Antiviral Phenolic Compounds From Bamboo and Other Woody Sources.

[NNadir]

I came across an interesting paper this evening, which looks at some well known molecules from the pyrolysis of wood and bamboo and their activity as anti-viral compounds.

The paper is here: Antiviral Activity of Phenolic Derivatives in Pyroligneous Acid from Hardwood, Softwood, and Bamboo (Wantanabe et al, ACS Sustainable Chem. Eng., 2018, 6 (1), pp 119–126)

Here's a cute graphic from the paper:



And here's the opening texts:

Pyroligneous acids (PAs), also called wood vinegar, pyroligneous liquor, pyrolysis bio-oil, or liquid smoke, are the crude condensate of smoke produced through carbonization(1, 2) and consist of a pyrolyzate of cellulose, hemicelluloses, and lignin. Wood and bamboo PAs are complex mixtures of water, alcohols, organic acids, esters, aldehydes, ketones, phenolics, and nitrogen compounds.(3-5) Acetic acid is the primary component of wood and bamboo PAs.(6)

Wood and bamboo PAs are used for sterilization, food additives, smoke flavoring, and antimicrobial agents. Furthermore, it has been shown that bamboo PA exerts a promotional effect on the germination and radicle growth of some types of seeds, e.g., lettuce.(7, 8) Interestingly, the chemical composition of PAs depends on the original wood species. For example, the chemical composition of moso bamboo (Phyllostachys pubescens) PA is different from that of madake bamboo (Phyllostachys bambusoides) despite their close phylogenetic relationship.(7) In addition, preparation of crude PA critically affects its efficacy. Regarding its effect on the regulation of germination and growth, it is known that bamboo PA collected at temperatures of up to 250 °C promotes radicle and hypocotyl growth, whereas bamboo PA collected at temperatures from 250 to 400 °C inhibits their growth.(8, 9)

Previous studies have shown that PA has the potential to modulate immune responses.(10, 11) For example, cresol derived from Moso bamboo PA inhibits inflammasome activation through reactive oxygen species production and inactivation of the protein kinase C-α/δ.(10) Furthermore, wood PA derived from sawtooth oak inhibits the phosphorylation of the signal transducer STAT3 and, thus, shows anti-inflammatory activity...(11)

The authors heat lignin from wood to obtain a number of pyrolytic products from the decomposition of lignin, a by product of the paper and pulp industries that is sometimes regarded as a waste material, although the use of lignin and lignin derived compounds is being increasingly utilized for a number of applications.

The structures of the molecules obtained is nothing incredibly remarkable, with many of the compounds being well known to most organic chemists:



But the authors look at them in a new way, investigating their properties as anti-viral agents against a disease causing virus, the encephalomyocarditis virus which causes a febrile disease.

They assay its activity agains the RNA of the virus:



And find these interesting results for the compounds listed above.



I'm not sure that many of these molecules or any will make it to clinical trials, and as their structure is well known, I can imagine difficulties in the patent space, but this is an interesting case utilizing some very simple chemistry, as opposed to the more complex chemistry that goes into far more sophisticated anti-virals, chemistry with which I have been familiar professionally.

It's pretty cool I think.

Have a pleasant Sunday.