Applications of Tea (Camellia sinensis) and Its Active Constituents in Cosmetics

Abstract

Studies on the cosmetic applications of plant extracts are increasingly appearing in the scientific literature, which is due to the growing popularity of skincare products around the world. In the light of the observed changes, a return to natural treatment and skincare with cosmetics free of harmful substances or toxic preservatives is visible. Currently, tea extracts, due to their rich composition and various biological actions, play an important role among the dietary supplements and cosmetics. This review is intended to collect the reports on the properties of the tea plant, its extracts and preparations in cosmetology: for skin care products and for the treatment of selected dermatological diseases. Particular attention is paid to its antioxidant, anti-hyaluronidase, anti-inflammatory, slimming, hair-strengthening, photoprotective and sealing blood vessels properties.

Full text

Molecules 2019, 24, 4277; doi:10.3390/molecules24234277 www.mdpi.com/journal/molecules
Review
Applications of Tea (Camellia sinensis) and its Active
Constituents in Cosmetics
Wojciech Koch 1,*, Justyna Zagórska 2, Zbigniew Marzec 1 and Wirginia Kukula-Koch 2
1 Chair and Department of Food and Nutrition, Medical University of Lublin, 4a, Chodźki str., 20-093 Lublin,
Poland; zbigniew.marzec@umlub.pl
2 Chair and Department of Pharmacognosy, Medical University of Lublin, 1 Chodźki str., 20-093 Lublin,
Poland; zagorska.justyna@gmail.com (J.Z.); virginia.kukula@gmail.com (W.K.-K.)
* Correspondence: kochw@interia.pl; Tel.: +48-814487143
Academic Editor: Saverio Bettuzzi
Received: 8 November 2019; Accepted: 22 November 2019; Published: 24 November 2019
Abstract: Studies on the cosmetic applications of plant extracts are increasingly appearing in the
scientific literature, which is due to the growing popularity of skincare products around the world.
In the light of the observed changes, a return to natural treatment and skincare with cosmetics free
of harmful substances or toxic preservatives is visible. Currently, tea extracts, due to their rich
composition and various biological actions, play an important role among the dietary supplements
and cosmetics. This review is intended to collect the reports on the properties of the tea plant, its
extracts and preparations in cosmetology: for skin care products and for the treatment of selected
dermatological diseases. Particular attention is paid to its antioxidant, anti-hyaluronidase,
anti-inflammatory, slimming, hair-strengthening, photoprotective and sealing blood vessels
properties.
Keywords: tea plant; skin care cosmetics; dermatology; Camellia sinensis (L.) Kuntze; catechins;
Theaceae
1. Introduction
Cosmetics market continues to grow globally within the last decade. The growth of the upper
middle class, an increasing number of senior citizens around the world and the expansion of online
beauty spending and social networks, which certainly set new trends among the consumers, are all
having an impact on an increasing interest in skin care products. Natural products as the cosmetics’
ingredients are often associated with safety, marked activity and good quality. That is why a great
interest in cosmetic products of natural origin can be observed [1].
Tea plant itself and its extracts together with their centuries-old tradition of use play an
important role on the cosmetics market. In general, cosmetics products containing tea extracts rich in
polyphenols have a positive effect on the skin appearance and ameliorate skin damage, erythema
and lipid peroxidation following UV exposure [2]. An increasing number of cosmetics containing tea
extracts, especially those produced using green tea infusions, but recently also black and white teas,
encourage the authors to provide a review, that is focused on the application of tea in cosmetics. For
the moment only a few review publications undertake the topic, however, the majority of them were
published more than a decade ago. Due to this fact the authors found it necessary to prepare a more
up-to-date manuscript that includes the information that have been spread in recent years, in the
times of a constant and significant growth of the cosmetic industry [2–4]. Some of the above
mentioned previously published references were also focused on the treatment of specific skin
diseases only and represent rather dermatology than cosmetic applications [5,6], or they described
the activity of specific tea ingredients, e.g., caffeine [7] than the extracts per se. Therefore the aim of

Molecules 2019, 24, 4277 2 of 28
the present review is to collect the reports on the properties of the tea plant, its extracts and
preparations in cosmetology: for skin care products and for the treatment of selected dermatological
diseases.
2. The Chemical Composition of Tea Plant (Camellia sinensis (L.) Kuntze)
Tea plant is a rich source of bioactive components. According to the scientific literature it
contains almost 4000 metabolites, among which the group of polyphenols constitutes a more than
one-third share [8]. Tea infusions deliver approx. 2–3% flavonol glycosides (kaempferol, myricetin
and quercetin), whereas their aglycones most often remain in the plant matrix upon water extraction
due to their lower polarity. The flavanols present in tea infusions, also called catechins, constitute as
much as 20–30% of tea’s dry matter. They are responsible for its taste: bitterness and astringency [9].
The composition of tea varies depending on the fermentation process applied. Black tea contains
(−)-epigallocatechin gallate (EGCG), (−)-gallocatechin gallate (GCG), (−)-gallocatechin (GC),
(+)-catechin (C), (−)-epicatechin (EC), gallate (−)-epicatechin (ECG) and (−)-epigallocatechin (EGC)
[10–12] in contrast to green tea that is rich in EGCG—present in the highest concentration, ECG, EC
and EGC [13]. The differences in the composition of these two the most common types of tea is
strictly related to the production process. To obtain green tea freshly harvested leaves of Camellia
sinensis are treated with hot steam to prevent fermentation and are later subjected to drying. On the
other hand, black tea is produced from the leaves, which are first dried, then rolled, ground and
finally fermented. This is the fermentation process that induces the oxidation of polyphenols
triggered by the influence of polyphenol oxidases [14]. This process results in the transformation of
simple flavonoids (e.g., catechins) into more complex structures, like thearubigins (TR), theaflavins
(TF) and theobrownins (TB) [10–12].
Therefore, the catechins’ concentration is inversely proportional to the degree of leaf processing
[15]. Their highest content was noted in green tea, then in oolong tea and in the end-in black tea,
which is due to a strong fermentation process that the latter type of tea is subjected to [10,16,17]. On
the other hand black tea is a rich source of TR and TF [16] and oolong tea-of theasinensins and other
condensed phenolic compounds [18]. TR, whose molecular weight is from 700 to 40,000 Da, gives the
brew of black tea a taste and a reddish-black color [19]. In contrast, theaflavins are responsible for a
golden yellow color of the infusion [9]. Catechins are certainly the best studied compounds of plant
origin. However, still not much is known about the chemical structures and pharmacological
properties of the catechins’ conjugates, as they are difficult to identify and isolate from tea leaves.
Some of the theaflavins have been, however, identified in tea extracts and include: 3-3′-theaflavin
digalusate (TF3), theaflavin 3-gallate (TF2B), theaflavin 3-gallate (TF2A) and theaflavin (TF1) [20].
Different types of tea are also rich sources of simple phenolic compounds (gallic acid—GA,
p-coumaric acid and caffeic acid) and their derivatives: theogaline and chlorogenic acid [21–24].
Other compounds present in tea include purine alkaloids (theophylline, theobromine and caffeine
(theine)), amino acids, theanine [25], carbohydrates, lipids (linoleic and linolenic acids), volatile
compounds, pigments (carotenoids and chlorophylls), vitamins (A, C, E, K and B) and chlorophylls
[26]. It also contains numerous mineral elements such as iron, zinc, sodium, magnesium, chromium,
phosphorus, potassium, titanium, manganese, nickel, copper, aluminum, silver and bromine [23,27–
31]. The structures of tea main catechins and theaflavins were presented in Figure 1.

