Jahrom is located 170 kilometers southeast of Shiraz, the capital of Fars Province, Iran. It is the largest city in the southern half of the province. The study area is located at 28° 30′ 00″ N and 53° 33′ 38″ E (Fig. 1). With a population of 14,130 inhabitants, Jahrom covers 5498 km² and is at an average altitude of 1050 m above sea level. A hot and arid climate with an average temperature around 19.5°C is dominant in this city. January (average temperature = 2°C) and July (average temperature = 40.5°C) are the coldest and hottest months of the year, respectively (Ghanbarian et al., 2011). Average annual rainfall measures about 200–500 mm. Calcareous, clay, and gypsum are the main soil types, and Jahrom’s vegetation is classified as woodland, scrubland, and subtropical annual grassland in 1,393,693 ha. Date palms, citrus, and many tropical and sub-tropical plants are grown in Jahrom, and the city’s economy is based mainly on agriculture and horticulture.

An ethnopharmacological survey of herbal shops in Jahrom city was conducted using the snowball method (Espinosa et al., 2014). A total of 21 herbal shops are located in the city, of which 16 agreed to cooperate in the current study. The aims of the present study were described to the participating herbal healers, and consent to participate was obtained from each of them according to the code of ethics of the International Society of Ethnobiology (ISE) (Hardison & Bannister, 2011). Semi-structured questionnaires were applied to systematically collect data on the treatment of skin diseases using herbal medicines (Appendix 1). Interviews were conducted in Persian with the herbal healers in their shops and included questions regarding their knowledge of various skin diseases, demographic characteristics (name, age, sex, years of experience, education), and data on medicinal plants (local names of plants, parts of plants used, methods of preparation and application of drugs). Plant specimens were identified using Flora of Iran (Assadi, 1988–2015) and Flora Iranica (Rechinger, 1965–2016), and vouchers were deposited in the herbarium of Shahid Beheshti University (HSBU).

Approximately 87% of participants in this study were men; only two participants (about 13%) were women. The age of herbal healers ranged between 24–55 years with an average of 38 years. The highest level of education was a high school diploma (56%). None of the participants had an academic education in a field related to herbal medicine. Most of their knowledge had been obtained only through experience or from the legacy of past generations (68%). Only 32% of participants used traditional medicine books in addition to personal experience.

A total of 38 species belonging to 34 genera and 23 families of medicinal plants were obtained in this study (Fig. 2; Table 1). Asteraceae (5), Fabaceae (3), and Malvaceae (3) were the most frequently used plant families, respectively (Fig. 3). Asteraceae with 23,600 species is one of the largest families of flowering plants, and most of the medicinal plants reported in many ethnopharmacological studies worldwide belong to this family (Ghorbani, 2005; Leitão et al., 2013). More than 50% of all species are annual herbs (Fig. 4), and 79% of them are native to Iran. The most used parts of plants for treating skin diseases were the fruits, seeds, and leaves (Fig. 5). Herbal mask (36%) was the most common mode of herbal drug preparation (Fig. 6). The use of an herbal mask is a simple and safe method with low complications. Because of the dust and toxic particles suspended in the air of Iran resulting from industrial pollution, exhaust fumes from automobiles, advancing deserts, and forest fires, using an herbal mask can help significantly reduce dermal complications resulting from air-borne pollutants. Medicinal herbs prescribed by herbal healers are often used for the treatment of acne (36%) as well as strengthening, clarifying, and adding freshness to the skin (26%) (Fig. 7). Acne is the 8th most common disease around the world affecting many people in their lifetimes (Tan & Bhate, 2015). Poor diet, hormonal changes, genetic factors, and inadequate cleansing of the skin are factors in acne. Considering the profusion of acne cases among the world’s population, the utilization of herbal medicine is a cheap but effective method to treat this condition, especially in developing countries.

Phytochemicals are chemical compounds found naturally in plants. Each plant species contains a variety of chemical compounds which, in most cases, are unique to the species. These compounds are produced and stored in different parts of the plant and can be used as pharmaceutical raw materials. Antioxidant, anticancer, and antimicrobial activities, stimulating the immune system, and affecting hormone metabolism are among some of the known properties of secondary plant compounds, which make phytochemicals suitable for preventing or treating a diverse range of diseases. Alkaloids, terpenoids, fatty acids, phenolic compounds are among the most important phytochemicals existing in medicinal plants. Interestingly, many phytochemicals which are known to contribute to the treatment of dermatological diseases and skincare were found in the plants collected in the current study (Table 1).

