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Phytochemistry and pharmacology of ornamental gingers, Hedychium coronarium and Alpinia purpurata: a review

Chan EW, Wong SK

J Integr Med, 2015 Nov;13(6):368-79.

PMID: 26559362 DOI: 10.1016/S2095-4964(15)60208-4

In this review, the phytochemistry and pharmacology of two ornamental gingers, Hedychium coronarium (butterfly ginger) and Alpinia purpurata (red ginger), are updated, and their botany and uses are described. Flowers of H. coronarium are large, showy, white, yellow or white with a yellow centre and highly fragrant. Inflorescences of A. purpurata are erect spikes with attractive red or pink bracts. Phytochemical investigations on the rhizomes of H. coronarium generated research interest globally. This resulted in the isolation of 53 labdane-type diterpenes, with little work done on the leaves and flowers. Pharmacological properties of H. coronarium included antioxidant, antibacterial, antifungal, cytotoxic, chemopreventive, anti-allergic, larvicidal, anthelminthic, analgesic, anti-inflammatory, anti-urolithiatic, anti-angiogenic, neuro-pharmacological, fibrinogenolytic, coagulant and hepatoprotective activities. On the contrary, little is known on the phytochemistry of A. purpurata with pharmacological properties of antioxidant, antibacterial, larvicidal, cytotoxic and vasodilator activities reported in the leaves and rhizomes. There is much disparity in terms of research effort within and between these two ornamental gingers.

Apocynaceae species with antiproliferative and/or antiplasmodial properties: a review of ten genera

Chan EW, Wong SK, Chan HT

J Integr Med, 2016 Jul;14(4):269-84.

PMID: 27417173 DOI: 10.1016/S2095-4964(16)60261-3

Apocynaceae is a large family of tropical trees, shrubs and vines with most species producing white latex. Major metabolites of species are triterpenoids, iridoids, alkaloids and cardenolides, which are known for a wide range of biological and pharmacological activities such as cardioprotective, hepatoprotective, neuroprotective, anti-inflammatory, anticancer and antimalarial properties. Prompted by their anticancer and antimalarial properties, the current knowledge on ten genera (Allamanda, Alstonia, Calotropis, Catharanthus, Cerbera, Dyera, Kopsia, Nerium, Plumeria and Vallaris) is updated. Major classes of metabolites are described using some species as examples. Species with antiproliferative (APF) and/or antiplasmodial (APM) properties have been identified. With the exception of the genus Dyera, nine genera of 22 species possess APF activity. Seven genera (Alstonia, Calotropis, Catharanthus, Dyera, Kopsia, Plumeria and Vallaris) of 13 species have APM properties. Among these species, Alstonia angustiloba, Alstonia macrophylla, Calotropis gigantea, Calotropis procera, Catharanthus roseus, Plumeria alba and Vallaris glabra displayed both APF and APM properties. The chemical constituents of these seven species are compiled for assessment and further research.

Fulltext Antiproliferative activity of Vallaris glabra Kuntze (Apocynaceae)

Wong SK, Lim YY, Ling SK, Chiang Chan EW

Pharmacogn Mag, 2014 Apr;10(Suppl 2):S232-9.

PMID: 24991097 DOI: 10.4103/0973-1296.133238

Our earlier study on the antiproliferative (APF) activity of leaf extracts of ten Apocynaceae species showed that leaves of Vallaris glabra possessed strong and broad-spectrum properties.

Fulltext Caffeoylquinic acids in leaves of selected Apocynaceae species: Their isolation and content

Wong SK, Lim YY, Ling SK, Chan EW

Pharmacognosy Res, 2014 Jan;6(1):67-72.

PMID: 24497746 DOI: 10.4103/0974-8490.122921

Three compounds isolated from the methanol (MeOH) leaf extract of Vallaris glabra (Apocynaceae) were those of caffeoylquinic acids (CQAs). This prompted a quantitative analysis of their contents in leaves of V. glabra in comparison with those of five other Apocynaceae species (Alstonia angustiloba, Dyera costulata, Kopsia fruticosa, Nerium oleander, and Plumeria obtusa), including flowers of Lonicera japonica (Japanese honeysuckle), the commercial source of chlorogenic acid (CGA).

Fulltext Standardised herbal extract of chlorogenic acid from leaves of Etlingera elatior (Zingiberaceae)

Chan EW, Lim YY, Tan SP

Pharmacognosy Res, 2011 Jul;3(3):178-84.

