Zushang Su

Phytochemical Constituents and Pharmacological Activities of Eryngium L. (Apiaceae)

Eryngium L. is the largest and arguably the most taxonomically complex genus of the family Apiaceae. The genus has approximately 250 species throughout the world, with the center of diversity in South America. Some Eryngium species are cultivated as ornamental, vegetable, or medicinal crops for folk uses. With increasing chemical and biological investigations, Eryngium has shown its potential as pharmaceutical crops. This review focuses on phytochemistry and pharmacological activities of 127 compounds isolated and identified from 23 species of Eryngium, particularly non- essential oil compounds such as terpenoids, triterpenoid saponins, flavonoids, coumarins, polyacetylenes, and steroids. Eryngium extracts or isolates have shown in vitro bioactivitities such as cytotoxicity against various human tumor cell lines, anti-inflammatory, anti-snake and scorpion venoms, antibacterial, antifungal, and antimalarial, antioxidant, and an- tihyperglycemic effects. In vivo studies through various animal models have also shown promising results. However, chemical constituents and their bioactivities of most species of this highly diversified genus have not been investigated. The molecular mechanism of bioactivities (particularly cytotoxicity and anti-snake and scorpion venoms) of Eryngium isolates remains elusive. Also, anti-tumor activity of polyhydroxylated triterpenoid saponins isolated from Eryngium needed to be furthur explored.

Cytotoxic compounds from invasive giant salvinia (Salvinia molesta) against human tumor cells.

Giant salvinia (Salvinia molesta) is one of the most noxious invasive species in the world. Our bioactivity-guided fractionation of ethanol extract of giant salvinia led to the isolation of 50 compounds. Of the six new compounds (1-6), salviniol (1) is a rare abietane diterpene with a new ferruginol-menthol coupled skeleton and both salviniside I (2) and salviniside II (3) are novel benzofuran glucose conjugates with unique 10-membered macrodiolide structures. Sixteen abietane diterpenes (1, 7-17, and 19-22) demonstrated in vitro activities against human tumor cells, and 7 and 8 showed selective cytotoxicity to tumor cells over normal cells.

Cytotoxic triterpenoid saponins from husks of Aesculus californica (Spach) Nutt.

Fifteen polyhydroxyoleanene saponins, aesculiosides C1-C15 (1-15), were isolated from husks of Aesculus californica. Their structures were established by extensive spectroscopic and chemical analyses. The triterpenoid saponins from A. californica have greater structural diversity than those from any other investigated species thus far in the genus Aesculus. The chemotaxonomic characteristic of aesculiosides C1-C15 is that the unit attached to the C-3 of the aglycone is a glucopyranosyl moiety, instead of a glucuronopyranosyl group in the saponins that have been isolated from other Aesculus species. The saponins isolated from A. californica then provide important evolutionary and chemotaxonomic knowledge of the Aesculus genus, a well-known intercontinental disjunct genus in the Northern hemisphere. Aesculiosides C1-C15 (1-15) showed cytotoxicity to human non-small cell lung tumor (A549) with GI50 ranged from 3.76 to >25μM.

Flavonoids and 3-arylcoumarin from Pterocarpus soyauxii.

Phytochemical study on the constituents of the heartwood of Pterocarpus soyauxii led to the isolation of five new isoflavonoids and one new 3-arylcoumarin, pterosonins A-F (1-6), together with 17 known analogues, among which 8, 9, and 18 were reported as natural products for the first time. Structure elucidation was achieved by way of spectroscopic measurements as well as by comparison with literature data. Only Compound 6 showed potent cytotoxicity against human non-small cell lung cancer (A549), pancreatic cancer (Panc-28), and colon carcinoma (HCT-116) cells with GI50 values at 7.39, 25, and 19.17 µM, respectively; the other isolates showed no cytotoxicity against the above tested cell lines with GI50 values > 50 µM.

Ethnobotany, Phytochemistry, and Biological Activities of Taxodium Rich.

