Agronomy, Chemical Analysis, and Antidiabetic Activity of Basil (Ocimum Species)

The use of natural products as potential preventive and therapeutic interventions for diabetes has drawn worldwide attention. Ocimum species have a multitude of applications in foods, pharmaceuticals, and cosmetics. The antidiabetic activity of Ocimum has previously been reported; however, the active compound(s) associated with such activity remains elusive. In an effort to identify both an accession that is the most effective against diabetes and the compound(s) that may be associated with its antidiabetic effects, 16 Ocimum accessions representing six different species were investigated. Fourteen compounds from diverse groups, viz., flavonoids, phenols, and terpenoids, were quantified utilizing a liquid chromatography coupled with a diode array detector and quadrupole time-of-flight (LC/DAD/Q-ToF) method. The results from the method validation demonstrated excellent linearity (R-2 > 0.99) and sensitivity as evident by the limit of detection (LOD) (0.04-0.6 mu g/mL) and limit of quantification (LOQ) (0.08-1 mu g/mL). Likewise, the method was found to be precise (RSD < 6%) with recoveries between 87.7% and 103.5%. The antidiabetic potential of methanol extracts of all samples was explored via an alpha-glucosidase inhibitory assay. Data from dose- response studies suggested that the methanol extract of O. gratissimum from Zambia (AR-XLVI-01-13) was comparable to the antidiabetic drug, acarbose. Furthermore, rosmarinic acid and caffeic acid present in O. gratissimum were reported for the first time to be responsible for the antidiabetic properties of this plant species. In addition, the plants of this accession were taller, with an average of 21 branches per plant and produced a significantly greater amount of leaf and above ground biomass than other accessions. The reported analytical and biological methods could be employed to evaluate the chemical composition and agronomic performance of Ocimum. Overall, this project provided scientific information necessary for the development of sustainable organic production systems, which enable commercial cultivation of Ocimum varieties with known bioactivity.