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Biomedical subjects

V S Srinivasan

Publications and source records attributed to V S Srinivasan.

5 recordsLinked to original sources
PubMed2001

Bioavailability of nutrients: a practical approach to in vitro demonstration of the availability of nutrients in multivitamin-mineral combination products.

As the dietary supplements industry is registering steady and rapid growth, consumers are demanding quality supplements. Consumer perception of the quality of oral solid dosage forms is changing. Good quality is associated with the ability to disintegrate and dissolve. Performance characteristics of oral solid dosage forms in public standards will address the in vitro dissolution requirements, which will be presented as they relate to multivitamin-mineral combination products.

Biological Availability↗
PubMed1994

Curcumin-derived transients: a pulsed laser and pulse radiolysis study.

In this paper we report a time-resolved investigation of transients derived from curcumin, which may be intimately involved in the processes leading to its biological activity. Fluorescence and triplet quantum yields are respectively 0.06 and 0.11. The high percentage of internal conversion is proposed to proceed via H-transfer within the thermodynamically favored enol structure of what is formally a 1,3-diketone. The triplet energy (191 +/- 2 kJ mol-1), natural lifetime (1.5 microseconds) and self-quenching rate constant (5.0 x 10(8) L mol-1 s-1) have been determined. Oxygen quenching of the triplet leads to the production of singlet oxygen with unit efficiency. Curcumin quenches the latter species very inefficiently (2.5 x 10(5) L mol-1 s-1). The curcumin radical has been produced via three mechanistically distinct methods. This species is unreactive toward oxygen but is repaired by vitamins C and E and anthralin.

Curcumin↗
PubMed1989

Photokilling of bacteria by the natural dye curcumin.

Curcumin is a yellow-orange compound derived from the root of Curcuma longa (Zingiberaceae family), that has been used as a medicine, spice and coloring agent. Curcumin has proved nontoxic in a number of cell culture and whole animal studies. Curcumin has, however, been reported to have bactericidal effects at very high concentrations. When illuminated, curcumin exerted potent phototoxic effects in micromolar amounts. Gram-negative bacteria displayed greater resistance to curcumin phototoxicity relative to Gram-positive bacteria. Oxygen was required for curcumin phototoxicity. Curcumin binding to cells was not required for photokilling; the reactive intermediate therefore must be relatively long-lived. The mechanism(s) of curcumin phototoxicity may involve hydrogen peroxide production. Singlet excited oxygen was not detected.

Catechols↗
PubMed1986

Metal-ion assisted detergent action on bacterial growth: detergent specificity and mechanism of inhibition.

Detergents in general inhibit bacterial growth. The anionic detergent, sodium lauryl sulphate (NaLS), seems to have a more specific inhibitory effect on growth of the Gram-positive Bacillus subtilis than on growth of the Gram-negative Escherichia coli. The specificity of anionic detergent towards B. subtilis has been traced to the difference in the nature of the cell wall. The inhibitory action of the detergent is markedly increased by the presence of metal ions like Cd++ or Mg++, due probably to the increase in the micellar phase, facilitating the solubilisation of bacterial species in the inner core of micelles. While metal ions like Cu++ do not influence the activity of NaLS, Na+, Ca++ or Mn++ ions seem to act against the detergent action on bacterial growth, probably by altering the structure of micelles.

Bacillus subtilis↗