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- 저자 : Waheed Arshad (검색결과 2 건)
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Effects of Vegetative and Flowering Stages on the Biosynthesis of Artemisinin in Artemisia Species
Abdul Mannan,Ibrar Ahmed,Waheed Arshad,Izhar Hussain,Bushra Mirza 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.10
Artemisinin is an endoperoxide sesquiterpene lactone, and has been proven to be very effective in treating drug resistant cases of malaria, cancer, etc. The compound is obtained from Artemisia species. In the current study, the effects of vegetative and flowering stages on artemisinin production were studied, to determine the proper harvesting time of naturally growing Artemisia species with the highest levels of artemisinin. Eight Artemisia species along with two varieties were selected for this analytical work. The results showed that artemisinin content was high in the leaves of Artemisia indica, A. sieversiana, A. roxburghiana var. roxburghiana, A. roxburghiana var. gratae, and A. parviflora at the flowering stage. The highest artemisinin content was measured in the leaves of A. dracunculus var. dracunculus. Upon comparisons of artemisinin content among the individual plant species, the highest amount of artemisinin was again in A. dracunculus var. dracunculus followed by A. sieversiana when harvested at the flowering stage. In overall comparisons, the plants at the flowering stage showed high levels of artemisinin, which is deemed the optimum harvesting time of Artemisia species in Pakistan for maximum artemisinin content.
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Muhammad Asim Rasheed,Kamran Ahmad,Nilem Khaliq,Yaqoob Khan,Muhammad Aftab Rafiq,Abdul Waheed,Attaullah Shah,Arshad Mahmood,Ghafar Ali 한국물리학회 2018 Current Applied Physics Vol.18 No.3
The effect of electrochemical reduction on the structural and electrical properties of amorphous as well as annealed TiO2 nanotubes (TNTs) is investigated under ambient conditions. TNTs were prepared by anodizing titanium sheet in ethylene glycol electrolyte containing NH4F and de-ionized water at 40 V for 6 h. Electrochemical reduction is carried out in 1 M aqueous KOH solution for ~15 s at 3 V. TNTs are characterized by SEM, XRD, XPS and impedance spectrometer. XRD results confirm an increase in dspacing for (101) and (200) planes, after electrochemical reduction. XPS data reveal that electrochemical reduction produced prominent shifts of ~0.7e1.0 eV in the binding energies of TNTs. Interestingly, these shifts recover completely (in case of amorphous TNTs) and partially (in case of anatase TNTs) within ~7 days after reduction process due to oxygen uptake. Partial recovery in the binding energies of anatase TNTs is due to the fact that the oxygen vacancies are thermodynamically more stable as compared to amorphous TNTs. Similarly, the electrochemical reduction process decreases the impedance values of TNTs by more than three orders of magnitudes (from MU to kU). The impedance values also recover to the similar values before reduction in a span of ~7days.
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