Chemical composition and biological activities of essential oil of the Malaysian endemic Syzygium variolosum (King) Chantar. & J.Parn.

This study was designed to investigate the chemical composition of the essential oil of Syzygium variolosum (King) Chantar. & J.Parn. and their cytotoxicity, acetylcholinesterase, antityrosinase, and anti-inflammatory activities. In total, 32 chemical components were identified in the essential oil, which made up 98.9%. The essential oil is mainly composed of ß-elemene (20.2%), bicyclogermacrene (13.5%), viridiflorol (11.1%), globulol (8.6%), and selin-11-en-4α-ol (5.3%). Acetylcholinesterase, antityrosinase, and anti-inflammatory activities were evaluated with the Ellman method, mushroom tyrosinase, and lipoxygenase enzymes, respectively, while cytotoxicity was assessed using an MTT assay. The results showed that essential oil gave significant percentage inhibition (I%: acetylcholinesterase 35.2%, antityrosinase 42.5%, lipoxygenase 48.6%). Furthermore, the essential oil exhibited cytotoxicity against three cancer cell lines, HepG2, MCF7, and A549, with IC50 values ranging from 90.2 to 95.2 µg/mL. The current study highlights the potential of the use of essential oils as an alternative to the development of pharmaceutical antichemopreventives or cosmetics.

Intermedianin, a new furofuran lignan from the leaves of Knema intermedia Warb.

Phytochemical investigation of the leaves of Knema intermedia has led to the isolation of a new furofuran lignan, intermedianin 1 together with five known lignans, α-cubebin 2, ß-cubebin 3, bicubebin A 4, bicubebin B 5, and bicubebin C 6. The characterisation and structural elucidation of the isolated compounds were established by extensive spectroscopic data analysis and comparison with literature data. The antifungal activity was tested using the broth microdilution assay, whereas the microbial biofilms were determined using a semi-quantitative static biofilm. Compound 1 exhibited activity against C. albicans, C. lusitanae, and C. auris, (each with MIC/MFC value 250 µg/mL) and increased the biofilm of C. auris (64.07 ± 3.83%) and Candida lusitanae (62.90 ± 3.41%) when treated with 500 µg/mL.

Chemical composition, antifungal, antibiofilm, and molecular docking studies of Syzygium dyerianum essential oil.

The current study describes the chemical composition, antifungal, antibiofilm, antibacterial and molecular docking studies of Syzygium dyerianum growing in Malaysia. The essential oil was obtained through hydrodistillation and characterized using gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The antifungal and antibacterial activities were developed using the broth microdilution assay, whereas the effect on the microbial biofilms was determined using a semi-quantitative static biofilm assay. A total of 31 components were identified, which represent 99.5 % of the essential oil. The results revealed that the essential oil consisted mainly of ß-pinene (15.6 %), α-terpineol (13.3 %), α-pinene (11.1 %), caryophyllene oxide (8.8 %), limonene (8.1 %), borneol (6.0 %) and viridiflorol (5.1 %). The results of the microdilution method showed that essential oil exhibited activity against Candida albicans and Streptococcus mutans with minimal inhibitory concentration values of 125 and 250 µg/mL, respectively. Furthermore, essential oil decreased the biofilm of C. albicans and S. mutans by 20.11 ± 0.27 % and 32.10 ± 4.81 % when treated with 250 µg/mL. The best docking energy was observed with viridiflorol (-29.7 kJ/mol). This study highlights that essential oil can potentially be a natural antifungal, antibacterial, and antibiofilm agent that could be applied in the pharmaceutical and food industries.

Essential oils composition of Litsea glauca and Litsea fulva and their anticholinesterase inhibitory activity.

This study was designed to examine the essential oils compositions of Litsea glauca Siebold and Litsea fulva Fern.-Vill. growing in Malaysia. The essential oils were achieved by hydrodistillation and fully characterized by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The study identified 17 and 19 components from the leaf oils from L. glauca (80.7%) and L. fulva (81.5%), respectively. The major components of L. glauca oil were ß-selinene (30.8%), ß-calacorene (11.3%), tridecanal (7.6%), isophytol (4.8%) and ß-eudesmol (4.5%); whereas in L. fulva oil gave ß-caryophyllene (27.8%), caryophyllene oxide (12.8%), α-cadinol (6.3%), (E)-nerolidol (5.7%), ß-selinene (5.5%) and tridecanal (5.0%). Anticholinesterase activity was evaluated using Ellman method. The essential oils showed moderate inhibitory activity on acetylcholinesterase and butyrylcholinesterase assays. Our findings demonstrate that the essential oil could be very useful for the characterization, pharmaceutical, and therapeutic applications of the essential oil from the genus Litsea.