Molecules 2019, 24, 4277 3 of 28
Figure 1. Chemical structures of the major secondary metabolites present in tea leaves.
3. The Application of Tea Extracts in Cosmetics
Tea extracts possess a wide spectrum of biological activities, which makes them precious
components not only for pharmaceutical applications, but also for cosmetics industry. Among these
activities antioxidant, photoprotective, anticellulite, slimming, improving skin, hair and
microcirculation condition properties should be underlined (Figure 2). They will be further
reviewed and discussed.
3.1. The Application of Tea Plant in Cosmetics and its Activity for the Skin Biochemistry

Molecules 2019, 24, 4277 4 of 28
The skin is the largest organ of the human body, which accounts for approximately 15% of its
weight. It is composed of three layers: the epidermis, the dermis and subcutaneous tissue [32]. The
epidermis is composed mainly from two types of the cells: keratinocytes and dendritic cells. The
morphology and position of the keratinocytes condition the structure of epidermis into four layers:
stratum germinativum (horny cells, including the basal cell layer), stratum spinosum (the squamous
cell layer), stratum granulosum (the granular cell layer) and stratum corneum (cornified or horny
cell layer) [33–35]. The epidermis is a constantly renewing layer and gives rise to derivative
structures, such as pilosebaceous apparatuses, nails and sweat glands. Cells from the stratum
germinativum undergo proliferation cycles and continuously provide new cells for the outer
epidermis. The epidermis is a dynamic layer, in which the cells are in a constant unsynchronized
motion, constantly differentiating into different types of cells [35]. Each layer of the skin possesses
different functions and is differently supplied with nutrients. The effects of the tea plant and its
active constituents differ depending on the skin layer. In the stratum corneum, this effect is mostly
due to the strong antioxidant activity of tea extracts. In deeper layers of the skin, the tea polyphenols
exhibit significant protective effects against the ultraviolet radiation and affect the activity of various
enzymes. By the inhibition of lipoxygenase, metalloproteinase, hyaluronidase and collagenase, tea
and its extracts significantly delay the signs of skin aging. This is because these enzymes have a
destructive effect on cellular cement lipids, such as hyaluronic acid, elastin and collagen, which are
important components for the skin [35].
When administered on the dermis, these compounds improve microcirculation and the
condition of blood vessels, which results in a better skin nutrition and oxygenation. Moreover,
polyphenols have a protective effect towards vitamin C, because they prevent its oxidation. This is
an important issue from a cosmetic point of view, as vitamin C is involved in the synthesis of
collagen, a main protein of blood vessels and skin.
Tea polyphenols also affect the sealing of blood vessels by protecting hyaluronic acid and
inhibiting histamine release. Their influence on the activity of adrenaline, which contracts blood
vessels, is also important. Low levels of this hormone lead to weakening of the vessels, because their
contractions are then short, but frequent. The polyphenolic compounds from tea plant indirectly
strengthen blood vessels, as they prevent the oxidation of adrenaline. In addition, they improve
blood flow through the inhibition of platelet aggregation by different mechanisms, e.g., by hindering
the thrombin proteolytic activity and inhibiting the tyrosine kinase Syk and Lyn activities [36].
According to Lee and co-investigators EGCG, the major green tea catechin, significantly inhibits
cyclooxygenase (COX)-1 and thromboxane synthase (TXAS) production in platelets, which are two
major enzymes responsible for the platelet aggregation. It is worth mentioning that, in the case of
EGCG, this effect was even stronger as compared to a nonsteroid anti-inflammatory drug aspirin,
which is commonly used to inhibit thrombotic disease-associated platelet aggregation [37].
Tea polyphenols have anti-inflammatory activity, which significantly improves skin
microcirculation. This particular action is related to the radical scavenging properties of tea
polyphenols, which decelerate the inflammatory processes, which disturb microcirculation and
protect the intracellular cement lipids. Moreover, an inhibition of nitric oxides, prostaglandins,
thromboxanes and leukotrienes, which are the main mediators of inflammation have been observed
upon the administration of tea extracts [37–39].
3.2. Antioxidant Activity
Antioxidant properties of polyphenolic compounds are widely known and were described in
numerous scientific papers [5,40–42]. Due to their specific structure, the antioxidant activity of
polyphenols may be related to almost all phenolics, however, it was proved that aglycones are
stronger antioxidants, compared to their corresponding glycosides [43]. All tea catechins were
described as very strong antioxidant agents based on in vitro [44,45] and in vivo studies [46–49].
Table 1 shows some selected results on antioxidant properties of tea extracts in relation to other
extracts used in cosmetics. A precise direct comparison of different antioxidant studies is often
difficult due to a variety of antioxidant tests applied and various methodological protocols used,

Molecules 2019, 24, 4277 5 of 28
however, some tendencies can be observed. Taking into account that, except water, tea is the most
widely consumed beverage in the world, tea catechins are considered as the most important
antioxidant substances present in human diet [5,50].
Figure 2. The major cosmetic properties of catechins ( —stimulation, —inhibition).
The effect of tea catechins towards the free radicals is multidirectional and includes:
• Direct quenching of reactive oxygen oxygen (ROS) and nitrogen (RNS) reactive species;
• Chelatation of trace elements that are involved in free radicals generation (e.g., copper or
iron);
• Enhancement of endogenic antioxidant enzymes production (SOD (superoxide dismutase)
and glutathione);
• Inhibition of enzymes involved in ROS generation (glutathione S-transferase, microsomal
monooxygenase, mitochondrial succinoxidase or NADH oxidase);
• Protection and regeneration of antioxidant compounds (vitamin C or E) [5,47,48].

Molecules 2019, 24, 4277 6 of 28
Table 1. The antioxidant activity assessment of some plant extracts used in cosmetics (TPC—total
phenolic content, Folin—Ciocalteu method, TE—trolox equivalents, GAE—gallic acid equivalents).
No
Type of Extract
Antioxidant Test Applied
Antioxidant Properties
References
1
Black tea
TPC
58.2 mg/100mL
[50]
1
Black tea
ABTS (TE)
3.11 mM/L
[50]
2
Green tea
TPC
97.3 mg/100ml
[51]
3
Green tea
ABTS (TE)
12.6 mM/L
[51]
4
Hawthorn
DPPH
IC50 = 48 μg/ml
[52]
5
Chokeberry
TPC (GAE)
0.957 mg/mL
[53]
6
Grapevine (red wine)
TPC
294.41 mg/100mL
[54]
7
Aloe
ABTS (IC50)
0.105 mg/Ml
[55]
gel
0.033 mg/mL
leaf
0.30 mg/mL
flower
8
Horse chestnut
TPC (GAE)
2.12 mg/g
[56]
Antioxidant properties of tea are the major and the oldest application for that cosmetics
industry needs Camellia sinensis extracts. Since the discovery of free radicals theory it became
obvious that free radicals can trigger chain reactions, which cause damage of biological
macromolecules like proteins, lipids and nucleic acids, and as a result are very harmful to skin and
mostly responsible for skin aging. Since oxidative stress is one of the most important processes
determining skin ageing, natural antioxidants are considered to be the most important factors in the
prevention of this process [57]. Polyphenols are able to protect and restore the content of vitamin C,
which is an important co-enzyme in the production of collagen—an important protein responsible
for the skin elasticity and strength, building up its structure along with elastin and keratin [34].
Different types of tea, including black, white and green, have been used to produce skin care
formulations, however, the latter one due to the highest concentration of polyphenols (EGCG and
EGC) can be found the most often in cosmetics formulations. Other ingredients of tea plant, like
previously described vitamins, lipids and pigments could also provide additional benefits to the
skin, like moisturizing and protective effects [4,58–60]. Some selected trials on the antioxidant
properties of tea plant leaf extracts have been collected in the Table 2.
3.3. Photoprotective Activity
UV radiation (UVR; 280–400 nm) may be very detrimental to the skin. There are proofs, which
indicate that UVR induces skin carcinogenesis by multiple mechanisms, including direct DNA
damage and indirect caused by ROS. UVR also induces cutaneous immunosuppression, potentially
allowing dysplastic cells to go undetected and progress to neoplasms [61–63]. The genotoxic and
cytotoxic effects of UVR in skin are well documented, and as a result malignant as well as
non-melanoma skin cancers occur. In the UK there are over 40,000 of a new cases of skin cancers
each year, of which 10% are malignant melanomas, with a significant risk of mortality [64].
Therefore there is a great need for searching effective photoprotective agents, with low side effects,
and natural products may be very helpful to find such.
Tea leaf extract absorbs ultraviolet radiation, due to which it protects the skin against its
harmful effects. It is a component of photoprotective cosmetics for daily care [65,66]. Additionally
polyphenolic compounds present in tea have strong antioxidant activity (which was reviewed
above) and due to it scavenging different free radicals, which are produced during UV radiation. Tea
extracts and the active compounds that they contain are increasingly applied in sunscreen cosmetics.
EGCG prevents the negative effects of UV radiation on the skin, through the inhibition of
collagenases, anti-inflammatory and anti-cancer properties towards the skin cells. Recent findings
revealed that green tea extract should be combined with zinc oxide and titanium dioxide in
sunscreen preparations. This combination increases skin protection against damage caused by UVA
and UVB rays. Tea extract, alone, protects only against UVB radiation [67,68].

