Drug Synchronicity in Amazon Tea

Some indigenous Peruvian people produce a brew which is fascinating from both a chemical and cultural standpoint. As part of a religious ritual, they drink a psychedellic tea (Ayahuasca)  produced from a variety of local plants, which could include Banisteriopsis caapi and Psychotria viridis. Several studies have concluded that the ritual use of ayahuasca is not associated with the drawbacks typically caused by drugs of abuse.

The first plant, caapi, has in its stems a class of alkaloids know as β-carbolines. These compounds which include harmine and harmaline act as inhibitors of mitochondrial oxidizing enzymes know as monoamine oxidases (MOA). The inhibitors themselves are abbreviated MOI.

Harmine_3d_structure

Harmine’s structure: the 3 rings are common to all B-carbolines, which inhibit oxidation of amine groups of the hallucinogen DMT

Psychotria viridis contains the psychedelic agent N-N-dimethyltryptamine(DMT), which acts similarly to mescaline in that it activates serotonin receptors in the brain. But DMT  is normally deactivated when taken orally. Its amino group is oxidized.

Psychotria viridis

Psychotria viridis, the source of DMT

DMT is active only when injected, which is not what Peruvian shamans do. So why does Ayahuasca tea induce hallucinations? Normally DMT is deactivated in the gastrointestinal tract and liver by MOAs. But since the tea also includes the β-carbolines that act as inhibitors of the degradating enzymes, the DMT is free to travel to the brain and induce its effects.

DMT.gif

DMT, an indole derivative used as an hallucinogen but also for treatment of migraines in parts of Peru.

How did past cultures discover this plant-combination and others? It may have involved not only trial and error but keeping a track-record of the attempts and, of course, transmitting the knowledge through generations. The Machiguenga people also use P. viridis as a source of eyedrops, which bypass the digestive tract. In low concentrations, DMT and associated natural products don’t induce hallucinations but help alleviate migraines. Many governments have made DMT illegal, in a situation parallel to other drugs where a compound is purified and stripped not only of its auxiliary natural products but of its cultural context.

Drug synchronicity involving MOIs is not unique. Recently,  I came across a blog by  Federico Germani (sorry the site has been taken down), who is sensitive to both coffee and chocolate. As he explains, due to genetic variance of a cytochrome enzyme, not everyone is equally efficient at breaking down theobromine, a companion-molecule of caffeine in coffee. Both theobromine and caffeine are MOIs, albeit weak ones, which could explain why he gets unusually euphoric after ingesting chocolate on an empty stomach. Chocolate contains phenylethylamine, which in the presence of MOAs normally gets broken down quickly. But if theobromine, which is also present in chocolate, persists due to his variant cytochrome enzyme, it interferes with phenylethylamine’s breakdown. And when the latter lingers, it boosts production of dopamine in his brain.

For those of you may share my fetish for structural formulas, here are more of the structures discussed above, and keep in mind that I love them more when the compounds are within the confines of living plant tissue. 🙂

Phenethylamine-3D-balls

phenylethylamine, found in chocolate and not always metabolized before reaching the brain

mescaline

Mescaline, a molecule from peyote. It’s similar in structure to chocolate’s phenylethylamine and acts similarly to DMT from Amazon tea.

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New Screen for Shellfish Poisoning

Dinophysis_acuminata

Dinophysis acuminata, a species of OA-producing algae

About 300  species can cause algal blooms, and a quarter of them are able to produce toxins. Among these are the okadaic acid group toxins(OA) made by some marine dinoflagellates. They are found in contaminated shellfish, and the maximum permitted level (MPL) is 160 μg OA equivalents/ kg shellfish meat ( 160 parts per billion).

okadaic acid

Okadaic acid and derivatives, a group of toxins from the dinoflagellate genera Dinophysis and Prorocentrum . From http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3917280/

OA has long been linked to severe diarrhea, but two years ago a Spanish review study highlighted its role as a neurotoxin and a cancer promoter. Okadaic acid has an intricate mechanism of action. Most (but not all) of its more recently discovered effects are due to its inhibition of protein phosphatase enzymes and its consequences. For example, when okadaic acid inhibits such enzymes, tau proteins bond to too many phosphate groups. Since such proteins play a role in memory in the hippocampus, not surprisingly, rats lose cognitive function when the acid is microinjected into their brains, where it causes an Alzheimer’s like-pathology.

