molecules Review Drone Brood Homogenate as Natural Remedy for Treating Health Care Problem: A Scientific and Practical Approach Ewelina Sidor * and Małgorzata D˙zugan Department of Chemistry and Food Toxicology, Institute of Food Technology and Nutrition, University of Rzeszow, Cwikli´nskiej1a´ Street, 35-601 Rzeszow, Poland; [email protected] * Correspondence: [email protected] Academic Editors: Nada Orsolic and Maja Jazvinš´cakJembrek Received: 19 November 2020; Accepted: 1 December 2020; Published: 3 December 2020 Abstract: Drone brood homogenate is a little-known bee product used in folk medicine to treat various health problems. It is a very nutritious milky substance with high content of nutrients: proteins, lipids, fatty acids, carbohydrates, vitamins (A, B, E and D), and minerals. Moreover, when collected on early stage of larvae development, it is, most of all, rich source of sex hormone (testosterone, progesterone and estradiol). Some beekeepers consider drone brood as a waste product, although in some countries they use it to fight Varroa. Meanwhile, in many scientific reports a curative effect of bee drone homogenate in treating urgent global health problems have been confirmed, including ovarian dysfunction in women and male infertility, thyroid and immunity disorders, as well as malnutrition in children. A few dietary supplements based on drone brood are available online. Many patents relating to drone brood-based dietary supplements have been filed in Russia, but their prevalence in EU countries is still limited. Further research is needed to fully recognize the pharmacological activity and increase the use of drone brood. Keywords: drone brood; apilarnil; steroid hormones; therapeutic value; dietary supplement 1. Introduction Honey and other bee products, i.e., pollen, bee bread, propolis, royal jelly, and wax have been valued as food stuffs all over the world since ancient times [1,2]. The basis for the comprehensive use of bee products in human nutrition and treatment is their diverse and unique chemical composition, including the content of numerous characteristic substances with a bioactive effect [3]. Bee products are naturally occurring pharmaceutical products with a multidirectional effect on the living organism, including humans. Their pharmacologically active fractions are used in many fields of treatment and pharmacy as pharmacopoeial raw materials, dietary supplements and cosmetics [4–6]. The biologically active compounds of bee products include bactericidal agents and antioxidants [7]. Drone brood is one of the bee products that are not commonly known in Europe but is a recognized and frequently used remedy in some countries of the world, such as Romania, China, Zambia, Senegal and Ecuador [8–12]. Drones, as male honeybees, are one of polymorphic forms of bees, next to the queen and worker bees. Drones bite their way out of the drone cell on the 24th day after egg laying [12] and are easily recognisable by their large size, oval body, large eyes and strong wings. They do not have pollen sacs, a wax gland or sting. They appear in bee colony in spring and their only task is to inseminate with a queen during her mating flight. The few drones that do get a chance to mate die after mating. Drones typically compose 5–10% of the adult population of bee colony during the breeding season from spring to autumn with a peak in the late spring or early summer. A colony might adjust Molecules 2020, 25, 5699; doi:10.3390/molecules25235699 www.mdpi.com/journal/molecules Molecules 20202020,, 2525,, 5699x FOR PEER REVIEW 22 ofof 1516 drone production in relation to season (length of day and temperature) and other environmental dronecues, including production size in of relation colony, to availability season (length of food of day as andwell temperature) as colony microclimate and other environmental [13]. cues, includingDrone size brood of colony, homogenate availability (known of foodas apilarnil as well or as less colony apistimul) microclimate is a bee [13 product]. obtained by the collectionDrone of brood drone homogenate larvae from drone (known cells, as apilarnilfrom 3 to or 11 less days apistimul) after hatching is a bee [14,15]. product Apilarnil, obtained which by themay collection be defined of droneas the larvae male fromequivalent drone cells,of roya froml jelly, 3 to is 11 obtained days after from hatching drone [ 14brood,15]. 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This During difference their time in caps of allowsenclosure for within the identification the cell, pre-pupa of male broodand pupa in the do comb. not feed, During metamorphosis their time of occurs enclosure (Figure within 1), the and cell, the pre-pupa process andof spermatogenesis pupa do not feed, is metamorphosiscompleted [22]. occurs (Figure1), and the process of spermatogenesis is completed [22]. Figure 1. Drone brood development stage [[23].23]. InIn thethe firstfirst daysdays of development (day 1–3), regardless ofof thethe polymorphicpolymorphic form,form, thethe larvalarva weighsweighs about 0.11 mg [[21].21]. It is only from the 4th day that the body weight and length of thethe variousvarious larvaelarvae begin to didiffer,ffer, dependingdepending onon theirtheir polymorphicpolymorphic form.form. A seven-day-old queen larva weighs 270 mg, a workerworker larvalarva 8080 mg,mg, andand aa dronedrone larvalarva 120120 mgmg [[2222,24].,24]. On the day of sealing (day 11) the dronedrone larvaelarvae reachreach aa weight weight of of 350 350 mg; mg; thus, thus, their their weight weight is greateris greater than than that that of the of motherthe mother and and bee larvabee larva [24]. Moreover,[24]. Moreover, they containthey contain more proteins,more proteins, lipids andlipids sulfhydryl and sulfhydryl groups. groups. Considering Considering the above the and above the easeand the of collecting ease of collecting from comb from wells, comb 11-day-old wells, 11-day-old drone brood drone is brood most suitable is most forsuitable technological for technological use [19]. use [19].In the field of beekeeping, drone brood is sometimes treated as waste whereas it should be used for theIn sakethe field of wealth of beekeeping, of valuable drone nutrients brood and is someti bioactivemes ingredients. treated as waste However, whereas the it amount should of be drone used broodfor the present sake of inwealth the colony