Chemical composition of essential oil from Lindera caesia Reinw. ex Fern.-Vill. and its antifungal, antibiofilm, and molecular docking studies.

The chemical composition, antifungal, antibiofilm, and molecular docking studies of the essential oil obtained from Lindera caesia were investigated. A total of thirty-nine components (96.7%) were identified using gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The major components included terpinen-4-ol (26.3%), neo-intermedeol (23.2%), eudesma-4,11-dien-3-one (10.4%), and o-cymene (5.3%). The antifungal activity was tested against Candida albicans and Streptococcus mutans using the broth microdilution assay, whereas the microbial biofilms were determined using a semi-quantitative static biofilm. The essential oil exhibited activity against C. albicans (MIC 125 µg/mL) and S. mutans (MIC 250 µg/mL), and increased the biofilm of C. albicans by 31.25% when treated with 500 µg/mL. The molecular docking study shows neo-intermedeol, eudesma-4,11-dien-3-one, α-selinene, and ß-selinene as the good candidate to target Erg11 with a binding energy of -7.3 kcal/mol. These findings demonstrated that the essential oil may have potential in dental application for caries prevention.

Chemical composition of essential oil from Lindera subumbelliflora Kosterm and its effect on the susceptibility and biofilm activities of Candida albicans and Streptococcus mutans.

The chemical composition of the essential oil of Lindera subumbelliflora (Lauraceae) was investigated for the first time. The essential oil was obtained by hydrodistillation and fully characterised by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antifungal activity of L. subumbelliflora essential oil was tested against Candida albicans and Streptococcus mutans using the broth microdilution assay, whereas the microbial biofilms were determined using a semi-quantitative static biofilm. A total of 28 components (99.6%) were successfully identified, which were characterised by ß-eudesmol (14.6%), cis-α-bergamotene (11.0%), α-copaene (8.5%), dodecen-1-ol (8.5%), and (E)-nerolidol (8.3%). The essential oil exhibited activity against Candida albicans and Streptococcus mutans with MIC values of 250 and 500 µg/mL, respectively. The essential oil increased the biofilm of Candida albicans by 38.25%, however, decreased the biofilm of Streptococcus mutans by 47.89% when treated with 500 µg/mL. Thus, the essential oil has a promising application in dentistry via inhibition of the growth of Candida albicans and Streptococcus mutans. However, the antibiofilm activity of the essential oil is only applicable for cariogenic Streptococcus mutans.

Chemical composition, acetylcholinesterase inhibition and molecular docking studies of essential oil from Knema hookeriana Warb. (Myristicaceae).

The genus Knema Lour. is distributed mainly in Southeast Asian and widely used in folk medicine for treating diseases such as jaundice, chronic fever, and inflammation. The chemical composition, acetylcholinesterase inhibition, and molecular docking studies of essential oil from Knema hookeriana Warb. were investigated in this study. The essential oil was achieved through hydrodistillation and was characterised using gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The acetylcholinesterase inhibitory activity was evaluated using Ellman method while molecular docking studies were carried out using Autodock v.4.3.2. The results revealed that the essential oil examined consisted mainly of ß-caryophyllene (26.2%), germacrene D (12.5%), δ-cadinene (9.2%), germacrene B (8.8%) and bicyclogermacrene (5.5%). The essential oil showed acetylcholinesterase activity with IC50 value of 70.5 µg/mL. The enzyme-ligand molecular docking study showed that ß-caryophyllene and δ-cadinene exhibited good binding affinities towards AChE with docking scores -8.1 kcal/mol and -8.3 kcal/mol, respectively.

Essential oil composition, anti-tyrosinase activity, and molecular docking studies of Knema intermedia Warb. (Myristicaceae).

Knema is one of the genera in the Myristicaceae family. The genus includes 60 species in Southeast Asia and is traditionally used for treating skin disorders. Here, for the first time, the essential oil, anti-tyrosinase, and molecular docking studies of Knema intermedia were evaluated. The essential oil was obtained by hydrodistillation and fully characterized by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Anti-tyrosinase activity was evaluated against mushroom tyrosinase, whereas molecular docking studies were performed using Autodock vina embedded in PyRx to evaluate the binding interactions of major components. A total of 37 components (97.3%) were successfully identified in the essential oil, which was characterized by high amounts of t-muurolol (20.1%), α-copaene (14.4%), δ-cadinene (13.9%), germacrene B (9.5%), and δ-selinene (7.0%). The essential oil displayed moderate inhibitory activity towards tyrosinase with an IC50 value of 70.2 µg/mL. The best docking energy was observed with δ-selinene (-7.8 kcal/mol), and it also forms interactions with His85, His263, and His244 which are important amino acid residues of the tyrosinase receptor. Hence, this study provides valuable scientific data on K. intermedia as potential candidate for the development of natural antiaging formulations.