Global Perspective of Plant-Based Cosmetic Industry and Possible Contribution of Sri Lanka to the Development of Herbal Cosmetics

The global consumption of plant-based cosmetics has shown spectacular growth in recent years because of rising consumer awareness regarding the long-term health benefits of natural ingredients. As the global demand for herbal cosmetics increases, there are ample opportunities for Sri Lanka as a tropical Asian country to expand its productions and global exports along with its unique biodiversity and inherited traditional knowledge. Therefore, the present review attempts to give an overview of the widely used medicinal plants in the global herbal cosmetic industry and strengths, challenges, and possible solutions for the development of the herbal cosmetic industry of Sri Lanka. Information was collected using electronic search (using Pub Med, Science Direct, Web of Science, Google Scholar, TEEAL, and Scopus) for articles published in peer-reviewed journals, industrial reports, market surveys, and library search for local books on ethnobotany. Important plant-derived ingredients used in the global herbal cosmetic industry are essential oils, colorants, oils, fats, and waxes. The traditional usage of 108 medicinal plant species (belonging to 58 families) in cosmetic treatments was identified from the local books of Sri Lanka. Of these, 49 plant species were reported as new ingredients for the herbal cosmetic industry. However, the lack of ethnobotanical and ethnopharmacological surveys to identify the cosmetic potential plants, insufficient or absence of continuous supply of raw materials for production in line with the existing demand, the lack of quality control of raw materials and finished cosmetic products, improper systematic cultivation systems for medicinal plants, poor postharvest practices, and the lack of innovations are major challenges encountered in Sri Lanka for the development of the herbal cosmetic industry. In conclusion, addressing these vital knowledge gaps is a timely requirement of the country for the sustainable development of the herbal cosmetic industry in Sri Lanka. Furthermore, assembling of the multidisciplinary cooperation of botanists, chemists, toxicologists, researchers, and biologists is crucial to analyze the interesting functional properties, efficacy, and effectiveness of documented medicinal plants with cosmetic potential.


Introduction
In today's world, being presentable and looking great have become necessary for everyone [1]. e growing consumer demand for cosmetics is mainly driven by the aspiring young population who want to invest in grooming while maintaining their health [2]. Nonetheless, most individuals in different age groups use cosmetics in various forms [3]. With its huge profitability, it is a challenge for a manufacturer to provide a good quality product at a low cost that is simultaneously environmentally friendly [4]. Although cosmetic products are not generally associated with serious health risks, there are possibilities of adverse long-term effects of extensive usage of cosmetics [5]. For instance, cosmetics and toiletries may contain several hazardous ingredients: allergens, carcinogens, and endocrine disruptors. e various harmful allergens present in cosmetics may be grouped under phthalates, parabens, metals, chlorofluorocarbon propellants, and dioxanes. e bioaccumulation of these harmful chemicals and metals in the body over time has been associated with cancers, reproductive and developmental disorders, contact dermatitis, hair loss, lung damage, aging, allergies, and skin diseases [5,6].
With the increasing awareness about the fewer side effects of herbal products [7], consumer demand for herbal cosmetics is becoming a rapidly growing segment globally [8]. e global natural and organic personal care products market is valued approximately at US$ 11 billion in 2016 and is expected to reach US$ 22 billion by 2022 [9]. North America is the major market for natural and organic personal care products, followed by Europe and Asia-Pacific. China and India are the specific countries that play a significant role in the global herbal cosmetics market. Natural and organic skin care maintains top billing in the global organic beauty market and is expected to emerge as the most attractive segment with a 30.9% share by 2024, followed by hair care [10].
Cosmeceuticals, which are cosmetic products containing naturally derived ingredients and fully organic cosmetic products, have become a trend at present. Consumer attraction for these products in the future is anticipated to grow significantly. us, the global demand for herbal cosmetics results in a huge trade from the local to the international level. At present, the majority of the developed countries' cosmetic manufacturers are continuously probing for new products and ingredients that are of tropical origin as their raw materials often have interesting properties because of varied climatic and topographical conditions [11]. Unfortunately, the plant-based cosmetic industry is still at its early stages in some tropical Asian countries, such as Sri Lanka, Vietnam, Indonesia, and ailand. For the successful development of the herbal cosmetic industry in those countries, several challenges must be addressed. is review aims to give an overview of these points while providing widely used medicinal plants in the global herbal cosmetic industry. Furthermore, this review will highlight the possible contribution of Sri Lanka as a tropical Asian country to the development of herbal cosmetics.

