Phytochemical composition of leaves and stems of Solanum nigrum L. And Solanum dulcamara L. (Solanaceae) from Bulgaria

Abstract

The objective of this study was the determination of certain phytochemical indices (cellulose, protein, amino acids, ash, minerals) of the leaves and stems of two Solanum species, S. dulcamara L. and S. nigrum L., collected from their natural habitats in Bulgaria. Both species, naturally occurring in many regions of Bulgaria, are important plants in folk medicine and fall under the regulations of the Medicinal Plant Act. The analysis of cellulose, protein and ash content in the dried leaves and stems revealed differences on a plant part basis. Stems contained higher amounts of cellulose (S. dulcamara, 29.4%; S. nigrum, 39.2%) than the leaves (14.9% in both species). The stems of S. nigrum contained nearly twice as much protein than the leaves (15.3% vs 8.1%); the ratio was reversed in S. dulcamara (12.3% vs 21.3%). The dominant macroelements in S. dulcamara were K (25925 and 14514 mg.kg-1, respectively in the leaves and stems), Ca (3588 and 326 mg.kg-1) and Mg (2561 and 308 mg.kg-1). In S. nigrum, the same macrominerals showed relatively less variation on a plant part basis. The dominant microminerals were Fe, Zn and Mn; reasonably, higher concentrations were found in the leaves. The dominant amino acids in S. dulcamara leaves were phenylalanine, glutamine, asparagine, tyrosine, and serine (2.2-2.5 mg.g-1); in the stems-proline (7.3 mg.g-1), alanine (7.2 mg.g-1), asparagine (5.0 mg.g-1), and lysine (4.6 mg.g-1). The dominant amino acid in S. nigrum leaves and stems was asparagine, 5.0 mg.g-1 and 20.6 mg.g-1, respectively. The results supported the assumption that the studied aerial parts contained valuable phytochemicals, which could provide grounds for their practical use in specific areas, such as human and animal nutrition, cosmetics, phytopharmacy or others.