Abstract:
Mexican mint (Plectranthus amboinicus), an aromatic and medicinal herb from the Lamiaceae family,
holds immense potential for the fragrance and pharmaceutical industries. As an indigenous plant, its
utilization aligns with sustainable and eco-friendly agricultural practices. This study evaluated its
aromatic, morphological, and genetic diversity to support its sustainable use and value-added
applications. An initial sniff test of 38 aromatic plants from home gardens and public markets in
Jaffna, Mullaitivu, and Kilinochchi ranked Mexican mint highly in aroma preference and intensity.
Five distinct morphotypes were identified and coded as M001, M002, M003, M004, and M005 based
on morphological traits such as leaf margin type and dentation count. Three morphotypes (M001,
M004, M005) with higher aroma intensity were selected for molecular analysis. ITS markers
confirmed species identity and genetic diversity. Phylogenetic analysis of Sri Lankan sequences
(GenBank: PQ387080, PQ390379, PQ390380) revealed unique genetic traits compared to Indian and
Indonesian sequences. Sequence PQ390380, from Jaffna, exhibited a distinct grouping pattern,
indicating local adaptations. M001, the morphotype with the highest aroma, underwent GC-MS
analysis, identifying 28 volatile organic compounds (VOCs), including p-Cymene (12.91%), Thymol
(12.01%), Cyclohexanol (10.84%), and Gamma-Terpinene (7.44%). These compounds, linked to
antimicrobial, anti-inflammatory, and antioxidant properties, highlight the plant’s therapeutic
potential. The unique chemical composition of P. amboinicus suggests broader pharmacological
applications. Its indigenous status, genetic, and aromatic diversity support selective breeding, essential
oil production, and eco-friendly agriculture, contributing to the sustainable utilization of local plant
resources.
