Background & Objective: Accelerated stability study (40°C/75% RH, 6 months)
as well as long term stability studies (30°C/65% RH, 36 months) are conducted on three
batches (I-III) of two commercially available CNS active herbal products (A and B) containing
Convolvulus pluricaulis with Centella asiatica or Bacopa monnieri.
Methods: Stability samples were withdrawn at periodic intervals, and evaluated for physical
stability (color, clarity, viscosity and pH), chemical stability (total phenolic (TPC), scopoletin,
asiatic acid and bacoside A content), and biological activities (free radical scavenging,
anti-acetylcholinesterase, and antianxiety). All stability samples retained the physical
characteristics compared to corresponding control samples. Control samples exhibited significant
batch-to-batch variation in TPC (46.8-65.9 mgGAE/L), scopoletin (165.78-206.15 ng/mL
in A and 2.61-28.78 ng/mL in B), asiatic acid (30.14-44.92 μg/mL in B), free radical scavenging
activity (IC50 0.5-1.25% v/v), AChE inhibitory activity (IC50 75.0-96.3% v/v), and antianxiety
Results: The chemical indicators and biological activities were significantly decreased in
both accelerated and long term stability samples compared to corresponding control samples.
A correlation between scopoletin and biological activities was established in products A
whereas asiatic acid/C. asiatica defies the logical correlation in product B.
Conclusion: The products exhibited significant batch-to-batch variation, and did not remain
stable for the recommended shelf life period of three years, which suggested that these are
suspected to lose therapeutic efficacy during their shelf life.