Chemical investigation of the two nudibranch species Phyllidiella pustulosa and Phyllidia ocellata collected in Queensland, Australia, provided new stereoisomers of 4-isocyano-9-amorphene (1) and of 10-isocyano-4-amorphene (2), respectively. A specimen of Phyllidia picta collected from Bali, Indonesia, contained the axane sesquiterpenoids pictaisonitrile-1 (3) and pictaisonitrile-2 (4). The planar structures were elucidated using 1D and 2D NMR spectroscopy, while relative configurations were established using NOESY correlations, coupling constant data, and comparison with literature data.

Marine organisms, in particular nudibranchs (Mollusca: nudibranchia), are known as a rich source of chemically diverse secondary metabolites exhibiting potential as antimalarial, antiinflammatory, antiviral and anticancer activity. We presented the chemical investigation of an extract of nudibranch Hypselodoris infucata collected from Bali, an unexplored water but rich in nudibranch diversity. The extract contained the known (-)furodysinin (1), a furanosesquiterpene that for the first time isolated from this species. Metabolite 1 was purified by chromatography and the structure was characterised by comparison of 1 H NMR data with that of the reported data. The absolute configuration was determined by comparing the optical rotation values with the known enantiomer. In vitro cytotoxic activity of compound 1 against HeLa cell line displayed an IC50 at 102.7µg/mL. We also report for the first time the development of a method to assay nudibranch extracts for their feeding deterrence activity against local shrimps Penaeus vannamei. The extract show food rejection with highly significant difference in respect to the control (P = 0.0061) at natural concentration of 3.0mg/mL.

This study aims to identify the secondary metabolite compounds and to test the antioxidant activity of ethanol extract, n-hexane fraction, and chloroform fraction of Hippobroma longiflora leaves. Extraction was carried out by the maceration method using ethanol. The resulting crude ethanol extract was then partitioned with n-hexane and chloroform. Each extract and fraction was then tested by phytochemical screening. Antioxidant activity testing was carried out using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The phytochemical screening test showed that the ethanol extract contained flavonoids, saponins, triterpenoids, and alkaloids; the n-hexane fraction contained steroids, and alkaloids; and the chloroform fraction contained flavonoids, steroids, and alkaloids. Analysis of the antioxidant activity revealed the following Inhibitory Concentration (IC50 values): 9.57 ppm of ethanol extract, 99.59 ppm of n-hexane fraction, 48.54 ppm of chloroform fraction, and 4.30 ppm of ascorbic acid. Based on these results, the antioxidant activity of the ethanol extract was more potential than the n-hexane and chloroform fractions, but smaller than ascorbic acid.

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Kaempferia galanga is a tropical plant with an impressive range of food and medicinal uses. This study, therefore, investigated the variation in yields, physicochemical properties, chemical compositions, and antioxidant activities of rhizome oils from two K. galanga varieties, K. galanga bigger rhizomes (V1) and K. galanga smaller rhizomes (V2), isolated by steam distillation (S) and maceration (M) techniques. The air-dried rhizomes' oil contents were found to be 2.81±0.09% (SV1O), 7.93±0.20% (MV1O), 3.60±0.10% (SV2O), and 8.76±0.22% (MV2O), respectively. From the GC-MS analysis, the SV1O, MV1O, SV2O, and MV2O samples contain 49, 48, 61, and 56 compounds, respectively. Furthermore, ethyl trans-p-methoxycinnamate was the most prevalent chemical constituent in four oils with a percentage contribution of 43.37% (SV1O), 60.62% (MV1O), 24.92% (SV2O), and 57.17% (MV2O). Several long-chain alcohols (6Z,9Z-pentadeca-6,9-dien-1-ol, 9E,12E-octadeca-9,12-dien-1-ol, heptadecan-1-ol), aldehyde (Z-octadec-9-enal), carboxylic acids (4-(4-methoxyphenyl)oxane-4-carboxylic acid, hexadecanoic acid), diterpene sandaracopimaradiene, steroid ergosterol, and alkaloid 2-imino-3-(3-nitrophenyl)-1,3-thiazolidin-4-one, were also identified in K. galanga rhizome oils isolated by maceration method. In addition, all oils showed high antioxidant activities with the IC50 values of 86.10±1.51, 85.24±1.48, 89.19±1.72, and 86.49±2.03 μg/mL for SV1O, MV1O, SV2O, and MV2O, respectively.