Decoction and various extracts (hexane, chloroform and aqueous) were prepared from the leaves of P. grisea. These extracts were subjected to evaluation of toxicity using the brine shrimp lethality test and their antioxidant properties were determined different methods namely the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical- scavenging test, the phosphomolybdenum method for the total antioxidant capacity test and the Folin-Ciocalteu method for the total phenolics test. The chloroform extract (PgC) exhibited the highest toxicity to the brine shrimp Artemiasalina with LC50 value of < 10 ppm. Results also indicated the decoction (PgD) of P. grisea leaves to have the most potent antioxidant properties, with percent antiradical activity of 92.85% at 500 ppm, total antioxidant capacity of 110.42 Ascorbic Acid Equivalents (AAE) and 147.14 ButylatedHydroxytolene Equivalents (BHTE) and total phenolics content of 319.00 Gallic Acid Equivalence (GAE). These data may help establish the medicinal potential of this plant and may serve as a guide for further biological and chemical investigations on this plant.