Igor A. Parshikov

Bio: Igor A. Parshikov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Hydroxylation & Aspergillus niger. The author has an hindex of 12, co-authored 29 publications receiving 387 citations. Previous affiliations of Igor A. Parshikov include Moscow State University & University of Mississippi.

Transformation of artemisinin by Cunninghamella elegans

Abstract: Semi-synthetic derivatives of the anti-malarial drug artemisinin hold great promise in the search for an effective and economical treatment of chloroquine-resistant forms of malaria. Unfortunately, synthetic functionalization of the artemisinin skeleton is often tedious and/or impractical. We seek to utilize 7β-hydroxyartemisinin, obtained from microbial transformation, as a semi-synthetic precursor for the synthesis of novel 7β-substituted artemisinin anti-malarial agents. Here we employ liquid cultures of Cunninghamella elegans as a means for the rational and economical bioconversion of artemisinin to 7β-hydroxyartemisinin in 78.6% yield. In addition, there were three other bioconversion products: 7β-hydroxy-9α-artemisinin (6.0%), 4α-hydroxy-1-deoxoartemisinin (5.4%), and 6β-hydroxyartemisinin (6.5%).

Microbial transformation of artemisinin to 5-hydroxyartemisinin by Eurotium amstelodami and Aspergillus niger

Abstract: Transformation of the anti-malarial drug artemisinin by the fungi Eurotium amstelodami and Aspergillus niger were investigated. Cultures were grown in sucrose/malt broth with artemisinin for 14 days and extracted with ethyl acetate. Extracts were characterized by liquid chromatography. Two metabolites from each fungal extract were isolated and identified using mass spectrometry and nuclear magnetic resonance. 5β-hydroxyartemisinin and 7β-hydroxyartemisinin were isolated in 63 and 32% yields, respectively, from the extract of E. amstelodami, and 80 and 19%, respectively, from the extract of A. niger.

Biotransformation of Steroids and Flavonoids by Cultures of Aspergillus niger

Abstract: Steroids are derivatives of the triterpenoid squalene, containing three fused cyclohexane rings and a cyclopentane ring, and flavonoids are derivatives of L-phenylalanine, containing two aromatic rings joined by a three-carbon bridge that may form part of a heterocyclic ring. A great variety of steroids and flavonoids are produced by plants, and many additional steroids are produced by animals or fungi. Because these compounds have many nutritional and pharmaceutical values, and many of them cannot be produced by chemical synthesis, biotechnological processes are being developed that use cultures of Aspergillus niger and other fungi to transform steroids and flavonoids to a variety of metabolites. These biochemical reactions, including hydroxylation, dehydrogenation, O-methylation, demethylation, cleavage of rings, epoxide hydrolysis, double bond reduction, and others, may be used for the production of higher-value compounds.

Fluoroquinolone Antibiotics in the Environment

Abstract: The occurrence of human and veterinary pharmaceuticals in soil and water (Thiele-Bruhn 2003; Snyder et al. 2003; Hamscher et al. 2004; Kay et al. 2004) has led to increased research activities among environmental scientists to find out their possible environmental threats. As antibiotics are used for human and animal medical care, there is a possibility for these drugs to reach the environment via direct or indirect contamination (Thiele-Bruhn 2003; Boxall et al. 2004). As they are produced and applied with the aim of being biologically highly effective, their occurrence is of ecotoxicological interest. In Berlin, Germany, the groundwater wells located near contaminated surface waters showed a concentration of pharmaceuticals at the µg/L level (Heberer 2002). Thus, at such a level of contamination, the use of groundwater for drinking purposes may pose a potential risk. Studies on the behavior of animal drugs and their metabolites after excretion, along with their transport from agricultural sources into surface water and groundwater by overland-flow runoff and leaching, are of utmost importance at present.

Human skin volatiles: a review

Abstract: Odors emitted by human skin are of great interest to biologists in many fields; applications range from forensic studies to diagnostic tools, the design of perfumes and deodorants, and the ecology of blood-sucking insect vectors of human disease. Numerous studies have investigated the chemical composition of skin odors, and various sampling methods have been used for this purpose. The literature shows that the chemical profile of skin volatiles varies greatly among studies, and the use of different sampling procedures is probably responsible for some of these variations. To our knowledge, this is the first review focused on human skin volatile compounds. We detail the different sampling techniques, each with its own set of advantages and disadvantages, which have been used for the collection of skin odors from different parts of the human body. We present the main skin volatile compounds found in these studies, with particular emphasis on the most frequently studied body regions, axillae, hands, and feet. We propose future directions for promising experimental studies on odors from human skin, particularly in relation to the chemical ecology of blood-sucking insects.