Leaf age, seasonal and annual variations in <i>Salvia officinalis</i> L. var. <i>purpurascens</i> biochemical characteristics

Abstract

Medicinal and aromatic plants (MAP’s) have gain new attention in the past years due to their content in bioactive compounds and recognized health-promoting effects. One of the most important species of MAP’s is Salvia officinalis L., rich in several phytochemicals (essential oil, phenolic compounds) and vitamins. Besides, it has various uses and pharmacological effects (including antibacterial, antiviral, antioxidative, anti-inflammatory, antidiabetic and antitumour activities). Salvia officinalis L. has many cultivars, including Salvia officinalis L. var. purpurascens, which is currently understudied. As few is known about this specific cultivar, characterization of this plant, as well as the study of biochemical variations occurring during its development, is of great significance. Hence, in this work, young and adult leaves of Salvia officinalis L. var. purpurascens, were collected in two different seasons (June and September) and in two different years (2011 and 2013). Several biochemical traits were analyzed, namely carbohydrate content, photosynthetic pigments concentration, total phenolics, soluble proteins, as well as oxidation parameters (thiobarbituric acid reactive substances, thiols and electrolyte leakage). The Year factor significantly influenced carbohydrate content (higher in 2013 for non-structural carbohydrates and soluble sugars, but lower for starch), but also chlorophyll and carotenoid content (higher in 2011), with a similar influence recorded for the Season of harvest (higher values for starch, chlorophyll and carotenoids in September, but lower for soluble sugars). The developmental stage of leaves showed significant influence mainly in the content of photosynthetic pigments, with higher values of chlorophyll and carotenoids recorded in young leaves. The results show the biochemical variations occurring in plants of Salvia officinalis L. var. purpurascens, during developmental stages, and others associated to season of harvest and year, and their relation to climatic factors. The gathered data, besides useful for the characterization of this plant, is also valuable when aiming for the optimization of sage cultivation.