Factors affecting the accumulation and variation of volatile and non-volatile constituents in rosemary, Rosmarinus officinalis L.

Plants have played important and essential roles in treatment of various diseases and have invigorated the discovery of newer medicines. The secondary metabolites, such as alkaloids, flavonoids, phenolic acids, saponins, and anthraquinones have generally been considered responsible for the medicinal plants' several biological activities and therapeutic applications. Variations in the secondary metabolites structures and their natural abundance in medicinal plants are major reasons behind their differing in biological activities, which are affected by several external and intrinsic factors, including environmental conditions, the maturation stage of the plant, and process of plant’s material preparation and extraction. The current review discusses the factors affecting secondary metabolites’ structural variations and accumulations in the plants. Rosemary, Salvia rosmarinus, or Rosmarinus officinalis L., served as a representative example. The rosemary herb contains two main categories of secondary metabolites; volatiles as essential oil, and non-volatile constituents, which is primarily composed of polyphenolics. These two categories of plant products play pivotal role in plant’s chemo-diversity, biological activity, and their applications in traditional system of medicine by various societies in different regions of the world. The rosemary plant's industrial applications, which are mostly attributed to its volatile constituents, and the famed, prominent antioxidant activity is correlated to its polyphenolic constituents. Hence, rosemary was selected as a candidate medicinal plant to study the factors influencing the constituents variations and their involvement in the bioactivity and efficacy of the plant. Environmental variants of humidity, drought, soil salinity, the intrinsic factor of maturation stage of the plant, and the techniques of harvested plant materials’ drying, and extraction have been reported as major factors affecting the variations in quality and quantity of the plant’s constituents. The volatile oil constituents of rosemary herbs were observed to be more sensitive to environmental conditions and plant material’s preparative methods, as compared to the non-volatile constituents of the plant. This review's contents and conclusive suggestions can be suitable to most of the aromatic and medicinal plants that are grown in different climatic zones under varied environmental conditions for obtaining the plants-based, economically-valuable products for the industrial and market use.