Tribulus terrestris - Bai Ji Li, "puncture vine", "goatshead"
While ayahuasca vine (Banisteriopsis caapi) and syrian rue (Peganum harmala) are undoubtedly the two most prevalent MAOIs used in plant and chemical admixtures, they aren't the only ones.
Tribulus terrestris seems to be a promising but underexplored candidate. People who work with rue or caapi (or their chemically refined constituents: harmine, harmaline, and THH) might be interested in exploring its potential. A major advantage of this plant is that it has a long established history of human use, and can be regarded as safe, within limits.
Tribulus also has the advantage of being pretty widely available either from a Chinese herbalist (if you can find one in your nearest Chinatown) or online. There is a site known to be a reliable source that sells the stuff for $1.99/lbs!
It's been confirmed by a couple of individuals that it acts sufficiently as an MAOI to allow for oral consumption of DMT admixtures. There have also been reports of it potentiating vaporized DMT. (Most of the reports come from this thread at the Ayahuasca forums)
What is it?
It is used in ayurvedic medicine as a sort of tonic... Apparently it:
[*]Regulates Stagnant Liver Qi
[*] Suppresses Internal Wind
[*] Regulates Blood Stagnation
[*] Treats Liver Yang Rising
[*] Kidney Yang tonic
...whatever that means. They consider it to be relatively safe for longterm use.
The part of the plant that you're looking for is the whole dried fruits. These fruits actually look like thorns, as you can see:
In the past, people have recieved bunk materials when ordering powdered Tribulus terrestris. It's unclear whether the material was misidentified, or what the problem was. When you get the whole fruits, you know you're getting the right material.
Dosage
The dosage indicated by an Chinese herbalist text is 6-12 g. The dosages recommended by people who have tried it for a harmala experience are about 2 flat tablespoons (according to one individual), or 15-20 g according to another. In general, I think it can be considered safe to brew up to at least an ounce, at least if you're doing a cold-water extraction and taking some dietary precautions (remember, we're dealing with MAOI-A and MAOI-B here).
A flat tablespoon of Bai Ji Li has been measured as being ~3 g, and alternately as being ~6 g. I'm guessing that ~3 g is for whole fruits and ~6 g is for powdered material?
Brewing
The reported brewing method was a 5 minute high boil of freshly powdered dry fruit (thorns). No acid is needed.
If you're using more than 12-15 g, it's probably better to do a coldwater extraction. You could leave it soaking in cold water for a couple days, or you could rig up a contraption Dagger calls the Herbal Percolator.
Chemical Constituents
In chemical terms, it has a very different MAOI profile than either rue or caapi. The main beta-carboline alkaloids in T. terrestris appear to be harman(e), norharman(e), harmol, and harmalol. Some sources make reference to harmine in the plant, but I haven't found any chemical source to back that claim. I think it may be a case of someone getting harmane and harmine confused in an early publication, and the mistake being reprinted through other sources.
Just for a quick overview of those alkaloids:
Harmane - 1-methyl-β-carboline
Norharmane - β-carboline
Harmol - 7-hydroxy-1-methyl-β-carboline
Harmalol - 3,4-dihydro-7-hydroxy-1-methyl-β-carboline
Norharmane - β-carboline
Harmol - 7-hydroxy-1-methyl-β-carboline
Harmalol - 3,4-dihydro-7-hydroxy-1-methyl-β-carboline
And compare those to the β-carbolines we're more familiar with: Harmine and harmaline are the methyl esters of harmol and harmalol
Harmane is an MAOI-A. Norharmane is an MAOI-B. This inhibition of MAOI-B is a major difference between Tribulus and the traditional plants (caapi and rue), which are pure MAOI-A. I was unable to find information on whether harmol and harmalol inhibit MAO-B or MAO-A preferentially, but they are known to have MAOI activity.
It has been said:
The equivalent of 100 mg harmine is 50 mg harmaline, 35 mg tetrahydraharman, 25 mg harmalol or harmol, 4 mg methoxyharmalan. Harmal alkaloids are synergistic (mutually potentiating) and are therefore most effective when combined in an appropriate balance.
Another interesting sidenote: Harmane and norharmane are found in tobacco, where norharmane in particular can potentiate the nicotine, because it inhibits the production of the form of MAO responsible for breaking down monoaminic neurotransmitters, like dopamine, in the brain.
All the literature seems to put the alkaloid content quite low. But these analyses were done on the seeds, and it's not clear whether "seeds" refers to the thorny fruit, or a smaller unit within it.
One analysis put the total alkaloid content at 44 mg alkaloids per kg dry mass, primarily composed of harmane and norharmane. That's a mere 0.0044%, or 44 micrograms per gram of plant used. Acta horticulturae. 2005 Feb., no 677, p11-17.
Another source reported harmol present at <453 ng/g, norharmane at <157 ng/g, harmane at <143 ng/g, and harmalol at <486 ng/g. That comes to a maximum alkaloid concentration of 1.24 micrograms per gram of seeds, or 0.00012% total alkaloid content. Phytochem Anal. 1999. 10/5:247-253
Considering the dosage at which the material has been reported active in human bioassays, I have to assume that there is some critical difference between the materials analyzed in the published reports and the material that has been used by the people at the Ayahuasca forum. The alternative is that the β-carbolines present in the T terrestris fruit are potent on the general order of magnitude of LSD... that's not a hypothesis that I'll consider tenable until some alternatives have been exhausted.
There are other chemicals in Tribulus besides β-carbolines. While it's the β-carbolines that interest us, this plant is used by weightlifters for another set of chemicals it contains, chemicals called steroid saponins. If you encounter Tribulus extract at a health food store, it's an extract of these chemicals, with the MAOIs removed.
Some studies have indicated that the steroid saponins increase the levels of testosterone (by increasing luteinizing hormone), DHEA, and estrogen. In fact, many of the attributes associated with Bai Ji Li as an ayurvedic medicine can probably be associated with the activity of its steroid saponins.
When using larger doses of Bai Ji Li, it may be desirable to prepare the brew as a cold-water extract to avoid most of the steroid saponins, while still extracting the β-carbolines.
Other Considerations
Someone noted that alcoholic extracts are contraindicated as hypotensive (presumably due to inhibition of MAO-B when consuming alcohol). But contrary to this claim, it turn out Tribulus terrestris fruit is actually used in Ladakh, as an ingredient to forify beer in the brewing process.
This plant is probably not a great idea for a person's first ayahuasca analogue mixture, as it is so much less explored in that capacity than rue and caapi. But for someone who is seeking another similar plant with its own idiosyncracies (and an intriguingly different MAOI profile), I think this plant warrants some consideration.
It has been reported that the effects are inhibited by a full stomache, and require consumption on an empty stomache to produce their characteristic effect.