Psidium guajava L., commonly known as guava and belonging to the Myrtaceae family,
is a widely cultivated plant valued in traditional medicine for its therapeutic properties.
Its leaves are used to treat various conditions, such as cancer, hypertension, intestinal
irregularities, diabetes, cough, scurvy, and weight loss. Bioactive compounds,
including terpenoids, flavonoids, coumarins, and cyanogenic acids, have been
identified in its leaves. This study aimed to investigate the chemical profile and
allelopathic activity of the hydroalcoholic crude extract from Psidium guajava leaves.
The plant material was collected in Itacoatiara, dried, ground, and extracted under
reflux with 70% ethanol. Liquid-liquid partitioning using hexane, chloroform, ethyl
acetate, and butanol was performed to obtain fractions of varying polarity. The
allelopathic assay evaluated the effect of P. guajava extracts on the germination and
growth of lettuce (Lactuca sativa) and tomato (Solanum lycopersicum) seeds. Seeds
were incubated with different extract concentrations, and results were compared to a
distilled water control. The observed inhibition confirmed the allelopathic activity of the
tested compounds. Chemical analysis of the crude extract identified hydrolyzable
tannins, flavanonols, saponins, and free steroids. The hexane and chloroform fractions
showed free steroids, while ethyl acetate, butanolic, and hydroalcoholic fractions
exhibited flavanonols. Phenols were detected in the ethyl acetate fraction, condensed
tannins in butanolic and hydroalcoholic fractions, and saponins in both the crude
extract and hydroalcoholic fraction. The allelopathic assay results revealed inhibitory
effects on lettuce and tomato seeds, with stronger activity at higher extract
concentrations. This study highlights the bioactive potential of Psidium guajava leaves
and their relevance for both pharmacological and agricultural applications.
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