Molecules 2019, 24, 4277 7 of 28
Recently several studies confirmed that tea and its active constituents, when taken orally or
applied topically, effectively protect skin against UVR. Morley and co-investigators proved that
consumption of 540 mL of green tea infusion significantly inhibited UVR-induced damage to
peripheral blood cells. Moreover obtained in vivo data were confirmed in in vitro experiments, in
which EGCG was proved to dose-dependently reduce UVR induced cells DNA damage in
fibroblasts and keratinocytes cell cultures [64]. Mnich and co-investigators revealed that topical
administration of a treatment lotion containing 4% green tea extract to skin patches irradiated with
UVB (up to 100 mJ/m2) significantly reduced UV-induced p53 expression in keratinocytes. The
number of apoptotic keratinocytes (sunburn cells and TUNEL-positive cells-Terminal transferase
dUTP-nick-end labeling assay) was also significantly decreased. On the other hand UV-induced
erythema and thymidine dimer formation were also significantly affected. The authors concluded
that topical application of a lotion rich in green tea extract even at low, cosmetically usable dosages
efficiently reduces UVB-mediated epithelial deterioration and therefore green tea extract should be
considered as suitable everyday photochemopreventive agents [69]. Not only green tea but also
white tea is considered as an effective photoprotective agent. Camouse and co-workers investigated
skin samples obtained from volunteers or skin explants treated with white or green tea after UV
irradiation. Tea extracts were administrated topically in a special cosmetic vehicle containing
deionized water, 1,3 butylene glycol, carbopol 980 triethanolamine and methyl paraben. A study
was a double-blind placebo-controlled assay. The experiment revealed that application of white and
green tea to a UV-irradiated skin caused a 22% and 35% reduction in CD1a+ (epidermal Langerhans
cells) staining relative to unirradiated skin, respectively. Moreover, application of both teas
significantly reduced oxidative DNA damage caused by UVR. As both agents were characterized by
SPF 1, it was concluded that their photoprotective activity towards the skin’s immune system was
not connected with their direct UV absorption or a “sunscreen” effect. Additionally white tea,
because of its lighter color, was considered more acceptable to use in topical preparations, especially
for a regular use around the face [63].
Photoprotective effects of green tea may be strengthened when using in combination with
another herbal extract. The market contains a large number of skin care formulations containing
different mixtures of botanical extracts with the claim that the combination provides enhanced skin
effects. However, so far few studies have confirmed their topical effect. One of the plant species
studied in a combination with green tea in a cosmetic formulation was Ginkgo biloba, which was
proved to significantly increase photoprotective activity of green tea extract. Topical formulation
containing 6% w/w of each extract (green tea and Ginkgo biloba glycolic extracts) was applied to a
dorsal skin of 24 male albino hairless mice (HRS/J-hairless, Jackson, Bar Harbor, ME, USA) in two
different areas with 5 mg/cm², 15 min prior to UVA/UVB irradiation. The study revealed that
combination of both extracts significantly decreased skin damage (dryness, irritation, presence of
erythema, sunburn cell formation and epidermal hyperplasia) caused by UVR. This effect was much
stronger in comparison to the application of green tea and Ginkgo biloba separately. Photoprotective
activity of both herbal extracts was not due to their UV-absorption ability, but to biological effects
caused in the skin, which were much stronger when both extracts were administrated together [70].
In general, different animal models and in vitro studies confirmed that topical treatment with
green tea polyphenols reduced UVB-induced inflammatory responses, immunosuppression and
oxidative stress, which may led to skin carcinogenesis (Table 2). It was also proved that external
application of EGCG decreased immunosuppressive interleukin (IL)-10 production at UV irradiated
skin and draining lymph nodes. Moreover, studies performed on animals revealed that topical
application of green tea catechins prior to exposure to UVB protects not only against local but also
systemic UVR-induced immune suppression [71].
3.4. Anti-Cellulite and Slimming Properties
Cellulite (gynoid lipodystrophy), often called ‘orange peel effect’, is a typical women’s ailment,
which mainly appears on the thighs and buttocks [72]. It is a complex disorder in which
microcirculatory and lymphatic systems as well as extracellular matrix are involved. Increased

Molecules 2019, 24, 4277 8 of 28
lipolysis can be observed, which lead to increased production of diglycerides, monoglycerides, free
fatty acids and glycerol. As a result excess of subcutaneous fat bulges into the dermis and forms a
characteristic view, typical for cellulite. Many different hormones are involved in the lipolysis
process. Adrenaline, noradrenaline, glucagon and adrenocorticotropin activate the lipases, while
insulin inhibits the activity of these enzymes and stimulates the collection of fat in adipose tissue
[73]. Different compounds, which activate the lipolysis pathway, stimulate structural changes of the
G-protein coupled receptor and stimulate the cytosolic cAMP production. Its increasing level
stimulates protein kinase A, which activates hormone-sensitive lipase (HSL) by phosphorylation.
The latter enzyme hydrolyses triglycerides and its activity is cAMP-dependent [7,74].
Tea, due to the content of alkaloids, is widely used in the production of cosmetics against
cellulite. The major one—caffeine (known also as theine) stimulates microcirculation in the skin,
which in turn improves cell oxygenation and accelerates fat burning in skin cells. Therefore,
cosmetic preparations containing alcoholic or glycolic tea extracts are used to maintain a slim figure,
reduce cellulite and remove toxic products from the body. Not only alkaloids, but also polyphenols,
are very effective in reducing cellulite. Catechins, which are a dominant compounds present in tea
extracts, were described to inhibit glycation and oxidation of proteins and thus preventing the
formation of cellulite, which is one of the symptoms of skin aging. Therefore, tea is a common
ingredient in cosmetic preparations with firming, slimming and anti-cellulite properties [75–77].
The main active ingredient of the tea is caffeine, which is frequently used as an anti-cellulite
agent. It can be used as a pure compound or green tea extract ingredient. Caffeine could influence
the mechanisms of cellulite formation in different ways. The most important is the acceleration of
lipolysis through the influence on the catecholamine secretion and thus increasing the cAMP
synthesis in adipocytes and activating HSL. This inhibits fat accumulation by increased degradation
of triglycerides and therefore reduction of cellulite [78,79].
Pires-de-Campos and co-investigators studied the effect of topical gel application with caffeine
using three different models: gel with ultrasound treatment (3 MHz, intensity: 0.2 W/cm2, rate: 1
min/cm2), gel with caffeine (5%, water-in-water) and gel with caffeine and ultrasound. The study
was conducted using a swine hypodermis and gel was applied daily during 15 days. A specified
area without any application was used as control. The study revealed that the model using caffeine
and ultrasounds was the most effective. The thickness of the subcutaneous adipose tissue, damage of
the adipocytes and the numbers of cells were significantly reduced [80]. Velasco and co-investigators
also investigated the effectiveness of the topical application (for 21 days) of emulsion containing
caffeine on the diameter and number of fatty cells using Wistar female mice. The study revealed that
emulsion-containing caffeine reduced by 17% the diameter of the fatty cells [81]. Recently Byun and
co-investigators evaluated the effectiveness of the slimming cream containing 3.5% of water-soluble
caffeine and xanthenes for the treatment of cellulite. Fifteen subjects with cellulite applied slimming
cream to the thighs and inner side of the upper arms twice daily for 6 weeks. The effectiveness was
evaluated using a standard visual scale, circuit changes of the thighs and upper arms, and patient
satisfaction using a questionnaire. Performed clinical study revealed significant improvement in
skin condition and cellulite reduction (by 19.8% in the standard visual scale score). Thigh and upper
arm circumferences decreased by 0.7 cm (1.7%) and 0.8 cm (2.3%), respectively, at week 6 and no
serious side effects were observed [82] (Table 2).
All the above-mentioned experimental data confirm that caffeine, which is the major alkaloid
present in tea leaves, is a very effective natural agent in the reduction of cellulite. When topically
applied, it inhibits fat accumulation in the hypodermis and decreases the number of adipocyte cells.
Therefore cosmetic formulations containing tea extracts or caffeine alone may be very efficient
products in reducing skin cellulite and improving body figure.
Not only caffeine, but also tea polyphenols may be very effective in reducing cellulite and
“slim” the figure. Weight reducing properties of different polyphenols, including tea catechins were
recently described in numerous scientific papers [5]. Oral ingestion as well as topical application of
tea extracts was described to reduce weight and decrease adipose tissue content. More than 24
clinical placebo-controlled trials, performed on obese patients, revealed that consumption of 600–900

