Kalanchoe pinnata - a Promising Source of Natural Antioxidants

Aims: Evaluation of natural antioxidant potential of Kalanchoe pinnata leaves attributable towards its therapeutic properties.

Study Design: In vitro experiments to validate antioxidant potential in aqueous and lipid phase.

Methodology: The aqueous-alcoholic whole leaf extract designated as KPE (K. pinnata extract) was subjected to comprehensive biochemical analysis to reveal its natural strength as an antioxidative agent. In lipid protection ability assay where lipid phase (pre-emulsion) was prepared using linoleic acid with Fe2+, Fe3+ and Cu2+ as stress-inducers, it’s potential to protect against peroxyl radical induced damage in non aqueous environment was tested. Deoxy-D-ribose degradation assay in presence or absence of chelating agent (EDTA) was tested to reveal non site-specific and site-specific hydroxyl radical (OHº) scavenging potential respectively. Sodium nitroprusside based nitric oxide (NO) quenching activity and nitroblue tetrazolium reduction based superoxide radical scavenging potential were also estimated.

Results: Total phenolic content of KPE was 28.4±2 μg mg-1. In lipid protection ability assay it exhibited maximally restricted Fe2+ induced amplification of peroxyl raical (ROOº) at 10 mg mL-1. It elicited a significant (P = .05) inhibition of lipid auto-oxidation by directly scavenging peroxyl radicals. In potassium ferrithiocyanate-based reducing power assay, KPE exhibited significantly higher potency as compared to the standard synthetic antioxidant butylated hydroxy toluene (BHT), in the range of 100-2000 µg mL-1. The ability of KPE to interact at the level of generation of hydroxyl radicals was also tested with deoxy-D-ribose degradation assay that revealed a two-fold higher non site-specific OHº scavenging potential than its site-specific activity. In sodium nitroprusside based NO quenching assay KPE showed >50% quenching activity at 0.5 mg mL-1.

Conclusions: KPE is a rich source of anti-oxidative properties and has strong protective potential against oxidative stress in both aqueous and lipid phases. Hydroxyl radical scavenging assay showed KPE’s ability to scavenge free radicals is more due to its reductive potency than its metal-chelation activity attributable towards its exploration in herbal drug discovery research.