Alpinia officinarum (and its close relative Alpinia galanga), a member of the Zingiberaceae family ( Zhong Xi Yi Jie He Xue Bao 2011;9:1061-5 ), has long been used in Chinese medicinals ( Bioorg. Med. Chem. 2009;17:6048-53 ). Specifically, the plant is used in traditional Chinese medicine as an aphrodisiac, abortifacient, carminative, antipyretic, anti-inflammatory, and emmenagogue as well as to treat disorders of the heart and kidneys, bronchitis, chronic enteritis, renal calculus, diabetes, and rheumatism ( Zhong Xi Yi Jie He Xue Bao 2011;9:1061-5 ; Bioorg. Med. Chem. 2009;17:6048-53 ). Stomach ailments are the most typical application of the herb in traditional Chinese and Thai medicine; it is also used in Ayurveda and Sidda medicine. A. officinarum is widely cultivated throughout Asia, including China, Thailand, India, Sri Lanka, Malaysia, and Indonesia, as well as the Middle East and Northern Africa (Saudi Arabia and Egypt, respectively) ( Zhong Xi Yi Jie He Xue Bao 2011;9:1061-5 ).
The flavonoid galangin (3,5,7-trihydroxyflavone) is the primary active constituent of A. officinarum ( Phytother. Res. 2014;28:1533-8 ; J. Cell Biochem. 2013;114:152-61 ). In vitro, it has demonstrated a cytotoxic effect on multiple cancer cell lines ( J. Cell Biochem. 2013;114[1]:152-61 ). Traditional Uighur medicine in China has incorporated galangin for the treatment of vitiligo ( Phytother. Res. 2014;28:1533-8 ). Overall, A. officinarum rhizomes have been associated with antiemetic, antigenotoxic, antimutagenic, and antioxidant activity, as well as inhibitory effects on prostaglandin and leukotriene biosynthesis, and modulatory effects on cytochrome P450 enzymes ( Bioorg. Med. Chem. 2009;17:6048-53 ; J. Cell Biochem. 2013;114:152-61 ). The rhizomes of A. officinarum have been used externally to treat skin infections, gum diseases, and skin cancer ( J. Nat. Med. 2008;62:374-8 ).
Constituents
The rhizomes of the plant, commonly referred to as galangal, contain several key active constituents, including essential oils, tannins, neolignans, phenol, glycosides, monoterpenes, diarylheptanoids, phenylpropanoids, carbohydrates, gallic acid glycoside, galangoisoflavonoid, beta-sitosterol, galangin, alpinin, zerumbone, and kampferide ( Zhong Xi Yi Jie He Xue Bao 2011;9:1061-5 ; Bioorg. Med. Chem. 2009;17:6048-53 ; J. Nat. Med. 2008;62:374-8 ).
In 2009, Matsuda et al. reported that the 80% aqueous acetone extract of the rhizomes of A. officinarum suppressed melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. They found that several isolated constituents had significant IC50 values (10-48 mcm) for inhibiting melanogenesis, including four diarylheptanoids (5-hydroxy-1,7-diphenyl-3-heptanone, 7-(4(‘’)-hydroxy-3(‘’)-methoxyphenyl)-1-phenylhept-4-en-3-one, 5-hydroxy-7-(4(‘’)-hydroxy-3(‘’)-methoxyphenyl)-1-phenyl-3-heptanone, and 3,5-dihydroxy-1,7-diphenylheptane) and two flavonol constituents (kaempferide and galangin). The mRNA expression of tyrosinase and tyrosinase-related proteins-1 and -2 was also hindered by 7-(4(‘’)-hydroxy-3(‘’)-methoxyphenyl)-1-phenylhept-4-en-3-one, kaempferide, and galangin, as was the protein level of a microphthalmia-associated transcription factor, the authors noted ( Bioorg. Med. Chem. 2009;17:6048-53 ).
Biologic activity
Penetration enhancement: In 2000, Shen et al. found that volatile oils from galangal, among other herbs, were effective in enhancing the skin permeation of 5-fluorouracil and notably more effective than azone ( Zhong Yao Cai 2000;23:697-9 ).