Molecules 2019, 24, 4277 9 of 28
mg of tea polyphenols per day (which is equal to 3–4 cups of green tea) significantly decreased total
abdominal fat, reduced serum triglycerides, induced adipogenesis, increased energy expenditure
and fat oxidation and improve fecal lipid excretion. As a result significant weight loss and reduction
of skin fat tissue was observed [83–85]. In vivo studies also performed in various animal models
showed that increased intake of tea extracts or its active constituents significantly decreased hepatic
lipid accumulation, white adipose tissue weight and downregulated over 100 genes related to tissue
inflammatory responses [86,87].
Rao and co-investigators tested a cream containing black pepper, sweet orange peel, ginger root
extract, cinnamon bark extract, capsaicin, green tea and caffeine. The formulation was applied under
occlusion with neoprene shorts to 20 patients. After testing 76% of the volunteers noticed an overall
improvement of their cellulite, with 54% reporting greater improvement in the thigh that received
garment occlusion. Professional dermatological examination revealed significant improvement of
the skin of the thighs condition (average circumference reduction was 1.2 cm; 1.3 cm in the group
with occlusion and a 1.1 cm reduction without occlusion) [88]. Although there are many cosmetic
preparations for the treatment of cellulite, which contain different tea extracts, the literature review
showed almost no studies evaluating the effectiveness of tea polyphenols in the treatment of
cellulite. Their efficacy towards cellulite reduction is mostly based on their properties to treat
obesity, decrease weight, reduce waist circumference and improve thermogenesis [89,90]. Therefore,
there is a strong need to perform studies, which will evaluate the influence of tea polyphenols on
cellulite, both orally and especially topically.
Although tea polyphenols were not studied towards their anti-cellulite activity, there are
experiments that proved that products rich in polyphenols might effectively reduce cellulite. Savikin
and co-investigators revealed that dietary supplementation with chokeberry juice rich in
polyphenols improve skin morphology in cellulite. They examined twenty-nine women aged 25–48
with a cellulite grade 2 according to the Nurnberger–Muller scale. All patients consumed 100 mL of
the juice for 90 days. Skin structure was analyzed by ultrasonography at 0, 45 and 90 days of the
study. The study revealed significant reduction in the subcutaneous tissue thickness (1.9 mm on
average). Moreover the length of subcutaneous tissue fascicles was reduced in 97% of subjects. It
was also observed that in the subjects with edema at the baseline, after 45 days of treatment, it was
reduced in 55.2% of patients, while after 90 days edemas were not observed in any of the individuals
involved in the study. The authors did not investigate polyphenolic composition of the juices, they
only performed determinations using a Folin-Ciocalteu reagent. Therefore it is difficult to state
which particular polyphenols were primarily responsible for such an effect [91].
3.5. Improvement of Skin Condition
Green tea is the type of tea that is the most extensively used in cosmetic preparations improving
skin and hair condition. Although an easy search for a term “green tea skin care products” allows us
to find over 50 different products that can be used on skin, nails and hair. These products are
targeted towards the improvement of aging skin, treating rosacea, acne, warts and increased sebum
production. However after closer evaluation of the product information, it occurs that there is little
information on the extract preparation, its concentration and other active ingredient content. It is
generally accepted that 5% is an effective concentration of green tea extract in cosmetic formulation,
however it should be remembered that catechins, being one of the most effective antioxidants, are
very sensitive to light and oxygen. Therefore they require a very careful formulation to retain their
biological activity. Another question is the skin permeability of catechins as these are a typical
hydrophilic compounds and they penetration in human skin is limited. Thus, according to Farris,
there should be a healthy dose of skepticism, for both consumers and dermatologists, regarding the
effectiveness and usefulness of cosmetics containing green tea [92]. There is also little scientific data,
especially clinical experiments, which support the wide use of tea extracts in cosmetics improving
the condition of the skin and hair. Another question is the fact that the term “improving” is very
relative and consumers may often have a big problem in proper evaluation of the cosmetic

Molecules 2019, 24, 4277 10 of 28
effectiveness, and their assessment may be incorrect. Only typical dermatological examination can
be an appropriate tool to evaluate the efficacy of the cosmetic formulation.
A clinical study conducted by Syed and co-workers revealed an improvement in skin texture
and appearance in 45% of volunteers after a 4-week application of gel containing EGCG [93]. In
another clinical study different cosmetic formulations containing vehicles supplemented with 6%
Camellia sinensis glycolic leaf extracts were applied to the forearm skin of 24 volunteers. Before the
study and after 2 h, 15 and 30 days the following parameters were evaluated: stratum corneum
water content, transepidermal water loss, skin viscoelastic-to-elastic ratio (Uv/Ue) and microrelief.
Obtained results revealed significant increase in skin moisture (immediate and long-term),
improved skin microrelief (skin texture), represented by reduced skin roughness and enhanced skin
smoothness (especially after 15–30 days of treatment). It was also proved that formulations
containing green tea extract after 30 days of topical administration significantly enhanced Uv/Ue
parameter in comparison to vehicle and control. The authors concluded that green tea might be a
promising botanical component of cosmetics, which especially improve moisture and microrelief of
the skin [42].
A clinical double-blind placebo study, sponsored by NuSkin (Provo, Utah, USA) was
conducted to evaluate the efficacy of the combined oral supplementation of the green tea extract and
topical application of the special cream containing 10% of green tea extract to improve the
appearance of the photoaged skin [94]. The study involved 40 women with moderate photoaging.
Eighteen individuals took a dietary supplement containing 300 mg of green tea extract (twice daily)
and applied two times per day a portion of green tea cream. In the placebo group 18 women took
placebo supplement and placebo cream also twice per day. All the subjects used the same sunscreen
and cleanser. The study was conducted for 8 weeks. After finishing, professional dermatological
external examination revealed no statistical changes of the skin of the patients from both groups.
However, the skin biopsy shown significant improvement in elastic tissue content in the green tea
treated group. Unfortunately, the design of the study, did not allow determining of whether the
obtained effect was due to the oral intake of green tea or its topical application.
Green tea based cosmetic formulations are also popular to reduce increased sebum production,
which is a main feature of an oily face. Sebum is a mixture of lipids, mainly squalene and wax esters,
which is produced by sebaceous glands, especially on the face and scalp. Sebum production is
hormonally regulated, and its increased production causes serious skin disorders, such as acne
vulgaris [6]. Topical application of green tea extract may be very beneficial in reducing excessive
sebum production and two independent clinical studies proved its effectiveness. Meethama and
co-workers in a randomized single-blind, placebo-controlled study proved anti-sebum efficacy of a
facial tonners containing green tea. The developed cosmetics contained 2%, 4.5% and 7% of green tea
extract with 100 mg% of polyphenols, whereas the base consisted of hydroxyethyl cellulose, glycerin
and panthenol. The study involved twenty healthy Thai volunteers (sixteen female and four male)
aged between 20 and 35 years old. All tested products were stable and caused no skin irritation,
which was proved using patch tests. Performed clinical investigation revealed significant
anti-greasy and anti-sebum activity of a green tea extract, which in both cases were positively
correlated with the concentration of the extract. Moreover it was proved that the effectiveness of a 28
days treatment was significantly better than 14 days. It was stated that cosmetics containing green
tea extract might effectively improve the condition of oily face [95]. In a single-blinded, placebo
controlled monocentric study performed by Mahmood and co-workers, a group of twenty two
non-smoker, healthy men was investigated towards the effectiveness of a lotus and green tea topical
application on facial sebum production. Volunteers were divided into two groups—in a first group
men used green tea (5%) topical on one cheek and placebo control on another (n = 11). The second
group used a combination of green tea and lotus (2.5% each) on one cheek and placebo control on
another (n = 11). Both groups were asked to apply their respective topicals at bedtime for 60 days.
Sebum secretion was measured using sebumeter in both groups at baseline and after 15, 30, 45 and
60 days. The study revealed a significant reduction of sebum production in both groups after 60 days
of treatment—in the group applying only green tea and the combination of green tea and lotus, the

