Euphorbia officinarum L. is a Moroccan endemic plant known as “Tikiout” and “Daghmus” that can also be found in Mauritania, Western Sahara, and Algeria. This species has been used in folk medicine as anti-diabetic; in the treatment of skin diseases when associated with Opuntia ficus-barbarica, Zea mays and Ziziphus lotus, and honey for eliminating helminths, in the treatment of pyelonephritis and cystitis. Triterpenes, phytosterols and ingol diterpenes have been isolated and identified in the latex of Moroccan E. officinarum, nevertheless the biggest interest has been to obtain derivatives by hemisynthesis from natural triterpenes with insecticidal and antimicrobial activity. In Morocco, the E. officinarum honey is considered the most precious; nevertheless, many times it is mixed with other Euphorbiaceae honeys. To increase the commercial value of a monofloral E. officinarum honey, it would be important to find one or more specific markers for this type of honey to be sure of its authenticity.
The succulent plants of the genus Euphorbia are the largest in the spurge family, which can be found in Africa, Canary Islands, in Madagascar, India, and the Americas and even Australia [1]. Euphorbia officinarum L., a Moroccan endemic plant, can be found in Mauritania, Western Sahara, and Algeria [1]. This species has milky white latex, which chemical characterization has been done as well as their biological attributes [2]. The term Euphorbia was named in honour of “Euphorbus”, the physician of King Juba II of Mauritania, who paid attention to the medicinal properties of E. officinarum, for the first time [3]. There is one infra-specific taxon of the species Euphorbia officinarum L (E. officinarum subsp. echinus (Hook.f. & Coss.) Vindt) [4].
From olden times that the milky sap of E. officinarum has been used in earache and as emetic in Buxar district, India [5], although this utilization as emetic has already been considered outdated [6]. In different regions of Morocco, E. officinarum subsp. echinus has been used in folk medicine particularly as anti-diabetic [7][8][9][10][11][7-11]. E. officinarum L. is also used as anti-diabetic, according to different authors [10][11][12][13][10–13]. Other applications of this species as well as its subsp echinus include treatment of pyelonephritis and cystitis, when in association with Opuntia ficus-barbarica, Zea mays and Ziziphus lotus) and honey [14]; treatment of wounds, skin infections and abscesses [15][16][17][18][16–18] and by the Sahrawi refugees in Algerian refugee camps [19]; elimination of helminths [18]; treatment of cancer, although not specifying which type [16][20][21][16,20,21]; for respiratory and circulatory systems [22], and as gum-resin for headache, paralysis and apoplexy [23], although an ethnobotanical study made by Blanco and Carrière [24] showed that this species was weakly cited by the informants. E. officinarum subsp. echinus aerial parts may also be chopped and cooked as a vegetable salad [25][26][25,26], despite its relative high toxicity [2].
2. Secondary Metabolites Isolated from
L. of Morocco
In the last century, the authors [27][28][29][27-29] isolated from the extracts of the latex of E. officinarum, collected in the North Atlantic coast of Agadir (Morocco), the triterpenic compounds lupeol (1) and lupeol acetate (2)), and seven steroidal compounds (lanostenol (3), lanosterol (4), 24-methylene lanostenol (5), 4α,14α-dimethyl-24-methylen-5α-cholest-8-en-3β-ol or obtusifoliol (6), 24(R)-4α,14α,24-trimethyl-5α-cholesta-8,25-dien-3-β-ol (7), 4α,14α-dimethyl-5α-cholest-8,24-dien- 3β-ol (8), and 4α,14α-dimethyl-5 α-cholest-8-en-3-β-ol (9), 3,7-dihydroxy-4,14-dimethyl-5-cholest-8-en-11-one (10) and 3,7-dihydroxy-4,14-dimethyl-5-ergost-8-en-11-one (11) (Figure 1). In the 90s and from the same region, some authors [28][29][28, 29] isolated more 2 new steroidal compounds:
Figure 1.
