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Chemical investigation of the cyanobacterium Dolichospermum sp. NIES-1697 afforded nostosin G (1), a linear tripeptide, spiroidesin B (2), and two known compounds, anabaenopeptins I (3) and J (4). Planar structures and absolute configurations for 1 and 2 were determined by 2D NMR, HRMS, Marfey's methodology, chiral-phase HPLC, and enzymatic degradation. Nostosin G (1) is a unique example of a linear peptide containing three subunits, 4-hydroxyphenyllactic acid (Hpla), homotyrosine (Hty), and argininal, with potent trypsin inhibitory properties. The biosynthetic gene clusters for nostosin G (1) and spiroidesin B (2) were investigated based on the genome sequence of Dolichospermum sp. NIES-1697.

New bioactive 13-epi-neoverrucosane diterpenoid, 5β-acetoxy-13-epi-neoverrucosanic acid (1) along with three known secondary metabolites, 13-epi-neoverrucosan-5β-ol (2), chelodane (3) and (E)-β-farnesene (4) were isolated from the MeOH extract of east Malaysia’s liverwort Pleurozia subinfata. The chemical structure of new compound was elucidated by the analyses of its spectroscopic data (FTIR, NMR and HR-ESI-MS). These epi-neoverrucosane-type compounds seem to be notable chemosystematic markers for P. subinfata in Borneo. Compound 3 was widespread in marine sponges however this is the frst record for 3 to be found in liverwort. These metabolites were tested for their antifungal potentials against selected fungi from the marine environment. Compound 1 exhibited efective antifungal activity against Lagenidium thermophilum.

Two new C15-acetogenins, 4-epi-isolaurallene (1) and 4-epi-itomanallene A (2) were isolated from a population of marine red alga Laurencia nangii Masuda from Carrington Reef. The structures of these compounds were determined intensively by NMR and HRESIMS data. Their configurations were elucidated by detailed comparison of chemical shifts, germinal protons splitting and NOE correlations with known and synthesized analogues. In addition, antibacterial activities of these compounds were evaluated. These compounds would serve as diastereomeric models for future reference. Since the isolaurallene, neolaurallene, 9-acetoxy-1,10,12-tribromo-4,7:6,13-bisepoxypentadeca-1,2-diene, itomanallene A and laurendecumallene A were isolated, compounds 1 and 2 were the sixth example of C15-acetogenin with dioxabicyclo[7.3.0]dodecene skeleton.

The combination of non-orthogonal multiple access (NOMA) and multi-input multi-output (MIMO) approaches has been considered as assuring multiple access for the fifth generation technology. In this study, the performance of a 2 × 2 MIMO- NOMA system with low-density parity check (LDPC) codes is investigated. Redundancy with randomly interleaved differential encoding (R-RIDE) is proposed and applied to LDPC encoded messages by two users. LDPC decoding is done using the sum-product algorithm (SPA), which has two types of decoding methods, hard-decision and soft-decision. For hard-decision, bit-flipping decoder is used and for soft-decision, probability domain, log-domain, and simplified log-domain decoders are used. Bit error rate (BER) versus signal-to-noise ratio (SNR) in (dB) and average mutual information (AMI) in (bps/Hz) versus SNR (dB) are evaluated to compare the performance of the proposed and conventional LDPC schemes in NOMA and MIMO-NOMA systems. Simulation results show that both AMI and BER of the proposed LDPC-R-RIDE in MIMO-NOMA system greatly outperforms conventional LDPC coded schemes in NOMA and MIMO-NOMA systems. Moreover, the proposed R-RIDE-LDPC in MIMO-NOMA system outperforms the proposed scheme in the NOMA system. From the simulation results, LDPC-R-RIDE with simplified log-domain decoder has the best AMI result and BER performance compared with other decoding methods.

A new cembranolide diterpene, sarcophytonolide V (1), along with 6 known compounds, isosarcophytonolide D (2), (4Z,8S*,9R*,12E,14E) -9-hydroxy-1- (prop-1-en-2-yl) -8,12- dimethyl- oxabicyclo[9.3.2]-hexadeca-4,12,14-trien-18-one (3), (7E,11E)-3,4-epoxy-7,11, 15- cembratriene (4), (1S*,3S*,4S*,7E,11E)-3,4-epoxy-13-oxo-7,11,15-cembratriene (5), (-) -eunicenone (6), and 2-[(E,E,E)-7′, 8′-epoxy-4′,8′,12′ -trimethylcyclotetradeca- 1′,3′,11′- trienyl] propan-2-ol (7) were isolated from the Bornean soft coral Sarcophyton sp. Their structures were elucidated based on spectroscopic data, such as nuclear magnetic resonance (NMR) and high resolution electron spray ionization mass spectroscopy (HRESIMS). These compounds were evaluated for their biological activity against marine pathogenic fungi.

A new sesquiterpene, capgermacrene H (1) was isolated together with 7 other compounds, capgermacrenes A-G (2-8), from a population of soft coral Capnella imbricata collected from Mantanani Island, Sabah, Malaysia. The structure of this metabolite was elucidated based on spectroscopic data such as nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry. Capgermacrene A (2) showed potent cytotoxicity against adult T-cell leukemia, S1T cells at half-maximal inhibitory concentration of 0.79 µg/mL.

