The Effects of 6-Benzylaminopurine (BAP) on Shoot Multiplication, Phenolic Content and Antioxidant Activities of Orthosiphon stamineus Benth.

Abstract

Orthosiphon stamineus Benth., or misai kucing, is a therapeutic herb from the Lamiaceae family, renowned
for its traditional uses in treating various ailments such as kidney disorders and hypertension. The herb is
abundant in phenolic compounds, flavonoids, and tannins, and it is known for its ability to neutralise
reactive oxygen species (ROS) present within the biological system. The increased popularity of natural
remedies as a safer option with more holistic approaches has led to overharvesting, risking their
sustainability and availability to meet the industrial demand. This study aimed to determine the optimal 6-
benzylaminopurine (BAP) concentration for shoot initiation and multiplication of Orthosiphon
stamineus and to assess the effects of different BAP levels on the phenolic content and antioxidant ability
of in vitro micropropagated plantlets of O. stamineus. Nodal segments were cultured on Murashige and
Skoog (MS) medium supplemented with varying concentrations of BAP (0, 2.5, 5, 7.5, and 10 mg/L) in a
completely randomised design (CRD) with three replicates. The treatment using 0.5 mg/L BAP resulted in
biomass increases, with the highest number of shoots (3.0) and leaves (10.27) being observed after 6 weeks
of culture. In contrast, using 10 mg/L BAP resulted in the highest levels of phenolic acid (28.13 mg GAE/g
DW), flavonoids (61.20 mg RE/g DW), tannins (4.15 mg TAE/g DW), and DPPH scavenging activity
(55.54 mg TE/g DW) showing that the increase in BAP concentrations led to a dynamic increase in
secondary metabolite production. This suggested that while moderate BAP promoted growth, higher
concentrations enhanced the medicinal quality of the plant by boosting bioactive compounds, providing
valuable insights for developing tissue culture protocols to enhance the medicinal value of this herb.