Pharmacognostic standardisation and antioxidant activity of <i>Cassia sieberiana</i> DC. (Fabaceae)

Secondary metabolites of medicinal plants can be used as dietary antioxidants, acting as free radical scavengers, radical chain reaction inhibitors, metal chelators, oxidative enzyme inhibitors and antioxidant enzyme cofactors. However, the major setback in promoting the use of medicinal plants is the lack of standardisation. This study aimed to set pharmacognostic standards and establish the antioxidant activity of Cassia sieberiana via in vitro method. Cassia sieberiana leaves methanol extract was partitioned into n-hexane, DCM, and ethyl acetate fractions. The macroscopic, microscopic and chemo-microscopic characters were assessed while antioxidant potential of the crude extract and partitioned fractions was assessed using DPPH radical scavenging assay. Total phenolic and total flavonoid contents were evaluated using gallic acid and quercetin as standards. The transverse section showed presence of bundle sheath and the parenchyma cells. The adaxial and abaxial surfaces showed straight polygonal epidermal cells and presence of palisade cells. Also, the adaxial surface showed the presence of tector trichomes while the abaxial surface showed presence of glandular trichomes. The ethyl acetate fraction had the highest antioxidant activity (IC50 = 71.42 ± 0.19 μg/mL), the highest total flavonoid content (TFC) and total phenolic content (TPC) with 203.19 ± 0.03 mgQE/g and 25.10 ± 0.61 mg GAE/g, respectively. Standards have been set in this study for the identification and authentication of Cassia sieberiana, and the in vivo antioxidant activity of the plant supported the traditional use of the plant for managing different ailments, which may enhance the production of reactive oxygen in the body system.