Methodology
e process of bibliographic research was conducted from January 2020 to August 2020, comprehending works from 1999 to 2019. is review was mainly focused to address the following research questions: (1) What is the present status of the global herbal cosmetic industry, including market annual growth, leading cosmetic product categories, and the pioneers of the herbal cosmetic industry by geographical zones and countries?
(2) What are the widely used specialty plant materials in global herbal cosmetic production and their functions? (3) What is the present status of the herbal cosmetic industry of Sri Lanka? (4) What are the strengths, challenges, and possible solutions for the development of the herbal cosmetic industry of Sri Lanka as a tropical Asian country? e research was organized in two phases. Data extraction was done by two investigators (D.G.N.D. Gamage and R.M. Dharmadasa) independently at each phase. Any inconsistencies between the investigators were resolved by consensus with a third investigator (D.C. Abeysinghe). Information was gathered by adopting databases, such as Pub Med, Science Direct, Web of Science, Google Scholar, TEEAL, Wiley Online Library (Wiley), and Scopus.
During the first phase, information was collected on the global herbal cosmetic industry. Extensive bibliographic research was performed using keywords and syntax, such as "herbal cosmetics," "global herbal cosmetic industry," "medicinal plants with cosmetic potential," "specialty plant materials used for cosmetic production and their functions," "essential oils," "plant-based dye and colorants," "plant oils used in cosmetics," "fat and waxes for cosmetics," "herbal cosmetic industry in China," "herbal cosmetic industry in India," "medicinal plants used in cosmetics in China," "Cosmetic treatments and traditional Chinese medicine," and "medicinal plants used in skin care/hair care/oral care in India." Furthermore, references listed in relevant journals were also screened. 218 journals were identified using databases, whereas 20 web resources, 13 industrial reports, 01 book, and 03 book chapters were identified using "Google" search. However, 93 journals, 14 web resources, 10 industrial reports, 01 book (International Cosmetic Ingredient Dictionary and Handbook, published by Personal Care Products Council, Washington), and 03 book chapters ( e erapeutic Benefits of Essential Oils, Chinese Topical Herbal Treatments and Essential Oil Protocols and Cosmetics' Quality Control) were utilized for writing on the global herbal cosmetic industry after excluding repeated records, suspected plagiarisms, non-peer reviewed journals, incomplete data or obvious errors of information (e.g., errors in scientific, vernacular, or English names of medicinal plants), and records in different languages. Materials in the English language alone were chosen during this phase. Furthermore, peer-reviewed journals and books, market analysis done by reputed research organizations (e.g., Future Market Insights/FMI), industry reports developed by governments or recognized non-governmental associations (e.g., Basic Chemicals, Cosmetics and Dyes Export Promotion Council, India/CHEMEXCIL, e Associated Chambers of Commerce and Industry of India/ ASSOCHAM), ethnobotanical and ethnopharmacological surveys with minimum sample size and in vitro bioactivity studies of medicinal plants with a minimum number of replications were considered to be eligibility materials for writing in this phase. Moreover, extracted data from the publications on medicinal plants with cosmetic potential in China were compared with the "Inventory of Existing During the second phase, information on the herbal cosmetic industry of Sri Lanka, the traditional usage of medicinal plants in cosmetic treatments, strengths, and challenges for the development of the herbal cosmetic industry of Sri Lanka was accumulated. e bibliographic research was performed using keywords and syntax, such as "herbal cosmetics of Sri Lanka," "herbal cosmetic industry of Sri Lanka," "medicinal plants used for cosmetic treatments in Sri Lanka," "medicinal plants and bioactivity studies in Sri Lanka," and "medicinal plants used in skin care/hair care/oral care in Sri Lanka." e numbers of records identified using databases and "Google" searching were 95 and 17, respectively. After applying the same inclusion and exclusion criteria, only 14 publications and 2 conference proceedings (Current scenario on the import of plant-based Ayurvedic raw materials in Sri Lanka and Current scenario of herbal medicine in Sri Lanka) were accepted for writing in this phase. Because of the lack of relevant publications available in databases, data extraction was focused by searching local books from the libraries of Industrial Technology Institute, National Science Foundation and Institute of Indigenous Medicine, University of Colombo in Sri Lanka. erefore, both English and Sinhala languages were considered during the search of libraries. Four Ayurveda authentic books, namely the "Compendium of medicinal plants-Sri Lankan study, volumes I, II, III, and IV," published by the Ayurveda Department of Sri Lanka and the book called "A collection of medicinal plants in Sri Lanka," published by Nature's Beauty Creations Limited, Sri Lanka, were selected to identify potential medicinal plants for cosmetic productions. e current usage of identified medicinal plants with cosmetic potential through books was compared with the survey conducted on identifying medicinal plants used in the herbal cosmetic industry of Sri Lanka [12] to recognize new plant materials for the Sri Lankan herbal cosmetic industry.
In total, 107 peer-reviewed journal articles, 14 web resources, 10 industrial reports, 6 books, 2 conference papers from proceedings, and 3 book chapters were employed for writing this review. Figure 1 illustrates the schematic diagram of the employed methodology. e results were summarized in a narrative manner using tables. e scientific names of documented plants were validated based on the collections listed on the homepages http://www.theplantlist.org and http://www.worldfloraonline.org. In addition, important links have been given where all details cannot be provided. Administration (FDA), the law defines cosmetics as "articles intended to be rubbed, poured, sprinkled, sprayed on, introduced into, or otherwise applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance" [3]. However, products that are formulated using various permissible cosmetic ingredients to form the base in which one or more herbal ingredients are used to provide defined cosmetic benefits, e.g., influencing the functions of the skin and providing nutrients necessary for healthy skin or healthy hair, can be described as "herbal cosmetics" [13,14]. Free-radical scavenging, anti-inflammatory, antiaging, sun protection, the reduction of hyperpigmentation, and antimicrobial effects are some of the functional benefits [15]. In the formulation of herbal cosmetics, plants are used in three ways: a total extract, a single molecule obtained from the purification of extracts, or a selective extract [16]. Some important plantderived ingredients used in cosmetics are oils, fats, waxes, essential oils, plant extracts, and colorants. ese ingredients have numerous roles in the final cosmetic products, such as coloring, scenting, moisturizing, thickening, and stabilizing [15]. e usage amount of these specialty plant materials or their extracts in herbal cosmetic products is varied according to the product category, plant materials used, national, regional (e.g., EU cosmetics regulations), and international (e.g., e International Organization for Standardization (ISO), Food and Drug Administration (FDA)) rules and regulations. For instance, the allowable level of Citrus bergamia Risso (Bergamot oil) in cosmetics is 0.1 ppm in Austria. Furthermore, in line with the EU Cosmetics Regulation, the permissible concentration of essential oil in shower gels and baths (rinse-off products) is 0.01%, while the permissible concentration of essential oil in body oils, massage oils, and creams is 0.001% [17]. However, information on the acceptable concentrations of these individual specialty plant materials in cosmetics is scarce.