Molecules 2019, 24, 4277 11 of 28
sebum production was reduced by 27% and 25%, respectively. The performed study revealed that
cosmetic therapy using green tea extract alone as well as a combination of green tea and lotus
extracts may be a very effective tool in the treatment of skin disorders associated with increased
sebum production, such as acne vulgaris [96]. In another study performed by Mahmood and
co-workers ten healthy men aged 24–40 years old used topically to their cheeks a cosmetic
formulation containing 3% of green tea extract. The experiment was conducted for eight weeks and a
sebumeter was used to evaluate the reduction in sebum production, which was then calculated to a
percentage value. Obtained results revealed significant decrease in sebum production during the
eight weeks study. The strongest effect was observed after eight weeks of treatment (the reduction of
60%). However, already after the first week significant improvement was noted (10%) [97]. It should
be strongly emphasized that both of the above mentioned studies had significant limitations. A
small sample size, the investigated group that involved only men and no comparison treatment or
placebo control (in the case of the latter study [98]) were the biggest disadvantages of both of these
studies (Table 2).
3.6. Improvement of Hair Condition
Cosmetic preparations containing tea extracts are recommended for patients with androgenetic
alopecia and hair loss, regardless of gender. The occurrence of androgenic alopecia is directly related
to the conversion of testosterone into more active dihydrotestosterone (DHT), which is mainly
responsible for baldness. Hair follicles are particularly sensitive to DHT, which shortens the anagen
phase of the hair growth cycle. As a result, most of the hair passes into the telogen phase, which is
characterized by follicle miniaturization and reduction of hair roots. The newly growing hair is
weaker—thinner and shorter and after several cycles, they stop to growth and hair loss can be
observed [69]. In several studies tea polyphenols, essential oils and caffeine present in tea plant
leaves inhibit the activity of 5α-reductase, which results in a decreased DHT formation [97,99]. The
former compounds were also found stimulate hair roots and extend the hair growth phase (anagen
phase) [77]. Therefore, constituents of tea are important ingredients of hair and scalp care cosmetics,
which are especially recommended to individuals having excessive greasy hair and dandruff
[11,75,77].
Fischer and co-investigators performed an in vitro study, which have shown that external
application of caffeine in a concentration of 0.001% and 0.005% led to a significant stimulation of
human hair follicle growth. It was concluded that caffeine reduces smooth muscle tension near the
hair follicle and therefore significantly increases delivery of nutrients through the microcirculation
of the papillae of the hair [99].
Green tea polyphenols were proved to significantly improve hair loss in mice. A group of 30
mice were fed with 50% fraction of polyphenol extract from dehydrated green tea in their drinking
water for six months, whereas the control group received regular drinking water. Both groups
received the same diet. The study revealed significant improvement in hair growth (33% of animals)
in comparison to control group [100]. One of the main catechins present in green tea extract—EGCG
was proved to be strong 5α-reductase and aromatase inhibitor [101,102]. This fact may significantly
explain the effectiveness of using green tea polyphenols to treat androgenic alopecia, which is
mainly associated with increased activity of these both enzymes. Such a mechanism was proved by
Kwon and co-workers who evaluated the efficacy of EGCG on human hair growth. The study
revealed that EGCG stimulated hair growth in hair follicles ex vivo culture and the proliferation of
cultured human dermal papilla cells. Moreover, it was shown that epigallocatechin-3-gallate
promoted hair growth in vivo dermal papillae of human scalps. It was concluded that EGCG
stimulates hair growth through dual proliferative and anti-apoptotic effect [103].
All the above mentioned experiments proved practical usefulness of tea extract in formulating
cosmetics, which improve skin appearance and hair condition and growth. However, majority of
these studies deal with green tea extract, therefore more research regarding black or white tea
application should be performed.

Molecules 2019, 24, 4277 12 of 28
3.7. Improvement of Skin Microcirculation
It is widely known that tea polyphenols improve microvessel system and microcirculation in
the skin and—through different receptors—increase microvessels elasticity [37]. Polyphenols are
thromboxane A2 synthesis inhibitors, which induce the anticoagulant effect. Due to their strong
antioxidant properties these compounds also have a protective activity towards prostacyclines.
Their influence on microvessels permeability is also indirect as they inhibit the oxidation of vitamin
C, which is a key factor in collagen synthesis—a protein that is a crucial component of vascular wall
[38]. There are studies, which based on the above mentioned mechanisms, proved that internal and
external use of tea polyphenols may significantly improve skin microcirculation [5].
Heinrich and co-investigators performed a 12-week, double-blind, placebo-controlled study,
involving 60 female volunteers, who were randomized to an intervention or control group. The first
group received a beverage containing green tea polyphenols providing 1402 mg of catechins per
day. The second group received a control beverage. Several skin parameters (skin photoprotection,
structure and function) were measured at baseline, after 6 weeks and after 12 weeks. The study
revealed significant improvement in skin deterioration following UV-radiation, elasticity,
roughness, scaling, density and water homeostasis. What is important, the consumption of beverage
rich in green tea catechins significantly increased blood flow (40% by week 6 and 29% by week 12)
and oxygen delivery to the skin (from 30% at the baseline up to 38% and 40% by week 6 and 12,
respectively). Within the same experiment a randomized, double-blind, single-dose (0.5, 1.0 and 2.0
g) study of green tea polyphenols, which were administrated in a form of a capsule was performed
on a group of 15 female volunteers who had not participated in the 12-week study. This short-term
study showed that blood flow was maximized at 30 min after ingestion. In general, performed
clinical investigation proved that increased intake of green tea catechins significantly improves skin
condition, including blood flow and microcirculation in the skin tissue 5]. Rothenberger and
co-workers investigated whether tea tree oil increases skin blood flow, which is a very important
task in wound treatment. Therefore the authors analyzed the direct effect of topical antiseptic agents,
including oil from a tea tree, on the microcirculation of intact human skin. The study was conducted
in a group of 20 volunteers (nine men and 11 women). Patients immersed their fore, middle, ring
and little fingers of the right hand in cups with appropriate solutions, including 5% of tea tree oil,
which was dissolved in 0.9% of NaCl. An oxygen to see diagnostic device was used to evaluate
oxygen supply in microcirculation of blood perfused tissues (blood flow, hemoglobin oxygenation
and the relative amount of hemoglobin). Obtained results showed that tea tree oil significantly
increased (+19%) blood flow compared to control. Moreover, the improvement after using tea tree oil
was the highest in comparison to other substances used in the study (ocetnidine and polyhexanide).
The alterations in the hemoglobin oxygenation were not significant. Tea was proved to be a very
effective antibacterial agent, which significantly improves skin perfusion, which is an important
factor in wound healing [104] (Table 2).
Caffeine was also proved to improve the microcirculation in the skin of the head and therefore
to increase nutrients delivery to the hair bulbs, which strengthens and stimulates rapid growth of the
hair [105]. This alkaloid was also proved to improve the circulation in other tissues. An in vivo study
performed using positron emission tomography (PET) revealed that oral administration of 250 mg of
caffeine improved blood circulation in the human brain by 30% [106], whereas a dose of 100 mg
given orally increased microcirculation in the human ocular fundus, which was revealed in a study
performed on 10 healthy volunteers using a laser speckle tissue circulation analyzer [107]. Lupi and
co-workers performed a clinical investigation in a group of 134 women with cellulite, aged between
20 and 39 years, to evaluate the effectiveness of a commercially available cosmetic (Elancyl®
Chrono-Active) composed mainly of a 7% caffeine solution, to improve microcirculation and reduce
cellulite. Microcirculatory parameters evaluated were functional capillary density (FCD; number of
flowing capillaries per unit area), diameter of the dermic papilla (DPD) and capillary diameter (CD).
Moreover different clinical parameters, such as centimetrical measurements of thighs and hips, were
evaluated. Additionally the influence of tobacco smoking, alcohol consumption and physical
activity on the efficacy of the treatment was assessed. The study was conducted for 1 month.

