Hedychium flavum flower essential oil: Chemical composition, anti-inflammatory activities and related mechanisms in vitro and in vivo.

ETHNOPHARMACOLOGICAL RELEVANCE: Hedychium flavum, an ornamental, edible, and medicinal plant, is extensively cultivated as a source of aromatic essential oils (EO). Its flower is a traditional Chinese medicine for treating inflammation-related diseases like indigestion, diarrhea, and stomach pain. In particular, H. flavum flower EO has been used in cosmetics and as an aromatic stomachic to treat chronic gastritis in China. AIM OF THE STUDY: This research aimed to analyze H. flavum flower EO's chemical composition and explore its anti-inflammatory activities and related mechanisms in vitro and in vivo. MATERIALS AND METHODS: EO's chemical composition was determined by GC-FID/MS analysis. For in vitro test, the anti-inflammatory activity of EO was demonstrated by measuring the LPS-induced release of NO, PGE2, IL-1ß, TNF-α, and IL-6 in RAW264.7 macrophages, and then its related mechanisms were explored using qRT-PCR, western blot, and immunofluorescent staining analysis. Next, EO's in vivo anti-inflammatory potential was further evaluated using a xylene-induced ear edema model, in which ear swelling and TNF-α, IL-6, and IL-1ß levels in serum and tissue were examined. RESULTS: The main components of EO were ß-pinene (20.2%), α-pinene (9.3%), α-phellandrene (8.3%), 1,8-cineole (7.1%), E-nerolidol (5.4%), limonene (4.4%), borneol (4.1%), and ß-caryophyllene (3.7%). For the anti-inflammatory activities in vitro, EO dramatically reduced the LPS-stimulated NO and PGE2 release by suppressing the mRNA and protein expression of iNOS and COX-2. Meanwhile, it remarkably decreased IL-6, TNF-α, and IL-1ß production by inhibiting their mRNA levels. Related mechanism studies indicated that it not only inhibited IκBα phosphorylation and degradation, leading to blockade of NF-κB nuclear transfer but also suppressed MAPKs (ERK, p38, and JNK) phosphorylation in LPS-stimulated RAW264.7 cells. Further in vivo assay showed that EO ameliorated xylene-induced ear edema in mice and reduced TNF-α, IL-6, and IL-1ß levels in serum and tissue. CONCLUSIONS: H. flavum EO exerted significant anti-inflammatory activity in vivo and in vitro, and its mechanism of action is related to the inhibition of MAPK and NF-κB activation. Thus, H. flavum EO could be considered a novel and promising anti-inflammatory agent and possess high potential for utilization in the pharmaceutical field.

Phytochemical Analysis, Antioxidant, Antibacterial, Cytotoxic, and Enzyme Inhibitory Activities of Hedychium flavum Rhizome.

Hedychium flavum Roxb., a medicinal, edible, and ornamental plant, is widely cultivated throughout China, India, and Southeast Asia. The rhizome from this plant has been used for food flavoring and in traditional Chinese medicine to treat diverse diseases, but the detailed constituents and bioactivities are still limited known. Therefore, phytochemical analysis by GC-MS and UHPLC-Q-Orbitrap-MS, and antioxidant, antibacterial, cytotoxic, and enzyme inhibitory activities tests have been conducted in the current study. Based on the GC-MS results, the essential oil (EO) of rhizome was mainly composed of coronarin E (20.3%), ß-pinene (16.8%), E-nerolidol (11.8%), and linalool (8.5%). Among them, coronarin E was reported in H. flavum EO firstly. Furthermore, the spectrophotometric indicated rhizome had high total phenolic content (TPC, 50.08-57.42 mg GAEs/g extract) and total flavonoid content (TFC, 12.45-21.83 mg REs/g extract), no matter in water extract (WE) or in 70% ethanol extract (EE). UHPLC-Q-Orbitrap-MS was applied to further characterize composition, and 86 compounds were putatively identified from WE and EE, including 13 phenolic components. For the bioactivities, both WE and EE showed remarkable antioxidant activity by DPPH and ABTS tests, being superior to the positive control (butylated hydroxytoluene, BTH). EO revealed significant antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Proteus vulgaris with DIZ (10.34-24.43 mm), MIC (78.13-312.50 µg/mL), and MBC (156.25-625.00 µg/mL). Moreover, EO exhibited a considerable selectivity to human tumor cell K562 (IC50 = 27.16 µg/mL), and its toxicity was more than 3.5-fold different from that of non-cancerous MRC-5 cell (IC50 = 95.96 µg/mL) and L929 cell (IC50 = 129.91 µg/mL). A series of apoptosis analysis demonstrated that EO induced apoptosis against K562 cells in a dose-dependent manner. In enzyme inhibitory effect assays, WE and EE showed strong α-glucosidase inhibition activity, being superior to the positive control (acarbose). Besides, the EO, WE, and EE didn't show a promising inhibition on tyrosinase (19.30-32.51 mg KAEs/g sample) and exhibited a weak inhibitory effect on cholinesterase. Based on the current results, H. flavum could be considered as a source of bioactive compounds and has high exploitation potential in the cosmetics, food, and pharmaceutical industries.