Bioassay Guided Fractionation of Senna singueana and Its Potential for Development of Poultry Phytogenic Feed Additives

Prosper Jambwa; Fikile N Makhubu; Gift Matope; Gerda Fouche; Lyndy J McGaw

doi:10.3389/fvets.2021.800272

Bioassay Guided Fractionation of Senna singueana and Its Potential for Development of Poultry Phytogenic Feed Additives

Front Vet Sci. 2022 Jan 13:8:800272. doi: 10.3389/fvets.2021.800272. eCollection 2021.

Authors

Prosper Jambwa^{1

2}, Fikile N Makhubu¹, Gift Matope³, Gerda Fouche⁴, Lyndy J McGaw¹

Affiliations

¹ Phytomedicine Programme, Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa.
² Department of Veterinary Biosciences, University of Zimbabwe, Harare, Zimbabwe.
³ Department of Veterinary Pathobiology, University of Zimbabwe, Harare, Zimbabwe.
⁴ Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa.

Abstract

There has been burgeoning interest in plant-based feed additives following restrictions placed on the use of antibiotic feed additives in many countries. Phytogenic feed additives are recommended to have a range of useful properties to support the growth and development of poultry to a similar level as that obtained by supplementing feed with antibiotics. The aim of this study was to evaluate the antibacterial, anti-lipoxygenase and antioxidant activity, and in vitro safety of fractions and isolated compounds from leaves of Senna singueana. Antibacterial activities of the fractions and isolated compounds were determined against a panel of bacteria using a two-fold serial microdilution assay and qualitative bioautography assays. Anti-lipoxygenase activity was evaluated using the ferrous oxidation-xylenol orange (FOX) method. Antioxidant activity was assessed qualitatively and quantitatively using radical scavenging assays. Dichloromethane and ethyl acetate fractions from solvent-solvent partitioning had the best antibacterial activity with MIC values ranging from 156 to 313 μg/ml. Fractions obtained from column chromatography had significant to weak antibacterial activity with MIC values ranging from 50 to 1,250 μg/ml. Bioautography showed clear bands of bacterial inhibition, indicating the presence of a number of active compounds in several fractions. The ethyl acetate fraction and all the tested column fractions had potent anti-lipoxygenase activity with IC₅₀ values of ≤2.5 μg/ml which were lower than that of quercetin (positive control), indicating anti-inflammatory potential. The ethyl acetate fraction and several column fractions had powerful antioxidant activity with IC₅₀ values of ≤5 μg/ml in the ABTS assay. Cytotoxicity values against Vero kidney cells ranged from LC₅₀ = 40.0-989.3 μg/ml. Bioassay-guided fractionation led to the isolation and identification of a known bioactive compound, luteolin. S. singueana is a promising candidate for the development of poultry phytogenic feed additives.

Keywords: Senna singueana; anti-lipoxygenase; antibacterial; antioxidant; cytotoxicity; phytogenic; poultry feed additives.