Kaempferol and Kaempferol Rhamnosides with Depigmenting and Anti-Inflammatory Properties

Ho Sik Rho,Jae Youl Cho,Dong Ha Cho,Sun Sang Kwon,Soo Mi Ahn,Dae Sung Yoo,Keun Ha Lee,Amal Kumar Ghimeray

doi:10.3390/molecules16043338

Abstract

The objective of this study was to examine the biological activity of kaempferol and its rhamnosides. We isolated kaempferol (1), α-rhamnoisorobin (2), afzelin (3), and kaempferitrin (4) as pure compounds by far-infrared (FIR) irradiation of kenaf (Hibiscus cannabinus L.) leaves. The depigmenting and anti-inflammatory activity of the compounds was evaluated by analyzing their structure-activity relationships. The order of the inhibitory activity with regard to depigmentation and nitric oxide (NO) production was kaempferol (1) > α-rhamnoisorobin (2) > afzelin (3) > kaempferitrin (4). However, α-rhamnoisorobin (2) was more potent than kaempferol (1) in NF-κB-mediated luciferase assays. From these results, we conclude that the 3-hydroxyl group of kaempferol is an important pharmacophore and that additional rhamnose moieties affect the biological activity negatively.

Highlights

Flavonoids are naturally occurring phenolic phytochemicals which are reported to possess various biologically important properties [1]
We previously reported the anti-tyrosinase activities of kaempferol and its rhamnosides [9]
We investigated the relationship of structure and biological activity in these compounds by evaluating the inhibitory activity of kaempferol and its rhamnosides on melanogenesis and inflammation

Summary

Introduction

Flavonoids are naturally occurring phenolic phytochemicals which are reported to possess various biologically important properties [1]. Kenaf (Hibiscus cannabinus L.) is a member of the Malvaceae family and is used as a traditional folk medicine in Africa and India. It exhibits a broad spectrum of biological properties such as hepatoprotective activity [5], anti-oxidative activity [6], haematinic activity [7], and immunomodulatory effects [8]. The derhamnosylation products were isolated as pure compounds [9]. Chemical investigations identified their structures as kaempferol, α-rhamnoisorobin (kaempferol 7-O-α-Lrhamnopyranoside), and afzelin (kaempferol 3-O-α-L-rhamnopyranoside) (Figure 1). We evaluated the depigmenting and anti-inflammatory properties of kaempferol and its rhamnosides by analyzing their structure-activity relationships

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Results

Conclusion