Immunomodulatory activities of isolated compounds from the root-bark of Cussonia arborea

Abstract

Context: Cussonia arborea Hochst. ex A. Rich (Araliaceae) is a folk medicine used to treat various diseases. However, there is no report of the root phytochemistry.

Objective: This study isolates and identifies the immunomodulatory compounds from root-bark of C. arborea.

Materials and methods: The methanol extract (18 g) was subjected to repeated column chromatography resulting in isolation of five compounds (1–5). Structure determination was achieved by analysis of their 1 D and 2 D NMR, and mass spectroscopy. The compounds (100–1.0 μg/mL) were examined immunomodulatory for effect on production of reactive oxygen species (ROS) from whole blood phagocytes and on proliferation of T-cells. The compounds cytotoxicity (100–1.0 μg/mL) was evaluated on NIH-3T3 normal fibroblast cells.

Results: Three pentacyclic triterpenoids [3, 23-dihydroxy-12-oleanen-28-oic acid (1), 3β-hydroxylolean-12-en-28-oic (2) and 23-hydoxy-oxo-urs-12-en-28-oic acid (5)], two phytosterols: [stigmasterol (3)] and [3-O-β-d-glucopyranosyl stigmasterol (4)] were all isolated from the methanol soluble extract. All the tested compounds (1–4) were found to be nontoxic on NIH-3T3 cells. Compound 1 and 2 moderately inhibited the production of ROS (IC₅₀ = 24.4 ± 4.3 and 37.5 ± 0.1 μg/mL, respectively) whereas compound 2 exhibited the highest inhibitory effect (IC₅₀ = 12.6 ± 0.4 μg/mL) on proliferation of phytoheamagglutinin (PHA) activated T-cells.

Conclusions: The isolated compounds (1–5) are reported for the first time from this species. In addition, compound 2 with suppressive potential on production of intracellular ROS and proliferation of T-cells could be of immense value in control of autoimmune diseases as well as in immune compromised patients.

Keywords:

• Araliaceae
• T-cell proliferation assay
• reactive oxygen species
• triterpenoids
• oleanolic acid
• hederagenin
• stigmasterol
• NMR spectroscopy
• steroid

Acknowledgements

The authors are grateful to ICCBS-TWAS for Postdoctoral fellowship (FR: 3240287178) support to Oladimeji A. O. We thank Prof. Dr. O. Aiyelaagbe (Chemistry Dept. UI) and Mr. Erukainure O. L. (FIIRO) for useful comments on earlier version of this manuscript.

Disclosure statement

The authors have no declaration of interest to report. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.