The impact of seasonal variation on the volatile profile of leaves and stems of Brownea grandiceps (Jacq.) with evaluation of their anti-mycobacterial and anti-inflammatory activities

Abstract

Brownea species were used in folk medicine for the treatment of tuberculosis in South America. Volatile oils prepared by hydro-distillation from fresh leaves and stems of Brownea grandiceps Jacq. (Fabaceae) collected in different seasons were analyzed separately by GC/MS. The anti-mycobacterial and anti-inflammatory activities of the volatile oils were also assessed. A total of 60 compounds were identified in the leaves and stems volatile oils accordingly. The most abundant components were methyl salicylate (53.06% - 9.56%), hexanal (38.27% - 0.26%), n-nonacosane (21.23% - 0.46%) and (E)-2-hexenal (31.2%- 0.91%). Results revealed a remarkable influence of the season of collection on the yield and chemical composition of the obtained oils. The leaf volatile oil exerted higher anti-mycobacterial and anti-inflammatory effects compared to stem volatile oil. The leaf volatile oil showed remarkable inhibition of M. tuberculosis ATCC 27294 (MIC 3.9 μg/mL) comparable to standard isoniazid. It also exerted a promising membrane stabilizing anti-inflammatory effect (IC50 value of 27.1 μg/mL) comparable to methyl salicylate and standard indomethacin. From these findings, it may be concluded that the leaf volatile oil represents a promising anti-mycobacterial and anti-inflammatory agent. To the best of our knowledge, the present study describes the first to characterize B. grandiceps volatile oils and to emphasize the great promise for treatment of tuberculosis and inflammatory disorders.