Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer

Abstract

Cancer prevention and treatment using traditional Chinese medicines have attracted increasing interest. This study characterizes antioxidant activity and phenolic compounds of traditional Chinese medicinal plants associated with anticancer, comprising 112 species from 50 plant families. The improved ABTS(*+) method was used to systematically assess the total antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC) of the medicinal extracts. The TEAC values and total phenolic content for methanolic extracts of herbs ranged from 46.7 to 17,323 micromol Trolox equivalent/100 g dry weight (DW), and from 0.22 to 50.3 g of gallic acid equivalent/100 g DW, respectively. A positive, significant linear relationship between antioxidant activity and total phenolic content (all R(2) values>/=0.95) showed that phenolic compounds were the dominant antioxidant components in the tested medicinal herbs. Major types of phenolic compounds from most of the tested herbs were preliminarily identified and analyzed, and mainly included phenolic acids, flavonoids, tannins, coumarins, lignans, quinones, stilbenes, and curcuminoids. These medicinal herbs exhibited far stronger antioxidant activity and contained significantly higher levels of phenolics than common vegetables and fruits. Traditional Chinese medicinal plants associated with anticancer might be potential sources of potent natural antioxidants and beneficial chemopreventive agents.

Fig. 1

Distribution (percentage) of 112 medicinal herbs associated with anticancer among different ranges of antioxidant activity (TEAC value). A: <100.0 μmol TEAC/100 g DW; B: 100.1−500.0 μmol/100 g; C: 500.1−1,000.0 μmol/100 g; and D: >1,000.1 μmol/100 g (TEAC value of methanol extracts).

Fig. 2

Relationship between total antioxidant capacity (μmol TEAC/100 g DW) and total phenolic content (g gallic acid equivalents/100 g DW) of methanolic (A, B) and aqueous (C, D) extracts from 112/110 medicinal herbs associated with anticancer.

Fig. 3

Typical HPLC chromatogram of parts of phenolic standards at 280 nm analyzed with the improved method. Peaks: 1, gallic acid; 2, catechin; 3, vanillic acid; 4, caffeic acid; 5, cyanidin-3-O-glucoside; 6, ferulic acid; 7, coumarin; 8, resveratrol; 9, myricitrin; 10, rutin; 11, quercitrin; 12, diosmin; 13, daidzein; 14, glycitein; 15, quercetin; 16, emodin-8-O-glucoside; 17, luteolin; 18, hesperetin; 19, kaempferol; 20, baicalein; 21, alizarin; 22, galangin; 23, flavonol; 24, chalcone; 25, rhein; 26, emodin; 27, quininzarin; 28, physcion.

Fig. 4

HPLC profiles of methanolic extracts from four selected medicinal herbs: (A) phenolic acids, coumarins and flavonoids from aerial parts of Artemisia annua; (B) lignans and phenolic acid from fruits of Arctium lappa; (C) anthraquinones, stilbene and phenolic acid from rhizomes of Polygonum cuspidatum (tannins removed); and (D) flavonoids, phenolic acid and tannins from flowers of Rosa chinensis. Elution monitored at 250 nm (C), 280 nm (B and D), and 370 nm (A).

Fig. 4

HPLC profiles of methanolic extracts from four selected medicinal herbs: (A) phenolic acids, coumarins and flavonoids from aerial parts of Artemisia annua; (B) lignans and phenolic acid from fruits of Arctium lappa; (C) anthraquinones, stilbene and phenolic acid from rhizomes of Polygonum cuspidatum (tannins removed); and (D) flavonoids, phenolic acid and tannins from flowers of Rosa chinensis. Elution monitored at 250 nm (C), 280 nm (B and D), and 370 nm (A).