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In the present study, phloroglucinol, a phenolic derivative, was extracted from the brown seaweeds Sargassum wightii, Sargassum tenerrimum and Turbinaria conoides. The secondary metabolite purified by reversed phase-high-performance liquid chromatography (RP-HPLC) was characterized using Fourier transform infrared spectroscopy (FT-IR), fluorescence spectroscopy, matrix-assisted laser desorption/ionization-time of flight/mass spectrometry (MALDI-TOF/MS) and H-1 nuclear magnetic resonance (NMR) spectroscopy. Phloroglucinol from S. tenerrimum exhibited higher total antioxidant (453.3 mg AscAE g(-1)), DPPH-scavenging (71.07 %), H2O2-scavenging (89.7 %) and metal chelating (14.28 %) activities. Anticoagulant activity was maximum in phloroglucinol from T. conoides (APTT 38.2 s, PT 22.7 s and FC 1.92 g dL(-1)). Phloroglucinol from S. wightii showed maximum lymphocyte migration inhibition (0.8 mm). Cytotoxicity and lactate dehydrogenase (LDH) leakage against MCF-7 cells was high in phloroglucinol from T. conoides (IC50 10.74 mu g mL(-1) and 56.17 %). These findings suggest that phloroglucinol from the selected brown seaweeds could be a rich functional food with appreciable biomedical properties.

The emergence of type 2 diabetes mellitus (T2DM) as the pre-eminent global non-infectious disease has driven the search for new anti-diabetic strategies including utilising traditional food and herbs. In this investigation, we describe the anti-diabetic potential of six selected Malaysian seaweed species against recognised pharmaco- logical targets. Specifically, we measured their ability to inhibit α-glucosidase and dipeptidyl-peptidase-4 (DPP-4) and also their ability to stimulate incretin hormone secretion in vitro.Crudewater extractsofHalimedamacroloba,Padina sulcata, Sargassum binderi and Turbinaria conoides pos- sessed potent inhibitory activities against α-glucosidase and DPP-4. The highest inhibitory activity against α-glucosidase was found in water extracts of the green seaweed species H. macroloba with an IC50 value of 6.388 mg mL �1 . Crude water extracts of the brown seaweeds studied namely P. sulcata, S. binderi and T. conoides, exhibited potent DPP-4 inhibition compared with the green seaweed H. macroloba. The brown seaweed also stimulates secretion of glucose-dependent insulinotrophic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) from pGIP neo STC-1 cells in vitro. H. macroloba stimulated GLP-1 secretion but not secretion of GIP.

The emission rates of eight volatile halogenated compounds by three tropical brown seaweed species collected from Cape Rachado, west coast Peninsular Malaysia, under different irradiances have been determined. A purge-and-trap sample preparation system with a gas chromatograph and mass-selective detector was used to measure a suite of halocarbons released by Sargassum binderi Sonder ex J. Agardh, Padina australis Hauck, and Turbinaria conoides (J. Agardh) Kutzing. All species are widely distributed in Peninsular Malaysia, with S. binderi a dominant seaweed species at our survey site. Release of few halocarbons was found to be influenced by irradiance. Correlations were also observed between emission of certain halocarbons with photosynthetic activity, especially bromo-and iodinated compounds (0.6 < r

Four species of brown seaweeds, namely Sargassum baccularia, Sargassum binderi, Sargassum siliquosum and Turbinaria conoides, harvested from Port Dickson, Negeri Sembilan, Malaysia were analysed for ash content, alginate yield and alginate properties. Seaweeds calcined at 450°C were found to have low amount of non-combustible residue as these were not contaminated by calcareous animals. Alginate was extracted from these seaweeds by two methods: hot and cold. In the hot method, the storing time was 3 h and the processing temperature was 50°C, whilst in the cold method, the sample was stored overnight at room temperature. Higher yield of alginate was obtained by the hot method compared to the cold method, but alginate extracted by the cold method gave higher molecular weight. In the hot method, 49.9% of alginate was extracted from S. siliquosum, followed by T. conoides (41.4%), S. binderi (38.9%) and S. baccularia (26.7%). Alginate extracted from T. conoides has an average molecular weight, M w, of 8.06 × 105 g mol−1, whereas alginate from S. siliquosum was the lowest in M w (4.81 × 105 g mol−1) when the extraction was done at room temperature. Alginate extracted from S. baccularia was found to be very heat-sensitive. Its M w has dropped more than 83%, from 7.52 × 105 to 1.23 × 105 g mol−1, when the extraction temperature was raised. The effect of heat on the extent of depolymerisation of the alginate molecule of the other three brown seaweed species was less significant, with decrease in molecular weight ranging between 13% and 16%.

The ability of the brown seaweed, Turbinaria conoides to absorb rhodamine B (RB) from aqueous solution was investigated in a batch system. The effects of various experimental parameters (e.g., morphology, initial dye concentration, temperature, and pH) were investigated and optimal experimental condition was ascertained. The results revealed that sorption capacity of T. conoides increased with increasing temperature, and decreasing initial dye concentration and pH. Sorption equilibrium studies using Langmuir and Freundlich models demonstrated that RB biosorption fitted well to the Langmuir isotherm. This study suggested that T. conoides can be used as a potential biosorbent for the removal of RB from wastewater.

The tissue culture of phycocolloid yielding seaweeds included preparation of axenic explants, callus induction, subculture of excised callus and regeneration of plantlets from pigmented callus in the laboratory. Treatment of algal material with 0.1–0.5% detergent for 10 min and 1–2% betadine for 1–5 min and 3–5% antibiotic treatment for 48–72 h successively enabled viable axenic explants to be obtained as high as 60% for Gracilariacorticata, Sargassumtenerrimum and Turbinariaconoides and 10% for Hypneamusciformis. Callus induction was more conspicuous in T. conoides than in the other three species investigated. Of the irradiances investigated, 30 μmol photons m−2 s−1 produced calluses in as many as 40% explants in G. corticata and T. conoides and 10% in H. musciformis and S. tenerrimum. The explants cultured at 5 and 70 μmol photons m−2 s−1 did not produce any callus in all the species studied except for H. musciformis in which 10% explants developed callus at 5 μmol photons m−2 s−1. Most of the species investigated showed uniseriate filamentous Type of growths and buds from cut ends and from all over the surface of explants. Nevertheless, T. conoides had three Types of callus developments, namely (1) uniseriate filamentous Type of outgrowths from the centre of the cut end of explant, (2) bubbly Type of callus and (3) club-shaped callus clumps. The subculture of T. conoides callus embedded in 0.4% agar produced two Types of filamentous growth, namely filiform (with elongated cells) and moniliform filaments (with round cells) in the 2 months period after inoculation. Further, friable callus with loose cells was also found associated with excised callus. The moniliform filaments showed prolific growth of micro-colonies resembling to somatic embryo-like growth which, in liquid cultures, differentiated and developed into propagules with deformed shoots and distinct rhizoids. The shoots of these propagules remained stunted with abnormal leaf stalks without forming triangular shaped leaves as the parental plant and rhizoids had prolific growth in the laboratory cultures. The excised callus of G. corticata continued to grow when transferred to liquid cultures and showed differentiation of new shoots within 10 days. The shoots grew to a maximum length of 5–6 cm in the 2 months period in aerated cultures in the laboratory.