Electronic databases including Google Scholar, PubMed, and Web of Science were searched for the scientific names of all species and the keywords “chemical profiling” and “pharmacological properties”. An extensive number of studies published in various journals was collected, including research reports, review articles, book chapters, and books. The literature was divided into different sections based on the title and abstract, and all non-relevant and duplicate articles were removed. Finally, some of the newest articles with a comprehensive amount of information were selected.

Comparing the results of the present study with those of previous works on phytochemicals revealed that herbal medicines prescribed by herbal healers in the Jahrom region comprise the most efficient and suitable natural compounds for the treatment of skin diseases. For example, tannins, which have astringent properties and cause the coagulation of albumin, are found in Lawsonia inermis L. (henna) and Ziziphus spina-christi (L.) Willd., both of which are rich in tannins and are suitable herbal remedies for the treatment of acne (Maleki et al., 2007). The skin softening properties of saponins, mucilage, and salicylic acid which are abundant in the Viola L. species make this species a great candidate for remedies to soften and refresh skin (Bedi & Shenefelt, 2002). Amino acids, with their great water holding capacity, can promote freshness in skin and represent an effective treatment for dry skin (e.g. in Aloe vera; Maleki et al., 2007). Fumaric acid found in Fumaria L. is effective in curing skin disorders (Khalighi Sigaroodi et al., 2005). Wheat germ (the flour of embryos of wheat grains) is rich in vitamins A and E as well as antioxidants and can be considered a potent softening and moisturizing agent for skincare (Bakhtiyari & Radan, 2013). Moreover, vitamin A is a rejuvenating and anti-aging agent which stimulates the formation of new cells and helps reduce wrinkling (Gediya et al., 2011). In Matricaria chamomilla (chamomile), linoleic and oleic fatty acids and chamazulene improve the process of wound healing and water retention in the horny layer of the skin (Maleki et al., 2007).

Some of the plant species presented in the current study, such as Trigonella foenum-graecum L., Lawsonia inermis, Olea europaea Wall. & G. Don, Nigella sativa L., Urtica dioica L., and Aloe vera, are also used in other parts of Iran and the world to treat skin disease (Malik et al., 2019; Nambejja et al., 2019; Sinkar & Samarth, 2019; Tsioutsiou et al., 2019). Similar to the indigenous people of Jahrom, the locals of Central Macedonia and Greece use Matricaria chamomilla, for wound healing (Ghafari et al., 2017; Tsioutsiou et al., 2019). Silybum marianum (L.) Gaertn., Alcea rosea L., Malva sylvestris L., Rosa ×damascena Herrm., Urtica dioica, Cucumis sativus L., Ficus carica L., and Trigonella foenum-graecum are used globally for the treatment of hyperpigmentation (Ghafari et al., 2017). Trigonella foenum-graecum is used in Jahrom and northern Pakistan to treat wounds (Malik et al., 2019). Cucumis sativus in Katabi, Uganda (Nambejja et al., 2019) and Calendula officinalis, in the Warud region of Maharashtra, India (Sinkar & Samarth, 2019) are used to treat different skin diseases. Cichorium intybus L. is used traditionally by the indigenous people of Urmia, Iran, for head itching (Baharvand-Ahmadi et al., 2015). The indigenous people of Jahrom and Chagharzai Valley (in Pakistan) use C. officinalis to treat skin diseases (Sheri et al., 2011). Punica granatum L. and C. sativus have the same therapeutic use for the treatment of skin disorders in Jahrom and the northwest Frontier Province of Pakistan (Abbasi et al., 2010). Senna alexandrina Mill. is used to treat pimples in Jahrom and northwest Punjab, Pakistan (Gul et al., 2012). Descurainia sophia (L.) Webb ex Prantl and L. inermis (henna) are used as traditional herbal medicines in Jahrom and in the Saravan region of Iran (Sadeghi et al., 2014). Malva sylvestris is a common medicinal plant for the treatment of skin diseases in Sirjan, Saravan, and Jahrom (Khajoei Nasab & Khosravi, 2014; Sadeghi et al., 2014). Fumaria parviflora Lam. has the same therapeutic use on the skin in the Hormozgan province of Iran as it does in Jahrom (Safa et al., 2013).