University of Massachusetts Amherst University of Massachusetts Amherst
ScholarWorks@UMass Amherst ScholarWorks@UMass Amherst
Stockbridge Faculty Publication Series Stockbridge School of Agriculture
2016
An Overview of Plant Phenolic Compounds and Their Importance An Overview of Plant Phenolic Compounds and Their Importance
in Human Nutrition and Management of Type 2 Diabetes in Human Nutrition and Management of Type 2 Diabetes
Derong Lin
Sichuan Agricultural University
Mengshi Xiao
Sichuan Agricultural University
Jingjing Zhao
Sichuan Agricultural University
Zhuohao Li
Sichuan Agricultural University
Baoshan Xing
University of Massachusetts Amherst
See next page for additional authors
Follow this and additional works at: https://scholarworks.umass.edu/stockbridge_faculty_pubs
Lin, Derong; Xiao, Mengshi; Zhao, Jingjing; Li, Zhuohao; Xing, Baoshan; Li, Xindan; King, Maozhu; Li,
Liangyu; Zhang, Qing; Liu, Yaowen; Chen, Hong; Qin, Wen; Wu, Hejun; and Chen, Saiyan, "An Overview of
Plant Phenolic Compounds and Their Importance in Human Nutrition and Management of Type 2
Diabetes" (2016).
Molecules
. 9.
https://doi.org/10.3390/molecules21101374
This Article is brought to you for free and open access by the Stockbridge School of Agriculture at
ScholarWorks@UMass Amherst. It has been accepted for inclusion in Stockbridge Faculty Publication Series by an
authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact
scholarworks@library.umass.edu.
Authors Authors
Derong Lin, Mengshi Xiao, Jingjing Zhao, Zhuohao Li, Baoshan Xing, Xindan Li, Maozhu King, Liangyu Li,
Qing Zhang, Yaowen Liu, Hong Chen, Wen Qin, Hejun Wu, and Saiyan Chen
This article is available at ScholarWorks@UMass Amherst: https://scholarworks.umass.edu/
stockbridge_faculty_pubs/9
molecules
Review
An Overview of Plant Phenolic Compounds and
Their Importance in Human Nutrition and
Management of Type 2 Diabetes
Derong Lin
1,
*
,†
, Mengshi Xiao
1,†
, Jingjing Zhao
1,†
, Zhuohao Li
1,†
, Baoshan Xing
2
,
Xindan Li
1,†
, Maozhu Kong
1,†
, Liangyu Li
1,†
, Qing Zhang
1
, Yaowen Liu
1
, Hong Chen
1
,
Wen Qin
1
, Hejun Wu
1
and Saiyan Chen
1
1
College of Food Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an 625014, Sichuan,
China; 18227591863@126.com (M.X.); 18227591123@126.com (J.Z.); sakataharuka@hotmail.com (Z.L.);
18227589580@163.com (X.L.); 18227589574@163.com (M.K.); 18227584828@163.com (L.L.);
zhangqing@sicau.edu.cn (Q.Z.); lyw@my.swjtu.edu.cn (Y.L.); chenhong945@sicau.edu.cn (H.C.);
qinwen@sicau.edu.cn (W.Q.); hejunwu520@163.com (H.W.); 13551570482@163.com (S.C.)
2
Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA; bx@umass.edu
* Correspondence: lindr2018@sicau.edu.cn; Tel.: +86-835-288-2311
† These authors contributed equally to this work.
Academic Editor: Pinarosa Avato
Received: 8 September 2016; Accepted: 12 October 2016; Published: 15 October 2016
Abstract:
In this paper, the biosynthesis process of phenolic compounds in plants is summarized,
which includes the shikimate, pentose phosphate and phenylpropanoid pathways. Plant phenolic
compounds can act as antioxidants, structural polymers (lignin), attractants (flavonoids and
carotenoids), UV screens (flavonoids), signal compounds (salicylic acid and flavonoids) and defense
response chemicals (tannins and phytoalexins). From a human physiological standpoint, phenolic
compounds are vital in defense responses, such as anti-aging, anti-inflammatory, antioxidant and
anti-proliferative activities. Therefore, it is beneficial to eat such plant foods that have a high
antioxidant compound content, which will cut down the incidence of certain chronic diseases, for
instance diabetes, cancers and cardiovascular diseases, through the management of oxidative stress.
Furthermore, berries and other fruits with low-amylase and high-glucosidase inhibitory activities
could be regarded as candidate food items in the control of the early stages of hyperglycemia
associated with type 2 diabetes.
