Regulation of Lipid Peroxidation and Cell Membrane Fluidity Mechanisms Using Stem-Bark Extracts from Greenwayodendron suaveolens (Engl. & Diels) Verdc

Abstract

Pneumonia, a respiratory infection induces acute or chronic inflammation, characterized by increased activity of lymphocytes and neutrophils, thus generating oxygen-free radicals that decrease the endogenous antioxidants defence system. Greenwayodendron suaveolens (Engl. & Diels) Verdc. is used by the population of Cameroon to treat gonorrhoea, infertility, malaria, stomach ache, headache, epilepsy, toothache psychosis and rheumatism. It’s also considered as facilitating childbirth, diuretic, purgative and aphrodisiac. There is limited documented data are available on the preventive or curative effect of G. suaveolens species on oxidative stress and inflammatory damage. The aim of this experimental study focused on the capacity of nontoxic aqueous, hydroethanolic and ethanolic extracts of Greenwayodendron suaveolens (Engl. & Diels) Verdc. subsp. suaveolens to regulate free reactive species and protein inflammation generated by infectious disease. The phytochemical screenings of G. suaveolens extracts were carried out according to precipitation and colorimetric methods. The total antioxidant and flavonoid contents were determined by the Folin-Ciocalteu and Aluminium Chloride ethanolic methods. The efficiency of G. suaveolens extracts on free radicals was evaluated using DPPH•, ABTS+•, and FRAP methods. The anti-inflammatory properties of extracts were evaluated according to in vitro protein (BSA) denaturation, Proteinase Inhibitory Action, and Red Blood Cell Membrane stabilization assays. The G. suaveolens aqueous, hydroethanolic and ethanolic extracts were used for the acute toxicity assessment according to the OECD protocol. One-way ANOVA (Tukey’s and Dunnett’s tests) was used for analysis. A difference between standard molecules and G. suaveolens extracts concentrations was considered significant at p < 0.05. The obtained results showed the presence of flavonoids, phenols, polyphenols, tannins, anthocyanins, alkaloids, terpenoids, and sterols as secondary metabolites families in G. suaveolens extracts. The highest contents of total antioxidants and flavonoids were highlighted in the hydroethanolic extract. However, it’s the G. suaveolens aqueous extract that showed the best free radical DPPH• and ABTS+• scavenging activities (SC50) of 11.06 µg/mL and 15.16 µg/mL respectively. The highest ferric-reducing activity was found in G. suaveolens ethanolic extract with 866.23 µg EGA/mg of dry weight. The hydroethanolic extract has shown a high anti-inflammatory activity through BSA denaturation and erythrocyte membrane haemolysis with inhibitory concentrations 50 (IC50) of 48.63 and 59.22 µg/mL respec- tively. In contrast, proteinase inhibitory activity revealed a better potential of IC50 (34.19 µg/mL) for the ethanolic extract. In oral acute toxicity, all treated groups revealed neither mortality nor any significant alteration in behaviour and locomotion. The lethal dose 50 (LD50) of G. suaveolens extracts was >5000 mg/kg. Lower respiratory tract diseases, the main pathophysiological mechanism of which is inflammation is mainly induced by reactive oxygen species. These diseases are caused by microorganisms and the immune system response of the host. In vitro study of G. suaveolens stem-barks extracts revealed the antioxidant and anti-inflammatory activities of this plant. These results suggest that G. suaveolens stem-barks extracts may serve as therapeutic sources to prevent inflammation induced by oxidative stress, an important feature of infectious diseases.