The Biotransformation of Sesquiterpenoids by Mucor plumbeus

Abstract

The regiospecificity of the microbiological hydroxylation of sesquiterpenoids by the fungus, Mucor plumbeus is reviewed. It is shown to fit a pattern which can be rationalized in terms of a model. INTRODUCTIONBiotransformations can provide economical and environmentally friendly means of carrying out reactions with a regio-and stereospecificity that can sometimes complement that of chemical methods. Amongst these methods, microbiological hydroxylations constitute powerful synthetic tools for substitution at centres that are often otherwise chemically inert. These biohydroxylations may have a high regioselectivity and they can proceed without the use of protecting groups under fermentation conditions which are chemically mild. The method has been reviewed on many occasions and is the subject of several books [1]. However these reviews have tended to concentrate on groups of substrates such as steroids [2], sesquiterpenoids [3] and diterpenoids [4] and the products of biotransformation by several organisms rather than addressing the capabilities of particular organisms. If an organism is to be considered for general preparative use, a predictive model of its capabilities is required.In order to overcome difficulties associated with factor regeneration and the isolation of potentially sensitive enzyme systems, intact organisms are commonly used for microbiological hydroxylation. The application of microbiological hydroxylation is limited by a shortage of predictive models for particular organisms. Such models have the obvious limitations that they are constructed in terms of the whole organism even though more than one hydroxylase may be present. Nevertheless useful information on the steric relationships which exist between polar groups in a substrate and the site of hydroxylation has accrued from the study of steroid transformations. Some models have been proposed as a consequence of this work [5]. However the steroids are relatively flat and hence there is a limit to the extent to which they can probe the three-dimensional geometry of the active site. Despite these limitations it is possible to predict the likely sites of microbiological hydroxylation of a steroid by a particular organism.Mucor species are common saprophytic fungi which grow on a variety of materials suggesting that they may be capable of transforming a range of different substrates, i.e. they are potentially useful organisms for microbiological transformations. A number have been used for this purpose, including Mucor plumbeus which is the subject of this review.

Microbial Transformation of Triterpenoids

“…Several reviews on microbial transformation of terpenoids have been published in recent years [22][23][24]. Biotransformation has also been used to expand the chemical diversity of terpenoids, the largest group of natural products.…”

Sesquiterpene Lactones from Artemisia absinthium. Biotransformation and Rearrangement of the Insect Antifeedant 3α-hydroxypelenolide

“…Thus, this carbon appears in 12 at δ C 203.4, a value more similar to that of 6-hydroxytremetone (15) (δ C 201.9) [23] than that of 6-methoxytremetone ( 16) (δ C 197.9) [24]. On the other hand, espeletone (11), which we have now also isolated from A. absinthium, could be a possible biogenetic precursor of this new compound, ajenjol (12). Structure 17, with an OH group at C-4, had been assigned to glutinosol, which was obtained from A. glutinosa [25].…”

“…Structures 12 and 13 met the data indicated above. Ajenjol was assigned to structure 12 on the basis of the following considerations: We have now described and assigned the 13 C NMR spectrum (Figure S12) of espeletone (11) [21], which values of C-10. C-11, C-12 and C-13 in its side chain and those of ajenjol ( 12) were identical (Table 1).…”

“…Biotransformations of terpenoids can modify the biological activities of the starting compounds [9] and are also used to study structure-activity relationships of bioactive compounds [10]. In this context, Mucor plumbeus, with a broad substrate specificity [11,12], has been used in biotransformations of diterpenes to develop models to explain their hydroxylations [13][14][15][16][17] and for the biotransformation of an africanane sesquiterpene to give epoxy Plants 2021, 10, 891 2 of 14 derivatives with improved insect antifeedants and insecticidal effects [18]. In this work we describe three unknown compounds, the sesquiterpene lactones absilactone (1) and hansonlactone (2) and the acetophenone derivative artenol (12) [4], isolated from A. absinthium var.…”

Fungal transformation of isosteviol lactone and its biological evaluation for inhibiting the AP-1 transcription factor

“…Microbial transformation is an area of great interest for preparing products which are difficult to obtain by conventional chemical methods (Arantes and Hanson, 2007). There is an increasing body of information about use of biocatalysis for selective conversion of synthetic and natural products to intensify either their biological properties or to lead to new biological activities (Buchanan and Reese, 2001;Gładkowski et al, 2007;Venisetty and Ciddi, 2003).…”