Investigation of apigenin-7-O-β-glucoside hydrolysis by β-glucosidase from almonds

Summary The enzymatic transformation of apigenin-7-O--glucoside into apigenin is effected using -glucosidase from almonds. Kinetic studies gave the following values K_m=7.63×10^–4mol/dm³, v_max=10.37 mol mg^–1 min^–1 and E₁=65.21 kJ/mol when the substrate was pure apigenin-7-O--glucoside, while in case of apigenin-7-O--glucoside from dry extract of camomile ligulate flowers E₂ = 65.57 kJ/mol.Nomenclature S_o initial substrate concentration (g/100 cm³) - P product concentration (g/100 cm³) - k reaction rate constant (min^–1) - t reaction time (min)     

Investigation of camomile fermentation

Summary The content of apigenin is an important factor of camomile spasmolytic activity. The hydrolysis of apigenin-7-O--glucoside into free aglycone in camomile ligulate flowers was possible using -glucosidase from almonds. The transformation of apigenin glucosides into apigenin has been achieved by autofermentation of camomile ligulate flowers and camomile flower heads. There is a significant increase of apigenin content, whereas the composition of other active components in camomile practically were not changed by autofermentation.     

Observations on the floral morphology of someDioscorea species (Dioscoreaceae) in Nigeria

Observations on floral morphology of eight species ofDioscorea L., namely,D. bulbifera L.,D. dumetorum (Kunth) Pax,D. hirtiflora Benth.,D. minutiflora Engl.,D. preussii Pax,D. odoratissima Pax,D. rotundata Poir. andD. Smilacifolia De Wild. are presented. The most remarkable distinctive features of the taxa studied are: the presence of large fruits and raceme inflorescences inD. preussii, the absence of pendulous inflorescences inD. dumetorum, and the absence of stalks in female flowers ofD. bulbifera.     

Fluted pumpkin,Telfairia occidentalis: West African vegetable crop

Fluted pumpkin, Telfairia occidentalis, is native to West Africa but occurs mostly in its cultivated form in various parts of southern Nigeria.It is widely cultivated for its palatable and nutritious leaves which are used mainly as vegetable. The seeds are also nutritious and rich in an oil which may be used for cooking and soap manufacture. Its taxonomy, morphology and potential uses are discussed in relation to its economic importance as a tropical crop.     

Influence of aeration of Candida albicans during culturing on their surface aggregation in the presence of adhering Streptococcus gordonii

Candida albicans surfaces are extremely sensitive to changes in growth conditions. In this study, adhesion to glass of aerated and non-aerated C. albicans ATCC 10261 in the presence and absence of adhering Streptococcus gordonii NCTC 7869 was determined in a parallel plate flow chamber. In addition, the influence of aeration on the yeast cell surface hydrophobicity, surface charge, and elemental cell surface composition was measured. S. gordonii adhering at the glass surface caused a reduction in the initial deposition rate of C. albicans, regardless of aeration. In a stationary end-point, only adhesion of non-aerated C. albicans was suppressed by the adhering S. gordonii. Non-aerated yeasts had a higher O/C elemental surface concentration ratio, indicative of cell surface polysaccharides, than aerated yeasts, at the expense of nitrogen-rich cell surface proteins. Both yeasts were essentially uncharged, but the nitrogen-rich cell surface of aerated yeasts had a slightly higher water contact angle than non-aerated yeasts. Summarizing, this study suggests that highly localized, hydrophobic cell surface proteins on C. albicans are a prerequisite for their interaction with adhering streptococci.     

Electrophoretic distribution and dissociation into subunits of lactate dehydrogenase derived from human myeloid leukemia cells before and after induction of differentiation

The electrophoretic distribution of lactate dehydrogenase (LDH) isoenzymes, Michaelis constant, reaction with substrate, and dissociation into subunits with guanidine hydrochloride was examined in undifferentiated and differentiated human myeloid leukemia cells. Differentiation was induced with 1/microgram/ml tunicamycin. Undifferentiated cells did not display phagocytic ability, and less than 5% of these cells had Fc receptors. After exposure to tunicamycin for 40 hr, 40% of these differentiated cells had Fc receptors, and 35% showed phagocytic activity after 160 hr. The majority of the LDH activity in the undifferentiated cells was found in fraction 3, and following differentiation almost a 50% reduction in LDH activity was observed in this fraction. In addition, LDH 3 isoenzyme levels were found to be greater in patients containing a high percentage of undifferentiated cells than in patients containing a high percentage of differentiated cells. Differentiated cells displayed LDH isoenzyme fraction pattern, Michaelis constant, and reaction with substrate similar to those found in the normal granulocytes. Differences in the dissociation of LDH into subunits with guanidine hydrochloride were found between undifferentiated and differentiated acute myeloid leukemia (AML) cells. Treatment with 0.75 M guanidine hydrochloride caused complete inactivation of LDH derived from normal differentiated cells, whereas similar treatment caused complete inactivation of LDH derived from AML or normal granulocytes. LDH isoenzymes derived from normal granulocytes and differentiated AML cells were also more sensitive to guanidine hydrochloride depression of fluorescence intensity. The sedimentation constant for single peak LDH at 5.5 M guanidine hydrochloride was calculated as 1.65 sec for differentiated and 1.70 sec for undifferentiated cells. The molecular weight of the polypeptide subunits for undifferentiated cells was 30,000 and for differentiated cells was 39,000. The apparent parallel between leukemic cells after induction of differentiation and normal granulocytes indicates that the leukemic cells retain their maturation potential when exposed to an inducer of differentiation.