Comparison of antioxidant levels and anti-inflammatory activities of kelulut honey harvested at different month of intervals and its chemical compositions

Background: Harvesting time might influence the biological activities of honey, which is crucial for honey quality. Objectives: This study aims to evaluate the optimum time for harvesting kelulut honey (KH) by determining its antioxidant and anti-inflammatory activities and chemical composition at different harvesting times. Materials and Methods: KH harvested at three different intervals (1, 2, and 3 months) was supplied by Rimbunan Hijau Bee Farm, located in Sarawak, Malaysia. The total phenolic content (TPC) and antioxidant level of KH were determined using Folin–Ciocalteu reagent and 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), and ferric-reducing ability of plasma assays, respectively. The cytotoxicity and anti-inflammatory effects of KH were evaluated on murine macrophage cells (RAW 264.7) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lipopolysaccharide (LPS)-induced nitric oxide (NO) production. The chemical composition of KH was analyzed by gas chromatography-mass spectrometry (GC-MS). Results: TPC and antioxidant levels of KH collected at different intervals showed no statistically significant difference (P > 0.05). KH at 1% concentration showed no cytotoxic activity toward RAW 264.7 cells after 24 h incubation. However, 1% KH showed no inhibition on NO production in LPS-induced RAW cells compared to the control. GC-MS revealed that hydroxymethylfurfural was present with the highest concentration in all samples. Conclusion: This study suggests that harvesting time does not influence the biological activities of KH.