HPLC and GC–MS characterization of bioactive lipophilic fractions from dragon fruit peels with anti-inflammatory activity

Dragon fruit ( Hylocereus spp.) is widely cultivated in Southeast Asia and is known for its nutritional and medicinal properties. Despite this potential, dragon fruit peel remains an underutilized by-product, while previous studies have largely focused on antioxidant activity, membrane-stabilizing effects, or enzyme-based anti-inflammatory assays, with limited evidence on cytokine modulation in human macrophages. Therefore, this study aimed to evaluate the anti-inflammatory activity of crude extracts and solvent-partitioned fractions from Hylocereus costaricensis (red flesh) and H. undatus (white flesh), and to characterize the phytochemical profiles of the most active fractions. Crude extracts were prepared using 80% ethanol and subsequently fractionated with hexane, ethyl acetate, and butanol. Cytotoxicity was assessed in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 human macrophages using the methyl thiazolyl tetrazolium (MTT) assay, while anti-inflammatory activity was evaluated in lipopolysaccharide (LPS)-stimulated THP-1 macrophages by quantifying interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α). All samples demonstrated low cytotoxicity up to 500 µg/mL. The peel hexane fractions showed the most pronounced cytokine suppression, particularly against IL-1β (81–84%) and IL-6 (74–75%), whereas TNF-α inhibition was moderate. Concentration–response studies revealed that the H. undatus peel hexane fraction was the most potent with IC 50 of 5.73 µg/mL and 76.64 µg/mL for IL-1β and IL-6, respectively. High-performance liquid chromatography (HPLC) identified β-amyrin and campesterol in both active fractions, while gas chromatography–mass spectrometry (GC-MS) detected fatty acids, tocopherols, and triterpenoids. Although H. costaricensis peel contained higher levels of β-amyrin (0.59%) and campesterol (2.83%), H. undatus peel (0.15% β-amyrin; 1.86% campesterol) showed stronger cytokine inhibition, suggesting that multiple lipophilic constituents may contribute to the observed activity. These findings indicate that dragon fruit peel lipophilic fractions are promising sources of cytokine-suppressive constituents and provide analytical support for the valorization of this underutilized by-product as functional food or nutraceutical ingredients.