Hydrolysis of soybean isoflavonoid glycosides by Dalbergia beta-glucosidases

Two beta-glucosidases from the legumes Dalbergia cochinchinensis and Dalbergia nigrescens were compared for their ability to hydrolyze isoflavonoid glycosides from soybean. Both D. nigrescens and D. cochinchinensis beta-glucosidases could hydrolyze conjugated soybean glycosides, but D. nigrescens beta-glucosidase hydrolyzed both conjugated and nonconjugated glycosides in crude soybean extract more rapidly. The kinetic properties Km, kcat, and kcat/Km of the Dalbergia beta-glucosidases toward conjugated isoflavonoid glycosides, determined using high-performance liquid chromatography, confirmed the higher efficiency of the D. nigrescens beta-glucosidase in hydrolyzing these substrates. The D. nigrescens beta-glucosidase could also efficiently hydrolyze isoflavone glycosides in soy flour suspensions, suggesting its application to increase free isoflavones in soy products.     

Anthocyanin composition of wild bananas in Thailand

Anthocyanins were isolated from male bracts of 10 wild species of bananas (Musa spp. and Ensete spp.) distributed in Thailand. Six major anthocyanin pigments were identified by high performance liquid chromatography (HPLC), mass spectrometry (MS), and tandem mass spectrometry (MS/MS). They are delphinidin-3-rutinoside (m/z 611.2), cyanidin-3-rutinoside (m/z 595.8), petunidin-3-rutinoside (m/z 624.9), pelargonidin-3-rutinoside (m/z 579.4), peonidin-3-rutinoside (m/z 608.7), and malvidin-3-rutinoside (m/z 638.8). On the basis of the types of pigment present, the wild bananas can be divided into 5 groups. The first group comprises M. itinerans, Musa sp. one, Musa sp. two, and M. acuminata accessions, which contain almost or all anthocyanin pigments except for pelargonidin-3-rutinoside, including both nonmethylated and methylated anthocyanins. The second group, M. acuminata subsp. truncata, contains only malvidin-3-rutinoside while the third group, M. coccinea, contains cyanidin-3-rutinoside and pelargonidin-3-rutinoside. The forth group, M. acuminata yellow bract and E. glaucum do not appear to contain any anthocyanin pigment. The fifth group consists of M. balbisiana, M. velutina, M. laterita, and E. superbum which contain only nonmethylated anthocyanin, delphinidin-3-rutinoside, and cyanidin-3-rutinoside. Total anthocyanin content in the analyzed bracts ranged from 0-119.70 mg/100 g bract fresh weight. The differences in the type of anthocyanin and variation in the amounts present indicate that wild bananas show biochemical diversity, which may be useful for identifying specific groups of bananas or for clarifying the evolution of flavonoid metabolism in each banana group.     

Hemagglutinating activity of Curcuma plants

Crude proteins obtained by Mg/NP-40 extraction from Thai medicinal plants of the Curcuma species exhibited agglutination activity against rabbit erythrocytes. A crude extract from Salingalinthong, a Thai Curcuma specie, exhibited the strongest hemagglutinating activity, 2 x 10(-5) mg/ml.     

Isolation and characterisation of crocosin,an antibacterial compound from crocodile (Crocodylus siamensis) plasma

An antibacterial compound from crocodile blood was partially purified and functionally characterised. The freshwater crocodile (Crocodylus siamensis) plasma with antibacterial activity was partially purified by using a centrifugal concentrator and reverse phase high powered liquid chromatography, and designated as crocosin. Crocosin exhibits antibacterial activity toward Salmonella typhi and Staphylococcus aureus. Crocosin is thermostable and resistant to pronase digestion. The structure of crocosin analyzed by mass spectrometry contains repeating units of 94 and 136 m/z. Scanning electron microscopy indicates that crocosin probably penetrates progressively into cytoplasm space, perturbing and damaging bacterial membranes. Crocosin may provide an early defense mechanism toward bacterial infection in freshwater.