Antiinflammatory Medicinal Plants from the Ugandan Greater Mpigi Region Act as Potent Inhibitors in the COX-2/PGH2 Pathway

Fabien Schultz; Ogechi Favour Osuji; Barbara Wack; Godwin Anywar; Leif-Alexander Garbe

doi:10.3390/plants10020351

Antiinflammatory Medicinal Plants from the Ugandan Greater Mpigi Region Act as Potent Inhibitors in the COX-2/PGH₂ Pathway

Plants (Basel). 2021 Feb 12;10(2):351. doi: 10.3390/plants10020351.

Authors

Fabien Schultz^{1

2}, Ogechi Favour Osuji², Barbara Wack², Godwin Anywar³, Leif-Alexander Garbe^{2

4}

Affiliations

¹ Institute of Biotechnology, Faculty III-Process Sciences, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.
² Department of Agriculture and Food Sciences, Neubrandenburg University of Applied Sciences, Brodaer Str. 2, 17033 Neubrandenburg, Germany.
³ Department of Plant Sciences, Microbiology and Biotechnology, Makerere University, P.O. Box 7062 Kampala, Uganda.
⁴ ZELT-Neubrandenburg Center for Nutrition and Food Technology gGmbH, Seestraße 7A, 17033 Neubrandenburg, Germany.

Abstract

Our study investigates 16 medicinal plants via assessment of inhibition of proinflammatory enzymes such as cyclooxygenases (COX). The plants are used by traditional healers in the Greater Mpigi region in Uganda to treat inflammation and related disorders. We present results of diverse in vitro experiments performed with 76 different plant extracts, namely, (1) selective COX-2 and COX-1 inhibitor screening; (2) 15-LOX inhibition screening; (3) antibacterial resazurin assay against multidrug-resistant Staphylococcus aureus, Listeria innocua, Listeria monocytogenes, and Escherichia coli K12; (4) DPPH assay for antioxidant activity; and (5) determination of the total phenolic content (TPC). Results showed a high correlation between traditional use and pharmacological activity, e.g., extracts of 15 out of the 16 plant species displayed significant selective COX-2 inhibition activity in the PGH₂ pathway. The most active COX-2 inhibitors (IC₅₀ < 20 µg/mL) were nine extracts from Leucas calostachys, Solanum aculeastrum, Sesamum calycinum subsp. angustifolium, Plectranthus hadiensis, Morella kandtiana, Zanthoxylum chalybeum, and Warburgia ugandensis. There was no counteractivity between COX-2 and 15-LOX inhibition in these nine extracts. The ethyl acetate extract of Leucas calostachys showed the lowest IC₅₀ value with 0.66 µg/mL (COX-2), as well as the most promising selectivity ratio with 0.1 (COX-2/COX-1). The TPCs and the EC₅₀ values for DPPH radical scavenging activity showed no correlation with COX-2 inhibitory activity. This led to the assumption that the mechanisms of action are most likely not based on scavenging of reactive oxygen species and antioxidant activities. The diethyl ether extract of Harungana madagascariensis stem bark displayed the highest growth inhibition activity against S. aureus (MIC value: 13 µg/mL), L. innocua (MIC value: 40 µg/mL), and L. monocytogenes (MIC value: 150 µg/mL). This study provides further evidence for the therapeutic use of the previously identified plants used medicinally in the Greater Mpigi region.

Keywords: Albizia coriaria; Cassine buchananii; Combretum molle; Erythrina abyssinica; Ficus saussureana; Harungana madagascariensis; Leucas calostachys; Microgramma lycopodioides; Morella kandtiana; Plectranthus hadiensis; Securidaca longipedunculata; Sesamum calycinum subsp. angustifolium; Solanum aculeastrum; Toddalia asiatica; Warburgia ugandensis; Zanthoxylum chalybeum; antibiotics; cyclooxygenase; ethnopharmacology; fever; inflammation; lipoxygenase; pain; traditional medicine.

Abstract

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