HERBS AND HERBAL TEAS WITH ANTIOXIDANT PROPERTIES COMPARABLE TO OR SUPERIOR THAN THOSE OF CAMELLIA SINENSISHTML Full Text
HERBS AND HERBAL TEAS WITH ANTIOXIDANT PROPERTIES COMPARABLE TO OR SUPERIOR THAN THOSE OF CAMELLIA SINENSIS
Eric Wei Chiang Chan * 1 and Siu Kuin Wong 2
Faculty of Applied Sciences, UCSI University 1, 56000 Cheras, Kuala Lumpur, Malaysia.
School of Science, Monash University Sunway 2, 46150 Petaling Jaya, Selangor, Malaysia.
ABSTRACT: The antioxidant properties of 20 herbs and 28 herbal teas were analyzed in comparison with those of Camellia sinensis based on total phenolic content (TPC), free radical scavenging (FRS) activity, ferric reducing power (FRP) and ferrous ion chelating (FIC) ability. The main objective was to find out if there are herbs and herbal teas with antioxidant properties comparable to or superior to those of C. sinensis. Results showed that TPC, FRS, and FRP of C. sinensis leave outperformed all herbs. FIC values were, however, weaker than those of banaba and cashew leaves. TPC, FRS, and FRP of C. sinensis teas outperformed all herbal teas except those of banaba, lemon myrtle and stevia. Eleven herbal teas displayed stronger FIC values than C. sinensis teas with those of banaba, spearmint, and peppermint being the most potent. Overall, C. sinensis leaves and teas remain the king of antioxidants based on phenolic content and primary antioxidant properties of FRS and FRP, but not on secondary antioxidant properties of FIC.
Banaba, Cashew, Lemon Myrtle, Stevia, Spearmint, Peppermint
INTRODUCTION: The tea plant Camellia sinensis (L.) Kuntze is a shrub or small tree of the family Theaceae. Leaves are leathery with serrated margin and flowers are solitary, white with conspicuous yellow stamens Fig. 1. Cultivated mostly in the highlands worldwide, teas of C. sinensis are the most widely consumed beverage in the world, second only to water 1. Of the total amount of teas produced and consumed in the world, 78% are black, 20% are green and 2% are oolong tea. The health-promotion and pharmacological properties of C. sinensis teas are widely recognized.
FIG. 1: THE TEA PLANT CAMELLIA SINENSIS
In this short note, data of our research work in the last decade on the antioxidant properties (AOP) of 20 fresh herbs and 28 herbal teas were analyzed in comparison with leaves and teas of C. sinensis. AOP was based on total phenolic content (TPC), free radical scavenging (FRS) activity, ferric reducing power (FRP) and ferrous ion chelating (FIC) ability. The main objective was to find out if there are species of herbs and herbal teas with AOP comparable to or superior to those of C. sinensis.
Leaves of C. sinensis were sampled from tea plantations in Bukit Cheeding, Malaysia. Fresh herbs were purchased from markets in Kuala Lumpur, Malaysia. Of the 28 herbal teas analyzed, 13 were from Thailand, and the remaining 15 were from Malaysia, USA, UK, Japan, South Africa, Sri Lanka, and Vietnam. The green, oolong and black teas of C. sinensis were from China, Malaysia, and Thailand.
MATERIAL AND METHODS: Leaves of fresh herbs (1 g) were powdered in a mortar using liquid nitrogen and extracted with 50 ml of methanol. Teas (1 g) were extracted with 50 ml of boiling water, mimicking the natural process of brewing tea. Infusions were allowed to steep for 1 h with continuous swirling. The extracts were then filtered under suction and stored at 4 ºC for analysis in triplicate within a week. TPC, FRS, FRP, and FIC of the extracts were measured using the respective Folin-Ciocalteu, DPPH, potassium ferricyanide, and ferrozine assays, following the procedures described earlier 2-4. TPC and FRP were expressed as mg gallic acid equivalent (GAE)/100g. FRS was expressed as ascorbic acid equivalent antioxidant capacity (AEAC) in mg ascorbic acid (AA)/100 g. FIC ability was expressed as chelating efficiency concentration (CEC50) in mg/ml or the effective concentration of the extract to chelate ferrous ions by 50%.
RESULT AND DISCUSSION: Fresh herbs with AOP comparable to or superior to C. sinensis leaves are shown in Table 1. Based on TPC, AEAC, FRP, and CEC50, values of leaf shoots and young leaves of C. sinensis were significantly higher than mature leaves. Leaves of C. sinensis outperformed all 20 fresh herbs except for Lagerstroemia speciosa and Anacardium occidentale. These two herbs had stronger CEC50 values than leaf shoots and young leaves, and higher FRP values than mature leaves of C. sinensis.