Molecules 2019, 24, 4277 13 of 28
Obtained results revealed an increase of the all microcirculation parameters (FCD, DPD and CD) in
the studied group. However, the changes were not statistically significant. Thigh and hip
circumferences were significantly reduced, in more than 80% and 67% of cases, respectively.
Moreover, it was shown that tobacco smoking, alcohol consumption and the level of physical
activity had no influence on the circumference of the treated thighs and hips [108]. Table 2
summarizes studies and their results, which were performed regarding the beneficial effects of tea
and its active constituents towards the skin.

Molecules 2019, 24, 4277 14 of 28
Table 2. Beneficial effects of tea and its active constituents towards the skin-summary.
Activity
Experimental Model
Type of Tea/Active Constituent
Mechanism of Action/Effect
Reference
In vitro
In vivo/Ex vivo
Tea catechins (EC, EGCG,
EGCG)
• Direct ROS and RNS scavenging
• Chelation of trace elements, which are
involved in free radicals generation (Cu, Fe)
• Increasing of the endogenic antioxidant
enzymes production (SOD, glutathione)
• Inhibition of enzymes involved in ROS
generation (glutathione S-transferase,
microsomal monooxygenase, mitochondrial
succinoxidase or NADH oxidase)
• Protection and regeneration of
antioxidant substances (vitamin C or E)
[5,43,44,47,48]
Antioxidant
DPPH, ABTS, FRAP
assays
Different animal models
Phase II, clinical
evaluation
Topical application of gel
containing EGCG
Improvement in skin texture and skin
appearance in 45% of volunteers after a
4-week application
[93]
Double-blinded,
placebo-controlled trial 40
women with moderate
photoaging 8 weeks of
treatment
Green tea extract
- oral supplementation (300 mg,
2 per day)
- topical application of 10% green
tea cream
- Skin biopsies revealed significant
improvement in the elastic tissue content
- No clinically significant changes regarding
protection from cutaneous signs of
photoaging were detected
[94]
24 volunteers
Different cosmetic formulations
containing vehicles
supplemented with 6% Camellia
sinensis glycolic leaf extracts
Application to the forearm skin
- Significant increase in skin moisture
(immediate and long-term)
- Improved skin microrelief (skin texture)
(especially after 15–30 days of treatment)
- Significant enhancement of the skin
viscoelastic-to-elastic ratio (Uv/Ue; after 30
days)
[41]
Photoprotective
Normal fetal lung
fibroblasts (MRC5)
Adult skin
fibroblasts (84BR)
Normal human
epidermal
keratinocytes
(NHEK)
Peripheral blood cells
obtained from10 healthy
non-smoking volunteers
(six female and four men)
EGCG (in vitro assay)
540 mL of green tea infusion (in
vivo study)
- Significant inhibition of UVR-induced
damage to peripheral blood cells
- Dose-dependent inhibition of the
UVR-induced DNA damage in fibroblasts
and keratinocytes cell cultures
- 250 µM of EGCG was found to be optimal
concentration to inhibit DNA cell damage
caused by UVR
[64]

Molecules 2019, 24, 4277 15 of 28
21 voluntary healthy
participants
Skin patches irradiated
with UVB (up to 100
mJ/m2)
External application of a water in
oil emulsion containing 4% of
green tea extract
- Significant decrease of UV-induced p53
expression in keratinocytes
- Significant reduction of apoptotic
keratinocytes
- Significant reduction of the UV-induced
erythema and thymidine dimer formation
[73]
A double-blind
placebo-controlled assay
- 10 healthy volunteers
- skin explants (ex vivo
study)
White and green tea extracts
applied topically in a specially
prepared cosmetic vehiculum
- Significant reduction of cutaneous
immunity in UV-irradiated skin (stronger in
the case of green tea)
- Prevention of UV-induced oxidative DNA
damage in the form of 8-OHdG
(8-hydroxy-2’-deoxyguanosine)
[67]
24 male albino hairless
mice (HRS/J-hairless,
Jackson, Bar Harbor, ME,
USA)
Green tea and Ginkgo biloba
glycolic extracts
Topical formulation containing
6% of each extract applied in two
different areas in a concentration
of 5 mg/cm², 15 min prior UV
irradiation
- Significant reduction of the UV-induced
skin damage (dryness, irritation, presence of
erythema, sunburn cell formation and
epidermal hyperplasia)
- Much stronger effect when both extracts
were applied together
- Strong photoprotective activity due to
biological effects caused in the skin and not
photo-absorption properties of both herbal
extracts
[70]
Anticellulite and
slimming
properties
More than 24 clinical
placebo-controlled trials
performed on obese
patients
Oral ingestion of 600–900 mg of
tea polyphenols per day
(equal to 3–4 cups of green tea)
- Significant reduction of the total abdominal
fat
- Significant reduction of the weight
- Significant reduction of the skin fat tissue
- Reduced serum triglycerides
- Induced adipogenesis
- Increased energy expenditure–increased fat
oxidation
- Improved fecal lipid excretion
[5,83–85]
Swine hypodermis
Caffeine
Three models:
- Gel with ultrasound treatment
(3 MHz, intensity: 0.2 W/cm2,
rate: 1 min/cm2 ),
- Gel with caffeine (5%,
water-in-water)
- Model using caffeine and ultrasound was
proved to be the most effective
- Significant reduction of the subcutaneous
adipose tissue, damage of the adipocytes and
the numbers of cells
[80]

Molecules 2019, 24, 4277 16 of 28
- Gel with caffeine and
ultrasound
Application during 15 days
Wistar female mice
Cosmetic emulsion containing
4% of caffeine applied topically
for 21 days
- Significant reduction (by 17%) of the fatty
cells diameter
[81]
Clinical study
- 15 healthy female
volunteers with cellulite
on the thigh and medial
side of the upper arms
Slimming cream containing 3.5%
of water-soluble caffeine and
xanthenes for the treatment of
cellulite
Topical application twice daily
for 6 weeks
- Significant improvement in skin condition
- Significant reduction of the cellulite (by
19.8%)
- Reduction of thigh (0.7 cm-1.7%) and upper
arm (0.8 cm-2.3%) circumferences
- No side effects
[82]
Double-blinded,
randomized trial
20 women with a
moderate degree of
cellulite
4-week treatment
Anti-cellulite cream containing
black pepper, sweet orange peel,
ginger root extract, cinnamon
bark extract, capsaicin, green tea
and caffeine.
Topical application
Combination of anti-cellulite
cream and occlusive
bioceramic-coated neoprene
garment
- 76% volunteers reported improvement of
their cellulite
- 54% women declared greater improvement
in the thigh that received garment occlusion
- Significant improvement of the skin of the
thighs condition (average circumference
reduction was 1.2 cm; 1.3 cm in the group
with oclussion and a 1.1 cm reduction
without occlusion)
[88]
29 women aged 25–48
with a cellulite grade 2
according to the
Nurnberger–Muller scale
Dietary supplementation with
chokeberry juice rich in
polyphenols
100 mL/day for 90 days
- Significant reduction in the subcutaneous
tissue thickness (1.9 mm on average)
- Length of subcutaneous tissue fascicles was
reduced in 97% of subjects
- Reduction of edema in 55.2% of patients
after 45 days of treatment
- Lack of edema in all subjects after 90 days of
treatment
- No qualitative or quantitative
determinations of the phenolic composition
of the juices were performed
[91]
Improvement of
skin and hair
condition
Clinical double-blind
placebo study
36 participants (18 in the
study group and 18 in the
Dietary supplement containing
300 mg of green tea extract
(twice daily) and topical
application of a green tea cream
- No statistical changes of the skin of the
patients from both groups (dermatological
examination)
- Skin biopsy revealed significant
[94]