Triterpenic (
1
and
2
) and steroid compounds isolated and identified in the Moroccan latex of
Euphorbia officinarum
.
More recently, Daoubi et al. [2] isolated and identified the highly functionalized ingol diterpenes ingol 7,8,12-triacetate 3-phenylacetate) (1), ingol 7,8,12-triacetate 3-(4-methoxyphenyl) acetate (2) and 8-methoxyingol 7,12-diacetate 3-phenylacetate (3) (Figure 2), along with the novel spirotriterpene 3S,4S,5R,7S,9R,14R-3,7-dihydroxy-4,14-dimethyl-7[8→9]-abeo-cholestan-8-one (4) (Figure 2), in samples also collected in the North Atlantic coast of Agadir (Morocco).
Figure 2.
Phenylacetylingol derivatives (
1
-
3
) and spirotriterpenoid (
4
) isolated from the methanolic extract of
E. officinarum
latex.
3. Hemisynthesis of Triterpene Derivatives Isolated from
Latex and Their Biological Properties
The biological properties (cytotoxic, antimicrobial, human immunodeficiency virus type 1 reactivation, among others) found in latex or some of their isolated compounds of Euphorbia species [1][2][30][31][32][33][1,2,30–33] have led chemical modifications to obtain derivative compounds with enhanced biological properties. For example, Mazoir et al. and other authors (see below) published several works in order to obtain triterpenic or steroidal derivatives that show good biological activities (Table 1) (Figure 3).
Table 1. Triterpene and steroidal derivatives obtained by hemisynthesis and their biological properties.
Table 1. Triterpene and steroidal derivatives obtained by hemisynthesis and their biological properties
Start compounds |
Reagents |
Final product |
Biological properties |
References |
24-Methylene lanostenol |
Chromic anhydride, acetone |
(3S)-Acetyl-24-methyl-elemo-lanosta -8,24-diene-7,11-dione (1) |
ND |
[34] |
3(S)-Tosyl-24-methylene lanostenol |
(3S)-Tosyl-24-methyl-elemo-lanosta-8,24-diene-7,11-dione (2) |
ND |
[35] |
|
Eupho-lanosta-8,24-dien-3-ol |
Ruthenium(III) chloride trihydrate, esterification, acetylation reactions |
(3S,5S,10S,13S,14S,17S)-Methyl-3-acetyl-25,26,27-trisnorlanost-8-en-24-oate (3) |
ND |
[29] |
(6, Fig.1) |
Chromic anhydride, acetone |
4,14-Dimethyl-5-ergost-8,24-dien-3-one (4) |
ND |
[36] |
(9, Fig.1) |
Chromic anhydride, acetone |
4,14-Dimethyl-5-cholest-8-en-3-one (5) |
ND |
[36] |
(4) |
Ethyl formate, benzene, sodium methoxide |
2-Formyl-4α,14α-dimethyl-5α-ergost-2,8,24-trien-3-ol (6) |
ND |
[36] |
(5) |
Ethyl formate, benzene, sodium methoxide |
2-Formyl-4α,14α-dimethyl-5α-cholesta-2,8-dien-3-ol (7) |
ND |
[36] |
(6) |
Acetic acid, hydroxylamine hydrochloride |
[1,2]Isoxazolo [4,3-]-4α,14α-dimethyl-5α-ergosta-8,24-diene (8) |
ND |
[36] |
