Phytochemical Profiling and Pharmacological Evaluation of Methanolic Leaf Extract of C. digyna for Cytotoxic, Anti-inflammatory, Antioxidant, Antiarthritic, and Analgesic Activities.

Caesalpinia digyna (Family: Fabaceae) is traditionally used in Ayurvedic medicine for various medicinal purposes, including as a treatment for wounds, leprosy, skin diseases, fever, diabetes, etc. Although the root and stem of this plant have a significant medicinal value, there was little research on the leaves of this plant. This study aimed to investigate the qualitative phytochemical profile and evaluate the in vitro cytotoxic, anti-inflammatory, antioxidant, and antiarthritic activities, as well as the in vivo anti-inflammatory and analgesic activities, of C. digyna leaf extract. The methanolic extract of C. digyna leaves was prepared using an ultrasonic-assisted extraction process. In vitro and in vivo anti-inflammatory activities were evaluated using the hypotonicity-induced hemolysis and carrageenan-induced paw edema methods, respectively. Additionally, the extract was assessed for in vitro DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging, antiarthritic (protein denaturation), and in vivo analgesic (acetic acid-induced writhing and tail immersion) activities. Brine shrimp lethality bioassay (BSLB) showed moderate cytotoxic activity (LC50 = 2.25 μg/mL) compared with the standard vincristine sulfate (LC50 = 1.61 μg/mL). In vitro, anti-inflammatory activity exhibited 85.13% (IC50 value = 2.51 μg/mL) inhibition of Human Red Blood Cell (HRBC) membrane lysis at a concentration of 2000 μg/mL whereas in vivo anti-inflammatory study exerted its maximum effect (p < 0.05) at 400 mg/kg bw dose. This extract also showed significant antioxidant (IC50 = 0.218 μg/mL), antiarthritic (83.61% inhibition) activity, and moderate analgesic effect (p < 0.05) in both methods. These research findings indicated that C. digyna leaves extract has potent antioxidant, analgesic, and anti-inflammatory effects which can be used as a supplementary medication for inflammatory pain-relieving factors. In future, finding the mechanism involved in these effects could have significant impact on clinical science.