This post describes

1. C60 and three related materials
2. How reactive oxygen species modification of C60 makes it fuel for the intestinal microbiome
3. absorption and deposition of C60 in rats
4. absorption, deposition, and liver protection of C60 in rats
5. summary

Three related compounds

C60, also known as buckyball and buckeminsterfullerene is a 60 carbon spherical molecule. Note the presence of double bonds in this PubChem rendering of the structure. Buckminsterfullerene, is a skin, eye, and pulmonary irritant. Note that C60 is a spherical form of graphene.

These compounds are not far removed from charcoal, aka activated carbon. Wikipedia authors list van der Waal interactions and London dispersion forces as the means of small molecules bindint to activated carbon structures. The structure of activated carbon was solved in 2008 by PG Harris and coworkers.

Smart Solutions and Nutricost are both brands of activated charcoal available on Amazon.com. It is somewhat concerning that Amazon does not require its sellers to make their certificates of analysis extremely obvious. Sigma Aldrich also sells activated charcoal.

Less than 1% of the Sigma Aldrich activated charcoal contains materials than can be extracted with ethanol. This is looking good.

Oxidized C60s,

A group of Peking Union Medical College prepared Fullerenols, C60s with hydroxyl or ketone groups. (Fol 1) were synthesized by the alkaline
reaction of C60 in a solution containing NaOH with a catalyst tetra ammonium butyl hydroxide (TABH). Fol 113 was prepared using 30% H₂O₂ in place of TABH, [1]

It was not totally clear if Ji and coworkers were thinking that these fullerenols / fullerenones are one a patient would encounter when consuming C60 as a reactive oxygen species scavenger. Attaching oxygen groups to pure carbon polymers is a strategy our bodies use in the degradation of pure carbon compounds. In very simple terms, mice were then divided into 3 groups of 8 and fed normal chow. Mice were gavaged with 20mg/kg Fol1 or Fol113 per day for a month. The normal control group was gavaged with distilled water. [1]. Fresh feces were collected for short chain fatty acid and microbiome analysis. [1] This post will skip the big data analysis of microbiome changes.

The liver and blood total cholesterol (TC) and triglycerides (TG) of these mice were also analyzed. [1]

Fresh feces were used to inoculate fermentation vessels. [1] Fol1 and Fol 113 NPs were added to a final concentration of 0.1 mg/mL. Inulin, known to promote short chain fatty acid fermentation products, was added at a concentration of 5g/L. The cultures were fermented for 48 hours under micro anaerobic conditions. Wikipedia authors have little to say about Allobculum expect that this genus has but one species that was isolated from the feces of a dog. Slightly better results were obtained from PubMed

What wasn’t covered was why not just use graphene with hydroxyl and ketone groups?

How to absorb C60

This study came out of the Russian Federation. While C50 is insoluble in water, it is soluble in vegetable oils, one being olive oil containing weight percent: palmitic acid (7.00–20.00), palmitoleic acid (0.3–3.5), stearic acid (1.5–4.3), oleic acid (56.0–86.0),
linoleic acid (3.3–20.0), linolenic acid (0.4–1.5), arachidonic acid (0.2–1.6), gondoic acid (0.2–0.5), toluene 99.9%. These authors used C60 sold by Sigma Aldrich but produced by MST-NANO (St. Petersburg).
Semenov and coauthors launched into a rather lengthy discussion of the srufactnt TWEEN-80 as a surfactant used in the cosmetic industry to mix oils and water.Much discussion was given to the “original ExtraOx” technology developed by “AQUANOVA RUS” For whatever reason, the authors thought that the micelles up to 30 nm in size because this is the size of micelles absorbed by humans, and presumably mice too. The content of fullerene C 60 in the oil form is 0.1 wt.%, in the micellar form is 0.01 wt.%. [2] Male mice weighing 30 ± 3 g were starved 12 hours before the experiment while allowing complete access to water. These two forms of C60 were given by intragastric lavage:

• 15 mg·kg⁻¹ for the oil formulation
• 1.5 mg·kg ⁻¹ for the micellar formulation one, shown previously to be more effective than the oil based formulation in a cell culture model.

Mice were sacrificed 24 h after administration of the final dose of fullerene. The tissues of the liver, lungs,kidneys, heart, brain, adrenal glands, thymus, testicles, and spleen were collected, weighed, and stored at − 80 °C. Blood samples were collected in tubes containing 5 IU·ml⁻¹ heparin sodium salt. A portion of the biological material was frozen and homogenised. Fullerene was extracted with 1 ml of toluene in an ultrasonic water bath for 30 minutes.

