*2.2. Mineral, Chlorophyll and Nutritional Content*

The mineral content of the leaves was determined using six replicates (two plants pooled/replicate) according to Chrysargyris et al. [11]. Dried plant material was ashed in a furnace (Carbolite, AAF 1100, GERO, Neuhausen, Germany) at 500 ◦C for 6 h and then acid digested using 2 M HCl. Determination of Potassium (K), Calcium (Ca), Magnesium (Mg), Sodium (Na), Iron (Fe), Copper (Cu) and Zinc (Zn) content was performed using atomic absorption spectrophotometry (PG Instruments AA500FG, Leicestershire, UK) and Nitrogen (N) content was determined using the Kjeldahl method (BUCHI, Digest automat K-439 and Distillation Kjelflex K-360). A colorimetric method using molybdate/vanadate was used for the determination of Phosphorus (P) content [12].

Leaf chlorophylls were extracted with 10 mL dimethyl sulfoxide (DMSO) at 65 ◦C for 30 min. The photosynthetic leaf pigments, Chlorophyll a (Chl a), Chlorophyll b (Chl b) and total Chlorophyll (t-Chl) content were then calculated [13].

The nutritional value of *S. perfoliata* was assessed by determining moisture, protein, fat, carbohydrate and ash composition, following AOAC procedures [14]. Briefly, nutrient content was determined by using the macro-Kjeldahl (N × 6.25), petroleum ether Soxhlet extraction, and incineration (600 ◦C) methods for protein, fat and moisture, respectively. The carbohydrate content was determined by difference in dry weight and the energetic value was estimated by applying the formula:

$$\text{Energy} \left( \frac{\text{kcal}}{100 \text{ g}} \,\text{d.w.} \right) = 4 \times \left( \frac{\text{g protein}}{100 \text{ g}} \,\text{d.w.} + \frac{\text{g carbo} \text{ydrate}}{100 \text{ g}} \,\text{d.w.} \right) + 9 \times \left( \frac{\text{g fat}}{100 \text{ g}} \,\text{d.w.} \right)$$

The results were expressed in g/100 g d. w.
