The Loveliness of Green

Raspberry ketone, also known as oxyphenalon, betuligenol, 4-Hydroxybenzylacetone, 4-(4-Hydroxyphenyl)butan-2-one, and p-hydroxybenzylacetone, and some other 54+ names, is the compound mainly responsible for the raspberry aroma which is widely used in food industry as a flavoring and fragrance agent. Besides being a widely used flavoring agent, raspberry ketone has been tested as a pesticidally active ingredient in a number of formulations for interacting with the neurotransmitters of GABA receptor sites in plant and animal pests (Ecosmart Technologies, Inc.), as a colorant dispersing agent for hot melt ink used in printers, and as a flavor imparting compound in coated photographic paper.

Recently it has been declared by popular TV personalities a fat-burning "miracle in a bottle." If those folks want to be taken seriously, they should not use the words medicine and miracle in the same context because they are mutually exclusive. On the other hand, manufacturers make absolutely ridiculous claims. The NutraBio caught my attention because of their aggressive advertising on Google. Here is one of their advertising pearls

"Pure Raspberry Ketones by NutraBio contains 250 mg of stimulant free raspberry ketones extract in each vegetable capsule. Just one capsule contains more raspberry ketones than a large bowl of fresh raspberries. Raspberry ketones is a compound in red raspberries that gives the fruit its aroma and is used widely in the US as a food fragrance and flavoring. In Japan, raspberry ketones have become a popular ingredient in weight management supplements. It’s thought that raspberry ketones may influence lipolysis, the process of breaking down fat in the body. Preliminary (animal) research has shown some positive results, but further investigation is necessary to confirm the effects."

Quote: "Stimulant free." What exactly does 'stimulant free' mean in this context? Hormone-free? Then just say it. Otherwise, this does not make any sense because raspberry ketone IS a stimulant, it "influences lipolysis, the process of breaking down fat."

Quote: "Preliminary (animal) research has shown some positive results." The research is quite dated (2005). Why sell products to humans based ONLY on two published animal studies?

Quote: "Without the side effects associated with most diet pills… Vegetarian and Hypoallergenic."
If there are no human research documented reports, where do these claims come from? And what about the adverse effects such as increase in relative weight of liver, adrenal glands and kidneys documented in rodents? Such side effects happen as a result of the hormonal overstimulation. Indeed, raspberry ketone shares many properties with synephrine, which is similar to ephedrine, an alkaloid that increases the activity of noradrenaline hormone. Both can cause irregular heart beat and even heart attack.

Quote: "Just one capsule contains more raspberry ketones than a large bowl of fresh raspberries." Considering that only a tiny quantity of raspberry ketone can be obtained from fruit, where do your ketones come from? Most "natural" raspberry ketones can be obtained through a biotechnological route using fungi, yeast, and growth stimulants, such as UV irradiation. Only 3.7 mg of raspberry ketone can be extracted from 1 kg of raspberries, and if the compound were isolated and purified from fresh berries, natural raspberry ketone would cost 6 million dollars per kg (cost of fruit only), compared to $8-10 per kg for the synthetic product. It is obvious that isolation and purification of this compound from berries make it prohibitively unprofitable.

That being said, it is borderline deceptive to place a picture of red raspberries next to the product name when the fruit is NOT the source of the product. Most often raspberry ketone is synthesized from inorganic chemicals, because even biotechnological route (enzymatic conversion using Aspergillus niger black mold, Candida boidinii yeast, and Acetobacter bacteria) is quite expensive. Just like we do not call a mixture of corn syrup, starch and artificial color "bluberries," any attempt to make us believe that the product is extracted from real fruit is misleading and unethical.

The synthetic transformation of 4-(4-hydroxyphenyl)butan-2-one (raspberry ketone) from (E)-4-(4-hydroxyphenyl)but-3-en-2-one can be prepared hands down in a laboratory and seems like a slam dunk even for an average college student. Here are the instructions:

"Use a three-necked flask, fitted with a reflux condenser and septa and purge with nitrogen gas 15 min. Make a zinc/THF slurry and transfer to the flask dropwise. Heat Zn suspension to reflux. Add methonal solution of (E)-4-(4-hydroxyphenyl)but-3-ene-2-one and add water in the ratio of THF: methanol:water used 7:5:1. Reflux 2.5 hours under nitrogen. Cool and flood with 150 mL of ether. Extract successively with 10% ammonium chloride (25 mL), 10% sodium bicarbonate (25 mL), and saturated sodium chloride (25 mL). Dry over anhydrous magnesium sulfate and strip solvents by rotary evaporation." Voila! Your fountain of youth is ready to be bottled.

Pass the raspberries, please. No extra ketones, just raspberries. Thank you.

Visiting a contact zoo can be very therapeutic in many ways. These creatures are very lucky as they are truly loved by the wonderful people who take care of them.