Bioactive (Poly)phenols, Volatile Compounds from Vegetables, Medicinal and Aromatic Plants

Abstract

Polyphenols, as well as volatile compounds responsible for aromatic features, play a critical role in the quality of vegetables and medicinal, and aromatic plants (MAPs). The research conducted in recent years has shown that these plants contain biologically active compounds, mainly polyphenols, that relate to the prevention of inflammatory processes, neurodegenerative diseases, cancers, and cardiovascular disorders as well as to antimicrobial, antioxidant, and antiparasitic properties. Throughout the years, many researchers have deeply studied polyphenols and volatile compounds in medicinal and aromatic plants, particularly those associated with consumer's choices or with their beneficial properties. In this context, the purpose of this review is to provide an overview of the presence of volatile and nonvolatile compounds in some of the most economically relevant and consumed vegetables and medicinal and aromatic plants, with an emphasis on bioactive polyphenols, polyphenols as prebiotics, and, also, the most important factors that affect the contents and profiles of the volatile and nonvolatile compounds responsible for the aromatic features of vegetables and MAPs. Additionally, the new challenges for science in terms of improving polyphenol composition and intensifying volatile compounds responsible for the positive characteristics of vegetables and medicinal and aromatic plants are reported.

Keywords: aromatic plants; bioactive compounds; consumers; medicinal plants; phenolic compounds; plant breeders; vegetables; volatile compounds.

Figure 1

Chemical structures of hydroxybenzoic acids (a) and hydroxycinnamic acids (b).

Figure 2

Chemical structures of rosmarinic acid and chlorogenic acid.

Figure 3

Structures of the major flavones.

Figure 4

Structures of the major flavonol aglycones.

Figure 5

Structures of monomeric flavan-3-ols.

Figure 6

Chemical structures of isoflavonoids.

Figure 7

Chemical structures of anthocyanidins.

Figure 8

Chemical structure of procyanidins.

Figure 9

Quinone structures.

Figure 10

Chemical structure resveratrol.

Figure 11

Chemical structure of (Z, Z)-3,6-nonadienol.

Figure 12

Chemical structure of (E)-2-nonenal and (Z)-3-hexenal.

Figure 13

Chemical structure of 3-butylphthalide.

Figure 14

Chemical structure of 2-Isobutyl 3-methoxypyrazine and 3-sec-butyl-2-methoxypyrazine.

Figure 15

Chemical structure of geosmin.

Figure 16

Chemical structure of sulphur-containing volatile compounds.

Figure 17

The principal plant volatile compounds are derived from four biosynthetic classes of precursors: terpenoids, fatty acid catabolites, aroma, and amino acid derived products. Many of these products are made more lipophilic (storage in membranes or oil bodies) before their release by removing or masking hydrophilic functional groups through reduction, methylation, or acylation reactions. Adapted from Baldwin et al. [157].

Figure 18

Generalized pathways for the synthesis of some nonvolatile compounds present in plants. Adapted from Ncube and Staden [161].