Moringa oleifera flowers: insights into their aroma chemistry, anti-inflammatory, antioxidant, and enzyme inhibitory properties

Background: Moringa oleifera is a highly nutritious plant widely used in traditional medicine. Results: The aroma constituents present in the fresh flowers of M. oleifera versus the hydrodistilled oil and hexane extract were studied using GC-MS. Aldehydes were the major class detected in the fresh flowers (64.75%) with E-2-hexenal being the predominant component constituting > 50%. Alkane hydrocarbons, monoterpenes, and aldehydes constituted > 50% of the hydrodistilled oil, while alkane hydrocarbons exclusively constitute up to 65.48% of the hexane extract with heptacosane being the major component (46.2%). The cytotoxicity of the hexane extract was assessed on RAW 264.7 macrophages using the MTT assay which revealed no significant cytotoxicity at concentrations of 1 µg/mL and displayed IC50 value at 398.53 µg/mL as compared to celecoxib (anti-inflammatory drug) with IC50 value at 274.55 µg/ml. The hexane extract of Moringa flowers displayed good anti-inflammatory activity through suppression of NO, IL-6, and TNF-α in lipopolysaccharide-induced RAW 264.7 macrophages. The total phenolic and flavonoid content in the hexane extract was found to be 12.51 ± 0.28 mg GAE/g extract and 0.16 ± 0.01 mg RuE/g extract, respectively. It displayed moderate antioxidant activity as indicated by the in vitro DPPH, ABTS, CUPRAC, FRAP, and phosphomolybdenum (PBA) assays. No metal chelating properties were observed for the extract. The enzyme inhibitory potential of the hexane extract was evaluated on acetyl- and butyrylcholinesterases (for neuroprotective assessment), α-amylase and α-glucosidase (for antihyperglycemic assessment), and tyrosinase (for dermoprotective assessment) revealing promising results on cholinesterases, tyrosinase, and α-glucosidase. Conclusion: Our findings suggested that M. oleifera leaves can be considered as a multidirectional ingredient for preparing functional applications. Graphical abstract: (Figure presented.).