2000. 3000. 4000. Salvia limbata. Malva neglecta. Phlomis armeniaca. Plantago lanceolata. Anchonium elichrysifolium a a c b d. ORAC (μ mol Trolox Eq./g DW).
Phenolic contents, antioxidant capacities and inhibitory activities against key metabolic syndrome relevant enzymes of herbal teas from Eastern Anatolia, Turkey Abdullah Dalar a, b, Musa Türker b, Izabela Konczak a a
CSIRO Food and Nutritional Sciences, North Ryde, NSW, Australia b Yüzüncü Yıl University, Faculty of Science, Department of Biology, Van, Turkey Introduction Herbal teas are hot water infusions of fresh or dried plants (roots, leaves, fruits or grains), which are different from tea bush (C. sinensis). While black and/or green tea prepared from C. sinensis leaf dominates in some Asian countries where tea drinking is a ritual and a lifestyle, in many European and Middle East countries various types of traditional fruit teas/herbal infusions are preferred. The type of herbal teas in use depends on local culture, traditions, ethnobotanic knowledge and diversity of local flora. In the Eastern Anatolia herbal teas are an essential part of a lifestyle with their primary function to warm up during long-cold winters and cool summer’s days of the mountain climate. The objective of this study was to evaluate the hydrophilic extracts representing herbal infusions of five common herbs used for preparation of teas with regards to their composition, antioxidant capacities and in vitro inhibitory activities against key digestive enzymes.
Figure 2. Dose dependent suppression of α-glucosidase (A) and lipase (B) by hydrophilic extracts representing herbal teas from Eastern Anatolia
60
ta lim ba S.
ac a en i m ar
hr
P.
ys ifo liu
ta A. e
lic
eg lec
lim ba S.
ac a en i m ar
hr A .e
P.
ys ifo liu
ta eo la nc la
P.
ta
0 ta
0 m
20
m
40
20
eg le ct
2.5 mg/ml
eo la
40
5 mg/ml
nc
3.3 mg/ml
7.5 mg/ml
80
la
60
10 mg/ml
P.
6.6 mg/ml
M .n
d
Anchonium elichrysifolium
B 100
10 mg/ml
80
a
I
13.3 mg/ml
lic
Figure 1. Phenolic contents (I), oxygen radical absorbance capacities (II) and total reducing capacities (III) of hydrophylic extracts representing herbal teas from Eastern Anatolia
Inhibition (%)
A 100
M .n
Results and discussion Lyophilized aqueous extracts representing herbal infusions contained a high level of total phenolics and exhibited pronounced antioxidant capacities, as evaluated using two reagent-based methods: oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) (Figure 1). This indicates that the evaluated herbal infusions comprise a rich mixture of phytochemicals that offer a comprehensive protection from reactive oxygen species and oxidants.
All teas successfully suppressed the activities of key enzymes involved in metabolic syndrome: α-amylase, α-glucosidase, pancreatic lipase and ACE. P. armeniaca, S. limbata and P. lanceolata had weak inhibitory activities against α-amylase and pronounced inhibitory activities against α-glucosidase which may suggest potential anti-diabetic properties (Figure 2 and Table 1). Moreover, P. lanceolata was the strongest inhibitor of pancreatic lipase and appears to be an interesting source for potential anti-diabetic and anti-obesity activity studies. The HPLC and LC/MS analysis revealed that the main phenolic compound of P.lanceolata was luteolin-7-O-glucoside. Traces of rutin, chlorogenic acid and quercetin hexoside were also detected. These results suggest that luteolin glucoside could be the main contributor to the antioxidant, antidiabetic and antiobesity properties of P. lanceolata herbal infusion and supports its traditional use as anti-diabetic tea.
Inhibition (%)
Materials and Methods 1. Collection of plant material (leaf) during vegetation season and air-drying 2. Preparation of ethanol-based lyophilized hydrophlic extracts 3. Determination of total phenolics (Folin-Ciocalteu assay) and antioxidant capacities (FRAP and ORAC assays) 4. In vitro inhibitory activity towards α-amylase,α-glucosidase, pancreatic lipase and angiotensin converting enzyme (ACE) 5. Identification and quantification of phenolic compounds by LC-PDA-MS/MS and HPLC-DAD
a
Plantago lanceolata
b
Phlomis armeniaca Malva neglecta
d c
Salvia limbata 0
20
40
60
80
100
Total phenol i cs (mg Gal l i c aci d Eq./g DW)
II Anchonium elichrysifolium
c a
Plantago lanceolata
b
Phlomis armeniaca
d
Malva neglecta
a
Salvia limbata 0
1000
2000
3000
4000
ORAC ( mol Trol ox Eq./g DW)
III d
Anchonium elichrysifolium
a
Plantago lanceolata
c
Phlomis armeniaca
d
Malva neglecta Salvia limbata
b 0
500
1000
1500
FRAP ( mol Fe 2+ Eq./g DW)
Conclusion Hydrophilic lyophilized extracts representing herbal infusions exhibited comparable or superior levels of phenolic compounds and antioxidant capacity to commercially available black tea (Camellia sinensis) and numerous herbal infusions. All teas successfully suppressed the activities of key enzymes involved in metabolic syndrome. Phenolic compounds were identified as the source of antioxidant capacities and enzyme-inhibitory activities. This study for the first time revealed potential healthenhancing properties of traditional herbal infusions from Eastern Anatolia and it warrants further studies towards identification of novel sources for the prevention of metabolic syndrome related health ailments.
Means with different letters were significantly different at the level (p
