Malaysian stingless bee and Tualang honeys: A comparative characterization of total antioxidant capacity and phenolic profile using liquid chromatography-mass spectrometry

Highlights

• Malaysian Stingless bee honey has higher vitamin C, protein, polyphenols content than Tualang honey.

• LC-MS identified several phenolic compounds in stingless bee honey.

• Stingless bee honey had the highest anti-oxidant performance.

• Polyphenol content of stingless bee honey was associated with antioxidant activities.

Abstract

This study aims to examine and compare the phenolic profile and antioxidant properties of two kinds of honey: Stingless bee honey (Kelulut honey) and Tualang honeys. Using liquid chromatography mass spectrometry, a total of eighteen phenolic acids and flavonoids have been identified in Kelulut honey samples. The phenolic content and total antioxidant capacity (three assays: DPPH, ABTS, and ORAC) for Kelulut and Tualang honeys were evaluated and statistically estimated. There was a significant (p < 0.05) phenolic content (228.09 ± 7.9–235.28 ± 0.6 mg gallic acid equivalent per kg) and flavonoid content (97.88 ± 10.1–101.5 ± 11.4 mg catechin equivalent per kg) in Kelulut honey samples. The Kelulut honey samples have demonstrated a significantly stronger antioxidant capacity than Tualang honey samples. The correlations between antioxidant results and polyphenols content were found to be statistically significant (P < 0.05, P < 0.01). This research is the first to report data on phenolic profile and total antioxidant capacity of Kelulut honey. Our data suggest that Kelulut honey has prominent medical properties and could be exploited as a natural nutraceutical to treat free radical associated diseases.

Introduction

It has been well established in the literature that Reactive Oxygen Species (ROS), due to cellular metabolic reactions, are naturally formed in living organisms. The high concentration of radical species, including superoxide radical (O^2-), hydrogen peroxide (H₂O₂), Nitric oxide radical (NO), hydroxyl radical (OH) and peroxyl radical (ROO) has recently proved to induce antagonistic modifications in cell component (D'Autréaux and Toledano, 2007, Valko et al., 2006). The occurrence of any negative functional alterations and/or destructive actions against cell components, such as protein, lipid and nucleic acid could also lead to various pathological conditions, including cancer, arthritis, neurological disorders, atherosclerosis, diabetes and hypertension (Cominelli, 2004, Dröge, 2002, Reuter et al., 2010). Similarly, the low levels of antioxidant and/or high levels of free radicals have been reported to result in chronic diseases and oxidative stress damage (Halliwell, 2011, Keen, 2001). Research has attempted various preventive and therapeutic approaches to manipulate these chronic diseases. There has been a particular interest in improving and implementing new natural agents that combat oxidative stress-related diseases (Nimse & Pal, 2015). For example, a considerable number of epidemiological studies has emphasized the importance of diet-rich in antioxidant that are thought to have a role in longevity and increased healthy features (Chang et al., 2016, Kamiloglu et al., 2016, Zhang and Tsao, 2016).

It is quite common that bee honey has been a preferable natural therapy for wound healing and intestine-related diseases since centuries (Bogdanov, 2014, pp. 1–24). The use of honey in treatments has recently been termed as an apitherapy (Ghosh & Playford, 2003). Several studies have indicated that the scavenging and redox properties of natural honey are due to its content of various bioactive compounds; namely, phenolic acids, flavonoids, vitamins, and enzymes (Erejuwa, Sulaiman, & Ab Wahab, 2012). However, the geographical and botanical areas as well as the type of bees play a vital role in determining the biological composition of honey as well as the total antioxidant capacity (TAC) (Erejuwa, Sulaiman, & Wahab, 2012). The variety of flower species and its abundance all year round in Malaysia is thought to be the main source beyond the availability of different kinds of bee honey. Tualang honey (TH) and Kelulut honey (KH) are believed to be the most famous.

The TH, a tropical multifloral rain forest honey, is produced mainly by Apis dorsata (the rock bee), whereas KH is produced by Trigona, a stingless bee (Boorn et al., 2010). In Malaysia, these two kinds of honey have become very famous for being taken for different traditional treatment purposes (Barakhbah, Anisah, & Agil, 2007). Being gathered from plants' nectar, modified and stored by different types of honey bees, as well as being rich in polyphenols, there is an increasing number of studies attempting to figure out the biological composition of these two types of honey today (Abd Jalil et al., 2017, Barakhbah et al., 2007, Bogdanov, 2014, pp. 1–24; Boorn et al., 2010). More recently, there are research reports that have found various benefits for Tualang honey, for being particularly anti-inflammatory (Othman, 2012), anti-microbial (Alvarez-Suarez et al., 2010), anti-oxidant (Barakhbah et al., 2007), and anti-ageing (Al-Rahbi et al., 2014). These therapeutic activities have been strongly attributed to the phenolic acid and flavonoids content of Tualang honey. More importantly, the polyphenolic compound accompanying its biological activities makes it of a particular interest from the nutritional and pharmacological viewpoints (Ghosh & Playford, 2003). Nonetheless, there is still much lacking about the phenolic profile and antioxidant capacity of KH.

Stingless bee honey (KH) is thought to have a higher content of polyphenol than any other kind of honey (Biluca et al., 2016, Kek et al., 2014). This is likely attributed to the small size of Trigona's body that helps her stretch itself inside a bigger number of flowers, and hence diversifying the bioactive compounds collected and put in the make-up of honey. It is presumed that the periodical monitoring of Total Antioxidant Capacity (TAC) as well as the polyphenols profile of KH and TH are crucially useful for health care and product quality insurance. Although previous studies have used several methods to measure TAC, they did not have measurements for more many samples together, and hence they did not have one unified report of their results. The development of a more efficient method for measuring TAC and a validation using 96-well microplate makes this study particularly important (Kambayashi et al., 2009). This study aims to examine the identification and quantification of polyphenols profile in KH and TH samples and to chart the differences between the antioxidant properties for KH and TH with known synthetic antioxidants in vitro.