk I, Boonzaaijer G, Spies-Faber EJ, Vaes WHJ. Determination of kava lactones in food supplements by liquid chromatography-atmospheric pressure chemical ionisation tandem mass spectrometry. Journal of Chromatography A. 2005 Mar;1067(1–2):107–14. https://pubmed.ncbi.nlm.nih.gov/15844515/

21 Bilia A, et al. Kava-kava and anxiety: growing knowledge about the efficacy and safety. Life Sci. 2002;70(22):2581–97. https://pubmed.ncbi.nlm.nih.gov/12269386/ 

22 Dr. E. F. Steinmetz. Kava Kava: Famous Drug Plant of the South Sea Islands. Paperback – January 1, 1960.

https://www.amazon.com/Kava-Famous-Plant-South-Islands/dp/B003LDH5ME 

23 Lebot, V., Merlin, M., and Lindstrom, L. Kava: The Pacific Elixir: The Definite Guide to its Ethnobotany, History and Chemistry, (1997), pages 219 – 222. Vol ISBN 0-89281-726-7 (Rochester: Healing Arts Press).

24 Patricia Siméon, Vincent Lebot. Buveurs de Kava. Éditions Géo-Consulte; 1st edition (January 1, 2014), page 248. ISBN-10:2953336230 ISBN-13:978-2953336238 https://www.amazon.com/Buveurs-dek-Kava-Patricia-Sim%C3%A9oni/dp/2953336230