Separation and Identification of Antioxidants and Aldose Reductase Inhibitors in Lepechinia meyenii (Walp.) Epling.

Guanglei Zuo,Kyong-Oh Shin,Yanymee N Guillen Quispe,Paul H Gonzales Arce,Soon Sung Lim,Kang-Hoon Je,Kang Hyuk Kim,Hyun Yong Kim

doi:10.3390/plants10122773

Guanglei Zuo, Kyong-Oh Shin + Show 6 more

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https://doi.org/10.3390/plants10122773

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Abstract

We previously reported that Lepechinia meyenii (Walp.) Epling has antioxidant and aldose reductase (AR) inhibitory activities. In this study, L. meyenii was extracted in a 50% MeOH and CH2Cl2/MeOH system. The active extracts of MeOH and 50% MeOH were subjected to fractionation, followed by separation using high-speed counter-current chromatography (HSCCC) and preparative HPLC. Separation and identification revealed the presence of caffeic acid, hesperidin, rosmarinic acid, diosmin, methyl rosmarinate, diosmetin, and butyl rosmarinate. Of these, rosmarinic acid, methyl rosmarinate, and butyl rosmarinate possessed remarkable antioxidant and AR inhibitory activities. The other compounds were less active. In particular, rosmarinic acid is the key contributor to the antioxidant and AR inhibitory activities of L. meyenii; it is rich in the MeOH extract (333.84 mg/g) and 50% MeOH extract (135.41 mg/g) of L. meyenii and is especially abundant in the EtOAc and n-BuOH fractions (373.71–804.07 mg/g) of the MeOH and 50% MeOH extracts. The results clarified the basis of antioxidant and AR inhibitory activity of L. meyenii, adding scientific evidence supporting its traditional use as an anti-diabetic herbal medicine. The HSCCC separation method established in this study can be used for the preparative separation of rosmarinic acid from natural products.

Highlights

Diabetes mellitus, characterized by hyperglycemia and diabetic complications, is one of the most common chronic degenerative diseases worldwide, with nearly 463 million cases reported in 2019 alone [1]
We found that the 70% MeOH extract of L. meyenii exhibited strong DPPH radical scavenging activity and aldose reductase (AR) inhibitory activity [15]
In order to discover the active components in L. meyenii, the activities of the CH2Cl2, MeOH, and 50% MeOH extracts of L. meyenii against DPPH radicals and AR were comparatively determined using quercetin as a positive control [23,24]

Summary

Introduction

Diabetes mellitus, characterized by hyperglycemia and diabetic complications, is one of the most common chronic degenerative diseases worldwide, with nearly 463 million cases reported in 2019 alone [1]. Multi-therapeutical strategies beyond glycemic control are required to treat diabetes and its complications. Aldose reductase (AR) and oxidative stress are considered significant therapeutic targets [2,3]. AR is activated and the polyol pathway flux is increased; it causes depletion of NADPH and overproduction of sorbitol, leading to cellular oxidative stress and sorbitol-induced osmotic stress, which are implicated in diabetic complications in insulin-independent tissues, including kidney, lens, retina, and neural tissues [3,4]. Reactive oxygen species (ROS) and the resulting oxidative stress are key contributors to diabetic complications [5,6]. Inhibition of AR and ROS/oxidative stress is considered a therapeutic target for treating diabetic complications [2,3]

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