Humiria balsamifera (Aubl), commonly known as “mirim”, is a plant of the Humiriaceae family, which consists of 39 species divided between eight genera: Duckesia, Endopleura, Humiria, Humiriastrum, Hylocara, Sacoglottis, Schistostemon, and Vantenea. This study aimed to characterize H. balsamifera extracts by LC-MS/MS and evaluate their antimicrobial potential through in vitro and in vivo assays.
1. Introduction
Microorganisms are naturally well-spread out in the environment, and they can easily reach surfaces people come into contact with, including food products, whether at the harvest, slaughter, processing, or even packaging. Once in contact with the food, they start their growth process by consuming nutrients and causing the product to deteriorate
[1,2,3][1][2][3].
Bacteria, fungi, viruses, and protozoa are the main microorganisms responsible for food contamination, infecting humans through the consumption of beef, fish, poultry, eggs, unhygienic fruits and fresh produce, causing a variety of diseases
[4,5][4][5]. The World Health Organization estimates that one in 10 people worldwide become ill after consuming contaminated food and about 420,000 people die each year, resulting in the loss of 33 million healthy life years (DALYs)
[2,6][2][6].
Bacteria represent an added concern for health and food safety organizations, especially those able to grow at low temperatures and resist a wide range of temperature variations
[7,8][7][8]. Bacterial pathogens such as
Escherichia coli,
Salmonella enterica,
Listeria monocytogenes, and
Staphylococcus aureus, among others, are responsible for several global foodborne outbreaks and cause life-threatening illnesses such as diarrheal diseases
[5,9,10,11,12][5][9][10][11][12]. Another problem in fighting bacteria is their ability to develop resistance to conventional antimicrobials. These pathogens can use various strategies to inhibit the effects of antimicrobials, such as the production of inactivating enzymes, reduction of outer membrane permeability, efflux system, and blocking or altering the target site of antibiotics, further motivating the research focused on finding alternative ways to combat them
[13,14][13][14].
In the search for new effective substances against resistant pathogens, several secondary metabolites from plants and endophytic microorganisms have shown promise
[15,16][15][16]. Most of the drugs used in general today were developed based on ethnopharmacological knowledge
[17[17][18][19],
18,19], indicating that the chemistry of natural products is a big ally in the development of therapeutic agents
[20,21][20][21].
The plant species
Humiria balsamifera (Aubl), popularly known as “mirim”, presents interesting biological activities. The literature reports, most of all, anti-inflammatory
[22,23][22][23], antimalarial
[24], antioxidant
[25,26][25][26], and antifungal activity
[27], highlighting the therapeutic potential of this plant. Some substances isolated from this species so far have already been reported as well, such as bergenin, arjunolic acid, friedelin, lupeol, phytol, caryophyllene oxide, epoxide humulene, and trans-isolongifolanone, among others
[24]. However, the antibacterial and antibiofilm activities of its derived products have not been extensively examined. Thus, this work aims to characterize and evaluate the effectiveness of
H. balsamifera extracts in terms of the antimicrobial and antibiofilm activities against foodborne pathogens (
Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 15313,
Salmonella enterica Typhimurium ATCC 14028, and
Staphylococcus aureus ATCC 6538). The in vivo antimicrobial action of the most active extract was analyzed using a method based on the infection of
Tenebrio molitor larvae.
2. Antimicrobial Activity Evaluation
The antimicrobial activity of
Humiria balsamifera (Aubl) leaf and stem bark extracts was evaluated by the determination of their minimum inhibitory concentrations (MIC) against four foodborne bacteria species:
E. coli,
L. monocytogenes,
S. enterica Typhimurium, and
S. aureus (
Table 1).
Table 1. Determination of the minimum inhibitory concentrations (MIC) of the leaf and stem bark extracts of Humiria balsamifera (Aubl).
Bacteria Species |
HSBE |
EASBE |
MSBE |
HLE |
EALE |
MLE |
E. coli ATCC 25922 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
L. monocytogenes ATCC 6538 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
3120 |
3120 |
S. aureus ATCC 6538 |
>12,500 |
>12,500 |
>12,500 |
1560 |
780 |
780 |
S. enterica Typhimurium ATCC 14028 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |
>12,500 |