Recently, a new test-strip (lateral flow immunoassay or LFIA ) has been developed to detect the presence of okadaic acid toxins. LFIA is cheaper than mass spectrometry-chromatography, and LFIA does not rely on animal testing. After coming across an explanation of its mechanism in the Economist, I drew something simple to illustrate the clever design behind these strips, the fruit of research led by Waqass Jawaid, of Queen’s University in Belfast.

okadaic!I contacted one of the coauthors  (Julie Meneely) to make sure my illustration was adequate, and she was kind enough to promptly look at it and let me know that it was an accurate portrayal. The sample—see adjacent diagram— flows through three regions on the strip. The first region contains mobile antibodies capable of bonding to okadoic acid(OA). The second region will bind to the antibody only if it did not already bond with OA. Finally, the third region binds to the antibody regardless of whether it’s holding OA. In other words, it serves as a control, making sure that the antibody has indeed migrated down the strip.

okadaic2

The next illustration reveals how a safe sample will produce two red zones. Being free of the toxin it is capable of binding to the antibody. But a contaminated shellfish sample’s OA occupies the site in the antibody meant to interact with the 2nd zone. Once the group migrates to the second area, no additional bonding occurs and no red color band shows up on the middle part of the strip.

The frequency of algal blooms has increased in the Great Lakes and in other regions of the world.  And since the toxins are more harmful than previously imagined, this convenient test will hopefully encourage citizens, lawmakers, the seafood and agricultural industries to lower the phosphate and nitrate concentrations in our waterways. They are, after all, the promoters of algal growth.

 

 

Backyard Science: The Benefits of a Broken Branch

written in July 2013

The branch actually ripped from the base of the tree. After sawing off most of the length, I pushed it back towards the trunk.

The branch actually ripped from the base of the tree. After sawing off most of the length, I pushed it back towards the trunk.

My son decided to pick some cherries during last week’s heat wave. Luckily, 5 minutes later, he lost interest and walked away, and my daughter who normally would have been in front of the tree, was at her grandmother’s, learning to bake pineapple-coconut pie. As a result, neither of them was in the way of the 15-foot branch that my wife sent crashing down, and luckily for us, she maintained her balance on the step-ladder.

After sawing it to begin the cleanup, I noticed that the tree rings on the thick branch’s cross section were irregular. Why, I wondered?

In the spring, my wife’s relative, a forestry student, had sent me a set of research papers by Quebec scientists who had found a correlation between temperature and tree ring thickness in the boreal forest, where moisture is rarely the limiting factor. But the cherry tree is not a conifer, and it’s growing in a temperate forest biome. Other hypotheses came to mind.

cherry2

The cross section of the branch whose tree rings were measured.

First I drew a radius through the widest gaps (the rings were not perfect circles) and measured all the rings (figure 1). The branch was at least 11 years old. Then I consulted Environment Canada to obtain precipitation and temperature data in Montreal for that time period. Here’s what I found.