Results and Discussion
(1) Essential Oils. People have been using aromatic plants and oils for thousands of years in incense, perfumes, cosmetics, medicinal, and culinary applications [15]. Essential oils are highly concentrated, volatile, hydrophobic mixtures of chemicals extracted from plants. It is estimated that more than 3000 essential oils are of commercial importance and are used in flavor and cosmetic industries [18]. e largest consumer of essential oils is the United States of America, followed by western European countries, namely France, Germany, and the United Kingdom. At present, the United States and developing countries are dominant in the production of the most important essential oils. Essential oils are primarily used for their fragrance properties in cosmetic products. However, certain essential oils possess other interesting properties, such as antibacterial or antifungal, conditioning hair, and improving skin elasticity. Because of the unique functional properties and fragrances of plant-derived essential oils, the cosmetic industry uses them profoundly in a wide range of cosmetic products [11]. Table 1 lists the examples of plant-derived essential oils used in cosmetic products.
(2) Dye and Colorants. Currently, the market for natural colors in cosmetics continues to grow throughout the world. Manufacturers seek natural plant-based coloring materials Evidence-Based Complementary and Alternative Medicine that offer health benefits, such as antioxidant, antimicrobial, anti-inflammatory, antiaging, and UV protection properties, beyond their coloring properties alone [22][23][24][25]. At present, the main exporting countries of natural dyes are China, Peru, and India [11]. Plant colorants and pigments are used in a whole range of cosmetic products, such as creams, soaps, lotions, hair dyes, and make-up products [15,26]. Table 2 lists various plant origin colorants and dyes used in the cosmetic industry.
(3) Oils. Oils are rich sources of fatty acids. Plant-derived oils from edible vegetables, fruits, seeds, plant seedlings, groundnuts, and trees have been safely consumed by humans for millennia. Various oils have been used on the skin since ancient times for cosmetic purposes. Oils are used as the base in a wide variety of cosmetic products, such as creams, emulsions, cosmetic milk, creams, ointments, hair conditioners, brilliantine, cosmetic masks, protective lipstick, bath fluids, nail varnish, and nail cleaners, along with their conditioning, occlusive, emollient, and moisturizing properties [28,29]. As highlighted by Lubbe and Verpoorte [11], Zielinska and Nowak [29], and Athar and Nasir [30], Table 3 summarizes some commonly used plant-derived oils in cosmetic products.
(4) Fat and Waxes. Fats and waxes form an important group of ingredients for the manufacture of personal care products and decorative cosmetics. ese are harder substances and very resistant to moisture, oxidation, and microbial attack. Waxes are widely used in a large variety of cosmetic products, such as creams, lotions, balms, ointments,  Evidence-Based Complementary and Alternative Medicine  [56] highlight, China is the largest exporter of herbal cosmetics. Traditional Chinese medicine (TCM) has a deep history of herbal cosmetics production. ere are plentiful instances where herbal skincare therapies have been popularly used in TCM. Most cosmetic products belong to the two categories called "antiaging products" and "moisturizer products." Herbal drugs utilized in TCMs for medicinal purposes are used in cosmetics and personal care products. erefore, the use of TCM compounds in the production of cosmetic products is very much derived from the medicinal and pharmaceutical applications of TCM [57]. TCM uses approximately 5000 plant species in a wide variety of herbal products [58].  Table 4, are no longer considered cosmetic ingredients according to the IECIC 2015.
IECIC 2015 was the latest version issued by the China Food and Drug Administration (CFDA) in 2015. It is a list of existing cosmetic ingredients that have already been used in cosmetics in China. According to IECIC [105], 8783 cosmetic ingredients are allowed to be used in China. Approximately, one-third of these ingredients are classified as Evidence-Based Complementary and Alternative Medicine "botanical extracts." However, many of these ingredients are various formulations of the same plant material [104]. Cosmetic ingredients that are not listed are regarded as new cosmetic ingredients. erefore, new cosmetic ingredients, including botanicals, must be approved by CFDA first before they can be used in cosmetics in China. Furthermore, more information about the approved cosmetic plant ingredients can be found from this link (http://www.cirs-reach.com/ China_Chemical_Regulation/SFDA_Registration_of_New_ Cosmetic_Ingredient_in_China.html). In India, traditional medicine literature like the Ayurveda has proved the concept of using herbs for beautification in the past. e cosmetic preparations were used for worship and sensual enjoyment. Moreover, herbal extracts have been used for various skin and hair ailments and for enhancing the overall appearance over centuries. Over the last couple of decades, the Indian cosmetics industry has witnessed rapid and strong growth. Today, it is recognized as one of the emerging industries with immense growth potential [106]. Next to