HPLC based fractionation and microtiter plate-based bioactivity profiling of Ocimum sanctum Linn. leaves for potential pancreatic lipase inhibitor(s)

Background: Ocimum sanctum (family- Lamiaceae) is used in the TMS of India, China, Malaysia, and Thailand. The aerial parts are used to treat various health ailments viz. stomachache, common colds, headaches, obesity, and heart disease.

Aim: The objective of the present study is to explore pancreatic lipase (PL) inhibitory activity of Ocimum sanctum leaves fractions and to identify the bioactive phytochemical(s).

Method: Air-dried (O.sanctum) plant material (200 g) was collected and extracted in ethanol (3×500 ml) at room temperature (25±5°C) by cold percolation. The solvent was filtered and evaporated under a vacuum. The prepared extract was investigated for in-vitro lipase activity using the spectrophotometric assay. OS leaves part shows potent PL inhibition. Isolation of compounds through upscaling in semi-preparative HPLC with isocratic elution of solvent-A (0.1% v/v, AcOH) and Solvent-B (MeOH) at flow rate 3.0 mL/min was performed at 280 nm.

Results: HPLC-based profiling and activity-guided fractionation using in-vitro PL inhibition were developed. In the present investigation, three flavone and two phenolic aldehyde compounds were isolated from OS and tested for PL activity. Apigenin shows significant PL activity. The extracted compounds were characterized by spectroscopic methods HPLC, HR-MS, and NMR.

Conclusion: The PL inhibitory activity of OS extract (IC₅₀ < 100 µg/ml) and its phytomolecules (IC₅₀ = 7.80 - 95.31 µg/ml) was evaluated. The study confirmed that OS leaves contain potential PL inhibitor(s). Ayurvedic plants may be useful for the management of obesity, which correlates with ethnomedicinal data on the use of these plants in Indian traditional medicines.