avg.temp mm precip avg.temp mm precip avg.temp mm precip avg.temp mm precip
apr   may   june   july  
2012 6.8 67 15.9 91.8 20 73.6 22.3 94.2
2011 6.6 134.4 14 144.8 19.3 93.8 23.1 59.2
2010 9.5 89.4 15.7 38 18.4 158 23 96.6
2009 7.7 76 12.7 93.2 18 74.6 20 116.6
2008 8.1 74.8 12.4 74 19.9 70.6 21.5 118.8
2007 5.8 139.6 13.7 63.2 19.6 60.4 20.4 106
2006 7.6 114 14.5 173.4 19.2 104.2 22.6 135.2
2005 7.7 158.8 17.4 113 21.5 129 22.2 125.6
2004 6 68.8 13.5 81.8 17.5 64 21.5 139.4
2003 4.2 76.9 13.4 110.5 18.8 70 21.6 54
2002 6.9 79.9 11.3 127.5 17.5 106 22.1 55
avg.temp mm precip avg.temp mm precip
aug   sep   AVG temp total mm avg july, aug, sep total july, aug, sep mm
22.2 48.2 16 103 17.2 477.8 20.2 245.4
21 224.8 17.7 110.4 17.0 767.4 20.6 394.4
20.9 139.2 16.3 157.2 17.3 678.4 20.1 393
20.8 81 15.3 44.8 15.8 486.2 18.7 242.4
19.7 77.6 16.7 49.4 16.4 465.2 19.3 245.8
20.1 80.4 16.7 47.8 16.1 497.4 19.1 234.2
19.3 154.4 15.1 65.4 16.4 746.6 19.0 355
21.7 134 17.4 113 18.0 773.4 20.4 372.6
19.3 90 16.4 71.8 15.7 515.8 19.1 301.2
21.6 79 17.7 104 16.2 494.4 20.3 237
21.8 11 18.3 64.5 16.3 443.9 20.7 130.5

At first, there seemed to no correlation of any kind. Here’s a summary of the hypotheses I entertained:

Hypothesis Results
Temperature is the variable responsible No correlation
Total precipitation from April to September is the variable responsible No correlation
A combination of precipitation and temperature plays a defining role. No correlation
If a specific cold spell after flowering affects cherry production, the tree will subsequently have more energy to devote to trunk growth. No data
Erratic fertilization could be the limiting factor No data
Most trunk growth occurs in July, August and Sep after cherry production and temperature during those months will be the controlling factor. No correlation
Most trunk growth occurs in July, August and Sep after cherry production and total precipitation during those months will be the controlling factor. No correlation
Most trunk growth occurs in July, August and Sep after cherry production and a combination of temperature and total precipitation during those months will be the controlling factor.  No correlation

Then I thought of the possibility that most of the trunk growth occurred in July, and that the controlling variable was moisture. Since we rarely, if ever, water the tree, trunk growth suffers when not enough rain falls. During that month, the days are still close to being their longest, and the tree is no longer devoting energy to producing fruit.

The correlation was stronger, but still disappointing. If, however, out of the eleven years, I ignored two of them, when other factors could have caused anomalies, the correlation coefficient became 0.88.

But, pardon the pun, was I merely cherry-picking the data? Also, was there anything in the research literature to support the idea that the bulk of cherry trunk growth did indeed occur during one single summer month?cherrygraph

July mm rain width of ring
2012 94.2 3.5
2011 59.2 3.0
2010 96.6 2.7
2009 116.6 4.9
2007 106 4.1
2006 135.2 6.1
2005 125.6 5.1
2004 139.4 4.6
2002 55 2.0
correlation 0.88

I contacted an Oregon State University horticultural scientist, Todd Einhorn, summarized my adventure and waited for a reply. Surprisingly, he responded on the same Sunday and wrote:

Thanks for your interesting email.

We have documented, as others have, the rapid growth of trunks after harvest. It appears that trunks compete poorly for carbohydrates when other sinks are active; fruit having the greatest sink strength. So, your findings are supported. Regarding the omission of 2 years of data…I imagine you would have to run stats for spurious data. Nine of eleven years isn’t bad!, what do you suppose could have resulted in the deviation? Perhaps low temperature injury (affecting either cambial tissue, or reducing bloom resulting in light crop loads) be a contributing [covariate] factor?

Regards
Todd

cherry4

This batch of cherries is actually not from the broken branch but from an adjacent one.

Not only did the broken branch lead to some interesting science, but it yielded over 25 pounds of cherries. Most fruit from an unbroken branch would have remained out of reach but would have been well within the grasp of competing birds. Now that the pineapple-coconut pie has been vacuumed down, we can feast on cherry pie and jam. After that, it would be nice to get data from more trees in the city!