New Hygrocins K–U and Streptophenylpropanamide A and Bioactive Compounds from the Marine-Associated Streptomyces sp. ZZ1956

Marine-derived Streptomyces actinomycetes are one of the most important sources for the discovery of novel bioactive natural products. This study characterized the isolation, structural elucidation and biological activity evaluation of thirty compounds, including twelve previously undescribed compounds, namely hygrocins K–U (5–13, 17 and 18) and streptophenylpropanamide A (23), from the marine-associated actinomycete Streptomyces sp. ZZ1956. Structures of the isolated compounds were determined by a combination of extensive NMR spectroscopic analyses, HRESIMS data, the Mosher’s method, ECD calculations, single crystal X-ray diffraction and comparison with reported data. Hygrocins C (1), D (2), F (4), N (8), Q (11) and R (12), 2-acetamide-6-hydroxy-7-methyl-1,4-naphthoquinone (22), echoside C (27), echoside A (28) and 11,11′-O-dimethylelaiophylin (30) had antiproliferative activity (IC50: 0.16–19.39 μM) against both human glioma U87MG and U251 cells with hygrocin C as the strongest active compound (IC50: 0.16 and 0.35 μM, respectively). The analysis of the structure–activity relationship indicated that a small change in the structures of the naphthalenic ansamycins had significant influence on their antiglioma activities. Hygrocins N (8), O (9), R (12), T (17) and U (18), 2-amino-6-hydroxy-7-methyl-1,4-naphthoquinone (21), 2-acetamide-6-hydroxy-7-methyl-1,4-naphthoquinone (22), 3′-methoxy(1,1′,4′,1″-terphenyl)-2′,6′-diol (26), echoside C (27) and echoside A (28) showed antibacterial activity against methicillin-resistant Staphylococcus aureus and Escherichia coli with MIC values of 3–48 μg/mL

Yield optimization, physicochemical characterizations, and antioxidant properties of food grade agar from Gracilaria tenuistipitata of Cox's Bazar coast, Bangladesh

Abstract The present study was aimed at investigating the optimization of extraction variables for food grade quality agar from Gracilaria tenuistipitata, so far, the first study on Bangladeshi seaweed. Water (native)‐ and NaOH (alkali)‐pretreated agars were comparatively analyzed by several physicochemical parameters. All extraction variables significantly affected the agar yield in both extraction conditions. Alkali‐pretreated agar provided a better yield (12–13% w/w) and gel strength (201 g/cm2) in extraction conditions as followed by 2% NaOH pretreatment at 30°C for 3 h, seaweed to water ratio at 1:150, and extraction temperature at 100°C for 2 h. Gelling and melting temperatures, color, and pH values of both agars were found to be comparable with commercial agar. Significantly higher sulfate contents including organic and inorganic and total carotenoids were reported in native (3.14% and 1.29 μg/mL) than that in alkali‐pretreated agar (1.27% and 0.62 μg/mL). FTIR spectrum demonstrated the purity of the agar as characterized by the stronger relative intensity with higher degree of conversion of L‐galactose 6‐sulfate to 3,6‐anhydrogalactose in alkali pretreatment group than that of native ones. Moreover, antioxidant activity (% DPPH scavenging) was observed and confirmed by IC50 values of 5.42 and 9.02 mg/mL in water‐ and alkali‐pretreated agars, respectively. The results suggested that agar from G. tenuistipitata with optimized alkali extraction conditions could promote cost‐effective yield with improved physicochemical characteristics and biofunctional values upon consumption by the consumers as food materials

Effects of Different Drying Methods on Quality Parameters of Tilapia (Oreochromis niloticus) Obtained from the Local Market of Bangladesh

This study aimed to evaluate the effects of various drying methods on quality parameters such as proximate composition, rehydration characteristics, total volatile basic Nitrogen (TVB-N), and consumer acceptance of tilapia. Three different types of dryers, viz., ring tunnel dryer (RTD), oven dryer (OD), and smoke dryer (SD), were used for a specific period. The proximate composition of dried tilapia varied from each drying method. The moisture content of SD samples (25.33%) contains more moisture than others, while significantly lower moisture contents were observed in RTD. High protein levels (62.81%) and (61.69%) were found in a sample obtained from OD and RTD, respectively. The protein content was significantly (P≤0.05) reduced in SD tilapia (54.35%). The higher lipid contents found in RTD and OD samples were 7.48% and 7.49%, respectively. The highest ash contents were recorded in RTD (14.89%). TVB-N content ranged between 7.03 to 7.45 mg/100 g, and the lowest TVB-N value was observed in RTD products. The RTD products hold more water, and the rehydration rate was faster than others. The sensory characteristics of dried tilapia obtained from RTD had better in terms of odor, color, texture, and general appearance, except the texture of SD products, was found to be better as compared to others. Overall, the results demonstrated that RTD products compete with SD with few exceptions RTD would be the better choice for tilapia drying

Physicochemical and Nutritional Characteristics of Cookies Prepared with Untapped Seaweed <i>Ulva intestinalis</i>: An Approach to Value Addition as a Functional Food

The present study was investigated to know the sensory, physicochemical, nutritional and fatty acid properties of seaweed-based cookies prepared with untapped seaweed Ulva intestinalis (UI) from Bangladesh coast. The cookies were formulated with different percentages of UI inclusions both in powdered (PUI) and fragmented (FUI) forms, in order to evaluate different quality attributes in prepared value-added cookies. In sensory analysis, seaweed inclusion levels of 1% PUI, 2.5% PUI, 1% FUI, 2.5% FUI and 5% FUI to cookies were acceptable by panelists. Considering the maximum percentage of seaweed inclusions, 2.5% PUI and 5% FUI were selected for further analysis. The results of physicochemical properties such as moisture content, spread factor, baking loss, pH, cookie density, color, texture properties, volatile basic nitrogen and thiobarbituric acid reactive species were within acceptable limits. In nutritional analysis, 2.5% PUI and 5% FUI cookies showed a remarkable and significant increase in lipid and ash contents, compared to untreated controls. Being the first report on fatty acids profile by UI from Bangladesh, among 24 fatty acids identified, the amount of total saturated, mono-unsaturated, omega-3 fatty acids and omega-6 fatty acids were reported to be 641.9 (36.2%), 563.7 (31.8%), 133.8 (7.6%) and 436.3 (24.6%) μg/g DW, respectively. The results suggest that cookies with 2.5% PUI and 5% FUI can be marketed as healthy foods for consumers