The present invention provides a process of extracting the leaves of Labisia pumila with water into a free flowing powder using accelerated solvent system and drying. The invention also relates to the immunopotentiating effects of the extract against stress. The extract has effects on fatigue, hypoxia time, potentiation of swimming endurance, bod weight, weight of the thymus and spleen and levels of CD244+ NK cells, CD4+ and CD8+ T cells, expression of ThI cytokines IL-2 and IFN-gamma, corticosterone, glutathione, alanine aminotransferase and lipid peroxidation levels.