TABLE 1: LEAVES OF FRESH HERBS WITH ANTIOXIDANT PROPERTIES COMPARABLE TO OR SUPERIOR TO THOSE OF CAMELLIA SINENSIS
|Camellia sinensis (LS)||7670 ± 450||14,470 ± 580||5560 ± 180||3.0 ± 0.8|
|Camellia sinensis (YL)||7280 ± 130||12,820 ± 540||5450 ± 280||4.7 ± 1.4|
|Camellia sinensis (ML)||5840 ± 290||10,220 ± 670||2130 ± 350||7.0 ± 0.6|
|Anacardium occidentale||3890 ± 340||6620 ± 510||3260 ± 240||1.9 ± 0.2|
|Lagerstroemia speciosa||4150 ± 20||6120 ± 330||2960 ± 30||2.1 ± 0.6|
Data on phenolic content and antioxidant activity in fresh weight are means ± standard deviations. Abbreviations and units: TPC = total phenolic content (mg GAE/100 g), AEAC = ascorbic acid equivalent antioxidant capacity (mg AA/100 g), FRP = ferric reducing power (mg GAE/100 g), CEC50 = chelating efficiency concentration to chelate ferrous ions by 50% (mg/ml), (LS) = leaf shoots, (YL) = young leaves and (ML) = mature leaves. Lower CEC50 values indicate stronger ferrous ion chelating ability. Values in bold are significantly stronger than or comparable to those of C. sinensis at p<0.05.
Three other herbs with stronger CEC50 than leaf shoots and young leaves of C. sinensis were Citrus hystrix, Morus alba and Piper sarmentosum with values of 1.2 ± 0.2, 2.7 ± 0.2 and 2.7 ± 0.2 mg/ml, respectively. Most of the 20 herbs had superior FIC than mature C. sinensis leaves. This would imply that these herbs have a better ability to chelate metal ions and inhibit metal-catalyzed free radical formation than C. sinensis.
The potent AOP of C. sinensis leaves is well documented 2, 5, which have been attributed to their ‘signature’ flavanols or catechins, which constitute up to 30% of dry weight 6. Principal catechins are epigallocatechin- 3- gallate (EGCG), epigallo-catechin (EGC), epicatechin-3-gallate (ECG), gallocatechin (GC) and epicatechin (EC). Studies have been conducted on the chemical composition, and content of C. sinensis leaves of different ages. EGCG, the main flavanol in leaf shoots, constituted up to 115 mg/g dry weight 7. The contents of EGC, EGCG, and ECG in young leaves were 1.7, 2.3 and 2.4 times greater than in mature leaves 8.
The outstanding AOP of L. speciosa and A. occidentale leaves far exceeded those of Piper species including temperate culinary herbs of rosemary, thyme and marjoram 9, 10.
Leaves of L. speciosa trees with purple flowers had significantly higher values than those with pink flowers 11. Ellagitannins, terpenoids, flavonoids, phenolic acids, and ellagic acid derivatives are the major constituents of L. speciosa leaves 12. Leaves of A. occidentale contain kaempferol 3-O-glucoside, kaempferol 3-O-arabinofuranoside, quercetin 3-O-glucoside and quercetin 3-O-galactoside as major flavonoids 13.
Herbal teas with AOP comparable to or superior to teas of C. sinensis are shown in Table 2. Only teas of L. speciosa, Backhousia citriodora, and Stevia rebaudiana could match those of C. sinensis. All teas of C. sinensis possessed very strong TPC, AEAC, and FRP with green tea having the highest values followed by oolong and black teas.
