MONOREG – an expert system for structural elucidation of monoterpenes

Abstract

This paper describes a new expert system denominated MONOREG for structural determination of monoterpenes. This system is composed of five programs capable of performing 13 C NMR spectra data analyses and analyses of systematic data from living organisms. At the end of this procedure, it shows the likely skeletons of the compound in question as well as the substructures compatible with the 13 C NMR data. The system was tested on the skeleton elucidation of 40 monoterpenes from a wide variety of structure types and exhibited excellent results in the skeleton prediction process.Résumé : Cet article décrit un nouveau système expert, dénommé MONOREG, utilisé pour la détermination structurale des monoterpènes. Ce système se compose de cinq programmes qui réalisent l'analyse RMN du 13 C d'un composé et utilize aussi des données de systématiques d'organismes vivants. Les squelettes probables sont déterminés ainsi que les sous-structures compatibles avec les données spectrales. Le système a été testé pour l'élucidation de 40 monoterpènes qui appartiennent à divers types de squelettes, et montre d'excellents résultats.Mots clés : monoterpènes, RMN du 13 C, élucidation structurale, analyse assisteé par ordinateur, système expert. Ferreira et al. 1925The MONOREG system MONOREG is a system that performs data analyses of monoterpenes. The idea for this name comes from the Portuguese words monoterpenos (Engl., monoterpenes) and regras (Engl. rules). Basically, this system is composed of five programs: MACRONO, SISCONST, C13MACH, SISOCBOT, Can. ). and REGRAS, which propose, at the end of analysis, a probable skeleton compatible with the entered data. This system is also capable of carrying out analyses of data from MS, however, these data were not inserted in the system. Therefore, they were not evaluated. The programs mentioned above are described below. The MACRONO programThe MACRONO program (22, 23) identifies the common substituent groups present in the natural products, such as acetate, angelate, tiglate. From the 13 C NMR chemical shifts and respective multiplicities of the substance in question, the program searches the database for the most probable substituent groups present in this substance and shows to the user the selected substituent groups together with their average error range of chemical shifts. The average error range is the average deviation calculated from the chemical shifts of the sample in question and then matched with the chemical shifts values stored in the database. Therefore, the smaller the range, the more reliable the result be will.The database especially elaborated for this program contains 161 substituent groups that are frequently encountered in terpenoid compounds. It is essential that the MACRONO program is the first program to be used in the MONOREG

Chemotaxonomic Relationships in Celastraceae Inferred from Principal Component Analysis (PCA) and Partial Least Squares (PLS)

“…In higher hierarchical levels, such as tribe, the NOC is the sum of the NOCs of all genera in the tribe, and thus successively for subfamily, etc. The data obtained from the literature search were used to build a database containing 664 botanical occurrences of triterpenes, whose structures were coded by the program DATASIS of our expert system SISTEMAT [23][24][25].…”

“…The first routine of the SISTEMAT system [25][26][27][28] showed the number of occurrences for each triterpene skeleton grouped by genus and, consequently, by tribe and subfamily. Table 2 shows a summary of triterpene occurrences by tribes of Celastraceae.…”

Application of a New Program, H1MACH, for Prediction of Iridoid Skeletons

“…[23 -39] Also, the same compounds were tested with the C13MACH program [20,21] that did the same type of analysis but for 13 C NMR spectra data. [23 -39] Also, the same compounds were tested with the C13MACH program [20,21] that did the same type of analysis but for 13 C NMR spectra data.…”

“…However, when the DENDRAL researchers tried to use the structure generator to identify chemical structures of natural products, whose structural diversity and complexity are higher, numerous problems were detected. [19] The SISTEMAT system has been developed with the construction of specific databases of each natural product class, such as monoterpenes, [20] sesquiterpenes, [14] diterpenes, [15] triterpenes [21] and flavonoids. The solution to this problem was the use of information restrictions in the structural determination process, so that this process was not random.…”

Self-Organizing Maps as a New Tool for Classification of Plants at Lower Hierarchical Levels

“…The Asteraceae produces several chemical classes, mainly from the mevalonate pathway, such as monoterpenes, sesquiterpenes, sesquiterpene lactones, diterpenes, and triterpenes [45][46][47][48][49], and compounds produced by other biosynthetic routes, such as, for example, coumarins, flavonoids, polyacetylenes, benzopyranes and benzofuranes [50][51][52][53][54]. Other compounds that are not found in most tribes of Asteraceae, such as pyrrolizidine alkaloids, are not included in this study.…”