Taxodium Rich. is a genus of the family Cupressaceae. The trees are especially prized for their rot and termite resistant wood. Taxodium leaves and cones, which are particularly rich in essential oils were used as folk medicine to treat skin, gastro-intestinal, respiratory, inflammation, and infections. Preliminary bioactivity assays reported antimicrobial, an- titumor, antitermitic, antispasmodic and bronchodilator activities of the extracts or isolates from Taxodium but further pharmacological investigations of bioactive compounds are not available. To data, at least 130 compounds have been identified from extant or fossil Taxodium. Fifty-seven compounds have been isolated primarily from the cones, leaves, and branches of extant Taxodium, with diterpenoids and flavonoids as the major components. At least three major abie- tane diterpenoids (sugiol (1), ferruginol (2), and 6,7-dehydroferruginol (3)) are also identified in the fossil Taxodium by GC/MS. The diterpenoids may be important marker compounds for understanding the evolution of the genus Taxodium. However, the taxonomy and evolutionary pattern of Taxodium remains elusive until a full understanding of the chemical constituents of all Taxodium taxa is determined.

Germplasm, chemical constituents, biological activities, utilization, and control of Chinese tallow (Triadica sebifera (L.) Small)

Chinese tallow (Triadica sebifera, also known as Sapium sebiferum) is an important oil seed crop in its native China but has become a noxious invasive species in USA. This review covers 601 publications since 1946. To date, grape (var. conferticarpa), chicken claw (var. laxiarpa), long claw, and mixed types are recognized within the species with 77 compounds isolated from various tissues. Some of the known 13 tetracyclic diterpenoids or phorbols showed pro-inflammatory and skin irritant activities or antibacterial and antiviral activities. In contrast, leaf extracts of T. sebifera showed analgesic and anti-inflammatory activities in animal models. Tallow leaves have been used to treated bacterial infections in birds and fish in China and also showed molluscicidal activities. Seed fats and oils have a long history of uses in China. The seed aril has been used to produce Chinese tallow cocoa butter equivalent since the late 1980s, but product quality and cost need improvement. The kernel oil showed promising potential for biodiesel production. In USA, the plantings were well developed before the mid-1900s since it introduced in 1772. The tree spread quickly in the southeastern USA due to its high fertility, fast growth and broad adaptability, lack of natural enemies, increasing habitat fragmentation, disturbance events like hurricanes, and selection and development of superior high-seed yield cultivars/clones. It is now considered as one of the worst invasive species in the area. Its conventional herbicide, biological, and mechanical control methods are costly, and either largely ineffective or not environmental friendly.

Endocidal Regulation of Secondary Metabolites in the Producing Organisms.

Secondary metabolites are defined as organic compounds that are not directly involved in the normal growth, development, and reproduction of an organism. They are widely believed to be responsible for interactions between the producing organism and its environment, with the producer avoiding their toxicities. In our experiments, however, none of the randomly selected 44 species representing different groups of plants and insects can avoid autotoxicity by its endogenous metabolites once made available. We coined the term endocides (endogenous biocides) to describe such metabolites that can poison or inhibit the parent via induced biosynthesis or external applications. Dosage-dependent endocides can selectively induce morphological mutations in the parent organism (e.g., shrubbiness/dwarfism, pleiocotyly, abnormal leaf morphogenesis, disturbed phyllotaxis, fasciated stems, and variegation in plants), inhibit its growth, development, and reproduction and cause death than non-closely related species. The propagule, as well as the organism itself contains or produces adequate endocides to kill itself.

Endocide-Induced Abnormal Growth Forms of Invasive Giant Salvinia ( Salvinia molesta )

Giant salvinia (Salvinia molesta) is one of the most noxious invasive species in the world. The fern is known to have primary, secondary, and tertiary growth forms, which are also commonly hypothesized as growth stages. The identification of these forms is primarily based on the size and folding status of the floating leaves. However, we identified 12 forms in the greenhouse and the field. Our experiments showed that the folding of floating leaves is a reversible trait dependent on water access. The floating leaves quickly fold in response to water shortage, reducing water loss and needs, decreasing growth, and avoiding trichome damage. The leaves re-open to allow trichomes repel water and enhance growth when having adequate water supply. Larger secondary or tertiary forms do not produce small-leaf primary forms without high intensity stress. These results do not support the hypothesis that three growth forms represent sequential growth stages. The abnormal small-leaf forms are the result of endocide-induced autotoxicity and some of them never grow into other forms. The development of abnormal forms and reversible leaf folding strategy in response to high stress along with rapid asexual reproduction are major adaptive traits contributing to the invasiveness of S. molesta.