This study aimed to develop a delivery system for the
dried aqueous
extract of Rubia cordifolia leaves
(RCE) that could improve the neuroprotective potential of RCE by improving
the bioavailability of the chief chemical constituent rubiadin. Rubiadin,
an anthraquinone chemically, is a biomarker phytoconstituent of RCE.
Rubiadin is reported to have strong antioxidant and neuroprotective
activity but demonstrates poor bioavailability. In order to resolve
the problem related to bioavailability, RCE and phospholipids were
reacted in disparate ratios of 1:1, 1:2, and 1:3 to prepare phytosome
formulations PC1, PC2, and PC3, respectively. The formulation PC2
showed particle size of 289.1 ± 0.21 nm, ζ potential of
−6.92 ± 0.10 mV, entrapment efficiency of 72.12%, and in vitro release of rubiadin of 89.42% at pH 7.4 for a period
up to 48 h. The oral bioavailability and neuroprotective potential
of PC2 and RCE were assessed to evaluate the benefit of PC2 formulation
over the crude extract RCE. Formulation PC2 showed a relative bioavailability
of 134.14% with a higher neuroprotective potential and significantly
(p < 0.05) augmented the nociceptive threshold
against neuropathic pain induced by partial sciatic nerve ligation
method. Antioxidant enzyme levels and histopathological studies of
the sciatic nerves in various treatment groups significantly divulged
that PC2 has enough potential to reverse the damaged nerves into a
normal state. Finally, it was concluded that encapsulated RCE as a
phytosome is a potential carrier system for enhancing the delivery
of RCE for the efficient treatment of neuropathic pain.