Quantification of Phenolic Compounds and In Vitro Radical Scavenging Abilities with Leaf Extracts from Two Varieties of Psidium guajava L.

Julio Camarena-Tello,José Rodiles-López,Osvaldo Alvarez-Cortes,José Padilla-Ramírez,Héctor Martínez-Flores,Ma Garnica-Romo,Alfredo Saavedra-Molina,María Bartolomé-Camacho

doi:10.3390/antiox7030034

Abstract

Guava leaf (Psidium guajava L.) extracts are used in both traditional medicine and the pharmaceutical industry. The antioxidant compounds in P. guajava leaves can have positive effects including anti-inflammatory, anti-hyperglycemic, hepatoprotective, analgesic, anti-cancer effects, as well as protecting against cardiovascular diseases. In the present study, phenolic compounds and in vitro antioxidant capacity were measured in extracts obtained with polar and non-polar solvents from leaves of two varieties of guava, Calvillo Siglo XXI and Hidrozac. The quantity of total phenolics and total flavonoids were expressed as equivalents of gallic acid and quercetin, respectively. Hydroxyl radical, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and Oxygen Radical Absorbance Capacity using fluorescein (ORAC-FL) in vitro tests were used to assess the radical scavenging abilities of the extracts. The total phenolics were higher in the aqueous fraction of the variety Calvillo Siglo XXI, while in the Hidrozac variety total phenolics were higher in the acetone and chloroform fractions. Total flavonoids were higher in all fractions in the variety Calvillo Siglo XXI. Total phenolics showed a highly positive correlation for ORAC-FL, and a moderately positive correlation with hydroxyl radicals. Finally, total flavonoids showed a slightly positive correlation for ORAC-FL and hydroxyl radicals. Both varieties of guava leaf extract showed excellent antioxidant properties.

Highlights

Psidium guajava L. is a small tree that belongs to the Myrtaceae family
The total phenolic compounds in the extract of the acetone fraction for both varieties was more than double the 141 mg EAG/g measured by You et al [18] who extracted with acetone for one night following maceration
The phenolic compounds obtained in our aqueous extracts were greater than those quantified by Seo et al [15] from extracts boiled for 4 h in guava leaves (140 mg gallic acid equivalent (GAE)/g)

Summary

Introduction

Psidium guajava L. is a small tree that belongs to the Myrtaceae family. Guava is the common name used for species of P. guajava. The guava tree is distributed in tropical and subtropical regions of Antioxidants 2018, 7, 34; doi:10.3390/antiox7030034 www.mdpi.com/journal/antioxidants. The primary producers of guava fruit are India, China, Thailand, Pakistan, and Mexico [2,3]. Most of the commercialized orchards of guava fruits in Mexico present a great phenotypic, genetic, and morphological diversity due to propagation methods. This variability affects the productive potential of the guava crop, as well as the uniformity and quality of the harvested fruit

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