## 1 Introduction  
_Area catechu_ is a medium-sized palm tree and is part of the Arecaceae family, which contains more than 200 genera and about 2600 species. This palm tree is commonly known as area palm, area nuct palm, betel palm, betel nut palm, Indian nut, Pinang palm, or catechu. The betel nut (or area nuct) is a seed of the fruit of the palm tree _Area catechu_. This palm tree is widely distributed in South and Southeast Asia, including China, India, Indonesia, Malaysia, the Philippines, and New Guinea. The traditional habit in these countries is to chew betel quid, which contains betel leaf, area nuct, and slaked lime (calcium hydroxide) and can contain tobacco. Furthermore, other substances, particularly spices, such as cardamom, saffron, cloves, aniseed, turmeric, mustard, or sweeteners, are added according to local preferences [1, 2, 3]. Up to 10-20% of the world's population (up to 600 million people) chews betel quid, making it the fourth most used drug, after alcohol, nicotine, and caffeine. Humans use this drug primarily for stimulating effects that are comparable to the use of nicotine [4, 5]. Arecoline can also produce addiction and withdrawal symptoms, such as nicotine. The chewing of area nuts causes many effects on the autonomic nervous system, such as euphoria, increased alertness, focused attention, sweating, stimulation of excitement, elation, and anxiolysis [6].  
Chewing betel quid has been found to improve oral hygiene. People chewing betel quid have less dental caries compared to the nonusing population [7, 8]. The substances contained in the area nuts inhibit Gram-positive microorganisms that cause dental caries.  
The antimicrobial activity of different extracts of the area nut was proved [9; 10]. However, it should be mentioned that the chewing of the area nut has negative effects on human health (high blood pressure, liver cirrhosis, and cardiovascular diseases) [11]. There are many studies [12; 13; 14] that have proven the carcinogenity of area nuts.  
Areca nuts contain many different groups of compounds such as alkaloids; the most known alkaloids are arecoline, arecaidin, guavacoline, and guavacin [15], and the newly identified alkaloids are homoarecoline and areactamines [16]. Other compounds belong to the group of flavonoids [17], carbohydrates, lipids, proteins, crude fibers, and minerals [18]. Differences in the composition and concentration of substances in area nuts can be caused by the different geographical location or degree of ripeness of the nut.  
Despite the fact that area nut is a widely known drug and plant, there are not enough reports dealing with the volatile profiles of this matrix. Only three studies analyzed compounds in area nuts using GC-MS after different types of extraction techniques. One of them was Soxhlet extraction of green immature fruits [19]. The other was solvent extraction with dichloromethane after 24 h of soaking a small piece of betel nut in alkaline distilled water [20]. The last was the use of 50% aqueous acetone for the extraction of betel nuts, and the extract was revealed to be a mixture of fatty acids (lauric, myristic, palmitic, and oleic) [21]. By using high-performance liquid chromatography with different types of detectors, there were determined following groups of compounds in area nuts or chewable products--alkaloids [15; 18; 22; 23], polyphenols [18], and phenols [23]. The simple and rapid capillary zone electrophoresis method was tested for the analysis of alkaloids in the area nut extract (water sonication) and saliva from area nut chewers [24].  
The objective of the present study was to determine the volatile compounds of the area nut by using two different extraction methods (headspace solid-phase microextraction (HS-SPME) and simultaneous hydrodistillation-extraction (SHDE)). SHDE products were tested for antimicrobial activity using the agar disk diffusion method.