Secondary phenol metabolites (SPhMs), distribution and content of some Aloe species, originated from arid zones of South Africa: A review

This review is concentrated on internal and external factors affecting the distribution of Secondary Phenol Metabolites (SPhMs) in the succulent leaves of Aloe species as follows: Appearance of a few of SPhMs together in the same leaf in different tissues, as a defense strategy, quantitative distribution of SPhMs in the different parts of the leaves as a peripheral defense strategy, distribution of SPhMs in the different parts of the succulent leaves of Aloe plants species according to their: age, location and orientation, content of SPhMs in renewed leave parts after leaf pruning according to their: age, location, direction, orientation and portion of leaf pruning - as a peripheral defense strategy, leaf exudates and leaf water extract of Aloe plant, classification of Aloe species, using the anthrone-C-glycosides as a biochemical marker and In the conclusions was summarized the main findings mentioned in this review. This study has been done on more than 100 Aloe species originated from the desert of South Africa. These plant species were introduced during the last 20 years, in the Garden of the Jacob Blaustein Institutes for Desert Research, at Sede Boker in the Negev Desert of Israel (34° 46E 30° 51′N, 460 m, asl). The Aloe plants have flourished in the Negev desert conditions when planted in loess soil. They are wetted by an annual average of 100 mm of rain in this area in winter; in addition they are irrigated by about 300-400 mm water per year. The aim of this review is to summarize about 15 years of our scientific investigations on the SPhMs content in the succulent leaves of Aloe plants species as well as to study agro-technical methods in order to increase the SPhMs content under different treatments. These results were also compared and related to other publications.