Ethnomedicinal Plants in Herbal Remedies Used for Treatment of Skin Diseases by Traditional Healers in Songkhla Province, Thailand

Skin disorders are a worldwide health problem that normally affect human life. A traditional healer is an important expert in researching notable medicinal plants for skin disease treatment. This study aimed to determine the traditional knowledge and the use of medicinal plants for the treatment of skin diseases among traditional healers in the Songkhla province, Thailand. The ethnobotanical information was collected from experienced traditional healers by semi-structured interviews and participant observations. Plant specimens were also collected and identified using the standard taxonomic method. The data were analyzed by interpretation and descriptive statistics. Twenty-five polyherbal formulations for the treatment of skin diseases were obtained from traditional healers with at least 10 years of experience. A total of 66 plant species in 38 families were documented. Leaves and trees were the most commonly employed plant parts and plant habits included in the herbal remedies, respectively. Fabaceae, Rubiaceae, and Zingiberaceae were the majority of the cited families. Oryza sativa L. and Zingiber montanum (J. Koenig) Link ex A.Dietr. were the most preferred plants combined in the prescriptions, which had the highest use value (UV = 0.83). The highest relative frequency of citation was represented by Curcuma longa L., Eurycoma longifolia Jack, Knema globularia (Lamk.) Warb, and Senna siamea (Lam.) Irwin & Barneby. (0.55 each). This research suggests the importance of traditional healers in the healing of skin diseases with herbal remedies. A variety of medicinal plants are used in the prescriptions for the treatment of skin disorders in the Songkhla province, in the south of Thailand. Pharmacological and toxicological activities as well as phytochemical constituents of polyherbal remedies should be further investigated to scientifically verify further applications of widely practiced herbal medicines.


Introduction
Skin disease is a global public health problem that often has physiological, psychological, and social impacts [1]. The occurrence of skin diseases usually affects human health, from newborns to elderly people. Common skin diseases impact global distribution both in resource-poor areas and advanced economic settings. Scabies and pyoderma are examples of skin diseases in resource-poor settings. Skin disorders such as atopic eczema, psoriasis, skin ulcers, and pruritus are commonly distributed in both resource-poor areas and advanced economic settings [2]. Infectious skin diseases include a variety of conditions ranging in severity. The clinical presentation and the pattern of infectious skin diseases

Socio-Demographic Characteristics of Informants
Traditional medicines as well as herbal medicines have been used for health care in Southeast Asia and other global regions. They have been established and have developed empirical experience. This wisdom and knowledge are part of the social and cultural heritage of people and countries and can be passed from one generation to another [16]. In this study, six traditional healers participated. All professional folk healers were males. The informants were divided into three age groups, including 50-59 (16.7%), 60-69 (33.3%), and over 70 (50%) ( Table 1). This finding is similar to a previous study that reported the majority of experienced healers were males aged 69-79 years old [8]. Based on education, fifty percent of the participants had graduated from primary school, while 16.7% in each group were secondary school, vocational diploma, and bachelor's degree holders. The majority of the informants were Buddhists. In the past, Thai men had more opportunities to be educated than women. Additionally, Buddhist males had a chance to enter the monkhood. They could be the causes of men's ability to write and read. Moreover, men take their duty of obtaining plant materials for their family's living, leading to intensive experience in plant utilization [17].  Islam 1 All informants had at least 10 years of experienced.

Prescriptions of Polyherbal Remedies Applied for the Treatment of Skin Diseases
Twenty-five polyherbal remedies obtained from the folk healers were used to treat skin disorders including ulcers (24%), herpes simplex (20%), abscesses (16%), and tinea (12%). The rest of the treated skin diseases are presented in Figure 1.
enter the monkhood. They could be the causes of men's ability to write and read. More ver, men take their duty of obtaining plant materials for their family's living, leading intensive experience in plant utilization [17].

