Zeb Saddiqe

A review of the antibacterial activity of Hypericum perforatum L.

Hypericum perforatum L. (Hypericaceae) is a perennial herb that is commonly known as St. Johns Wort. The plant has been valued for its important biological and chemical perspectives and its use in the treatment of infectious diseases has been documented in ethnobotanical reports. Most recent interest in H. perforatum has focused on its antidepressant effects, and only recently has its antimicrobial activity been evaluated against a number of bacterial and fungal strains. The present review gives a comprehensive summary of the ethnobotanical uses, chemical constituents and biological effects (antibacterial and antifungal) of this species. A comprehensive account of the chemical constituents including anthraquinone derivatives (naphthodianthrones), flavonoids, prenylated phloroglucinols, tannins and volatile oils is also included. Various types of preparations, ointments, creams and extracts prepared with and compounds isolated from this species have been found to possess a broad spectrum of biological and pharmacological effects such as antidepressant effects, wound-healing, antiviral and antimicrobial activity. The antibacterial activity of crude extracts can be related to the use of the herb as a wound healer in ancient times. The sole antibacterial principle isolated to date is a tetraketone, hyperforin, also thought to be responsible for the antidepressant activity of the herb. The available literature indicates that it has a higher antibacterial activity against Gram-positive than Gram-negative bacteria, and alcoholic extracts (methanolic/ethanolic) were shown to possess more pronounced activity than aqueous extracts. Based on the chemical and pharmacological characteristics of H. perforatum, we concluded that this species has beneficial therapeutic properties and has the potential for use as an effective adaptogenic herbal remedy.

A review on biological, nutraceutical and clinical aspects of French maritime pine bark extract.

Bark extract of Pinus pinaster has a long history of ethnomedicinal use and is available commercially as herbal dietary supplement with proprietary name pycnogenol. It is used as a food supplement to overcome many degenerative disorders. Rohdewald (2002) wrote the first comprehensive review of extract highlighting its antioxidative nature and its role in different diseases. Later, Watson (2003) and Gulati (2005) in their reviews about cardiovascular health, described the extract as a best neutraceutical agent in this regard. The objective of this paper is to review the current research on this extract in terms of extraction methods, its pharmacological, toxicological and nutraceutical effects and clinical studies. Web sites of Google Scholar, Pubmed and Medline were searched for articles written in English and published in peer-reviewed journals from 2006 to 2009 and sixty-nine research articles were extracted. Of these, two are about extraction advancement and analysis while the rest relate to its clinical, biological and nutraceutical aspects.

Probe of ZrTiO 2 thin films with TiO 2 -ZrO 2 binary oxides deposited by dip coating technique

Zirconium Titanium dioxide (TiO2: Zr) thin films were synthesized on glass substrates by the dip coating technique. The structural, optical, magnetic, photo-catalytic and antibacterial properties were explored for the films synthesized with zirconium concentration 10, 15, 20, 25 and 30 at.%. X-ray diffraction (XRD) revealed that the thin films contain anatase-rutile-brookite TiO2 and cubic-ZrO2 phases. Moreover, it was noticed that ZrO2 retarded the anatase-to-rutile transformation at high Zr doping percentage.The crystallite size of ZrO2 phase was in the range of 10.93-18.22 nm, whereas it was in the range of 13.5-21.59 nm for TiO2 phase for same Zr doping percentage. The band gap of films was in the range of 2.99-3.17 eV. The band gap value decreased with increase in Zr-doping percentage due to the creation localized levels near the conduction band providing a large number of electrons to reach the conduction band. Films showed room temperature ferro-magnetism due to the defects produced by Zr in TiO2 lattice. The antibacterial efficiency of ZrTiO2 thin films was investigated by utilizing disc diffusion method. Band gap was quite low, then pure TiO2 in the range 2.99-3.14 eV with Zr percentage 10-30% atom. The ZrTiO2 thin films with 20 and 25% Zr showed better antibacterial activity against Escherichia coli than 10, 15 and 30% Zr. It was found that ZrTiO2 thin films were effective solar light photo-catalyst.

Biological and optical properties of sol–gel derived ZnO using different percentages of silver contents

The role of Ag dopant on ZnO thin films are studied. Ag doped ZnO thin films were deposited by sol-gel dip coating on glass substrates. The X-ray diffraction analysis shows hexagonal wurtzite with preferred orientation along the (101) plane. The crystallite size decreases from 33.40 nm to 28.37 nm with increase in silver doping percentage. Optical examination shows that the band gap decrease with an increase in the Ag doping in ZnO. The structural and optical results prove that Ag has substituted Zn in ZnO lattice. Silver doped ZnO is effective against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria. The roughness and the surface oxygen species accelerate the bacteria killing properties of Ag doped ZnO. They have pharmacological utility as a replacement of the antibiotics, bactericide and disinfectants. The TGA study showed that the thermal stability of the Ag doped ZnO takes place between 380-435 °C.