China, India is the largest producer of medicinal plants, and India owns more than 40% of global diversity [16]. According to the research report [107], India is one of the 12 mega biodiverse countries around the world. In India, nearly 45,000 plants are used in the Indian system of medicine, while 9,500 plant species are used by tribals in their daily requirements. Out of these 9500 species, 7,500 plants have direct medicinal use, while 950 are giving new leads and claims that require scientific scrutiny [108]. Furthermore, in India, more than 70% of the population uses herbal cosmetics for health care [109]. However, as indicated in the "International cosmetic ingredient dictionary and handbook" issued in 2016, India has not been included as the country that recognizes the need for uniformity in cosmetic ingredient nomenclature and has not formally identified dictionary (potential cosmetic ingredients) in its regulations [110]. Table 5 lists the most common herbal plants used for cosmetics and toiletries in India. Evidence-Based Complementary and Alternative Medicine hotspot of global and national importance. Sri Lanka has a traditional system of medicine, which is as ancient as the civilization of the island and practiced from generation to generation [116]. Natural resources, including herbal, mineral, and animal products, are the key resources of the Ayurveda and indigenous systems of medicine in Sri Lanka. Since time immemorial, plants have been playing a    [109,113] Aloe vera (L.) Burm.f. Aloe Gel Dissolving the dead skin cells and excessive sebum that can clog hair follicles [109,113] Phyllanthus emblica L. Indian gooseberry Fruit Promoting hair growth [109,111,114] Ocimum basilicum L. Basil Anti-inflammatory properties, strengthening hair against breakage, and improving circulation in the hair follicles, which helps to stimulate growth [109] Eclipta prostrata (L.) L.  [109] vital role in the healthcare system of Sri Lankans' livelihoods [117]. As specified in the literature, Sri Lanka has rich traditional systems of medicine, such as Ayurveda, Siddha, Unani, and Deshiya Chikitsa. It plays a pivotal role by fulfilling 60% to 70% of the rural populations' primary health care needs [118]. Sri Lanka is one of the most biologically diverse countries in Asia and currently possesses 29.7% of forest cover [119]. ere are 3,771 flowering plant species, out of which about 927 (24%) are endemic to the country [120]. According to Sugathadasa et al. [ It reveals that most of the conducted studies were activity-based studies, such as toxicity, antibacterial, antifungal, hypoglycemic, antioxidant, anti-inflammatory, and diuretic activities. It was followed by general studies, such as physicochemical, chemical, postharvest, horticultural, and propagation studies of plants.  [115] is study shows the largely unexplored knowledge gap of medicinal plants in Sri Lanka.
However, considering the herbal cosmetics in Sri Lanka, the available data on herbal cosmetics' production and cosmetic potential medicinal plants are very scarce. Although the herbal cosmetic industry has exponentially increased throughout the world, the supply of potential cosmetic herbal products from Sri Lanka is still very limited. As Napagoda et al. [125] stated, only a handful of scientific evidence is available on the bioactivity studies of medicinal plants in Sri Lanka that could lead to the development of herbal cosmetics. Apart from the study on "cosmetic perspective of ethnobotany in the northern part of Sri Lanka," [126] there has been hardly any ethnobotany report on the cosmetic potential of Sri Lankan medicinal plants. A total of 62 plant species belonging to 36 families have been identified based on the traditional knowledge and practices of the local community through this study. e identified plants are used for beautifying purposes, such as skin care, hair care, nail care, lip care, and eye care. However, the assembling of the multidisciplinary cooperation of botanists, chemists, toxicologists, researchers, and biologists is crucial to analyze interesting functional properties, efficacy, and effectiveness of documented cosmetic potential medicinal plants. Furthermore, Napagoda et al. [125] highlighted the probable usage of Atalantia ceylanica (Arn.) Oliv., Hibiscus furcatus Mullend., Leucas zeylanica (L.) W.T.Aiton, Mollugo cerviana (L.) Ser., Olax zeylanica L., and Ophiorrhiza mungos L. for the development of photoprotective cosmetic products by analyzing the antioxidant activity and the sun protection factor (SPF). Moreover, the research study conducted by Liyanaarachchi et al. [9] reveals the possible usage of Artocarpus nobilis waites, Artocarpus altilis (Parkinson ex F.A.Zorn) Fosberg, Elaeocarpus serratus Heyne, Curcuma aromatica, and Artocarpus heterophyllus Lam. in the treatment of various skin disorders, such as hyperpigmentation, wrinkling, premature aging, and biological aging by analyzing tyrosinase, elastase, and hyaluronidase enzyme inhibitory and antioxidant activities.
Furthermore, Dissanayake [124] reports that most of the medicinal plant-related studies in Sri Lanka are still on the laboratory scale. us, investigating the cosmetic potential medicinal plants, isolation of active compounds, and bioactivity studies of medicinal plants has become necessary for Sri Lanka to support herbal cosmetic productions and innovations.