Prescriptions of Polyherbal Remedies Applied for the Treatment of Skin Diseases
Twenty-five polyherbal remedies obtained from the folk healers were used to tre skin disorders including ulcers (24%), herpes simplex (20%), abscesses (16%), and tin (12%). The rest of the treated skin diseases are presented in Figure 1. The information from the prescriptions in Table 2 showed that twenty-two formul tions (81.8%) were applied for microbial skin infectious diseases, including bacterial i fections such as ulcers, abscesses, acne, and pus, viral infections (herpes simplex), an  The information from the prescriptions in Table 2 showed that twenty-two formulations (81.8%) were applied for microbial skin infectious diseases, including bacterial infections such as ulcers, abscesses, acne, and pus, viral infections (herpes simplex), and fungal infections (tinea). The traditional healers possessed the medical expertise to formulate the herbal medicine for the treatment of each patient. The polyherbal prescription was defined by the combination of each plant at equal weight. Many diseases can be healed using one or a combination of plants as a synergistic effect. In addition, the plant's scientific name, local name, family, and plant part used are also shown in Table 2.    The traditional preparations of the remedies were made by poultice (44%), decoction (28%), hot oil extraction (20%), ointment (4%) and powder (4%) as shown in Figure 2. A variety of medicinal plant preparation methods for skin disorder treatment, such as powder, paste, oil, infusion, decoction, and concoction, have been documented in many ethnobotanical surveys [8,18,19]. The poultice was the most famous preparation method applied to the patients in this study. It might be due to the convenient preparation used for topical skin disease treatment.
N. Kiankhun 032 * Materia medica was bought from the drug store and the scientific name was referred to valid books in traditional Thai pharmacy.
The traditional preparations of the remedies were made by poultice (44%), decoction (28%), hot oil extraction (20%), ointment (4%) and powder (4%) as shown in Figure 2. A variety of medicinal plant preparation methods for skin disorder treatment, such as powder, paste, oil, infusion, decoction, and concoction, have been documented in many ethnobotanical surveys [8,18,19]. The poultice was the most famous preparation method applied to the patients in this study. It might be due to the convenient preparation used for topical skin disease treatment.

The Habits of Medicinal Plants and the Plant Part Used
All plant species in the 25 polyherbal remedies were classified into six habits ( Figure  3). Trees (42.4%) were found to be the most commonly used plant habit included in herbal remedies, followed by herbs (27.3%), shrubs (16.7%), and climbers (9.1%). Trees were the most preferable plant habit used in polyherbal prescriptions, which was consistent with the habits of medicinal plants from a previous study in the Songkhla province [12].

The Habits of Medicinal Plants and the Plant Part Used
All plant species in the 25 polyherbal remedies were classified into six habits ( Figure 3). Trees (42.4%) were found to be the most commonly used plant habit included in herbal remedies, followed by herbs (27.3%), shrubs (16.7%), and climbers (9.1%). Trees were the most preferable plant habit used in polyherbal prescriptions, which was consistent with the habits of medicinal plants from a previous study in the Songkhla province [12].
N. Kiankhun 032 * Materia medica was bought from the drug store and the scientific name was referred to valid books in traditional Thai pharmacy.
The traditional preparations of the remedies were made by poultice (44%), decoction (28%), hot oil extraction (20%), ointment (4%) and powder (4%) as shown in Figure 2. A variety of medicinal plant preparation methods for skin disorder treatment, such as powder, paste, oil, infusion, decoction, and concoction, have been documented in many ethnobotanical surveys [8,18,19]. The poultice was the most famous preparation method applied to the patients in this study. It might be due to the convenient preparation used for topical skin disease treatment.

The Habits of Medicinal Plants and the Plant Part Used
All plant species in the 25 polyherbal remedies were classified into six habits ( Figure  3). Trees (42.4%) were found to be the most commonly used plant habit included in herbal remedies, followed by herbs (27.3%), shrubs (16.7%), and climbers (9.1%). Trees were the most preferable plant habit used in polyherbal prescriptions, which was consistent with the habits of medicinal plants from a previous study in the Songkhla province [12].   Sixteen different plant parts were used in the polyherbal formulations for skin infection. Leaves were the most frequently used part (20.9%), followed by roots (16.4%), rhizomes (9.0%), seeds (9.0%), and stem bark (9%). The rest of the parts used of the plants are shown in Figure 4. In many reports [8,20], as well as in this study, leaves were the major plant part used for skin disease treatment. It could be due to the fact that the collection of leaves is easier than that of other parts, such as roots, seeds, bark, and rhizomes, and they are harvested every season. Another reason might be that leaves are soft and the chemical contents might be readily extracted [12].
Sixteen different plant parts were used in the polyherbal formulations for skin infe tion. Leaves were the most frequently used part (20.9%), followed by roots (16.4%), rh zomes (9.0%), seeds (9.0%), and stem bark (9%). The rest of the parts used of the plan are shown in Figure 4. In many reports [8,20], as well as in this study, leaves were th major plant part used for skin disease treatment. It could be due to the fact that the colle tion of leaves is easier than that of other parts, such as roots, seeds, bark, and rhizome and they are harvested every season. Another reason might be that leaves are soft and th chemical contents might be readily extracted [12].   (Table 2). In regard to the numbers of plant species used in the familie Fabaceae, Rubiaceae, and Zingiberaceae (7.6%) were the most notable families, followe by Acanthaceae (6.1%), as shown in Table 3

A Variety of Plant Materials Used in Polyherbal Remedies for Skin Disorders
Totally, 66 plant species and one animal material (Sepia spp. cuttlebone) were included in the 25 prescriptions of herbal remedies. The plants were classified into 61 genera and 38 families (Table 2). In regard to the numbers of plant species used in the families, Fabaceae, Rubiaceae, and Zingiberaceae (7.6%) were the most notable families, followed by Acanthaceae (6.1%), as shown in Table 3 [21]. Similarly, Zingiberaceae, Fabaceae, and Rubiaceae were the major families of plant species used and cited by traditional healers in the Patthalung province, in the south of Thailand [11]. In addition, five plant species in the Fabaceae family and three species in the Rubiaceae family were used in herbal remedies for skin diseases treated by a folk healer in the Songkhla province [22].

