Piliostigma thonningii Biosafety and Efficacy on Common Actinic Damage Endpoints

Abstract

Piliostigma thonningii from the Fabaceae and Caesalpinioideae sub-family is a huge deciduous tree from the woodlands of Southern Africa that can grow up to 10 meters tall with a rounded crown and a short, often crooked trunk. Prevalent in disturbed areas. P. thonningii is medicinally used in African traditional medicine to treat wounds, ulcers, gastric pain, gingivitis and as an antipyretic. The current study systematically, technically evaluated the potential use of the plant in managing photo damage end points through biosafety and pharmacological activity assessments. Various classical analytical techniques were used to screen for the presence of pharmacological secondary metabolites. The DPPH method was used to determine the anti oxidancy, the egg albumin test was used to determine the anti-inflammatory activity, OECD guideline 426 and 406 were used to determine the acute oral toxicity and the dermal toxicity of the lyophilised  extract. The phytoscreening confirmed the presence of numerous biomedically relevant secondary metabolites including, flavonoids, phenolic compounds, saponins, alkaloids, tannins, phytosterols, proteins and amino acids, carbohydrates, glycosides, terpenoids and lignans. The biosafety study using albino rat models confirmed that P. thonningii is nontoxic with an LD50 above 5000mg/kg.  The hydroethanolic extract demonstrated high anti-oxidant, high anti-inflammatory and antibacterial activities, which were comparable to the standards, ascorbic acid, diclofenac and ceftriaxone, respectively. The results confirm presence of relevant bioactive secondary metabolites in lyophilized extracts of the leaf parts of P. thonningii which possess satisfactory anti-inflammatory, antibacterial and anti-oxidant profiles which are all relevant in retarding actinic damage.  It was hereby substantiated that the lyophilised extract of P. thonningii is biologically active in photo damage retardation and safe thereby justifying its topical use in traditional medicine.