Antioxidant power of phytochemicals fromPsidium guajavaleaf

Abstract

Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to Folin-Ciocalteu's phenol method and calculated as gallic acid equivalent (GAE). Remarkably high total phenolic content 575.3 ±15.5 and 511.6±6.2 mg of GAE/g of dried weight material (for ethanol guava leaf extracts and water guava leaf extracts, respectively) were obtained. The antioxidant activity of lyophilized extracts was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydryzyl (DPPH˙) colorimetry with detection scheme at 515 nm. The activity was evaluated by the decrease in absorbance as the result of DPPH˙ color change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than the extracts from guava leaf. On the other hand, the commercial guava leaf extracts and ethanol guava leaf extracts showed almost the same antioxidant power whereas water guava leaf extracts showed lower antioxidant activity. The parameter EC 50 and the time needed to reach the steady state to EC 50 concentration (50 EC T) affected the antiradical capacity of the sample. The antioxidant efficiency (AE) has been shown to be a more adequate parameter for selecting antioxidants than the widely used EC 50. This study revealed that guava leaf extracts comprise effective potential source of natural antioxidants.

Traditional Chinese medicine formula Qing Huo Yi Hao as superoxide anion scavenger in high glucose-treated endothelial cells

“…However, when Num 3 was condensed, it showed antioxidant effects with concentrations ranging from 3.1% to 100% (Table 1). These results indicate that Num 3 produces pro-oxidant and antioxidant effects at different concentrations, which is similar to the properties of other natural materials, such as curcumin, tea extracts and guava extracts [28,29] . Because the mechanism underlying this activity of Num 3 is not clear, more studies are required to determine it.…”

Phytopharmacological overview of Psidium guajava Linn.

“…The higher the sample concentration used, the stronger is the free radical-scavenging effect. 49 Akinola et al 50 suggested that ethanolic leaf extract of P. guajava possesses the beneficial effect on gossypol-induced sperm toxicity, and hence it may enhance male fertility due to rich natural antioxidants in it. The total flavonoids are primarily identified in the aqueous and ethanolic leaf extracts of P. guajava which may possess the potential antioxidative activities.…”

Composition of the essential oil from the leaves of tree domestic varieties and one wild variety of the guava plant (Psidium guajava L., Myrtaceae)

“…They also possess antioxidant activity as a result of the presence of vitamins, carotenoids, polyphenols and, principally, ascorbic acid (Nogueira et al, 1978;Nascimento et al, 2000;Qian & Nihorimbere, 2004).…”