What is really lacking in the Semenov study is how this Russian invention compares with mixing olive oil and egg yolk or soybean lecithin and using a household blender to make the emulsion. The rats were fed this material were fed this material on an otherwise empty stomach. If hey were given C60 in olive oil with a meal, we see bile salts assisting with chylomicron formation. The authors of Wikipedia give a chylmicron size range of 1000nm. The Semenov micelle form of C60 had a size centered around 9 nm. [2] The frustrating thing about the concept is that we are unsure abut how C60 is absorbed and eliminated.

C60 has a hepatic protectant

A Serbian group induced liver damage in rats using thioacetamide, as a model liver toxin. [3] According to Wikipdia, thioacetamide undergoes this reaction with metal ions

M²⁺ + CH₃C(S)NH₂ + H₂O → MS + CH₃C(O)NH₂ + 2 H⁺ (M = Ni, Pb, Cd, Hg)

This study used 2.5 month old female rats weighting 280.79 ± 4.91 g, Five groups of 8 rats each were dosed for 4 months. C60 was dissolved at 0.2mg/mL in extra virgin olive oil. [3]

• Control standard rat food, with free access to tap water
• TAA—thioacetamide group of animals (free access to commercial standard rat food, and tap water with thioacetamide dissolved in 300 mg/L concentration);
• TAA+O—thioacetamide + virgin olive oil enriched food 10% mass/mass
• TAA+O F1 plus low dose fullerene, 1 mg/kg body mass
• TAA+O F2 plus high dose fullerene, 5a mg/kg body mass

At the end of the study the liver C60 fullerene bioaccumulation was 21.04 ± 0.60 33.32 ± 0.98 (μg/g tissue) in the low and high dose groups respectively.[3]

Note that the TAA livers appear to be less red than the others. The lowest dose of C60, F1, seems to have the most normal color and texture.

Liver enzyme activities

Olive oil seems to really increase the glutaredoxin and glutathione S transferase activities. whether or not C60 is there.

The comet assay measures chromosomal damage in single cells migrating through a gel in an electric field. Undamaged DNA migrates as a blob. Damaged DNA is released from super coiling and chromosomes and migrates as a comet tail. Alkaline phosphtase is one of the liver enzymes used to detect liver damage. It also has catalytic Zn²⁺ions bound to cysteines.

Microbiome changes

A few things stand out. The lower dose of C60 seems to bring back the numbers of the Lactobacillaceae family members (gray bars) in the lower dose of C60. This family disappears with TAA and olive oil without C60. As the name would suggest, lactic acid is a metabolic end product of their fermentation. Lachnospiraceae, mauve bars, are anaerobes that ferment a diverse array of carbohydrates. They seem to decrease in numbers when TAA is added. Desulfovibrionaceae, what little there is in the controls, is wiped out by the TAA. Desulfovibrio, a genus of sulfate reducing anaerobes, is one of the more famous members of this family.

Conclusions?

This post started out comparing related structures C60, graphene, and activated carbon and forces they used to absorb stuff. This post took a quick look at modifications that make C60 a better food for intestinal bacteria. Then this post looked at absorption and liver deposition of C60 in rats. When fed in conjunction with a liver toxin, C60 in the liver seems to offer some protection. How long does it stay in our livers? Perhaps these materials are pretty good at adsorbing stuff to their surfaces. Perhaps we should make sure that the carbon materials we consume for this purpose are too large to be absorbed until we know more. Just a thought.

References

1. Li J, Lei R, Li X, Xiong F, Zhang Q, Zhou Y, Yang S, Chang Y, Chen K, Gu W, Wu C, Xing G. (2018)The antihyperlipidemic effects of fullerenol nanoparticles via adjusting the gut microbiota in vivo. Part Fibre Toxicol. 2018 Jan 17;15(1):5. PMC free article
2. Semenov KN, Ivanova DA, Ageev SV, Petrov AV, Podolsky NE, Volochaeva EM, Fedorova EM, Meshcheriakov AA, Zakharov EE, Murin IV, Sharoyko VV. (2021) Evaluation of the C₆₀ biodistribution in mice in a micellar ExtraOx form and in an oil solution. Sci Rep. 2021 Apr 16;11(1):8362. free article
3. Đurašević S, Pejić S, Grigorov I, Nikolić G, Mitić-Ćulafić D, Dragićević M, Đorđević J, Todorović Vukotić N, Đorđević N, Todorović A, Drakulić D, Veljković F, Pajović SB, Todorović Z. Effects of C60 Fullerene on Thioacetamide-Induced Rat Liver Toxicity and Gut Microbiome Changes. Antioxidants (Basel). 2021 Jun 4;10(6):911. free article