Comparative effects of raw and commercialized edible bird's nest products on low-density lipoprotein receptor expression and cholesterol regulation in HepG2 cells.

Abstract

Background: Edible bird's nest (EBN), produced by swiftlets from salivary gland secretions, is a valuable glycoprotein source that offers significant nutritional benefits, particularly influencing consumer health lipid metabolism. Cleaning, bleaching, drying, and enzyme-based techniques can alter the physical quality, nutritional value, and bioactive characteristics of EBN.

Aim: This study aimed to compare the effects of raw and commercialized EBN extracts on cell viability, total cellular cholesterol (TCC), and LDLR gene expression in HepG2 cells.

Methods: HepG2 cells were cultured under controlled laboratory conditions and treated with graded concentrations of EBN extracts. Cell viability was evaluated using MTT assay. Enzymatically, intracellular cholesterol levels were quantified, and LDLR gene expression was measured using reverse transcription quantitative PCR.

Results: Raw EBN maintained higher cell viability and exhibited a nonlinear dose-response pattern, whereas commercialized EBN produced a clear dose-dependent cytotoxic effect. Both raw and commercialized EBN markedly upregulated LDLR gene expression, increasing transcription by approximately 23-fold and 24.5-fold, respectively, compared with untreated controls. Total cellular cholesterol did not differ significantly (p > 0.05), with TCC values of 1.85 ± 0.65, 1.80 ± 0.91, 2.07 ± 0.29, 1.90 ± 0.92, and 3.04 ± 1.04 µmol cholesterol/µmol protein in the BC, NC, PC, raw EBN, and commercialized EBN groups, respectively, although commercialized EBN showed the highest level, representing approximately a 1.6-fold increase relative to BC.

Conclusion: Both raw and commercialized EBN significantly enhance LDLR gene expression in HepG2 cells, indicating their potential to promote cholesterol uptake. However, processing may alter the biochemical composition and biological activity of EBN, contributing to differences in cytotoxicity and cholesterol response. These findings provide molecular insights into the potential of EBN as a functional food for cholesterol regulation and highlight the importance of processing integrity in preserving its bioactive efficacy.