Strengths of Sri Lanka as a Tropical Asian Country for the Development of Herbal Cosmetic Industry.
Medicinal plants have played a pivotal role in many ancient traditional systems of medicine in Asia, such as the Ayurvedic and Unani systems of India and the traditional Chinese medicine and their derivatives in most Asian countries. Tropical Asian countries are unique among the geographical regions of the world because of high biological diversity, high cultural diversity, diverse ancient civilizations, and abundant raw materials. Because of their widely diversified ecological conditions, particularly in tropical rain forests, they have relatively high biological diversity that is the greatest of all world regions. is high diversity of the region is reflected by the number of species of plants and animals, including medicinal plants. e areas of high biological diversity are among the most culturally disparate, with large numbers of distinct communities inhabiting adjacent areas, each with its own language, culture, and system of traditional medicine. A wealth of traditional knowledge about medicinal plants to cure illnesses has been accumulated over a long period and has been handed down from generation to generation until the present time [127].
Medicinal plants have been used for centuries in medicinal, therapeutic, and beauty applications in Sri Lanka by different traditional systems of medicine, which have a documented history of over 2,500 years. Many formulae of medicinal preparations in the Sri Lankan traditional system of medicine are handed down from generation to generation. Some formulae are found only in the scripts of old "ola leaf" books treasured by traditional and Ayurvedic practitioners [128]. Table 6 lists the traditional usage of medicinal plants in Sri Lanka for cosmetic treatments.
As listed in Table 6, a total of 108 different plant species belonging to 58 families were identified from the books, "Compendium of medicinal plants, Sri Lankan study, Volume I to IV" and "A collection of medicinal plants in Sri Lanka." e most dominant family was the family Fabaceae (13 plant species). A wide range of plant parts has been used for traditional cosmetic treatments. Based on the remedies, the identified plant parts were the leaves, bark, seeds, fruits, roots, flowers, rhizome, stem, heartwood, flower buds, tuber, gum, fruit rind, shoots, bulb, flower stamens, fruit kernel, inner bark, leaf gel, thorns, and wood. Medicinal plants are used in cosmetic treatments for various reasons, such as skin care, hair care, and oral care. e recent survey conducted by Gamage et al. [12] discloses the current usage of 115 plant species in herbal cosmetic productions in Sri Lanka. Furthermore, this study highlights the lack of proper cultivation systems of medicinal plants with cosmetic potential within the country for continuous herbal cosmetic productions. Although established cultivation systems are available for some highly used plants in the herbal cosmetic industry of Sri Lanka, such as Aloe vera (L.) Burm.f., most of the other medicinal plant materials are obtained either from the wild or through importation. Consequently, harvesting restrictions were imposed by the government for some wild species, such as Coscinium fenestratum (Goetgh.) Colebr. e adulteration of medicinal plant materials, lack of growers, declining suppliers, and lack of proper cultivation systems are major hindrances to the success of the herbal cosmetic industry in Sri Lanka. Sustaining youthful appearance, leaf gel is used to remove dead cells around the eye, freckles, and for curing pimples, [116,131] Leaf gel is applied to prevent hair loss and leaf gel with passion fruit (Passiflora edulis Sims) is applied to treat dandruff 15 Asteraceae Eclipta prostrata (L.) L.

