M. Afzal

Green tea polyphenols and their potential role in health and disease.

There is a growing body of evidence that plant polyphenols such as resveratrol, anthocyanins, catechins, and terpenes like taxol are effectively used in the treatment of chronic conditions including cancer, Alzheimer, Parkinsonism, diabetes, aging, etc. The link between oxidative stress and inflammation is well accepted. Thus, the mechanism of action of these natural products is partly believed to be through their significant antioxidant properties. The main constituent of green tea, with clinical significance, is epigallocatechin gallate (EGCG). It has been associated with antitumor, anti-Alzheimer, and anti-aging properties, improve redox status at the tissue level possibly preventing system level structural damage. This review focuses on EGCG and its potential therapeutic role in health and disease.Graphical abstract

Garlic and its medicinal potential

Garlic (Allium sativum L.) has many accentuating medicinal properties and has been used as an effective remedy for a variety of chronic ailments including cardiovascular conditions, hyperlipaemia, diabetes, cancer and infectious diseases. It has antitumourigenic, antibacterial, antigangrene and antiatherosclerosis activities, which date back to early human history. The past, present and future potential of garlic and its medicinal merits are presented and the pharmacology of garlic components is discussed.

High- and low-temperature limits to growth of tomato cells

The temperature dependence of the metabolic rates of cultured tomato cells (Lycopersicon esculentum Mill.) has been studied by differential scanning calorimetry as a continuous function over the range from near 0 to above 45°C. Metabolic rates increase exponentially with temperature over the permissive range for growth (approx. 10–30°C). Outside this range irreversible loss of metabolic activity occurs. The rate of activity loss is time and temperature dependent, increasing as the exposure temperature diverges from the permissive range and increasing with time at any nonpermissive temperature. Metabolic heat rates obtained while scanning down from intermediate (25°C) to low temperature (0°C) yielded Arrhenius plots with pronounced downward curvature below about 12°C. The increase in apparent activation energy below 12°C is a function of the scan rate, showing its time dependency. This time dependency caused by inactivation confounds many estimates of apparent activation energy. Scanning up to high temperature shows that activity loss at high temperature is also time and temperature dependent. No first-order phase transitions associated with the changes in metabolism were detected at either low or high temperatures. Studies with lamellar lipid preparations added to cells show that temperature-induced transitions of lipids at levels equivalent to 4% of the lipid content of the cells were detectable. Cells with altered lipid composition showed altered temperature dependence of inactivation. High pressures (in the range from 10 to 14 MPa) shift the high temperature threshold and the rate of metabolic activity loss, supporting a postulate that higher-order transitions may be associated with inactivation of metabolism. Higher-order transitions of lipids or first-order transitions encompassing only a small fraction of total lipid remain among several viable postulates to explain temperature-dependent loss in activity. Alternative postulates are discussed.

Accumulation of trace metals in aquatic insect Stenopsyche marmorata Navas transferred in streams

Instar V larvae of the aquatic insect Stenopsyche marmorata were transferred between a noncontaminated site and a contaminated site and changes in the accumulation of nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb) in larvae were monitored for 30 days. Concentrations of the four metals rapidly increased or decreased within 10 days in the transferred larvae and approached concentrations of the native larvae living in the transfer sites. The accumulation of Ni and Cu in the larval body was very noticeable. The decreased Ni concentrations are represented by two exponential rate formulas, suggesting a biological half-life of 1.4 and 12.1 days. Under laboratory conditions, routes of Ni and Cu uptake were examined and Ni uptake was found to be mainly from food. However, larvae accumulated Cu from both food and water sources. In this case, the amount of metal uptake from food was more than that from water. The results of this indoor experiment are discussed and compared with the results of the transfer field experiment. Active biomonitoring of trace metal in transferred larvae is useful since it enables rapid and easy assessment of metal contamination.

Studies on Bacillus stearothermophilus. Part 1. Transformation of progesterone to a new metabolite 9,10-seco-4-pregnene-3,9,20-trione.

When Bacillus stearothermophilus, a thermophilic bacterium isolated from the Kuwaiti desert, was incubated with exogenous progesterone for 24 h, three monohydroxylated metabolites were produced. 20alpha-Hydroxyprogesterone was the major metabolite produced in 60.8 relative percentage yield. The other two monohydroxylated metabolites were identified as 6beta-hydroxyprogesterone and the rare 6alpha-hydroxyprogesterone in 21.0 and 13.6 relative percentage yields, respectively. A new metabolite 9,10-seco-4-pregnene-3,9,20-trione was isolated in 3.7 relative percentage yield. All metabolites were purified by preparative TLC and HPLC followed by their identification using 1H, 13C NMR and other spectroscopic data.

Studies on Bacillus stearothermophilus. Part II. Transformation of progesterone.

Bacillus stearothermophilus, a thermophilic bacterium isolated from Kuwaiti desert, when incubated with exogenous progesterone for 10 days at 65 degrees C produced two new dihydroxy isomers of progesterone, and two known compounds, 5 alpha-pregnane-3,6,20-trione and 6-dehydroprogesterone, along with the earlier reported monohydroxylated metabolites and a B-Seco compound. The two new dihydroxy compounds were identified as 6 alpha,20 alpha-dihydroxyprogesterone and 6 beta,20 alpha-dihydroxyprogesterone. These metabolites were purified by TLC and HPLC followed by their identification through 1H, 13C NMR and other spectroscopic data.

