Anthocyanins and fatty acids from the flowers of Lathyrus odoratus L. and their antimicrobial activity

Flowers of sweet pea, Lathyrus odoratus L. (Leguminoseae) have an attractive color and pleasant odor. Anthocyanins of different cultivars of sweet pea were belonging to delphinidin, cyanidin, and pelargonidin series. Anthocyanins were reported to possess antioxidant, antiulcer and anti-inflammatory activities. Total anthocyanins of sweet pea flowers of different color, pale red, dark red and dark pink were determined [1]. The total anthocyanins were 0.026, 0.131 and 0.338 (g/100g) fresh weight, respectively. Four anthocyanins (cyanidin-3-glucoside, cyaniding-3,5-gluco-galactoside, malvidin-3,5-diglucoside and delphinidin-3,5-diglucoside) were isolated and identified from dark pink flowers. Pale red and dark red types contained similar anthocyanins (pelargonidin-3,5-gluco-xyloside and cyaniding-3,5-gluco-galactoside). GC/MS analysis of the ethanolic concrete extract of the sweet pea flowers revealed the presence of 30 components, 98% of the constituents were identified. The major components were palmitic acid (52.303%), linoleic acid (9.655%), methyl linolenate (6.683%), uncosanoic acid methyl esters (6.644%) and heptadecanoic acid (3.085%). Antimicrobial screening of total, isolated anthocyanins and the ethanolic concrete extract of sweet pea were conducted using disc diffusion assay against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Aspergillus niger, and the human pathogenic yeast, Candida albicans [2]. The total anthocyanins of pale red type was the most potent one as anti-bacterial, anti-yeast, anti-fungal followed by the total anthocyanins of dark red type and dark pink type. The total anthocyanins of the three types were more potent than their isolated compounds as antibacterial. The ethanolic extract of the concrete showed the lowest effect as anti-bacterial and yeast but showed the highest effect as anti-fungal. In conclusion, anthocyanins of sweet pea flowers might be valuable as antimicrobial agent that can be exploited for development of an alternative remedy for bacterial infection.

References: [1] Fuleki, T. and Francis, F.J. (1968)J. Food Sci. 33:72–77.

[2] Gould, J.C. (1952) Edinb. Med. J. 59:178–199.