(6) |
Pyridine, hydroxylamine hydrochloride |
[1,2]Isoxazolo [4,5-]-4α,14α-dimethyl-5α-ergosta-8,24-diene (9) |
ND |
[36] |
(7) |
Acetic acid, hydroxylamine hydrochloride |
[1,2]isoxazolo [4,3-b]-4α,14α-dimethyl-5α-cholesta-8-ene (10) |
ND |
[36] |
(7) |
Pyridine, hydroxylamine hydrochloride |
[1,2]isoxazolo [4,5-b]-4α,14α-dimethyl-5α-cholest-8-ene (11) |
ND |
[36] |
3-Tosyl-5-ergost-8,24-diene |
Ruthenium trichloride, allylic oxydation with chromic anhydride |
(3S,4S,5S,10S,13R,14R,17R)-4,14-Dimethyl-3-tosyl-5--ergost-8-ene-7,11,24-trione (12) |
ND |
[37] |
4,14-Dimethyl-5-cholest-8-en-3-ol (9, Fig.1) |
Chromic anhydride, meta-chloroperbenzoic acid (mCPBA) |
(4S,5S,10S,13R,14R,17R)-8,9-Epoxy-4,14-dimethyl-5-cholestan-3-one (13) |
ND |
[38] |
8,9-Epoxy-4,14-Dimethyl-5-cholestan-3-ol (14) |
Chromic anhydride |
(13) |
ND |
[39] |
(9, Fig.1) (5) |
Chromic anhydride Thiosemicarbazide in ethanol, concentrated sulphuric acid |
(5) thiosemicarbazone derivative (15) |
ND ND |
[40] |
(9, Fig.1) |
Acylation Oxidation |
3-Acetoxy-4,14-dimethyl-5-cholest-8-en-7-one (16) 3-Acetoxy-4,14-dimethyl-5-cholest-8-ene-7,11-dione (17) |
ND |
[39] |
(9, Fig.1) |
Tosyl chloride |
3-Tosyloxy-4,14-dimethyl-5-cholest-8-en-7-one (18) 3-tosyloxy-4,14-dimethyl-5-cholest-8-ene-7,11-dione (19) |
ND |
[39] |
(9, Fig.1) |
Chromic anhydride in acetone at 273 K, phenylhydrazine, acetic acid |
1-(1,5-Dimethylhexyl)-3a,5b,12a,14a-tetramethyl-2,3,3a,4,5,5a,5b,11,12,13,14, 14a-dodecahydro-1H,12aH-cyclopenta[1,2]-phenanthro[7,8-b]indole (20) |
ND |
[41] |
4-14-Dimethyl-5-ergost-8-en-3-ol |
Tosylation |
3-Tosyloxy-4,14-dimethyl-5-ergost-8-en-24-one (21) |
ND |
[39]
[39] |
(21) |
Oxidation |
3-Tosyloxy-4,14-dimethyl-5-ergost-8-ene-7,24-dione (22) 3-Tosyloxy-4,14-dimethyl-5-ergost-8-ene-7,11,24-trione (23) |
ND |
[38]
[39] |
Eupho-lanosta-8,24-dien-3-ol |
Sodium periodate-ruthenium (III), chloride trihydrate (NaIO4-(RuCl3,3H2O)), esterification, acetylation |
(3S,5S,10S,13S,14S,17S)3-acetyl-25,26,27-Trisnorlanost-8-en-24-oate (24) |
ND |
[31] |
(6 and 9, Fig.1) |
Modifications on positions 3,7, 11 and 24 |
(21), (4), (17), (19), -Tosyloxy-4,14-dimethyl-5-cholest-8-ene (25), 4,14-dimethyl-5-ergost-8-en-3,24-dione (26), 4,14-dimethyl-5-cholest-8-en-3,11-dione-7-thiosemicarbazone (27), 4,14-dimethyl-5-cholest-8-ene-3,11-dione-7-thiadiazoline (28), 4,14-dimethyl-5-cholesta-7,9-diene-3-thiosemicarbazone (29), 4,14-dimethyl-5-cholest-8-ene-7,11-dione-3-thiadiazoline (30) |