A potent thromboxane formation inhibitor in green tea leaves

A ninhydrin positive compound (L2) now identified as 2-amino-5-(N-ethylcarboxyamido)-pentanoic acid, from unprocessed tea leaves was a potent inhibitor of thrombin-stimulated thromboxane formation in rabbit whole blood (Ali and Afzal; Prostaglandins, Leukotrienes and Medicine, 27: 9, 1987). In the present study, processed and unprocessed tea leaf extracts were given to rats to consume for a period of eight weeks. Cholesterol and thromboxane levels were measured in the serum obtained from clotting the blood at 37 degrees C. A significant reduction in thromboxane levels was observed in rats taking unprocessed tea extract. This reduction was equally distributed in adult as well as in juvenile rats. However no appreciable changes in the levels of thromboxane were noticed in the serum of rats taking processed tea extracts. This might be due to the presence of a labile component which is destroyed during the processing of green tea leaves. A decreased level of cholesterol was observed in rats consuming unprocessed tea extract. This decrease could be linked to the decrease in thromboxane levels as observed. Processed tea refers to commercially available tea of different brands while unprocessed tea refers to dried green tea leaves.

Cyto-protective and immunomodulating effect of Curcuma longa in Wistar rats subjected to carbon tetrachloride-induced oxidative stress

Abstract.A comparison of crude curcuminoid extract and purified curcumin was made to evaluate hepato- and immunoprotective effect of Curcuma longa (turmeric) Zingiberaceae. Carbon tetrachloride (CCl4) induced cellular hepatic damage was evaluated by transmission electron microscopy, hepatic enzymes and thiobarbituric acid reactive species (TBAR) values. A selective cytolytic effect of CCl4 was observed among immature (PNA+) thymocytes and peripheral helper (CD4+) T lymphocytes in spleen and was paralleled by a significant reduction in CD25, CD71 and Con A receptor expression. Treatment with curcuminoid crude extract at two different doses, showed a significant cellular recovery among hepatocytes, which was reflected in a reduction of hepatic enzymes and TBAR values. A significant restoration of lymphocyte viability and CD25, CD71 and Con A receptor expression in both immature (PNA+) thymocytes and splenic helper (CD4+) T lymphocytes was observed. Turmeric crude extract, at both low and high dose, was found to be more efficient as compared to purified curcumin.

Purification and characterization of cloned alkaline protease gene of Geobacillus stearothermophilus

Thermostable alkaline serine protease gene of Geobacillus stearothermophilus B‐1172 was cloned and expressed in Escherichia coli BL21 (DE3) using pET‐22b(+), as an expression vector. The growth conditions were optimized for maximal production of the protease using variable fermentation parameters, i.e., pH, temperature, and addition of an inducer. Protease, thus produced, was purified by ammonium sulfate precipitation followed by ion exchange chromatography with 13.7‐fold purification, with specific activity of 97.5 U mg−1, and a recovery of 23.6%. Molecular weight of the purified protease, 39 kDa, was determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE). The enzyme was stable at 90 °C at pH 9. The enzyme activity was steady in the presence of EDTA indicating that the protease was not a metalloprotease. No significant change in the activity of protease after addition of various metal ions further strengthened this fact. However, an addition of 1% Triton X‐100 or SDS surfactants constrained the enzyme specific activity to 34 and 19%, respectively. Among organic solvents, an addition of 1‐butanol (20%) augmented the enzyme activity by 29% of the original activity. With casein as a substrate, the enzyme activity under optimized conditions was found to be 73.8 U mg−1. The effect of protease expression on the host cells growth was also studied and found to negatively affect E. coli cells to certain extent. Catalytic domains of serine proteases from eight important thermostable organisms were analyzed through WebLogo and found to be conserved in all serine protease sequences suggesting that protease of G. stearothermophilus could be beneficially used as a biocontrol agent and in many industries including detergent industry.

Studies on Bacillus stearothermophilus. Part IV. Influence of enhancers on biotransformation of testosterone.

The impact of chemical enhancers on the biotransformation of testosterone has been exploited. Application of crude cell concentrates to produce Bacillus stearothermophilus-mediated bioconversion of testosterone at 65 degrees C for 72 h has been examined. After incubation, the xenobiotic substrate was added to the concentrated whole cell suspensions. The enhancer molecules were included in the whole cell suspension. The resultant products, after extraction into an organic solvent, were purified by thin layer chromatography and identification was carried out through spectroscopic data. Five steroid metabolites 9,10-seco-4-androstene-3,9,17-trione, 5alpha-androstan-3,6,17-trione, 17beta-hydroxy-5alpha-androstan-3,6-dione, 3beta,17beta-dihydroxyandrost-4-ene-6-one and 17beta-hydroxyandrost-4,6-diene-3-one were identified as biotransformation products of testosterone. A possible biosynthetic route for these bioconversion products is postulated.