PMID: 22022166 DOI: 10.4103/0974-8490.85003

Chlorogenic acid (CGA) or 5-caffeoylquinic acid, was found to be the dominant phenolic compound in leaves of Etlingera elatior (Zingiberaceae). The CGA content of E. elatior leaves was significantly higher than flowers of Lonicera japonica (honeysuckle), the commercial source. In this study, a protocol to produce a standardised herbal CGA extract from leaves of E. elatior using column chromatography was developed.

Fulltext Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensis

Chan EW, Soh EY, Tie PP, Law YP

Pharmacognosy Res, 2011 Oct;3(4):266-72.

PMID: 22224051 DOI: 10.4103/0974-8490.89748

BACKGROUND: The role of non-polymeric phenolic (NP) and polymeric tannin (PT) constituents in the antioxidant and antibacterial properties of six brands of green, black, and herbal teas of Camellia sinensis were investigated.

MATERIALS AND METHODS: Total phenolic content (TPC) and ascorbic acid equivalent antioxidant capacity (AEAC) were assessed using the Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, respectively. Minimum inhibitory dose (MID) against Gram-positive Micrococcus luteus, Staphylococcus aureus, and Bacillus cereus, and Gram-negative. Escherichia coli, Salmonella typhi, and Pseudomonas aeruginosa was assessed using the disc-diffusion method. Teas were extracted with hot water successively three times for one hour each time. The extracts were fractionated using Sephadex LH-20 column chromatography to obtain the NP and PT constituents.

RESULTS: Extraction yields ranged from 12 to 23%. Yields of NP fractions (70-81%) were much higher than those of PT fractions (1-11%), suggesting that the former are the major tea components. Ranking of antioxidant properties of extracts was green tea>black tea>herbal tea. For all six teas, antioxidant properties of PT fractions were significantly higher than extracts and NP fractions. Extracts and fractions of all six teas showed no activity against the three Gram-negative bacteria. Green teas inhibited all three Gram-positive bacteria with S. aureus being the least susceptible. Black and herbal teas inhibited the growth of M. luteus and B. cereus, but not S. aureus. The most potent were the PT fractions of Boh Cameron Highlands and Ho Yan Hor with MID of 0.01 and 0.03 mg/disc against M. luteus.

CONCLUSION: Results suggested that NP constituents are major contributors to the antioxidant and antibacterial properties of teas of C. sinensis. Although PT constituents have stronger antioxidant and antibacterial properties, they constitute only a minor component of the teas.

Phytochemistry, pharmacology, and clinical trials of Morus alba

Chan EW, Lye PY, Wong SK

Chin J Nat Med, 2016 Jan;14(1):17-30.

PMID: 26850343 DOI: 10.3724/SP.J.1009.2016.00017

The present review is aimed at providing a comprehensive summary on the botany, utility, phytochemistry, pharmacology, and clinical trials of Morus alba (mulberry or sang shu). The mulberry foliage has remained the primary food for silkworms for centuries. Its leaves have also been used as animal feed for livestock and its fruits have been made into a variety of food products. With flavonoids as major constituents, mulberry leaves possess various biological activities, including antioxidant, antimicrobial, skin-whitening, cytotoxic, anti-diabetic, glucosidase inhibition, anti-hyperlipidemic, anti-atherosclerotic, anti-obesity, cardioprotective, and cognitive enhancement activities. Rich in anthocyanins and alkaloids, mulberry fruits have pharmacological properties, such as antioxidant, anti-diabetic, anti-atherosclerotic, anti-obesity, and hepatoprotective activities. The root bark of mulberry, containing flavonoids, alkaloids and stilbenoids, has antimicrobial, skin-whitening, cytotoxic, anti-inflammatory, and anti-hyperlipidemic properties. Other pharmacological properties of M. alba include anti-platelet, anxiolytic, anti-asthmatic, anthelmintic, antidepressant, cardioprotective, and immunomodulatory activities. Clinical trials on the efficiency of M. alba extracts in reducing blood glucose and cholesterol levels and enhancing cognitive ability have been conducted. The phytochemistry and pharmacology of the different parts of the mulberry tree confer its traditional and current uses as fodder, food, cosmetics, and medicine. Overall, M. alba is a multi-functional plant with promising medicinal properties.

Galloylated flavonol rhamnosides from the leaves of Calliandra tergemina with antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA)

Chan EW, Gray AI, Igoli JO, Lee SM, Goh JK

Phytochemistry, 2014 Nov;107:148-54.

PMID: 25174555 DOI: 10.1016/j.phytochem.2014.07.028

Galloylated flavonol rhamnosides identified as kaempferol-3-O-(2″,3″,4″-tri-O-galloyl)-α-l-rhamnopyranoside, quercetin-3-O-(3″,4″-di-O-galloyl)-α-l-rhamnopyranoside, and quercetin-3-O-(2″,3″,4″-tri-O-galloyl)-α-l-rhamnopyranoside, together with five known galloylated and non-galloylated flavonol rhamnosides, were isolated from leaves of Calliandra tergemina (L.) Benth. Their structures were established using spectroscopic methods and their antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA) were evaluated by a microdilution method.