Preferred Plants Used in Polyherbal Recipes for Skin Disorder Treatment
The preferred medicinal plants used in polyherbal remedies for skin diseases and their pharmacological activities are presented in Table 4. According to the quantitative analysis, Oryza sativa L. and Zingiber montanum (Koenig) Link ex Dietr. show the highest use value with 0.83, followed by Nicotiana tabacum L. with a use value of 0.67. Oryza sativa L. was applied for herpes simplex and abscess treatment, while Zingiber montanum (Koenig) Link ex Dietr. was used for treating tinea, acne, and ulcer leprosy, which is similar to Nicotiana tabacum L. Other important plants were Curcuma longa L., Eurycoma longifolia Jack, Knema globularia (Lamk.) Warb, and Senna siamea (Lam.) Irwin & Barneby. with a use value of 0.50. The species with a use value of 0.33 are listed in Table 4. Other plants (50 species) exhibited the UV of 0.17. In previous reports, the seed of Oryza sativa L. was frequently used in skin treatment. Oryza sativa L. contained high levels of anthocyanin polyphenols, which presented beneficial effects on health owing to their antioxidant properties. Anthocyanin from Oryza sativa L. exhibited anti-inflammatory properties and anti-aging activity by modulating type I collagen gene expression and suppressing H 2 O 2 -induced NF-κB activation in skin fibroblasts [23]. The crude extract, alkaloids, flavonoids, and saponins from Oryza sativa L. showed antibacterial effects against multidrug resistant Staphylococcus aureus [24]. In addition, the antimicrobial activity of Oryza sativa L. against fungi [25] and viruses [26] has been revealed. Cream containing niosomes loaded with purple glutinous rice (Oryza sativa L.) extract possessed anti-aging activity on human skin [27]. The antioxidative and immunomodulatory properties of Oryza sativa L. crude extract reduced the severity of psoriasis [28]. Zingiber montanum (Koenig) Link ex Dietr., another one of the most frequently used plants in this study, has been previously investigated for its phytochemicals and pharmacological activity. Numerous bioactive phytochemicals were discovered in the rhizomes of Zingiber montanum (Koenig) Link ex Dietr. including alkaloids, saponins, tannins, flavonoids, terpenoids, phenolic compounds, phlobatannins, steroids, and glycosides [29,30]. The essential oil of Zingiber montanum (Koenig) Link ex Dietr. rhizome exhibited antifungal activity against Candida albicans [31]. (E)-8(17),12labdadiene-15,16-dial, zerumbol, zerumbone, buddledone A, furanodienone, germacrone, borneol, and camphor were isolated from the rhizomes of Zingiber montanum. Among these terpenes, (E)-8(17),12-labdadiene-15,16-dial and zerumbol exhibited antibacterial activity against a number of clinical isolates of multi-drug-resistant (MDR) and methicillinresistant Staphylococcus aureus (MRSA) [32]. Zerumbone, a sesquiterpenoid, is one of the major compounds in the essential oils and rhizomes of Zingiber montanum. Furthermore, zerumbone-treated wound sections showed greater tissue regeneration and more fibroblasts, possibly through the enhanced expression of VEGF, TGF-β1 and collagen IV [33]. Cysteine protease glycoprotein, purified from Zingiber montanum rhizome, showed antioxidant activity in biochemical systems and THP-1 cells [34], and anti-inflammatory activity [35]. The leaf of Nicotiana tabacum L. was the preferred component in the formulations, and it possessed many biological activities. The different extracts of Nicotiana tabacum L. leaves contain the phytochemical constituents of alkaloids, phenolic compounds, tannins, flavonoids, steroids, terpenoids, cardiac glycosides, essential oils, resins, saponins, quinones, and polypeptides [36]. Antimicrobial activity was observed in the ethyl acetate extract of Nicotiana tabacum L. against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and biofilm-forming Escherichia coli and Klebsiella species. The most common phytochemical components found in the ethyl acetate extract were 3, 4, 5,6-tetrahydro-1, 3-dimethyl-2(1h)-pyrimidinone, pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)-, isododecane, n-pentadecane, and tetradecylaldehyde. The antibacterial property demonstrated could be due to pyridine, 3-(1-methyl-2-pyrrolidinyl)-(S), the major compound detected, with a broad spectrum of activity [37]. Six sesquiterpenes, including tabasesquiterpenes A−C, balsamiferine B, samboginone, and ent-4(15)-eudesmen-1α,11-diol were isolated from the leaves of Nicotiana tabacum L. Tabasesquiterpenes B exhibited high antiviral activity with an inhibition rate of 35.2%. The other compounds also demonstrated antiviral activity with inhibition rates ranging from 20.5-28.6% [38]. Nicotiana tabacum L. leaf cow urine extract was found to have potential anti-dandruff activity against a causative agent, Malassezia furfur [39].

