Utilization of orchids of Wallacea region and implication for conservation

Traditional Uses and Pharmacologically Active Constituents of Dendrobium Plants for Dermatological Disorders: A Review

Dendrobium Sw. is one of the largest genera in the orchidaceous family and includes 900-2000 species. Among them, more than 80 Dendrobium species have been reported in China. However, there are only six Dendrobium species, namely, D. bigibbum var. superbum (syn. D. phalaenopsis), D. chrysanthum, D. fimbriatum, D. loddigesii, D. nobile, and D. officinale (syn. D. candidum), listed in the New Inventory of Existing Cosmetic Ingredients in China Launched. Artificial planting of Dendrobium species has been a great success in China. To better utilize Dendrobium resources for medicinal and cosmetic purposes, we summarize their traditional uses and pharmacologically active compounds for treating dermatological disorders in this review. "Orchidaceae", "Dendrobium", "traditional use", "ethnobotany", "dermatological disorder", and "skin disease" were used as search terms to screen the literature. Cited references were collected between 1970 and 2020 from the Web of Science, China National Knowledge Internet (CNKI), SciFinder, Google Scholar, and Chinese books. From the search, it was found that there are 22 Dendrobium species with traditional uses in dermatological disorders, and 131 compounds from Dendrobium plants have been reported to possess anti-inflammatory, antimicrobial, antioxidant, antiaging, anti-psoriasis, and tyrosinase-inhibitory activities, implying that Dendrobium plants are important resources for the discovery of active compounds and the development of new drugs and cosmetics. D. crepidatum, D. denneanum, D. loddigesii, D. nobile, and D. officinale have been extensively studied. More research on other Dendrobium species is needed. The major active compounds found in Dendrobium species are phenanthrenes, alkaloids, flavonoids, phenylpropanoids, and lignans. Several compounds, such as loddigesiinol A, (S)-5-methoxy-2,4,7,9-tetrahydroxy-9,10-dihydrophenanthrene, (S)-4-methoxy-2,5,7,9-tetrahydroxy-9,10-dihydrophenanthrene, 2,5-dihydroxy-4-methoxy-phenanthrene 2-O-β-D-glucopyranoside, (9R)-1,2,5,9-tetrahydroxy-9,10-dihydrophenanthrene 5-O-β-D-glucopyranoside, (+)-homocrepidine A, and vicenin 2, have significant anti-inflammatory activities and inhibit nitric oxide (NO) production with IC50 values less than 5 μM, and these compounds are worthy of further study.

Traditional uses, chemical constituents, pharmacological activities, and toxicological effects of Dendrobium leaves: A review

ETHNOPHARMACOLOGICAL RELEVANCE

In China, shi hu (stems of Dendrobium chrysotoxum Lindl, D. fimbriatum Hook. D. huoshanense Z.Z. Tang & S.J. Cheng, or D. nobile Lindl) and tie pi shi hu (stems of D. officinale Kimura et Migo) are famous traditional medicines and are listed in the Chinese Pharmacopoeia. However, the leaves of these Dendrobium plants are largely discarded.

AIM OF THE STUDY

To better utilize Dendrobium leaves, we summarize their traditional uses, chemical constituents, pharmacological activities, and toxicological effects.

MATERIALS AND METHODS

"Orchidaceae", "Dendrobium", "leaf", "traditional use", and "ethnobotany" were used as search terms to screen the literature. Cited references were collected between 1960 and 2020 from the Web of Science, China National Knowledge Internet (CNKI), SciFinder, and Google Scholar, primarily in English and Chinese.

RESULTS

Traditional uses of leaves from 16 Dendrobium species were identified in the literature. The major uses of Dendrobium leaves include treatments for dermatologic disorders, metabolic syndromes, nervous system disorders, and musculoskeletal system disorders. More than 50 chemical compounds have been identified in the leaves of 10 Dendrobium species, which primarily include flavonoids, bibenzyls, coumarins, N-containing compounds, and polysaccharides. Antihyperlipidemia, antihypertensive, antihyperuricemia, anti-inflammatory, antimicrobial, antioxidant, cytotoxic and antitumor, hepatoprotective, immunomodulatory, lipase-inhibitory, and/or tyrosinase-inhibitory activities have been reported for the leaves of six Dendrobium species. D. officinale leaves have been shown to exhibit no reproductive toxicity against male rats, while D. speciosum Sm. leaves have been observed to exhibit slight genotoxicity in an in vitro study. Among Dendrobium species, D. officinale leaves are the most widely studied.

CONCLUSIONS

D. officinale leaves represent a good example of the utilization of leaf resources of the Dendrobium genus. In the future, more extensive research for the development of Dendrobium leaves is needed.