Fulltext Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

Chew YL, Chan EW, Tan PL, Lim YY, Stanslas J, Goh JK

BMC Complement Altern Med, 2011;11:12.

PMID: 21306653 DOI: 10.1186/1472-6882-11-12

Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family.

Impact of glaucoma severity and laterality on vision-specific functioning: the Singapore Malay eye study

Chan EW, Chiang PP, Wong TY, Saw SM, Loon SC, Aung T, et al.

Invest Ophthalmol Vis Sci, 2013 Feb;54(2):1169-75.

PMID: 23341009 DOI: 10.1167/iovs.12-10258

We determined the impact of glaucoma severity and laterality on vision-specific functioning (VF) in an Asian population.

Isoprenyl caffeate, a major compound in manuka propolis, is a quorum-sensing inhibitor in Chromobacterium violaceum

Gemiarto AT, Ninyio NN, Lee SW, Logis J, Fatima A, Chan EW, et al.

Antonie Van Leeuwenhoek, 2015 Aug;108(2):491-504.

PMID: 26059863 DOI: 10.1007/s10482-015-0503-6

The emergence of antibiotic-resistant bacterial pathogens, especially Gram-negative bacteria, has driven investigations into suppressing bacterial virulence via quorum sensing (QS) inhibition strategies instead of bactericidal and bacteriostatic approaches. Here, we investigated several bee products for potential compound(s) that exhibit significant QS inhibitory (QSI) properties at the phenotypic and molecular levels in Chromobacterium violaceum ATCC 12472 as a model organism. Manuka propolis produced the strongest violacein inhibition on C. violaceum lawn agar, while bee pollen had no detectable QSI activity and honey had bactericidal activity. Fractionated manuka propolis (pooled fraction 5 or PF5) exhibited the largest violacein inhibition zone (24.5 ± 2.5 mm) at 1 mg dry weight per disc. In C. violaceum liquid cultures, at least 450 µg/ml of manuka propolis PF5 completely inhibited violacein production. Gene expression studies of the vioABCDE operon, involved in violacein biosynthesis, showed significant (≥two-fold) down-regulation of vioA, vioD and vioE in response to manuka propolis PF5. A potential QSI compound identified in manuka propolis PF5 is a hydroxycinnamic acid-derivative, isoprenyl caffeate, with a [M-H] of 247. Complete violacein inhibition in C. violaceum liquid cultures was achieved with at least 50 µg/ml of commercial isoprenyl caffeate. In silico docking experiments suggest that isoprenyl caffeate may act as an inhibitor of the violacein biosynthetic pathway by acting as a competitor for the FAD-binding pockets of VioD and VioA. Further studies on these compounds are warranted toward the development of anti-pathogenic drugs as adjuvants to conventional antibiotic treatments, especially in antibiotic-resistant bacterial infections.

Fulltext Garcinia subelliptica Merr. (Fukugi): A multipurpose coastal tree with promising medicinal properties

Inoue T, Kainuma M, Baba K, Oshiro N, Kimura N, Chan EW

J Intercult Ethnopharmacol, 2017 Jan 3;6(1):121-127.

PMID: 28163970 DOI: 10.5455/jice.20161229060034

In this short review, the current knowledge on the botany, ecology, uses, and medicinal properties of the multipurpose Garcinia subelliptica (Fukugi) is updated. As yet, there are no reviews on this indigenous and heritage coastal tree species of the Ryukyu Islands in Japan, which has ethnocultural, ecological, and pharmacological significance. Planted by the Okinawan people some 300 years ago, Fukugi trees serve as windbreaks and accord protection against the destructive typhoons. The species has become a popular ornamental tree, and its bark has been used for dyeing fabrics. It forms part of the food chain for mammals and insects and serves as nesting sites for birds. Endowed with bioactive compounds of benzophenones, xanthones, biflavonoids, and triterpenoids, G. subelliptica possesses anticancer, anti-inflammatory, anti-tyrosinase, trypanocidal, antibacterial, DNA topoisomerase inhibitory, DNA strand scission, choline acetyltransferase enhancing, hypoxia-inducible factor-1 inhibitory, and antiandrogenic activities. Fukugetin and fukugiside are two novel biflavonoids named after the species. The chemical constituents of Fukugi fruits when compared with those of mangosteen yielded interesting contrasts.

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