Medicinal uses, chemistry and pharmacology of Dillenia species (Dilleniaceae)

1. Introduction

The genus Dillenia belongs to the Dilleniaceae family and contains approximately 100 known species (Lim, 2012). According to The Plant List (2013), as many as 175 scientific plant names from the genus Dillenia have been recorded with 58 accepted names (low and medium confidence levels) and 71 names of synonym species.
The name Dillenia is derived from Joannes Jacobus Dillenius, a British botanist who dedicated his efforts in the field of taxonomy of this genus (Quattrocchi, 2012). Dillenia species are monoecious plants which produce attractive flowers and yellow fruits. D. indica is known for its lemon-flavored fruits that are use to make jellies and curries. These species are evergreen and deciduous trees or shrubs of disjunct distribution in the seasonal tropics of Madagascar through South and South East Asia, North Australia, and Fiji (Dickison, 1979; Horn, 2007; Kerrigan et al., 2011; Lim, 2012). They grow from sea level to an elevation of about 2000 m. The plants also grow in forests, and several species show an adaptation to temporary flooded situations. They are mostly trees that form large leaves and flowers in few-flowered inflorescences (Dickison, 1979). Their barks are unique in fine colors of red, grayish, and reddish brown that are used in furniture making (Hoogland, 1952). Several species of this genus produce sweetishsour and astringent edible fruits (Hoogland, 1952; Jansen et al.,
1992; Kerrigan et al., 2011; Lim, 2012; Saha and Sundriyal, 2012) and are cultivated as ornamental plants (Hoogland, 1952; Kerrigan et al., 2011).
Based on our extensive search regarding medicinal uses, chemical constituents, and biological activities of the species from the genus Dillenia, only very few species have been described thus far. Starting from 1962 to the present, 19 species of the genus Dillenia have been reported for their medicinal uses and their phytochemistry. These 19 species are Dillenia andamanica C.E.Parkinson, D. aurea Sm., D. bracteata Wight, D. excelsa (Jack) Martelli ex Gilg., D. indica L., D. ovata Wall. ex Hook.f. & Thomson, D. papuana Martelli, D. parviflora Griff., D. pentagyna Roxb., D. philippinensis
Rolfe, D. pulchella (Jack) Gilg., D. reticulata King, D. retusa Thunb., D. scabrella (D.Don) Roxb. exWall., D. eximia Miq., D. serrata Thunb., D. suffruticosa (Griff.) Martelli, D. sumatrana Miq., and D. triquetra (Rottb.) Gilg. However, out of these, only 7 species have been evaluated for their biological activities. As part of our search for natural anti-inflammatory compounds, three triterpenes have been isolated from D. serrata and they performed pronounced inhibitory activity on the production of prostaglandin E2, which is known as a predominant inflammatory mediator (Jalil et al., 2015). This review describes the current state of their medicinal properties, chemistry, and pharmacological aspects.

4.1. Antimicrobial activity

Some of Dillenia species were investigated for antibacterial, antifungal, and antiviral activities. The extracts and fractions of D. indica, D. papuana, D. pentagyna, D. suffruticosa, and D. sumatrana were reported to possess growth inhibition against Gram positive and negative bacteria (Table 5). However, they were found to exhibit weak growth inhibition against tested fungi, including Aspergillus fumigatus, A. niger, Candida albicans, C. arriza, C. crusei, Penicillium sp., Rhizopus oryzae, Saccharomyces cerevisiae, and Trichoderma viride (Nick et al., 1995a; Wiart et al., 2004; Haque et al., 2008; Apu et al., 2010; Smitha et al., 2012). Seven triterpenoids (37, 42e45 and 47e48) from Dillenia plants were proven to have antimicrobial action (Nick et al., 1994, 1995b; Ragasa et al., 2009).

Strong growth inhibition against Escherichia coli and Bacillus subtilis has been shown by 45 that was assayed using the bioautographic method on TLC plate. Meanwhile, 48 was the most active against the growth of Micrococcus luteus (Nick et al., 1995b). Similar pronounce growth inhibition of 48 also reported towards E. coli, Pseudomonas aeruginosa, Staphylococcus aureus, and B. subtilis (Ragasa et al., 2009). These findings suggested that Dillenia plants traditional uses for the therapeutic remedies of microbial infectionrelated diseases such as diarrhea, dysentery, septicaemical infection and skin-related diseases had a potential as antimicrobial agent, which supported their traditional uses for the therapeutic remedies of microbial infectionrelated diseases such as diarrhea, dysentery, septicaemical infection and skin-related diseases

Antibacterial and antifungal

The leaves extract inhibited the growth of B. cereus, B. subtilis, P. aeruginosa, and C. albicans with zones ranging from 7 to 9 at 1 mg/disc as compared to gentamycin (10 mg/disc; 18e20 mm for B. cereus, B. subtilis, P. aeruginosa) and nystatin (20 mg/disc; 11 mm for C. albicans).