Extreme milieus are environments characterized by harsh weather conditions which strongly affect plant physiology. Previous works have attempted to examine the impacts of environmental conditions on the plants metabolism. However, there is lack of scientific data addressing these biological phenomena in the arid regions. The present work was designed to understand how arid conditions affect the phytochemical and antimicrobial analyses of Senna italica plant considering plant organ, organ-age, and elevational effects. In the first study, young and mature organs of Senna italica were subjected to pigments analyses to see how pigments contents vary according to the elevation, while the second study evaluated the effects of plant organs on the phytochemical and antimicrobial analyses of S. italica. Based on our results, plant growing from highest elevations exhibited greater values of pigments contents than the other. Higher pigments contents were recorded in the leaves than the branches. Greater values of pigment were observed in the mature than the young leaves, and young branches had more pigments levels than the matures. Calcium, manganese, ash, total flavonoids, vitamin E and B1 contents were greater in the leaves while; phosphorous, zinc, magnesium, copper, crude protein, total digestible nutrients were higher in the seeds. Branches exhibited elevated levels of sodium, dry matter, tannins and potassium, while fibers contents were greater in the fruits. Fruits extract showed higher antimicrobial effects than the other organs with the inhibition zones ranging from 14.33 to 16.33 mm. The findings of this work indicates that pigments adjustments could be one of the mechanisms of adaptations of S. italica and this adaptation could help identifying novel metabolites that could be used against drug-resistant microbes in the arid regions.