Biologically active components in seeds of three Nicotiana species

Abstract

Tobacco seeds, available as an untitilized byproduct of the commercial leaf production in many countries around the world, can be a valuable source of natural products with biological activity. The genus Nicotiana (Solanaceae) includes more than 65 species, but the most economically important and commercially cultivated is Nicotiana tabacum L. (common tobacco) and to a much lesser degree N. rustica L. (Aztec tobacco). The objective of this study was to evaluate tobacco seed oil and cakes of three tobacco species: two genotypes of N. alata Link & Otto (jasmine tobacco), N. rustica, and N. tabacum, with respect to their potential uses. The glyceride seed oil content was 37.6% and 40.9% for the two genotypes of N. alata, 37.5% for N. rustica, and 30.9% for N. tabacum. Overall, the content of phospholipids was 0.2–0.3% in the oils. Total sterol amount in the oils was 0.35–0.48%. The main component was β-sitosterol, followed by cholesterol and Δ5-avenasterol (in N. alata, white petals), cholesterol and campesterol (in N. alata, pink petals), campesterol and Δ5-avenasterol (in N. rustica), and campesterol and stigmasterol (in N. tabacum). In the tocopherol fraction (101, 117, 178, and 106 mgkg−1 in N. alata white and pink forms, N. rustica, and N. tabacum, respectively in the oils) the most predominant (higher than 97%) was the γ-tocopherol. Overall, the main fatty acids (FA) in the three Nicotiana species were linoleic (61.7–67.6% range), oleic (15.5–19.0%), and palmitic (9.1–12.5%). The remaining seed cakes (after Soxhlet extraction of glyceride oil), potentially valuable nutrient by-products, were characterized with regard to their content of minerals, cellulose, proteins, and amino acids. Seed cake cellulose content varied between 32.5 and 45.2%, and protein content was 26.7–34.1%. Seed cakes were rich in mineral macro- and micronutrients, with some differences between the species. Highest content of total nitrogen and protein were found in N. rustica (5.5% and 34.1%, respetively), and highest content of cellulose was found in N. alata (white petals genotype). Potassium concentration was higher in N. tabacum and N. rustica cakes, whereas the concentrations of iron and zinc were highest in N. alata (pink petals genotype). Amino acid composition was dominated by aspartic acid, arginine, and threonine in N. alata, and by arginine, aspartic acid, and histidine in N. rustica. The results suggest potential alternative uses of tobacco seeds and cake as animal feed, and possibly as feedstock for new consumer human health products. The concentration of amino acids important for animal nutrition (lysine, methionine, and cysteine) in tobacco seed cakes was low, implying a need for careful combination with other animal diet ingredients.