Exploring the Potential of Heliotropium indicum Aqueous and Ethanolic Leaf Extracts as Novel Antioxidant and Anti-inflammatory Agents: A Comparative in vitro Study
Alfred Ikechukwu Ajoh *
Department of Medical Biochemistry, Delta State University, Abraka, Nigeria and Department of Biochemistry, University of Port Harcourt, Rivers State, Nigeria.
Jude Chigozie Ikewuchi
Department of Biochemistry, University of Port Harcourt, Rivers State, Nigeria.
Ejiro Prosper Awhin
Department of Medical Biochemistry, Delta State University, Abraka, Nigeria.
Michael Okechukwu Monanu
Department of Biochemistry, University of Port Harcourt, Rivers State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Heliotropium indicum is used in traditional medicine, although direct comparative evidence on the antioxidant and anti-inflammatory activities of aqueous and ethanolic leaf extracts remains limited. This study compared the in vitro antioxidant and anti-inflammatory activities of these extracts. Aqueous and ethanolic leaf extracts were prepared by maceration. Antioxidant activity was assessed using total antioxidant capacity, 2,2-diphenyl-1-picrylhydrazyl radical scavenging, nitric oxide scavenging and hydroxyl radical scavenging assays. Anti-inflammatory activity was evaluated through inhibition of albumin denaturation, heat-induced human red blood cell haemolysis and trypsin activity. Extract responses were examined at concentrations ranging from 15.625 to 1000 µg/mL, and half-maximal inhibitory concentrations (IC₅₀) were compared. Both extracts showed concentration-dependent responses across the assays. The ethanolic extract had lower IC₅₀ values than the aqueous extract for DPPH scavenging (178.93 ± 1.14 versus 226.80 ± 11.87 µg/mL), nitric oxide scavenging (390.83 ± 25.75 versus 744.59 ± 3.79 µg/mL) and hydroxyl radical scavenging (267.13 ± 27.97 versus 679.29 ± 22.91 µg/mL). It also had lower IC₅₀ values for albumin denaturation (217.60 ± 2.09 versus 440.13 ± 6.43 µg/mL), membrane stabilisation (223.29 ± 6.91 versus 343.89 ± 1.79 µg/mL) and antiprotease activity (66.88 ± 1.34 versus 207.36 ± 27.47 µg/mL). Under the reported experimental conditions, the ethanolic extract demonstrated greater in vitro activity than the aqueous extract. Further investigation is required to establish its biological relevance beyond these assays.
Keywords: Heliotropium indicum, aqueous extract, ethanol extract, antioxidants, anti-inflammatory