The behaviour of some chemical compounds (alkaloids, sugars, proteins, polyphenols, enzymes etc.) during the technological process of tobacco leaves constitutes the object of numerous research works. These researches were done in accordance with the molecular conception about the living matter, corresponding to chemical compounds in molecular state. In the meantime, a new conception appeared, named"biostructural conception", belonging to the Rumanian academician Eugen Macovschi. In accordance with this conception, the living matter is constituted by two forms, which are interdependent : the living matter (the biostructure) and the non-living matter (coexistent molecular matter). This paper presents the distribution of some chemical compounds (alkaloids, sugars, polyphenols, enzymes etc.) between the two states of the matter and the transformations occurred during the tobacco leaf stages (growth, harvesting, curing and fermentation).