The chemical composition of the essential oil of Knema kunstleri Warb. (Myristicaceae) was investigated for the first time. The essential oil was obtained by hydrodistillation and fully characterized by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). In total, 36 components were identified in the essential oil, which made up 91.7% of the total oil. The essential oil is composed mainly of β-caryophyllene (23.2%), bicyclogermacrene (9.6%), δ-cadinene (7.3%), α-humulene (5.7%), and germacrene D (4.3%). The essential oil showed moderate activity towards DPPH free-radical scavenging and lipoxygenase inhibition. To the best of our knowledge, this is the first study of the composition and bioactivities of the essential oil report concerning the genus Knema.

This study aims to assess the chemical compositions of the essential oils from three Horsfieldia species namely H. fulva Warb., H. sucosa Warb. and H. superba Warb., which are found in Malaysia. The essential oils were derived from the samples through hydrodistillation which were then characterised by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Based on the findings, the H. fulva, H. sucosa and H. superba essential oils represented 98.2%, 98.7% and 98.5% of the total oils, respectively. The major component of H. fulva oil was identified to be germacrene D (20.8%), H. sucosa oil mainly contained α-cadinol (17.5%), whereas H. superba oil was rich in δ-cadinene (18.2%). To the best of our knowledge, this is the first study of the composition of the essential oils from these selected Horsfieldia species.

This study was designed to examine the chemical composition and anticholinesterase inhibitory activity of the essential oil of Pseuduvaria macrophylla (Oliv.) Merr. (Annonaceae) from Malaysia. The essential oil was obtained by hydrodistillation and fully analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The analysis led to the identification of thirty-four chemical components that represented 87.7 ± 0.5% of the total oil. The essential oil was found to be rich in germacrene D (21.1 ± 0.4%), bicyclogermacrene (10.5 ± 0.5%), δ-cadinene (5.6 ± 0.2%), α-copaene (5.1 ± 0.3%), and α-cadinol (5.0 ± 0.3%). Anticholinesterase activity was evaluated using Ellman method. The essential oil showed weak inhibitory activity against acetylcholinesterase (I%: 32.5%) and butyrylcholinesterase (I%: 35.4%) assays. Our findings demonstrate that the essential oil could be very useful for the characterization, pharmaceutical and therapeutic applications of the essential oil from Pseuduvaria macrophylla. Graphical Abstract

The chemical composition and the lipoxygenase activity of the leaves essential oil of Rothmannia macrophylla were determined via hydrodistillation. The essential oil was analysed by using gas chromatography and gas chromatography-mass spectrometry (GC/MS) techniques. A total of 20 chemical components (98.3 %) were identified in the oil, which was dominated by oxygenated sesquiterpenes (73.1 %). The major components were τ-muurolol (38.4 %), β-eudesmol (20.9 %), α-cadinol (5.8 %), and δ-cadinene (5.7 %). The essential oil displayed moderate activity towards lipoxygenase activity with IC₅₀ value of 50.5 μg/mL. To the best of the authors’ knowledge, this is the initial study that had looked into the essential oil composition of R. macrophylla collected from Malaysia.

The differences in pungency of “sirih” imply the probable occurrence of several variants of Piper betle L. in Malaysia. However, the metabolite profiles underlying the pungency of the different variants remain a subject of further research. The differences in metabolite profiles of selected Malaysian P. betle variants were thus investigated; specifically, the leaf aqueous methanolic extracts and essential oils were analyzed via ¹H-NMR and GC-MS metabolomics, respectively. Principal component analysis (PCA) of the ¹H-NMR spectral data showed quantitative differences in the metabolite profiles of “sirih melayu” and “sirih india” and revealed an ambiguous group of samples with low acetic acid content, which was identified as Piper rubro-venosum hort. ex Rodigas based on DNA sequences of the internal transcribed spacer 2 (ITS2) region. The finding was supported by PCA of two GC-MS datasets of P. betle samples obtained from several states in Peninsular Malaysia, which displayed clustering of the samples into “sirih melayu” and “sirih india” groups. Higher abundance of chavicol acetate was consistently found to be characteristic of “sirih melayu”. The present research has provided preliminary evidence supporting the notion of occurrence of two P. betle variants in Malaysia based on chemical profiles, which may be related to the different genders of P. betle.

Studies on floristic composition, forest structure and tree diversity are important to determine the pattern of stand structure, current status and floristic variation of firefly riverine mangrove habitats in Peninsular Malaysia. Thus, this study was conducted in three rivers, namely Sungai Chukai, Terengganu, Sungai Rembau-Linggi, Negeri Sembilan and Sungai Sepetang, Taiping, Perak. A total of 647,362 and 514 tree stands measuring 1 cm diameter and above were enumerated in 0.5 ha plots at the three sites, respectively. A total of 40 species were recorded in Sungai Chukai, 17 species in Sungai Rembau-Linggi and 14 species in Sungai Sepetang. The 0.5, 0.35 and 0.40 ha of each study site, respectively, were capable of capturing all the species in the mangrove forest. Rhizophoraceae family was found to have the highest density and basal area in all the study sites. The highest species density for Sungai Chukai, Sungai Rembau-Linggi and Sungai Sepetang was R. apiculata with a density of 262 ind ha-1, 120 ind ha-1 and 516 ind ha-1, respectively. The major contributor of total basal area at Sungai Chukai, Sungai Rembau-Linggi and Sungai Sepetang were X. granatum (5.5583 m2 ha-1) and R. apiculata with 10.6833 m2 ha-1 and 11.7491 m2 ha-1, respectively. Diversity and species richness were higher at Sungai Chukai (H’= 2.82, R’= 6.03) compared to Sungai Rembau-Linggi (H’=2.09, R’= 2.72) and Sungai Sepetang (H’=1.43, R’= 2.08). The highest total biomass of mangrove forest was at Sungai Rembau-Linggi with 321.21 t ha-1 followed by Sungai Sepetang (247.41 t ha-1) and Sungai Chukai (210.36 t ha-1). These results indicated that the current status of community structure and vegetation varied among the rivers. The study can act as a guideline in the management plan of firefly habitats, which also affect firefly distribution along the three rivers in Peninsular Malaysia.