Wood extract, or methanol, was first described by Robert Boyle in 1661 as the "sowrish spirit" of boxwood pyrolysis, and since then the role of methanol in plant and animal life has been unclear. In higher plants, cell wall (CW) pectin methylesterase (PME) produces methanol through pectin demethylation (248). Terrestrial atmospheric methanol emissions come from volcanoes, H2 and CO2 generation in submarine hydrothermal systems, and biomass combustion, but PME-mediated emissions from plants are most likely the largest source of atmospheric methanol (512). When stomata are closed at night, methanol accumulates in the air space or liquid pool between cells, and when stomata are opened in the morning, large amounts of methanol are released (193). Traditionally, gaseous methanol has been considered a biochemical "waste". However, recent studies have shown the effects of plant methanol (" transmitter ") produced by pme on plant defense responses (" receiver ") and plant-animal communication (11,112).
In humans, methanol is considered a poison because alcohol dehydrogenase 1b (ADH1b) mainly metabolizes methanol into the toxic formaldehyde (63). Methanol itself is not toxic to animal cells; However, formaldehyde is responsible for carcinogenic and age-related damage to neurons in the brain (472).
Until recently, it was thought that traces of methanol and formaldehyde in the blood of healthy people came only from drinking counterfeit or low-quality alcoholic beverages. However, recent data suggest that methanol and short-lived formaldehyde are in fact naturally occurring compounds in normal, healthy humans (413). There are several sources of physiological methanol in the human body (Figure 1). Fruits, vegetables and alcoholic beverages may be the main sources of exogenous methanol in healthy human body. More than 50 years ago (126), two other sources were proposed: anaerobic fermentation of intestinal bacteria (38,208,209,418) and conversion of S-adenosine methionine (SAM) to methanol by some metabolic process (16). Although human blood contains small amounts of methanol and formaldehyde, the amount of even ethanol (413) that does not contain methanol increases dramatically. This suggests the presence of an endogenous, low-level source of metabolized methanol in the blood whose regulation is controlled by a set of genes
Methanol is a ubiquitous biogeochemical active compound and an important component of volatile organic carbon in the atmosphere (177,199,239,356,390,519). The atmosphere contains ~ 4tg (teragram, 1012 g) of methanol (177). Methanol emissions from the terrestrial atmosphere come from a variety of sources, including H2 and CO2 production from volcanoes and submarine hydrothermal systems (512). Another source of atmospheric methanol is biomass burning (131,315), in which the wood pyrolysis of plant fibres (i.e. cellulose and lignin) causes methanol emissions (149,300,515). Wood pyrolysis, the decomposition of wood at high temperatures in the absence of oxygen, was the method by which Robert Boyle obtained the "sowrish spirit" (44) from boxwood; Much later, this was mainly referred to as methanol and acetone. However, VOCs are emitted from plants
