[randomcoder22]

Hi,

I'd like to extract rosmarinic acid from some plant, like lemon balm or spearmint. Rosmarinic acid is slightly soluble in water and well soluble in most organic solvents. I don't care about any impurities that come from the plant.

Would the following procedure work?

Put the plant matter (probably chopped into small pieces?) into ethanol, let it sit for some time (like a day?), filter solids out.

That would leave me with rosmarinic acid in an ethanol solution. How would I get rid of the ethanol? Can I just boil it and let it evaporate? But wouldn't the compounds from the plant evaporate with the ethanol?

Thanks a lot

(I apologize if this is in the wrong category or anything like that, I'm new to this site. I also have no experience with chemistry though I find it interesting.)

[rolnor]

Rosmarinic acid has a very high boilingpoint so there is no problem to remove ethanol via boiling. What will you use the material for?

Here is a reference;
https://en.m.wikipedia.org/wiki/Rosmarinic_acid

There is a reference where they isolate rosmarinic acid but its in italian.

[randomcoder22]

Thank you for that explanation. Now I see how evaporating the ethanol works.

I learned about rosmarinic acid a few days ago and it's an interesting substance. It inhibits an enzyme that breaks down GABA which is the reason why lemon balm has a calming and sedating effect. I'm interested in pharmacology but have no experience with chemistry, so this extraction looks like a nice introduction to me.

Will the extract be safe for consumption? I thought yes but I guess I'd have to use non-denatured ethanol? Perhaps some >50% alcohol, like a fruit spirit, would work as well?

[AWK]

Extraction of rosmarinic acid from plant sources are reported in the literature. The highest content of RA shows lemon balm - up to 80 mg/kg of dry mass.
For a greater scale, you need huge amounts of ethanol. Literature procedure uses 1 L of 40 % ethanol for 30 g of powdered lemon balm.

[randomcoder22]

Extraction of rosmarinic acid from plant sources are reported in the literature. The highest content of RA shows lemon balm - up to 80 mg/kg of dry mass.

According to this study, lemon balm has 36mg/g and spearmint 58mg/g of RA. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3307200/

For a greater scale, you need huge amounts of ethanol. Literature procedure uses 1 L of 40 % ethanol for 30 g of powdered lemon balm.

Why is that? Either way, that doesn't sound so huge. 30g of dried plant matter is a lot, so 1L of 40% ethanol doesn't sound like that much. For personal use (seeing how convenient it is to consume the extract), I doubt I will use more than 5-10g of dried plant matter, so ~0.1L of some >50% ethanol should work well enough.

[AWK]

I found my error kg instead of grams.
RA contents vary. Best result - 80 mg is from ultrasonic extraction.

[randomcoder22]

I also have two questions regarding temperature:

1. Can I find anywhere if/how does the water solubility change with temperature? Since lemon balm is mostly prepared as a tea and rosmarinic acid is not that soluble in water, I wonder if it's better with higher temperatures.
2. Can too high (100°C) temperature somehow destroy the rosmarinic acid, or would any issues with temperature be just that it would evaporate at 171°?

Thanks in advance!

[wildfyr]

Yes, heating too hot for too long can damage the molecule, but there is no hard and fast rule about what this is. I would do low heat for a longer time. Ethanol is quite volatile, you shouldn't haven't to torch it for it to evaporate. Remember that most ethanol you obtain will have some water in it too. And denatured alcohol should not be used to extract things which are being consumed. I assume your goal is to use everclear?

[randomcoder22]

Ethanol is quite volatile, you shouldn't haven't to torch it for it to evaporate. Remember that most ethanol you obtain will have some water in it too. And denatured alcohol should not be used to extract things which are being consumed. I assume your goal is to use everclear?

Not from the US, so a local moonshine (without methanol of course). What do you mean by "Ethanol is quite volatile, you shouldn't haven't to torch it for it to evaporate."? Are you saying that it can start burning at a too high temperature so I should evaporate it at a lower temperature?

[AWK]

Use Soxhlet extractor or keep the temperature about 5 degrees below boiling (~75°C) for 1-2 hrs with mixing. You may also use reflux condenser.

[randomcoder22]

What's the safest way of evaporating ethanol without any laboratory equipment? I've read that it evaporates even at room temperatures but that's probably impractical. And using a stove can be dangerous I guess.

[Enthalpy]

How will the rosmarinic acid be purified from all compounds that will dissolve in the ethanol?

[billnotgatez]

@Enthalpy
I think OP answered about impurities early on

...
 I don't care about any impurities that come from the plant.
...

I presume they just want to get rid of most of the plant matter.

[randomcoder22]

Yes, I don't really care about extracting other things too. I just want to have a powder extract instead of plant matter.

[Borek]

Will the extract be safe for consumption?

Sorry, we don't discuss self medication here. Please read the forum rules.

Topic locked.