Study Area
The Songkhla province is located in the eastern part of the south of Thailand between latitude 6 • 17 -7 •

Informants
In the present study, all traditional healers were selected from their extensive experience and actively practiced patient treatment. All the informants had experience of at least 10 years. According to the intensive criteria, six traditional healers were chosen. All the professional folk healers were males, 54-74 years old. Based on education, three of the healers had graduated from primary school, while one in each group was a secondary school, vocational diploma, and bachelor's degree holder. Five of the informants were Buddhist, and one of them was Muslim (Table 1).

Ethnobotanical Data Collection
Ethnobotanical information about skin diseases was obtained from local herbal healers. Before interviewing, the purposes of the study were distinctly explained to the traditional healers and their family members, and verbal informed consent was obtained.
The informants were interviewed using questionnaires and conversations. The interview was performed to investigate the prescriptions for skin disease treatment. Data on the plant's local names, plant parts used, skin diseases treated with herbal remedies, mode of use, and administration were gathered. Field trips to the sites where the traditional herbal healers normally go to harvest the plants were carried out. Plant materials were collected and processed according to the standard taxonomic method [115]. The scientific names of the plants in the polyherbal formulations were identified according to the principle of plant taxonomy using the Flora of Thailand and the related literature from neighboring areas. The accepted names were verified against The Plant List (2013) [116]. Voucher specimens were deposited at the Faculty of Thai Traditional Medicine, Prince of Songkla University, Songkhla, Thailand. However, some medicinal plants were not obtained from nature because they were exotic or not distributed in the study location. Therefore, they were purchased from the drug stores following the healers' suggestion, and for their scientific names, we referred to authentic books in traditional Thai pharmacy.

Data Analysis
The plants were analyzed regarding their habits of plants, and plant parts used in polyherbal remedies for treatment of skin diseases, frequency in families, and quantitative ethnobotany analysis including use value (UV) and relative frequency of citation (RFC).

Use Value (UV)
Use value was calculated based on the number of uses and the number of people citing a given plant. It indicated the most significant plant species, recognized by a given population [117]. UV = u/N where u is the total number of use reports stated by participants for a given species, and N is the whole number of participants. UV is normally "1" if there are more usages, and "0" if there are fewer usages reported for plant species.

Relative Frequency of Citation (RFC)
RFC was analyzed to intricate the knowledge of traditional flora about usage of therapeutic flora in the study site. RFC = FC/N (0 < RFC < 1) where RFC is denoted by relative frequency citation, FC (frequency of citation) is the number of participants mentioning the plant species and N is total number of participants [118].

Conclusions
Currently, the Thai government has a policy to promote and develop the use of traditional medicines. Thai traditional medicines as well as drugs developed from medicinal plants are included in the national list of essential medicines. The traditional healer is one of the most essential sources for determining the usage of herbal medicine for treating individuals in the community. The results from this study represent the polyherbal remedies used by experienced folk healers for the treatment of skin disorders in the Songkhla province, in the south of Thailand. Ethnopharmacological expertise is abundant among traditional healers. They have significant knowledge of many plant species used for a variety of skin disorder treatment. The utilization of medicinal plants was widespread in the prescriptions, with 66 species in 38 families. The poultice was the most frequent method of administration. The most prominent plant families were Fabaceae, Rubiaceae, and Zingiberaceae. The highest use values were reported for Oryza sativa L. and Zingiber montanum (Koenig) Link ex Dietr. Based on RFC, the highest was found for Curcuma longa L., Eurycoma longifolia Jack, Knema globularia (Lamk.) Warb, and Senna siamea (Lam.) Irwin & Barneby. Although local treatment of herbal prescriptions and ethnobotanical surveys are underway, more research on phytochemicals and their pharmacological activities is needed to ensure the application of polyherbal prescriptions used by traditional healers, as well as product development in herbal medicine for the treatment of skin diseases, in order to promote the sustainable and safe use of natural resources.