Red algae of the genus Laurencia have been known to produce a wide array of bioactive secondary metabolites. Here, we report the isolation of two new halogenated chamigrenes, lauremantanones A (1) and B (2), along with seven known compounds, dendroidiol (3), (+)-elatol (4), cartilagineol (5), obtusol (6), (+)-laurencenone B (7), 2-chloro-3-hydroxy- α-chamigren-9- one (8), and puertitol A (9), from a population of Laurencia majuscula (Harvey) Lucas from Mantanani Island (North Borneo). The structures of the two new metabolites were determined based on spectroscopic data (IR, 1D and 2D NMR, and MS). Compounds isolated from this alga exhibited potent cytotoxic (HeLa, MCF-7, P-388) and antibacterial (against antibiotic-resistant clinical bacteria) activities. The major metabolite of this population has significant importance in the geographical distribution of this species globally.

Three new cembrane diterpenes, nephthecrassocolides A-B (1–2) and 6-acetoxy nephthenol acetate (3) along with three known compounds, 6-acetoxy-7,8-epoxy nephthenol acetate (4), epoxy nephthenol acetate (5) and nephthenol (6) were isolated from one population of Nephthea sp. Their structures were elucidated based on spectroscopic data analysis and the antifungal activities of compounds 1–6 were evaluated.

A new aaptamine-related alkaloid, 1,3-dioxolo [4,5-d] benzo [de]-1,6-naphthyridine (methylenedioxyaaptamine, 1), was isolated from the organic extracts of the Bornean marine sponge Aaptos aaptos, together with a known aaptamine derivative, 8,9,9-trimethoxy-9H-benzo [de]-1,6-naphthyridine (2). The structure of compound 1 was elucidated by interpretation of its spectroscopic data. Two compounds were tested for their cytotoxic potentials against adult T-cell leukemia (ATL) cells, and compound 1 showed moderate cytotoxic potential.

One new compound, 12-epi-9-deacetoxyxenicin (1) along with a hydroperoxide product, 12-epi-9-deacetoxy-8-hydroperoxyxenicin (2) and two known sesquiterpenoids (3–4) were isolated from a population of Bornean soft coral Xenia sp. The structures of these secondary metabolites were elucidated based on their spectroscopic data. Compounds 1 and 2 showed cytotoxic activity against ATL cell line, S1T. In addition, compound 3 exhibited hyphal inhibition of Lagenidium thermophilum.

Chemical investigation of the barley and wheat fungal pathogen Bipolaris sorokiniana BRIP10943 yielded four new sativene-type sesquiterpenoid natural products, bipolenins K–N (1–4), together with seven related known analogues (5–11), and a sesterterpenoid (12). Their structures were determined by detailed analysis of spectroscopic data, supported by TDDFT calculations and comparison with previously reported analogues. These compounds were evaluated for their phytotoxic activity against wheat seedlings and wheat seed germination. The putative biosynthetic relationships between the isolated sesquiterpenoids were also explored.

One new phenylbutenoid, (3Z)-2',4',5'-trimethoxyphenylbutadiene (1) along with five known metabolites were isolated from aquatic galangal (Alpinia aquatica Rosc.) and their chemotaxonomy importance in five populations of A. aquatica collected from Kota Kinabalu, Ranau and Kota Belut in Sabah, Malaysia. The antibacterial potential as well as the chemosystematics importance of this discovery is discussed.

Soft corals are often the research interest organism due to their structural diverse secondary metabolites with wide spectrum of biological activities range from antibacterial to anticancer potentials. The Borneo Island is rich in diversity of marine organisms including soft coral. Therefore, a population of Bornean soft coral belongs to genus Nephthea was collected from Mantanani Island (Sabah, Malaysia) which led to the isolation of a novel norditerpene, chabrolene (1) together with three known compounds (2-4). The chemical structure of 1 was determined by NMR and HREIMS data. Compound 1 exhibited repellent activity against the maize weevil Sitophilus zeamais.

Four scalarane sesterterpenoids, scalarolide acetate (1), scalarolide (2), 12-O-deacetyl-12 -epi-19-O-methylscalarin (3) and methyl 18- hydroxy- 19-norscalar-16 -en-20- carboxylate (4) were isolated from the Bornean sponge Spongia sp. The distinction between 12α-OAc and 12β-OAc, and 19-olide and 20-olide in sesterterpenes were revealed as well as previously not assigned relative configuration at 18-OH of 4 is reported herein for the first time. In addition, compounds 1-3 showed strong cytotoxic activities against adult T-cell leukemia (ATL), S1T cells. This is the first record of scalarane sesterterpenes from the Bornean sponge.

Liverworts are the most primitive terrestrial plant which known to produce unique and wide variety of compounds. Ethyl acetate crude extract was subjected to several chromatographic techniques for purification. Three new compounds, saccatenes A-C (1-3) were isolated together with two known prenyl bibenzyl derivative, 2,2-dimethyl-5-hydroxy-6-carboxy-7-(2-phenylethyl) chromene (4) and radulanin A-5-one (5) from the Bornean liverwort Acrobolbus saccatus (Hook.) Trevis collected from Mountain Trus Madi, Sabah, Malaysia. The structures of the three new metabolites were established by analyses of the spectroscopic data (1D NMR, 2D NMR, HRESIMS and IR), and the antibacterial activity against eight selected human pathogenic species of bacteria were tested.