Bahman Nickavar

Bioassay-Guided Separation of an α-Amylase Inhibitor Anthocyanin from Vaccinium arctostaphylos Berries

Vaccinium arctostaphylos is a traditional medicinal plant in Iran used for the treatment of diabetes mellitus. In our search for antidiabetic compounds from natural sources, we found that the extract obtained from V. arctostaphylos berries showed an inhibitory effect on pancreatic α-amylase in vitro [IC50 = 1.91 (1.89 -1.94) mg/mL]. The activity-guided purification of the extract led to the isolation of malvidin-3-O-β-glucoside as an α-amylase inhibitor. The compound demonstrated a dose-dependent enzyme inihibitory activity [IC50 = 0.329 (0.316 - 0.342) mM].

Fungal transformation of androsta-1,4-diene-3, 17-dione by Aspergillus brasiliensis

BackgroundThe biotransformation of steroids by fungal biocatalysts has been recognized for many years. There are numerous fungi of the genus Aspergillu s which have been shown to transform different steroid substances. The possibility of using filamentous fungi Aspergillus brasiliensis cells in the biotransformation of androsta-1,4-diene-3,17-dione, was evaluated.MethodsThe fungal strain was inoculated into the transformation medium which supplemented with androstadienedione as a substrate and fermentation continued for 5 days. The metabolites were extracted and isolated by thin layer chromatography. The structures of these metabolites were elucidated using 1H-NMR, broadband decoupled 13C-NMR, EI Mass and IR spectroscopies.ResultsThe fermentation yielded one reduced product: 17β-hydroxyandrost-1,4-dien-3-one and two hydroxylated metabolites: 11α-hydroxyandrost-1,4-diene-3,17-dione and 12β-hydroxyandrost-1,4-diene-3,17-dione.ConclusionsThe results obtained in this study show that A. brasiliendsis could be considered as a biocatalyst for producing important derivatives from androstadienedione.

Comparative Analysis of Volatile Constituents from Two Ziziphora clinopodioides Subspecies (Z. clinopodioides subsp. elbursensis and Z. clinopodioides subsp. filicaulis)

Abstract The hydrodistilled volatile oil of Ziziphora clinopodioides subsp. elbursensis (Rech. f.) Rech. f. and Ziziphora clinopodioides subsp. filicaulis (Rech. f.) Rech. f. were analyzed by GC-FID and GC-MS. Twenty-eight compounds were identified in the oil of Z. clinopodioides subsp. elbursensis with pulegone (38.9 %), menthone (10.4 %), piperitenone (8.5 %), 1,8-cineol (7.5 %) and neo-menthol (5.2 %) as the main constituents. Thirty-four components were identified in the oil of Z. clinopodioides subsp. filicaulis with pulegone (21.5 %), carvacrol (16.6 %), thymol (10.1 %), piperitenone (9.3 %) and p-menth-3-en-8-ol (5.7 %). Both oils were rich in oxygenated monoterpenoids (86.2 % and 83.0 %, respectively).

Baeyer-Villiger oxidation of progesterone by Aspergillus sojae PTCC 5196

HIGHLIGHTSProgesterone converted by the fungus Aspergillus sojae PTCC 5196 produced testololactone.The production of testololactone indicated fungal Baeyer‐Villiger monooxygenase (BVMO) activity.Substrate‐induced cultures have a decisive impact on the metabolism of progesterone.Progesterone, a C‐21 steroidal compound, induced 17&bgr;‐acetyl side chain cleavage.Androstenedione, testosterone, and DHEA, C‐19 steroidal substances, induced ring‐D oxidation. ABSTRACT Microbial transformations are capable of producing steroid substances difficult to synthesize by chemical methods. Strains belonging to the genus Aspergillus are effective facilitators of microbial biotransformations due to their enzymatic diversity. In this study, the biotransformation of progesterone by the fungus Aspergillus sojae (A. sojae) PTCC 5196 was examined. Analysis of the bioconversion process revealed that progesterone was converted to testololactone through a three‐step pathway (17&bgr;‐acetyl side chain cleavage, 17&bgr;‐hydroxyl oxidation, and oxygenative lactonization of 17‐ketone), indicating the presence of Baeyer‐Villiger monooxygenase (BVMO) activity in the fungal strain. GC analysis confirmed the production of testololactone with a yield of 99% in 24h. Faster testololactone production was induced in the presence of both C‐21 (progesterone) and C‐19 (androstenedione, testosterone, and dehydroepiandrosterone [DHEA]) steroid substances. Due to the high biotransformation rate observed in the present study, A. sojae may be a novel and promising candidate in the production of testololactone.