The extract of male bee and beehive from Bombus terrestris has biological efficacies for promoting skin health

To the Editor,

Seventy percent of the animals living on Earth are insects, and the number of insect species reported so far is more than 1.2 million. Insects have been differentiated into so many species as they are today, probably because their adaptability to the environment is superior to that of any other animals. Recently, approaches to edible insects have been attempted as a functional food or to develop new protein sources in the future. On the other hand, insects have been used for medicinal purposes as a traditional medicine for the treatment of various diseases. In recent years, with the development of biotechnology, research on the efficacy of traditional medicines and the exploration of new medical substances have been actively conducted, and the industrial value of insects through this is very high.

Bombus terrestris (bumblebee) lives in a beehive as basic units consisting of queen bees, worker bees and male bees. The beehive can be eaten by humans, and its main ingredient is wood, which is made by worker bees chewing and softening. Recently, the excellent nutritional values of the pupa and the larvae from B. terrestris (male bees) have begun to be known. Therefore, using the extract of male bees, research on the development of functional foods, pharmaceutical substances and cosmetic raw materials is recognized as a very promising field for the purpose of developing insect industry. To date, little is known about the use of by-products derived from a beekeeping business. The purpose of this study was to find ways to utilize the by-products, such as male bee and beehive, from a beekeeping business. As a part of the purpose, it was investigated whether the extract of male bee and beehive (EMB) from B. terrestris has the effects in promoting skin health.

First, EMB was examined whether it has a cytotoxic effect on HaCaT cells. Cytotoxic effect by EMB on HaCaT cells was not observed (Figure 1A). The keratinocytes are important cells that play important roles in maintaining the structure and homeostasis of the epidermis [1]. Since differentiation of keratinocytes is a pivotal process to provide a skin barrier that is well tolerated by the adverse environment, disorders of keratinocyte differentiation are directly linked to skin disease. For example, defects in the skin barrier can result in overly dry skin, which can make skin conditions worse. The end product of keratinocyte differentiation, such as filaggrin, provides a natural moisturizing factor and helps maintain healthy skin. Skin can be moisturized by moisturizing factors such as hyaluronic acid and filaggrin. Hyaluronic acid not only protects skin elasticity by preventing moisture evaporation in the epidermis, but also plays an important role in cell migration, storage and diffusion of nutrients. To determine the moisturizing effect of EMB, we analyzed the levels of HAS (hyaluronic acid synthase)-3 and filaggrin mRNA induced by EMB in HaCaT cells. As a result, it was confirmed that EMB increases the expression of HAS-3 and filaggrin as compared with the control (Figure 1B, C). In order to investigate whether EMB promotes hyaluronic acid biosynthesis, hyaluronic acid contents in HaCaT cells were analyzed. As shown in Figure 1D, EMB increased the biosynthesis of hyaluronic acid in HaCaT cells compared with the control. Therefore, EMB is estimated to be effective in enhancing skin moisturizing efficacy.

Figure 1.

EMB has biological efficacies for promoting skin health. (A) HaCaT cells were treated with EMB, and cell viability was determined using the MTT assay. Error bars represent SD from three biological replicates. (B and C) EMB enhances HAS-3 and filaggrin expression in HaCaT cells. Quantitative real time-PCR (qRT-PCR) was performed. Error bars represent SD from three biological replicates. (D) EMB promotes hyaluronic acid biosynthesis in HaCaT cells. Retinoic acid (1 μM) was used as a positive control. Error bars represent SD from three biological replicates. (E and F) EMB reduces elastase and collagenase activity. Elastase and collagenase inhibitory activity assay were performed using EnzChek Elastase and Collagenase assay kit following the manufacturer’s instructions. N-methoxysuccinyl-Ala-Ala-Pro-Val-chloromethyl ketone (0.005 mM), a positive inhibitor (0.005 mM) for elastase assay and 1,10-phenanthroline (0.05 mM), a positive inhibitor for collagenase assay. Error bars represent the SD from three technical replicates.

Collagen is the main protein in the extracellular space and in the various connective tissues of the body [2]. As the main component of connective tissue, collagen is the most abundant protein in mammals. Collagenase is an endopeptidase that breaks the peptide bonds in collagen [3]. Elastin is a highly elastic protein in the connective tissue of the skin, allowing the skin to retain its shape when numerous body tissues expand or contract [4]. Elastase breaks down elastin and should be suppressed to maintain skin elasticity [5]. EMB was investigated for its elastase and collagenase inhibitory activity. The results revealed that EMB inhibits elastase and collagenase activity (Figure 1E, F). Therefore, EMB is estimated to have biological efficacy in improving skin wrinkles.

In summary, we explored the utilization of EMB, a by-product derived from a beekeeping business. EMB showed various efficacies for prompting skin health. Therefore, EMB can be used a raw material for cosmetics to improve skin health. The experimental methods used in this study are described in the supplement section.