Skin depigmenting action of silkworm (Bombyx mori L.) droppings in zebrafish

Abstract

The excrement of silkworms (Bombyx mori L.), referred to here as silkworm droppings (SDs), is used as a traditional drug in eastern medicine to treat skin diseases such as urticaria and atopy. However, the depigmentation effects of SDs have not previously been evaluated. We focused on the depigmentation effect of a methanol extract of SDs and isolated components of the extract using a zebrafish model system. (+)-Dehydrovomifoliol (M-1), (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one (M-2), (3S,5R,8R)-3,5-dihydroxymegastigma-6,7-dien-9-one (M-3), roseoside (M-4), and citroside A (M-5) were isolated from only SDs extract (SDE), and chemical structures were identified through spectroscopic methods. Toxicity of SDE was evaluated by assessing its effect on the viability of human fibroblast cells and the hatching rate of zebrafish embryos. In addition, the depigmentation ability of SDE and isolated constituents was evaluated using a zebrafish model. Binary threshold, histograms, and the size of the black spots on the dorsal region of zebrafish larvae were analyzed using image analysis tools. Finally, SDE is a non-toxic material and has a dose-dependent depigmentation effect in zebrafish larvae. Moreover, various doses of compounds isolated from SDE, namely, M-1 to M-5, had a depigmentation effect. In particular, M-5 inhibited melanin synthesis in melanocytes stimulated by α-melanocyte stimulating hormone (α-MSH). Together, our results suggest that SDs can be used for depigmentation purposes in health and/or cosmetic applications.

A Zebrafish Embryo as an Animal Model for the Treatment of Hyperpigmentation in Cosmetic Dermatology Medicine

“…Connections with many previous and current data of kojic acid and arbutin depigmenting assay in vitro (i.e., melanocytes) and in vivo (i.e., mice) help to support current investigation and better understanding using zebrafish embryo [13,57]. For instance, compound bis(4-hydroxybenzyl)sulfide reduces pigmentation level to about 41% (a percentage relative to untreated control), lower than arbutin and kojic acid, which indicates that bis (4-hydroxybenzyl)sulfide had a better depigmenting activity as compared to that of arbutin and kojic acid [13]. In addition, it was revealed that the bis(4-hydroxybenzyl)sulfide reduces melanogenesis in zebrafish comparably as effective as indicated by reduced melanin content, TYR, TRP-1, MITF in melanocytes in vitro [6,13].…”

“…The application of zebrafish depigmenting assay was supported by the effect of well-known bioactive agents such as kojic acid and arbutin on embryo depigmenting activity [40,57,58]. Connections with many previous and current data of kojic acid and arbutin depigmenting assay in vitro (i.e., melanocytes) and in vivo (i.e., mice) help to support current investigation and better understanding using zebrafish embryo [13,57]. For instance, compound bis(4-hydroxybenzyl)sulfide reduces pigmentation level to about 41% (a percentage relative to untreated control), lower than arbutin and kojic acid, which indicates that bis (4-hydroxybenzyl)sulfide had a better depigmenting activity as compared to that of arbutin and kojic acid [13].…”

“…For instance, compound bis(4-hydroxybenzyl)sulfide reduces pigmentation level to about 41% (a percentage relative to untreated control), lower than arbutin and kojic acid, which indicates that bis (4-hydroxybenzyl)sulfide had a better depigmenting activity as compared to that of arbutin and kojic acid [13]. In addition, it was revealed that the bis(4-hydroxybenzyl)sulfide reduces melanogenesis in zebrafish comparably as effective as indicated by reduced melanin content, TYR, TRP-1, MITF in melanocytes in vitro [6,13]. These findings have gained enormous interest from the cosmetics industry to develop the most powerful and safe depigmenting agents [59].…”

“…Table 1 shows bioactive compounds of lower molecular weight (100–300 g/mol) and their depigmenting activity towards zebrafish embryo. For instance, gallic acid strongly reduced pigmentation of zebrafish embryo to about 40% (percentage in relative to untreated control) at concentration of 40 µM, comparably similar to bis(4-hydroxybenzyl)sulfide, but had higher depigmenting activity than kojic acid and arbutin [6,13]. On the other hand, raspberry ketone reduced melanin content and TYR activity in zebrafish embryo to about 60% (percentage in relative to untreated control) at 600 µM comparable to kojic acid [60].…”

“…The application of this lower vertebrate has gained attention in the medicinal and cosmetic industry. At present, studies have demonstrated its novelty and reliability for evaluating many depigmenting agents [3,6,13,14,15]. Previous and very recent evidence in genomics, molecular genetics, genetic development and molecular biology on zebrafish pigmentation showed its correlation to human pigmentation [16,17,18,19,20,21].…”