Bioactive constituents of Lobostemon fruticosus: Anti-inflammatory properties and quantitative analysis of samples from different places in South Africa

Abstract

Lobostemon fruticosus is South Africa medicinal plant traditionally used in treatment of wounds and skin diseases. Nevertheless, there is no report on its phytochemical constituents. LC–LTQ-Orbitrap mass spectrometry was used for identification and quantification of its constituents. A total of 13 compounds were identified from the leaves and twigs of the plant using NMR, ESI-HRMS and reference substances. The identified compounds were p-hydroxybenzoic acid (1), lycopsamine-N-oxide (2), caffeic acid (3), loliolide (4), 3-indolcarbaldehyde (5), globoidnan B (6), rabdosiin (7), syringaresinol (8), pinoresinol (9), rutin (10), rosmarinic acid (11), keampferol-3-O-rutinoside (12) and globoidnan A (13). In addition, quantitative determination of 6 marker compounds in samples from 12 different locations in South Africa was established. Rosmarinic acid and globoidnan A were found in large amount in the leaves and flowers of the plant. Samples from West Cape contained relatively greater amount of the tested compounds per dry weight than the other samples. The anti-inflammatory activities of isolated compounds were assessed by measuring the levels of cytokines IL-1β, IL-2, IL-6, GM-CSF and TNF-α in the supernatant media of human peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS). At a concentration of 100 μM, compounds 7, 8 and 11 significantly decreased secretion of IL-1β, IL-2 and IL-6 compared to the LPS treated control (0.76–57.6%). All compounds significantly reduced the production of TNF-alpha compared to the LPS treated control (0.17–12.2%) and reference drug ibuprofen.