False daisy Keekirindiya
Leaf oil promotes hair growth [116,131] e juice of the crushed leaves is used to treat skin discolorations, and it possesses antiaging properties

Arjuna myrobalan
Kumbuk e bark powder mixed with honey is applied on pimples, and the bark is used for manufacturing toothpaste [131] 27 Terminalia bellirica (Gaertn.) Roxb.

Beleric myrobalan Bulu
Applying the seeds' oil improves the black colour of hair and controls hair loss [131] 28 Terminalia chebula Retz.
Myrabalans Aralu e infusion of the powdered, dried, young fruit is used as a mouthwash [116,129] Possesses antiaging properties and is used to manufacture yellow colour dye 29 Convolvulaceae Argyreia populifolia Choisy *

Sri Lankan elephant creeper
Giritilla e juice of the young shoots is applied on the gums for sanitation [116] 30 Cuscuta chinensis Lam. * Dodder Agamula nathi wal Concentrated plant extract with gingelly oil upon boiling is applied to improve the black color of hair and prevent hair loss, and it is used to treat dandruff [132] Evidence-Based Complementary and Alternative Medicine

Molucca bean Kumburu
Seeds' oil is applied to cure pimples, and fried seeds' powder is used for brushing the teeth [131] 44 Crotalaria verrucosa L. * Blue rattle weed Nil-adanahiriya Gargling and the infusion of young shoots and leaves promote mouth sanitation [116] 45 Entada rheedii Spreng. * Elephant creepes mackay Pus well Seed kernel powder mixed with white sandalwood powder in true lime juice is used to treat pimples [116,132] e ground seeds, stem, and bark, along with water, are used to clean the scalp and hair 46 Indigofera tinctoria L. Indigo Nilawari Medicated oil prepared with fresh leaf juice and king coconut oil is applied to improve skin complexion [116] Ground with false daisy, turmeric, and kurchi, it is applied to control hair loss, and the oil extracted from the leaves promotes hair growth 47 Mimosa pudica L. * Sensitive plant Nidikumba e ground aerial parts with gingelly oil are applied on the skin because of healing properties, and a decoction of the roots is used as a mouth wash to improve mouth hygiene [116] 16 Evidence-Based Complementary and Alternative Medicine Seed oil is used in soap manufacturing because of its antimicrobial properties [130] 49

Indian kino tree Gammalu
Dissolved dried gum in warm water is used as a mouthwash for healthy gums and teeth [116,131] 50 Pterocarpus santalinus L.f.

Red sandalwood
Rath-handun Crushed heartwood mixed with turmeric powder and milk is used to treat pimples and is used in soap manufacturing [116,130] [116,129] 77 Syzygium cumini (L.) Skeels * Indian black berry Madan e bark is used to prepare mouth washes for healthy gums and teeth used in manufacturing toothpastes [116,130] 78 Nymphaeaceae Nymphaea nouchali Burm.f. Blue water lily Nil manel e flowers are mixed with cow milk and stored in a covered clay pot approximately a month to colour grey or white hair into black [130] 79 Oleaceae Jasminum grandiflorum L. Jasmine Samanpichcha Ground roots and flowers improve skin discoloration, used to treat skin discolorations, plantextracted oil is applied to cool the scalp [116,130] 80 Jasminum multiflorum (Burm.f.) Andrews * Sambac Jasmine Geta pichcha Paste made by grinding the flower buds is applied on the skin for improved complexion [116] 81 Oxalidaceae Averrhoa bilimbi L. * Bilimbi Bilin Leaf juice is applied to cure pimples, herbal shampoo prepared from the plant is effective for pediculosis [116] 18 Evidence-Based Complementary and Alternative Medicine Heartwood powder mixed with lime juice is applied gently on pimples to improve skin complexion, the powder mixed with cow milk is used to treat freckles, and it possesses antiaging properties [116,130] 98 Sapindaceae Schleichera oleosa (Lour.) Merr. Ceylon oak Kon Seed oil is applied to promote healthy hair [116] However, a comparison between the plant list identified through this survey and the plant list identified from the local books shows the possible usage of 49 plant species in the herbal cosmetic industry as new ingredients. us, these findings can be utilized for inventing new products in the future. As global demand for herbal cosmetics increases, there are ample opportunities for Sri Lanka to expand global export with its unique biodiversity and a rich base of traditional knowledge. It will lead to the upliftment of people's livelihoods and the county's economic development.