Molecules 2019, 24, 4277 17 of 28
placebo group)
(10%)—two times per day, for 8
weeks
improvement in elastic tissue content in the
green tea treated group
Randomized single-blind,
placebo-controlled study
20 healthy Thai
volunteers (16 female and
4 male) aged between 20
and 35 years old
Cosmetics preparation, which
contained 2%, 4.5% and 7% of
green tea extract with 100 mg%
of polyphenols (the base
consisted of hydroxyethyl
cellulose, glycerin and
panthenol).
Topical application for 28 days.
- Significant anti-greasy and anti-sebum
activity of a green tea extract
- High efficiency in the improvement of oil
face condition
- The activity was highly correlated with the
concentration of green tea extract
- The effectiveness of a 28 days treatment was
significantly better than 14 days
- Patch testes revealed no irritation properties
[95]
Single-blinded, placebo
controlled monocentric
study
22 non-smoker, healthy
men
Cosmetic preparation containing
lotus and green tea extract.
Application on cheek at bedtime
for 60 days.
Sebum production was
evaluated at baseline and after
15, 30, 45 and 60 days.
- Significant reduction of sebum production
- Higher efficacy in the group applying only
green tea, compared to a combination of
green tea and lotus (not statistically
significant)
- The highest effectiveness was achieved after
60 days of treatment
[96]
Clinical investigation-10
healthy men aged 24–40
years
Cosmetic formulation containing
3% of green tea extract applied to
the cheeks for 8 weeks.
- Significant decrease in sebum production
- The highest efficiency was achieved after 8
weeks of treatment (60% of sebum reduction)
- Significant improvement already after 1
week of treatment (sebum production
decreased by 10%)
[98]
Hair follicles from 14
biopsies, taken from
the vertex areas
from male with
androgenic alopecia
Caffeine
External application of caffeine
in a concentration of 0.001 and
0.005%
- Significant stimulation of hair follicle
growth
- Reduction of a smooth muscle tension near
the hair follicle
- Significant increase of the nutrients delivery
to a hair papillae
[99]
Placebo controlled study
30 mice
Animals were fed with a diet
enriched with 50% fraction of
polyphenol extract from
dehydrated green tea in their
drinking water for six months
- Significant improvement in hair growth
(33% of animals) in comparison to control
group
[100]
Cultured human
dermal papilla cells
Hair follicles ex vivo
culture
Three normal human
EGCG
0.01, 0.1 or 0.5 μM (in vitro)
0.1, 1 or 5 μM (ex vivo)
- Stimulation of the culture cells growth
- Proliferative and anti-apoptotic effect
towards dermal papillae of human scalps
[103]

Molecules 2019, 24, 4277 18 of 28
volunteers
10% in ethanol or ethanol vehicle
(in vivo)
- Prolongation of anagen stage
Improvement of
skin
microcirculation
Double-blind,
placebo-controlled study
60 female volunteers
Green tea beverage (1402 mg of
catechins per day) for 12 weeks.
- Significant improvement in blood flow (40%
by week 6 and 29% by week 12)
- Significant improvement in oxygen delivery
to the skin (from 30% at the baseline up to
38% and 40% by week 6 and 12, respectively)
- Significant improvement of several skin
parameters (elasticity, roughness, scaling,
density and water homeostasis)
[5]
Randomized,
double-blind, single-dose
study
15 female volunteers
Green tea extract (0.5, 1.0 and 2.0
g) administrated orally in a form
of capsule
- Maximized blood flow 30 min. after
ingestion
- Significant improvement of skin condition
- Increased blood flow and microcirculation
in the skin tissue
[5]
Clinical investigation in a
group of 20 volunteers
(nine men and 11 women)
with wounds
Topical application of antiseptic
agent containing tee tree oil (5%
in a saline)
- Significant increase (+19%) of blood flow
compared to control
- Significant improvement of wound healing
(in comparison to ocetnidine and
polyhexanide)
- Alterations in the hemoglobin oxygenation
(not significant)
- Significant improvement of skin perfusion
- Strong antibacterial activity
[104]
Clinical investigation in a
group of 134 women with
cellulite, aged between
20–39 years
Commercially available cosmetic
(Elancyl® Chrono-Active)
containing 7% of caffeine
Topical application for 1 month
- Insignificant improvement of skin
microcirculation (functional capillary density,
number of flowing capillaries per unit area,
diameter of the dermic papilla and capillary
diameter)
- Significant reduction of thigh and hip
circumferences in 80% and 67% of cases,
respectively
- No influence of alcohol consumption,
tobacco smoking and level of physical
activity on thigh and hip circuit was revealed
[108]

Molecules 2019, 24, 4277 19 of 28
4. Skin Penetration of Tea Active Constituents
The efficacy of cosmetic formulation is strictly correlated with the skin permeability of its active
ingredients. One of the most important penetration-conditioning factors is the polarity of
components. According to Yanagida and co-investigators [109] the partition coefficients
(K(non-polar/polar)) of green tea polyphenols can be placed in the following order: ECG (6.25) >
EGCG (2.94) > EC(2.38) > C(2.33) > EGC(0.93). From all simple catechins present in tea extract EGC is
considered as the most hydrophilic molecule, while ECG is characterized by the smallest polarity
[109]. A study performed by Dal Belo and co-investigators [70] revealed that, after topical
application of a green tea extract containing cream, EGCG was significantly retained within the skin,
mostly in the stratum corneum, followed by the epidermis and dermis. This suggests a non-polar
character of EGCG, as non-polar compounds tend to stay within the stratum corneum layer, and not
penetrate into deeper parts of the skin, like the epidermis and dermis [110]. This is in agreement with
a previous finding of Yanagida and co-workers, which also suggests a non-polar character of EGCG
[109]. Zillich and co-investigators reported that both the size of the molecule as well as the
hydrophobicity are the most crucial parameters regarding the ability of green tea catechins to
penetrate the skin [6]. Definitely more experiments, especially in vivo and human studies, are
needed to expand the knowledge on the bioavailability of tea polyphenols from cosmetic
preparations.
Caffeine, a very important tea active constituent, is more often used as a hydrophilic model
substance in skin penetration experiments. An in vitro study performed by Van de Sandt and
co-workers [111] revealed that the maximal absorption rates of caffeine through the human skin
were found to be 2.24 ± 1.43 µg/cm2/h. The authors have also proved that the maximal absorption of
this alkaloid was reached 100 min after percutaneous application in the human skin [112]. Touitou
and co-investigators studied caffeine skin delivery by carrier design [113]. Using quantitative skin
autoradiography they have confirmed the highest concentration of caffeine (280 µg/g tissue) after 24
h in the epidermis, while the lowest amount of this alkaloid (50 g/g tissue) was detected in the
dermis. However, the caffeine’s ability to penetrate from different cosmetic preparations through the
skin barrier differs and is significantly correlated with the type of emulsion applied on the skin [73].
It occurs that its permeation mostly depends on the quantity of the formulation applied, rather than
on the concentration of caffeine in the cosmetic formulation [114]. It was also proved that the
composition of the cosmetic significantly affects caffeine absorption through the skin—water-in-oil
nanoemulsion formulations were much more effective in comparison to aqueous solutions of
caffeine, which was proved in Franz diffusion cells using rat skin as permeation membrane [115]. An
effective way to transfer caffeine through the skin barrier was based on the application of
microspheres in aqueous suspension (diameter of the microspheres: 2.8 µm, caffeine loading: 2.3
mg/g of particles). Such a formulation improved caffeine transfer across the skin, as microspheres
easily penetrated the skin barrier and gathered in the receptor compartment, providing continuous
alkaloid release [72,116]. Taking all into consideration it should be remembered that not only the
quality of the tea extract or the concentration of caffeine, but first of all the composition of the
cosmetic formulation is significant for the effectiveness of topical applications containing this
alkaloid.
5. Skincare Products Containing Tea Extracts
Tea extracts are important components of many cosmetics, including creams, moisturizing
lotions, tonics, shower gels, hair products as well as cosmetic facial masks. That frequent use of
Camellia sinensis extracts is due to its multidirectional effect. From all types of tea extracts, those
obtained from green tea are the most widely used. These are proposed not only for young and
problematic skin types, as they inhibit excessive sebum production, but can also be used by people
with sensitive and allergic skin [11,38]. However, on the market also cosmetic products containing
black and white tea can be found and their popularity is increasing. Due to a many producers and
cosmetic forms a large number of different products can be found and their exact number is hard to

