Antioxidant, Antibacterial, Enzyme Inhibitory, and Anticancer Activities and Chemical Composition of Alpinia galanga Flower Essential Oil.

Alpinia galanga is widely cultivated for its essential oil (EO), which has been used in cosmetics and perfumes. Previous studies of A. galanga focussed mostly on the rhizome but seldom on the flower. Therefore, this study was designed to identify the chemical composition of A. galanga flower EO and firstly estimate its antioxidant, antibacterial, enzyme inhibitory, and anticancer activities. According to the results of the gas chromatography with flame ionization or mass selective detection (GC-FID/MS) analysis, the most abundant component of the EO was farnesene (64.3%), followed by farnesyl acetate (3.6%), aceteugenol (3.2%), eugenol (3.1%), E-nerolidol (2.9%), decyl acetate (2.4%), octyl acetate (2.0%), sesquirosefuran (1.9%), (E)-ß-farnesene (1.7%), and germacrene D (1.5%). For the bioactivities, the EO exhibited moderate DPPH and ABTS radical scavenging effects with IC50 values of 138.62 ± 3.07 µg/mL and 40.48 ± 0.49 µg/mL, respectively. Moreover, the EO showed strong-to-moderate antibacterial activities with various diameter of inhibition zone (DIZ) (8.79−14.32 mm), minimal inhibitory concentration (MIC) (3.13−6.25 mg/mL), and minimal bactericidal concentration (MBC) (6.25−12.50 mg/mL) values against Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Proteus vulgaris. Interestingly, the EO possessed remarkable α-glucosidase inhibition (IC50 = 0.16 ± 0.03 mg/mL), which was equivalent to that of the positive control acarbose (IC50 = 0.15 ± 0.01 mg/mL) (p > 0.05). It showed moderate tyrosinase inhibition (IC50 = 0.62 ± 0.09 mg/mL) and weak inhibitory activity on acetylcholinesterase (AChE) (IC50 = 2.49 ± 0.24 mg/mL) and butyrylcholinesterase (BChE) (IC50 = 10.14 ± 0.59 mg/mL). Furthermore, the EO exhibited considerable selective cytotoxicity to K562 cells (IC50 = 41.55 ± 2.28 µg/mL) and lower cytotoxicity to non-cancerous L929 cells (IC50 = 120.54 ± 8.37 µg/mL), and it induced K562 cell apoptosis in a dose-dependent manner. Hence, A. galanga flower EO could be regarded as a bioactive natural product with great application potential in the pharmaceutical field.

Chemical Composition, Antibacterial, and Anti-Inflammatory Activities of Essential Oils from Flower, Leaf, and Stem of Rhynchanthus beesianus.

Rhynchanthus beesianus is a medicinal, ornamental, and edible plant, and its essential oil has been used as an aromatic stomachic in China. In this study, the chemical constituents, antibacterial, and anti-inflammatory properties of flower essential oil (F-EO), leaf essential oil (L-EO), and stem essential oil (S-EO) of R. beesianus were investigated for the first time. According to the GC-FID/MS assay, the F-EO was mainly composed of bornyl formate (21.7%), 1,8-cineole (21.6%), borneol (9.7%), methyleugenol (7.7%), ß-myrcene (5.4%), limonene (4.7%), camphene (4.5%), linalool (3.4%), and α-pinene (3.1%). The predominant components of L-EO were bornyl formate (33.9%), borneol (13.2%), 1,8-cineole (12.1%), methyleugenol (8.0%), camphene (7.8%), bornyl acetate (6.2%), and α-pinene (4.3%). The main components of S-EO were borneol (22.5%), 1,8-cineole (21.3%), methyleugenol (14.6%), bornyl formate (11.6%), and bornyl acetate (3.9%). For the bioactivities, the F-EO, L-EO, and S-EO exhibited significant antibacterial property against Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, and Escherichia coli with the inhibition zones (7.28-9.69 mm), MIC (3.13-12.50 mg/mL), and MBC (6.25-12.50 mg/mL). Besides, the F-EO, L-EO, and S-EO significantly inhibited the production of proinflammatory mediator nitric oxide (NO) (93.15-94.72%) and cytokines interleukin-6 (IL-6) (23.99-77.81%) and tumor necrosis factor-α (TNF-α) (17.69-24.93%) in LPS-stimulated RAW264.7 cells at the dose of 128 µg/mL in the absence of cytotoxicity. Hence, the essential oils of R. beesianus flower, leaf, and stem could be used as natural antibacterial and anti-inflammatory agents with a high application potential in the pharmaceutical and cosmetic fields.

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.

Chemical Composition, Antibacterial, Anti-Inflammatory, and Enzyme Inhibitory Activities of Essential Oil from Rhynchanthus beesianus Rhizome.

Rhynchanthus beesianus W. W. Smith, an edible, medicinal, and ornamental plant, is mainly cultivated in China and Myanmar. The essential oil (EO) from R. beesianus rhizome has been used as an aromatic stomachic in China. The chemical composition and biological activities of EO from R. beesianus rhizome were reported for the first time. Based on gas chromatography with flame ionization or mass selective detection (GC-FID/MS) results, the major constituents of EO were 1,8-cineole (47.6%), borneol (15.0%), methyleugenol (11.2%), and bornyl formate (7.6%). For bioactivities, EO showed a significant antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Proteus vulgaris with the diameter of the inhibition zone (DIZ) (8.66-10.56 mm), minimal inhibitory concentration (MIC) (3.13-6.25 mg/mL), and minimal bactericidal concentration (MBC) (6.25-12.5 mg/mL). Moreover, EO (128 µg/mL) significantly inhibited the production of proinflammatory mediators nitric oxide (NO) (92.73 ± 1.50%) and cytokines tumor necrosis factor-α (TNF-α) (20.29 ± 0.17%) and interleukin-6 (IL-6) (61.08 ± 0.13%) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages without any cytotoxic effect. Moreover, EO exhibited significant acetylcholinesterase (AChE) inhibitory activity (the concentration of the sample that affords a 50% inhibition in the assay (IC50) = 1.03 ± 0.18 mg/mL) and moderate α-glucosidase inhibition effect (IC50 = 11.60 ± 0.25 mg/mL). Thus, the EO could be regarded as a bioactive natural product and has a high exploitation potential in the cosmetics and pharmaceutical industries.