Major Challenges and Possible Solutions for Sri Lanka to Develop Plant-Based Cosmetic
Productions. At present, most developed countries' cosmetic manufacturers are continuously probing for new products and ingredients of tropical origin because their raw materials often have interesting properties. e interesting properties of tropical origin ingredients could vary based on climatic and topographical conditions [11]. However, the Association of Southeast Asian Nations (ASEAN) integration report issued in 2015 clearly indicates that developing cosmetic products and cosmetic product markets based on indigenous ingredients is one of the major challenges [133]. e lack of ethnobotanical and ethnopharmacological surveys to identify the cosmetic potential plants, insufficient or absence of continuous supply of raw materials for production in line with the existing demand, lack of quality control of raw materials and finished cosmetic products, improper systematic cultivation systems for medicinal plants, poor postharvest practices, lack of innovations, and the lack of efficacy tests (in vivo and in vitro) to ensure the safety are the major challenges found in Sri Lanka for the development of the herbal cosmetic industry [12,104,123,124,134].
To overcome the aforementioned challenges, collecting information on medicinal plants, traditional drugs, ethnobotany, and ethnopharmacology related to cosmetic treatments with traditional practitioners, Ayurveda physicians, and local communities in each country is required. As most of the traditional knowledge on medicinal plants and treatments in Sri Lanka is passed from generation to generation within families, conducting ethnobotanical and ethnopharmacological surveys will aid to identify cosmetic potential plants, important plant parts, remedies while preserving the traditional knowledge. Furthermore, information gathered through surveys could ultimately be 107 Kaempferia galanga L. * Java galanga Ingurupiyali Dried sliced rhizome infusion is used as a mouth wash, powdered rhizome with coconut oil on the skin to improves skin complexion, improves lustrous of hair, possesses antidandruff properties and skin whitening properties [116,129] 108