Molecules 2019, 24, 4277 20 of 28
estimate, also because almost every year new products appear on the market. Table 3 presents an
example of 30 different cosmetics containing green, black and white extracts, including a type of a
cosmetic form and manufacturer′s recommendations.
Table 3. Selected examples of cosmetic products containing tea.
Tea Extract
Cosmetic
Product
Cosmetic’s Effects (Manufacturer′s Declaration)
Production
Area
Green tea
Peeling mask
- Improved skin regeneration based on the
antioxidant, anti-inflammatory and toning properties
of green tea
Poland
Green tea
Face mask
- Strong soothing, anti-inflammatory and
regenerative properties
- antioxidant activity
- Protection against harmful environmental
influences
Poland
Green tea
Face mask
- Eliminated excess sebum
- Proper skin hydration
USA
Green tea
Shampoo
- Hair care for normal and slightly damaged hair
- Antioxidant properties
- Soothing action towards sensitive scalp (slightly
moisturized and refreshed)
Poland
Green tea (Fuji)
Shampoo
- Hair care for normal hair
- Refreshed and purified hair and scalp
UK
Green tea
(Matcha)
Shampoo
- Reduction of dandruff and greasy hair
- Clarified and toned scalp
- Intensive shine
UK
Green tea
Shampoo
- Antioxidant in hair care (protection of hair against
free radicals)
- Hydrated and moisturized scalp
Malaysia
Green tea
Hair conditioner
- Hair care for all hair types
- Protection against moisture loss
- Strong antioxidant and hair growth stimulant
properties
- Smooth and soft hair
UK
Green tea
Hair conditioner
- Strengthens hair
- Antioxidant properties towards hair
Japan
Green tea
Hand and Body
Lotion
- Nourishing cream for feet, hands and body
- Makes the skin smooth and hydrated
USA
Green tea
Body lotion
- A fresh fragrance
- Refreshing body and mind
- Improved mood
USA
Green tea
Balancing lotion
- Superior hydration and nourishment of the skin
- Softened and smoothed, cleansed skin leaving
USA
Green tea
Refreshing body
lotion
- Hydrated skin
- Skin fragrance for a long time
USA
Green tea
Body cream
- Nourished and moisturized skin
- Smoothed skin
- Soft and flexible skin
- Skin care for all skin types
USA
Green tea (Fuji)
Hand cream
- Nourished hands’ skin
- Softer and smoother hands
UK
Green tea
(Matcha)
Hand cream
- Skin care for all skin types
- Nourished and moisturized skin of the hands
UK
Green tea
Eye cream
- Removed six types of wrinkles under the eyes
- Improved production of hyaluronic acid by
epidermal cells
- Restored moisture in the skin to fill fine lines in dry
Japan

Molecules 2019, 24, 4277 21 of 28
skin
Black tea
Face mask
- Nourished and smoothed skin
- Antioxidant properties towards the skin
USA
Black tea
Instant
perfecting mask
Black tea complex:
- Protection against harmful effects of the
environment
- Reduction of the skin roughness, improved glow
and elasticity
- Softened, smoothed and soothed the skin
EU
Black tea
(Darjeeling tea)
Antiwrinkle
cream
- Protection against any harmful environmental
factors
- Moisturized and revitalized skin
South Korea
Black tea
Shampoo
- Everyday shampoo for all types of hair
- Removed build-up and excess oils
UK
Black tea
Lotion
- Hydration and the look of firm, radiant skin
- Provided SPF 20 UVA/UVB sun protection
- Protection against UV and free radicals-induced
damage
Recommended for:
- Dryness
- Dullness/uneven texture
- Loss of firmness/elasticity
EU
Black tea
Body cream
- Antioxidant benefits towards the skin
- Smoothed and moisturized the skin
USA
Black tea
Firming corset
cream
Black tea complex:
- Firms and redefines the contours
- Prevents loss of elasticity and smoothness
- Makes the skin look healthier and younger
- Protects the skin against free radicals
EU
Black tea
Eye concentrate
Black tea complex:
- Firmed and redefined eye contour
- Increased elasticity and smoothness
- Healthier and more youthful appearance
EU
Black tea
Hand cream
- Hand skin care for all skin types
- Regenerated and smoothed the skin
UK
White tea
Body cream
- Softened and hydrated skin
USA
White tea
Shower gel
- Refreshed and softened fragrant skin
USA
White tea
Toilet water
- Fragrant skin
USA
White tea
Hand cream
- Alleviated rough patches and calluses
USA
According to Możdżeń and co-workers, who analyzed the plant species, which are used to
produce cosmetic masks offered on the Polish market, Camellia sinensis is the most commonly used,
followed by Matricaria chamomilla L. and Vitis vinifera L [117].
After applying cosmetics containing tea extract, the skin appears more tense and refreshed,
which is the result of astringent activity of polyphenols and tannins and their interaction with
keratin present in the stratum corneum. This process also leads to a reduction in skin redness,
irritation and reduction of swelling. The facial masks, containing mainly green tea extracts, have a
disinfecting, antioxidant and toning effect. They also soothe inflammation, accelerate the healing of
wounds and skin eruptions, and also close skin pores by which they reduce their visibility [117].
Tea infusions are also used as compresses, which are applied after insect bites [77] or to soothe
the itching and burning around the eyes.
The latter effect results from the vasoconstriction induced by the metabolites of tea plant and is
shown up as a noticeable reduction of swelling around the eyes, which is often observed during
inflammation [11,77].
6. Conclusions and Perspectives

Molecules 2019, 24, 4277 22 of 28
Plentiful of biological effects of Camellia sinensis presented in this review shed light on the
application of its extracts in cosmetics apart from its better known usage in pharmaceutics. Tea plant
leaves are the most rich sources of catechins among plants, but also deliver caffeine—a purine
alkaloid of high cosmetic significance. Together with the development of the analytical
instrumentation and biological activity evaluation methodology, further precious properties of this
plant were revealed towards skin. The administration of tea plant in cosmetics seems to be
interesting and precious, due to the fact that it does not have any confirmed allergenic or irritating
effects after topical administration. Low toxicity of single metabolites of its extracts, often appearing
as synergistic actions with other antioxidants commonly added to different types of products and
additional preserving properties towards final cosmetics formulations encourages the use of tea
plant metabolites in various applications.
Among the benefits of tea plant and its extracts, its value in the anti-ageing treatment, skin and
hair care and slimming properties should be underlined. Its constituents are also effective in the skin
microcirculation enhancement and photoprotection against harmful effects of UV irradiation.
Therefore, it is of the highest importance to collect funds on the Camellia sinensis fermentation
type-bioactivity studies to reveal some more relations between the type f manufacturing process and
the obtained biological effects. Still the largest quantity of scientific results has been obtained for the
green tea extracts. The other types of leaves’ fermentation due to their different composition needs
further investigations, as they are also responsible for noticeable effects towards skin. On the other
hand, further trials on human skin or humans of all types of tea are necessary to confirm its
therapeutic benefits already revealed in in vitro models.
Certainly, this still insufficiently studied plant in terms of its cosmetic applications will draw
attention of researchers working in this sector in the nearest future.
Author Contributions: W.K. and W.K.-K. have designed the manuscript, W.K. W.K.-K., J.Z., Z.M. prepared the
original draft of the manuscript; W.K. has reviewed the manuscript.
Funding: This research was funded by the Medical University of Lublin within the statutory funds (DS No 07)
of the Chair and Department of Food and Nutrition.
Conflicts of Interest: The authors declare no conflict of interest.
Abbreviations:
C
(+)-catechin
cAMP
adenosine cyclic 3′5′-monophosphate
CD
capillary diameter
CD1a+
epidermal Langerhans cells
COX-1
cyclooxygenase 1
DHT
dihydrotestosterone
DPD
dermic papilla diameter
EC
(–)-epicatechin
ECG
(–)-epicatechin gallate
EGC
(–)-epigallocatechin
EGCG
(–)-epigallocatechin gallate
FCD
functional capillary density
GA
gallic acid
GC
(–)-gallocatechin
GCG
(–)-gallocatechin gallate
HSL
hormonesensitive lipase
IL-10
interleukin 10
NaCl
natrium chloride
NHEK
normal human epidermal keratinocytes
RNS
reactive nitrogen species
ROS
reactive oxygen species
SOD
super oxide dismutase
TB
theobrownins
TF
theaflavins
TF1
theaflavin

Molecules 2019, 24, 4277 23 of 28
TF2A
theaflavin 3-gallate
TF2B
theaflavin 3′-gallate
TF3
3-3′-theaflavin digalusate
TR
thearubigins
TXAS
thromboxane synthase
UV
ultraviolet
UVR
ultraviolet radiation
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