Anti-inflammatory effects: In 2008, Yasukawa et al. examined the inhibitory effect of galangal in a two-stage in vivo carcinogenesis model in mice. They observed that the A. officinarum rhizomes displayed significant antitumor-promoting activity against 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)–promoted lesions. Seven diarylheptanoids isolated from the active fraction of the methanol extracts demonstrated significant anti-inflammatory effects against TPA-induced inflammation ( J. Nat. Med. 2008;62:374-8 ).
Cancer prevention and pigmentary effects: Heo et al. reported in 2001 that in vitro and in vivo studies have demonstrated that the flavonoid galangin, found in high concentrations in A. officinarum, as well as the bee product propolis, exhibits significant antioxidant activity and can influence enzyme activities and inhibit genotoxicity without introducing a pro-oxidant effect. They concluded that galangin warrants consideration for its potential as a chemical cancer-preventing agent ( Mutat. Res. 2001;488:135-50 ).
In 2007, Lu et al. investigated the whitening effects of the flavonoid components of A. officinarum on melanin biosynthesis in B16 mouse melanoma cells, tyrosinase inhibition, and UV absorption. They found that galangin and the flavonoid mixture both decreased melanin content more than controls and also lowered melanin production, with galangin more effective than the flavonoid mixture. In addition, galangin and the flavonoid mixture exerted greater tyrosinase inhibition at lower concentrations. The A. officinarum constituents also displayed a broad absorption band in the UVB area (270 to 290 nm). The researchers concluded that galangin may be a viable whitening agent with the potential to prevent skin cancer ( J. Enzyme Inhib. Med. Chem. 2007;22:433-8 ).
Six years later, Zhang et al. noted that various doses of galangin resulted in the inhibition of B16F10 melanoma cell proliferation. The investigators also showed that galangin achieved an antimetastatic effect in vivo in C57BL/6J mice, reducing focal adhesion kinase. They concluded that focal adhesion kinase is a viable target in melanoma therapy, with B16F10 melanoma metastasis apparently checked by galangin in mice and in cell cultures ( J. Cell Biochem. 2013;114:152-61 ).
In 2014, Huo et al. tested galangin in a mouse model of vitiligo induced in C57BL/6 mice through the daily topical application of hydroquinone (2.5%) on shaved dorsal skin for 60 days. Thirty days after the final hydroquinone application, investigators began oral administration of galangin for 30 days. Hair grew back after treatment darker than the original color, with histologic analysis revealing that mice treated with galangin and the positive control 8-methoxypsoralen had an increased number of melanin-containing hair follicles, compared with untreated animals. In addition, galangin treatment was associated with significant increases in the number of cutaneous basal layer melanocytes and melanin-containing epidermal cells. Compared with controls, treatment with galangin and 8-methoxypsoralen led to increased serum levels of tyrosinase and decreased levels of malondialdehyde and lower cholinesterase activity. Galangin and 8-methoxypsoralen use also increased the expression of tyrosinase protein in treated skin. The investigators concluded that galangin improved hydroquinone-induced vitiligo in mice and warrants further study as a potential vitiligo treatment in humans ( Phytother. Res. 2014 28:1533-8 ).
Conclusion
Alpinia officinarum is one of many botanical agents with a long history of applications in traditional folk medicine, particularly in Asia. There is a relative paucity of evidence regarding the dermatologic applications of this plant, but recent findings support continued research into its various potential cutaneous benefits, with particular focus on the main active ingredient galangin.
Dr. Baumann is chief executive officer of the Baumann Cosmetic & Research Institute in the Design District in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote the textbook “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002), and a book for consumers, “The Skin Type Solution” (New York: Bantam Dell, 2006). She has contributed to the Cosmeceutical Critique column in Dermatology News since January 2001. Her latest book, “Cosmeceuticals and Cosmetic Ingredients,” was published in November 2014. Dr. Baumann has received funding for clinical grants from Allergan, Aveeno, Avon Products, Evolus, Galderma, GlaxoSmithKline, Kythera, Mary Kay, Medicis Pharmaceuticals, Neutrogena, Philosophy,Topix Pharmaceuticals, and Unilever.
