From Medicine to Ecology: A Comprehensive Review of Marigold (Tagetes spp.) as a Multipurpose Crop

Abstract

Marigold (Tagetes spp., family Asteraceae) is a genus of flowering plants whose documented applications span pharmacology, sustainable agriculture, industrial chemistry, and landscape ecology. Originating from Mesoamerica, the genus encompasses approximately 50–56 species, of which Tagetes erecta L. (African marigold) and Tagetes patula L. (French marigold) are the most widely cultivated and scientifically investigated. This review synthesises current evidence on the phytochemical composition of Tagetes spp.—encompassing carotenoids, flavonoids, terpenoid essential oils, and thiophene derivatives—and critically evaluates the mechanistic basis of their pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, wound-healing, and anticancer properties. The agricultural significance of Tagetes is examined in relation to nematode management, allelopathy, integrated pest management, and soil biological health. The ecological contributions of the genus, from pollinator support to phytoremediation, are assessed alongside the considerable industrial and commercial value of Tagetes-derived carotenoids in poultry nutrition, food science, cosmetics, and nutraceuticals. Four summary tables consolidate key findings on phytochemistry, pharmacology, agricultural applications, and industrial uses. The review identifies persistent gaps in the evidence base, notably the paucity of clinical data for medicinal applications, the limited mechanistic characterisation of soil microbiome interactions, and the absence of standardised protocols for extract preparation and quality control. The accumulated evidence firmly establishes Tagetes as a genuinely multipurpose genus, and suggests that its strategic integration into sustainable food and health systems warrants substantially greater scientific and policy attention.