TABLE 2: HERBAL TEAS WITH ANTIOXIDANT PROPERTIES COMPARABLE TO OR SUPERIOR TO TEAS OF CAMELLIA SINENSIS
|Species, tea, and brand||TPC||AEAC||FRP||CEC50|
|Camellia sinensis, green, Boh||14,120 ± 1810||25,000 ± 2780||14,300 ± 1100||1.8 ± 0.3|
|Camellia sinensis, green, Sea Dyke||11,370 ± 1480||18,460 ± 1740||8400 ± 1100||1.4 ± 0.1|
|Lagerstroemia speciosa, banaba, TriSiam||10,300 ± 260||17,890 ± 170||7840 ± 140||0.3 ± 0.0|
|Camellia sinensis, oolong, Sea Dyke||9090 ± 460||16,170 ± 2480||6900 ± 420||1.9 ± 0.2|
|Camellia sinensis, black, Lipton||8490 ± 800||11,550 ± 1150||5300 ± 300||1.7 ± 0.1|
|Backhousia citriodora, lemon myrtle, Boh||7560 ± 130||13,600 ± 800||6100 ± 60||1.2 ± 0.2|
|Camellia sinensis, oolong, An Xi||7500 ± 460||14,450 ± 31||5900 ± 230||1.8 ± 0.5|
|Camellia sinensis, black, Boh||7410 ± 120||10,300 ± 560||5300 ± 300||1.0 ± 0.2|
|Stevia rebaudiana, stevia, TriSiam||7780 ± 660||7730 ± 400||4810 ± 400||1.2 ± 0.0|
Data on phenolic content and antioxidant activity in dry weight are means ± standard deviations. Abbreviations and units: TPC = total phenolic content (mg GAE/100 g), AEAC = ascorbic acid equivalent antioxidant capacity (mg AA/100 g), FRP = ferric reducing power (mg GAE/100 g) and CEC50 = chelating efficiency concentration to chelate ferrous ions by 50% (mg/ml). Lower CEC50 values indicate stronger ferrous ion chelating ability. Values in bold are significantly stronger than or comparable to those of C. sinensis at p<0.05.
The potent AOP of S. rebaudiana can be attributed to its chemical constituents of diterpene glycosides comprising steviol, isosteviol, stevioside and rebaudioside 14. Of these compounds, stevioside and rebaudioside have been reported to be active scavengers of hydroxyl and superoxide radicals 15. Myricetin, hesperetin rhamnoside, and hesperetin hexoside are flavonoids reported in B. citriodora 16.
Many studies have reported stronger AOP in green tea than oolong and black teas 17, 18. This might be due to fermentation during tea manufacturing which reduced the levels of catechins. Total catechins were 140 mg/g in green tea and 42 mg/g in black tea. Green tea contained 30-42% of catechins and 5-10% of flavonols in comparison to 3-10% and 6-8% in black tea 19. EGCG, the most abundant catechin, is thought to be responsible for most of the biological activities of green tea. Conversely, black tea contained thearubigin (12-18%) and theaflavin (3-6%), not found in green tea.
In terms of CEC50, a ranking of C. sinensis teas was black > green > oolong. Eleven out of 28 herbal teas displayed stronger chelating ability than C. sinensis teas. Strongest FIC was observed in teas of Mentha spicata, Mentha piperita and L. speciosa with values of 0.3 ± 0.0, 0.4 ± 0.1 and 0.3 ± 0.0 mg/ml, respectively. Other herbal teas with stronger or comparable FIC were M. alba, Origanum vulgare, Alpinia zerumbet, Ficus deltoidea, Cassia angustifolia, and Syzygium guajava. Complementing our findings, green tea possessed high phenolic content and strong antioxidant activities, but its FIC was weaker than that of black tea 20. Among 15 Thai herbal teas analyzed, three had stronger metal chelating capacity than C. sinensis teas 21. Six out of eight herbal teas had stronger FIC than green and black teas 22.
It is important to note that FRS and FRP are primary antioxidant activities, which prevent oxidative damage by donating hydrogen ions directly to free radicals. FIC is a secondary antioxidant activity, which measures the ability of antioxidants to chelate metal ions. Secondary antioxidants act indirectly by preventing the formation of free radicals through the Fenton’s reaction, which has been implicated in many diseases. Herbal teas with high TPC tend to have high FRS and FRP (both R2 = 0.947). There is no such correlation with FIC (R2 = 0.165), i.e. herbal teas with high TPC can have weak FIC and vice versa.
CONCLUSION: In conclusion, fresh leaves and teas of C. sinensis remain the king of antioxidants in terms of phenolic content, and primary antioxidant activities of FRS and FRP, when compared with other herbs and herbal teas. However, its supremacy fades in terms of FIC. Much has been documented on the chelating potency of green tea. It is time that the chelating ability of black tea and some herbal teas be given due attention.
CONFLICT OF INTEREST: Nil
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How to cite this article:
Chan EWC and Wong SK: Herbs and herbal teas with antioxidant properties comparable to or superior than those of Camellia sinensis. Int J Pharmacognosy 2015; 2(1): 33-37. doi: 10.13040/IJPSR.0975-8232.2(1).33-37.
This Journal licensed under a Creative Commons Attribution-Non-commercial-Share Alike 3.0 Unported License.
E. W. C. Chan * and S. K. Wong
Faculty of Applied Sciences, UCSI University, Cheras, Kuala Lumpur, Malaysia.
29 November 2014
27 December 2014
30 December 2014
01 January 2015