In this work, methodologies are proposed to quantitatively estimate the photosynthetic potential of medicinal plants and relate it to the production of metabolites of pharmaceutical interest based on the E model of photosynthesis. Parameters such as the irradiance of the visible and ultraviolet band are estimated by solutions of the equation of radioactive transport in the atmosphere. In addition, the spectra are propagated in the water column using spectral radiation attenuation coefficients. The photosynthetic potential of the macroalga U. Lactuca was calculated for coastal water types C1 and C9. Both for water types C1 and C9 the Photosynthetic potential increased as depth increased, expressing results with similar behavior in the case of the production of secondary metabolites with respect to that referred to at the top of the canopy, due to its directly proportional relationship with the photosynthetic potential. Finally, perspectives for future work are presented.