Keywords: phenolic compounds; biosynthesis; function; complication; type 2 diabetes
1. Introduction
Phenolic compounds are secondary metabolites, which are produced in the shikimic acid
of plants and pentose phosphate through phenylpropanoid metabolization [
1
]. They contain
benzene rings, with one or more hydroxyl substituents, and range from simple phenolic molecules
to highly polymerized compounds [
2
] (Figure 1). In the synthesis of phenolic compounds, the
first procedure is the commitment of glucose to the pentose phosphate pathway (PPP) and
transforming glucose-6-phosphate irreversibly to ribulose-5-phosphate. The first committed procedure
in the conversion to ribulose-5-phosphate is put into effect by glucose-6-phosphate dehydrogenase
(G6PDH). On the one hand, the conversion to ribulose-5-phosphate produces reducing equivalents of
nicotinamide adenine dinucleotide phosphate (NADPH) for cellular anabolic reactions. On the other
hand, PPP also produces erythrose-4-phosphate along with phosphoenolpyruvate from glycolysis,
which is then used through the phenylpropanoid pathway to generate phenolic compounds after being
channeled to the shikimic acid pathway to produce phenylalanine [
3
,
4
] (Figure 2). Phenolics are the
Molecules 2016, 21, 1374; doi:10.3390/molecules21101374 www.mdpi.com/journal/molecules
Molecules 2016, 21, 1374 2 of 19
most pronounced secondary metabolites found in plants, and their distribution is shown throughout
the entire metabolic process. These phenolic substances, or polyphenols, contain numerous varieties
of compounds: simple flavonoids, phenolic acids, complex flavonoids and colored anthocyanins [
5
]
(Figure 1). These phenolic compounds are usually related to defense responses in the plant. However,
phenolic metabolites play an important part in other processes, for instance incorporating attractive
substances to accelerate pollination, coloring for camouflage and defense against herbivores, as well as
antibacterial and antifungal activities [6–8].
Molecules 2016, 21, 1374 2 of 18
most pronounced secondary metabolites found in plants, and their distribution is shown throughout
the entire metabolic process. These phenolic substances, or polyphenols, contain numerous varieties
of compounds: simple flavonoids, phenolic acids, complex flavonoids and colored anthocyanins [5]
(Figure 1). These phenolic compounds are usually related to defense responses in the plant. However,
phenolic metabolites play an important part in other processes, for instance incorporating attractive
substances to accelerate pollination, coloring for camouflage and defense against herbivores, as well
as antibacterial and antifungal activities [6–8].
Figure 1. Common phenolic compounds in plants comprise an aromatic ring, bear one or more hydroxyl
substituents and range from simple phenolic molecules to highly polymerized compounds (modified
from Velderrain-Rodríguez et al., 2014) [2].
Phenolic compounds, including stress-linked phytochemicals, have been related to favorable
impacts, which are caused by the consumption of fruits and vegetables, particularly due to their
antioxidant activity [9]. Balasundram et al., (2006) reviewed [10] the antioxidant activity, occurrence
and latent uses of phenolic compounds in plants and agri-industrial by-products. Under those
reports, fruits, vegetables and beverages are the principle sources of phenolic compounds in the
human diet. Plant polyphenols as dietary antioxidants in human health and disease might offer some
protection against oxidative damage. As natural antioxidants, phenolic compounds are found
abundantly in plant food and beverages, which play vital parts in pabulum and healthcare. Some
research has indicated that phenolic compounds are the most affluent in ordinary human diets
among the dietary antioxidants. Lately, phenolic compounds have obtained significant interest based
Figure 1.
Common phenolic compounds in plants comprise an aromatic ring, bear one or more
hydroxyl substituents and range from simple phenolic molecules to highly polymerized compounds
(modified from Velderrain-Rodríguez et al., 2014) [2].
Phenolic compounds, including stress-linked phytochemicals, have been related to favorable
impacts, which are caused by the consumption of fruits and vegetables, particularly due to their
antioxidant activity [
9
]. Balasundram et al., (2006) reviewed [
10
] the antioxidant activity, occurrence
and latent uses of phenolic compounds in plants and agri-industrial by-products. Under those
reports, fruits, vegetables and beverages are the principle sources of phenolic compounds in the
human diet. Plant polyphenols as dietary antioxidants in human health and disease might protect
against oxidative damage. As natural antioxidants, phenolic compounds are found abundantly in
plant food and beverages, which play vital parts in pabulum and healthcare. Some research have
indicated that phenolic compounds are the most affluent in ordinary human diets among the dietary
Molecules 2016, 21, 1374 3 of 19
antioxidants. Lately, phenolic compounds have obtained significant interest based on active reports
of their conjectural part in holding back a variety of human illnesses [
11
–
13
]. It is well-known that
normally consumed fresh and processed fruits, for instance raspberries, cranberries, apples, grapes,
pears and jams, are the major sources of phenolic compounds, and strawberries and their derived
products, like juices [
3
,
14
]. This review focuses on the present understanding of the potential efficacy
of polyphenols on carbohydrate metabolism and glucose homeostasis, which has been commendably
studied in vitro, some clinical experiments and animal models [15].
Molecules 2016, 21, 1374 3 of 18
on active reports of their conjectural part in holding back a variety of human illnesses [11–13]. It is
well-known that normally consumed fresh and processed fruits, for instance raspberries, cranberries,
apples, grapes, pears and jams, are the major sources of phenolic compounds, and strawberries and
their derived products, like juices [3,14]. This review focuses on the present understanding of the
potential efficacy of polyphenols on carbohydrate metabolism and glucose homeostasis, which has
been commendably studied in vitro, some clinical experiments and animal models [15].
Figure 2. Biosynthesis of phenol compounds in the pentose phosphate, shikimate and
phenylpropanoid pathways in plants (modified from Vattem et al., 2005, and Lin et al., 2010) [3,4].
2. Health Benefits of Phenolic Compounds
The chemical constituents extracted from plants, phenolic compounds, can inhibit the absorption
of amylase in the treatment of carbohydrate absorption, such as diabetes [16]. There are many fruits
Figure 2.
Biosynthesis of phenol compounds in the pentose phosphate, shikimate and phenylpropanoid
pathways in plants (modified from Vattem et al., 2005, and Lin et al., 2010) [3,4].