Zingiber officinale Roscoe Ginger Inguru
Juice-extracted ginger pulp is applied on pimples, and it is used to improve skin complexion [129] * e plant species that are currently not used in the herbal cosmetic industry of Sri Lanka (in comparison with the survey conducted on "Emerging herbal cosmetic production in Sri Lanka: Identifying the possible interventions for the development of herbal cosmetic industry" [12]). utilized to develop the herbal cosmetic industry by the isolation and characterization of bioactive compounds from identified plants. Cosmetic companies work with a wide range of suppliers to obtain botanical raw materials. ese suppliers purchase plant biomass from a wide array of sources ranging from large to small scale. However, harvesting plants from the wild is still popular for many medicinal herbs among local suppliers. Consequently, overharvesting can reduce plant populations to the point where the species' biodiversity is threatened, some species even to their extinction. erefore, establishing proper systematic cultivation systems for identified medicinal plants is paramount. Furthermore, future research must be focused on nursery techniques, field establishments, and the harvest management of medicinal plants. Cultivated plant materials are preferred for the cosmetic industry as it is easier to control the whole supply chain and chemical variations. With the use of cultivated plants, problems such as adulteration and misidentification of material are mostly eliminated. It is also easier to adhere to quality standards and has less batch-to-batch variation as the plants are grown under controlled conditions. Furthermore, the utilization of biotechnology techniques, such as tissue culture, will benefit from preserving biodiversity by utilizing the endangered or unavailable plants using conventional production or wildcrafting. Product development and innovation are other key factors to succeed in the herbal cosmetic industry in Sri Lanka. e process to bring a medicinal plant from field to finished good can be quite complicated with many challenges along the way. Stability testing on raw materials to anticipate any issues with color change, odor, viscosity, precipitation, separation, or degradation of actives must be carried out routinely by cosmetic manufacturers. e characteristics of cosmetic products can be affected by environmental factors, such as temperature, pH, light, air, and humidity, which impact their stability contributing to severe damage to the constituents of the product [135]. Because of the wide variety of cosmetic products and their inherent complexity, it is hard to find standard stability tests that can be applied to a vast range of products. However, generally used stability tests can be categorized into several categories namely stability and physical integrity of cosmetic products (under appropriate conditions of storage, transport, and use), chemical stability, microbiological stability, and the compatibility between the contents and the container. For example, the organoleptic characteristics of cosmetic preparations, such as color, smell, texture, and consistency, can be evaluated by visual inspection. Additionally, several physicochemical analyses can be performed, such as centrifugation, mechanical vibration, light tests, pH, density, viscosity determination, and spectrophotometric assays, besides accelerated and microbial stability tests [136]. Quality control testing must be performed and continuously monitored to ensure its physical and analytical characteristics are up to standard. Some current techniques used by the cosmetic industry can be applied to the evaluation of cosmetic's quality control in an efficient manner, such as sensory analysis, rheology, and small-angle X-ray scattering [137]. Efficacy/safety tests should be performed on medicinal plant ingredients as well. For instance, cosmetics companies can perform in vitro testing to screen for cell damage in skin cell cultures or irritation in skin construct models and animal testing to avoid adverse events. However, the European Commission Cosmetics Directive has executed an animal testing ban on finished cosmetic products and ingredients. In such situations, cosmetic manufacturers have to find an alternative method to ensure product safety. At present, many alternatives to animal testing have been developed and validated for the safety and efficacy testing of cosmetic products and cosmetic ingredients. For example, 2D cell culture models derived from the human skin for evaluating anti-inflammatory properties, or predicting skin sensitization potential and 3D human skin equivalent models for evaluating skin irritation potential and excised human skin are being currently used as the gold standard for evaluating dermal absorption [138]. If a medicinal plant ingredient is safe and stable, it can move on to the formulation phase, where it is added to a cosmetic formula and retested for the same parameters, safety, and stability. With careful management, cosmetic companies can offer innovative beauty products that enhance living standards while conserving natural resources, promoting economic development for the poor, and protecting the environmental resources of Sri Lanka [11,104,108,124,127,139,140].
In addition, the cosmetics industry must employ scientists from the discovery stage to product development. Universities can play an active role in medicinal plant research in Sri Lanka. Universities can initiate transferring technology to industries for product development using active natural compounds. In the discovery stage, many different strategies should be used, including monitoring consumer trends, evaluating scientific advances in developed countries for possible technology transfer opportunities, monitoring scientific publications, and press reports. Furthermore, external collaborations with universities, institutes, or non-governmental organizations will secure the supply chains of raw materials, gain certification of their raw materials, or find higher quality and more sustainable plantbased raw materials. For instance, collaborative research studies on medicinal plants between different faculties in the Wayamba University of Sri Lanka, faculty of agriculture and plantation management, faculty of technology, faculty of medicine, and the pioneer semigovernmental research organization, Industrial Technology Institute in Sri Lanka would be ideal for new discoveries in herbal cosmetics discipline by sharing knowledge and utilizing available facilities to a maximum extent in these two entities. rough these partnerships, the companies not only increase cosmetic manufacturers' scientific knowledge and acquire innovative raw materials but also contribute positively to society [104,124].

Conclusion
Medicinal plants provide accessible and culturally relevant sources of health care for most of the world's human population.
ere has been an increase in preference for herbal beauty products globally in recent years with rising Evidence-Based Complementary and Alternative Medicine consumer awareness regarding long-term health benefits. India and China have successfully utilized their traditional systems of medicine to become major producers in the global plant-based cosmetic industry. As cosmetic manufacturers in developed countries show their interest in herbal ingredients of tropical origin, Sri Lanka has a good potential to create numerous new avenues in herbal cosmetics, which can be easily capitalized on the global trends. However, the increasing interest in herbal cosmetics has raised important issues and highlighted vital gaps in the knowledge of cosmetics medicinal plants, their usages, cultivation technologies, postharvest technologies, and bioactivity studies in Sri Lanka. To overcome these issues, conducting ethnobotanical and ethnopharmacological surveys to identify medicinal plants with cosmetic potential, product development, and innovation in collaboration with universities, institutes, and non-governmental organizations are possible solutions. e study's findings could ultimately be utilized for the development of the herbal cosmetic industry by the isolation and characterization of bioactive compounds from identified plants while preserving traditional knowledge.

Data Availability
e data used to support the findings of this study are included in the article.

Conflicts of Interest
e authors declare that they have no conflicts of interest regarding the publication of this article.