- (9, Fig.1), (19), (26), (27) active in relation to Myzus persicae; (9, Fig.1), (17), (4) active in relation to Rhopalosiphum padi, -Insect cells Sf9 were more sensitive to terpene derivatives than mammalian CHO cells. - (28), (17), (26), (4), and (27) showed better activities on Leishmania infantum promastigotes with ED50 (the effective dose to give 50% cell viability) < 10 g/mL, regarding Trypanosoma cruzi only (26), (27) and (28) had ED50 < 10 g/mL |
|
(4), (5), ( (13), (19), 3-Acetoxy-30-nor-20-oxolupane (31), 4α,14α-dimethy-l-5α-cholest-8-ene-3,7,11-trione (32) |
Thiosemicarbazide, oxidation by chromic anhydride Thiosemicarbazone, pyridine, acetic anhydride |
(29), 4,14-Dimethyl-5-ergost-8,24-dien-3-one thiosemicarbazone (33), 4,14-dimethyl-5-cholest-8-en-3-one thiosemicarbazone (34), 3β-acetoxy-28-norlup-20-one thiosemicarbazone (35), 3-tosyloxy-4,14-dimethyl-5-cholest-8-ene-7,11-dione-7-thiosemicarbazone (36), 4α,14α-dimethyl-5α-cholest-8-ene-3,7,11-trione-7-thiosemicarbazone (37) 4,14-dimethyl-5-ergost-8,24-dien-3-one thiadiazoline (38), 4,14-dimethyl-5-cholest-8-en-3-one thiadiazoline (39), 4,14-dimethyl-5-cholest-7,9-diene-3-one thiadiazoline (40), 3-acetoxy-28-Norlup-20-one thiadiazoline (41), 3-tosyloxy-4,14-dimethyl-5-cholest-8-ene-7,11-dione-7-thiadiazoline (42), 4,14-dimethyl-5-cholest-8-ene-3,7,11-trione-7-thiadiazoline (43) |
ND ND |
[45] |
(9, Fig.1) |
Acetone, chromic anhydride, (mCPBA) Tosylation Lithium aluminium hydride (LiAlH4), tetrahydrofuran (THF) Sodium methoxide (MeONa)/methanol These reagents were used depending on the final product desired |
4α,14α-Dimethyl-5α-cholest-7,9-dien-3β-ol (44), 3-chloro-4α,14α-dimethyl-5α-cholest-8-en-7-one (45), 2-carbomethoxy-4α,14α-dimethyl-5α-cholest-2,8-dien-3-ol (46), 4α,14α-dimethyl-5α-cholest-8-en-3-one (47), 4α,14α-dimethyl-7-oxo-5α-cholest-8-en-3,4-lactone (48), 4α,14α-dimethyl-7,11-dioxo-5α-cholest-8-en-3,4-lactone (49), 8α,9α-epoxy-4α,14α-dimethyl-5α-cholest-3,4-lactone (50), 4α,14α-dimethyl-5α-cholest-7,9-dien-3,4-lactone (51), 4α,14α-dimethyl-3,4-seco-5α-cholest-7,9-dien-3,4-diol (52), 3-carbomethoxy-4-hydroxy-4α,14α-dimethyl-3,4-seco-5α-cholest-7,9-diene (53) |
- (53) was the strongest antiparasitic with activity levels similar to or better than the reference drugs against L. infantum and T. cruzi, respectively - (53) and (14) had the strongest cytotoxic effects on insect-derived Sf9 cells and not cytotoxic to mammalian CHO cells |
[46] |
(6, Fig.1) |
Acetone, chromic anhydride, meta-Chloroperoxybenzoic acid (mCPBA |
8α,9α,24,28-Diepoxy-4α,14α-dimethyl-5α-ergosta-3,4-lactone (54), 8α,9α,24,28-diepoxy-4α,14α-dimethyl-5α-ergost-3β-ol (55) |
[46] |
|
4α,14-dimethyl-5α,8α-8,9-epoxycholestan-3β-yl acetate (56), (32), 4α,14-dimethyl-5α-cholesta-7,9-dien-3-one (57), 4α,14-dimethyl-5α-cholest-8-en-3β-yl acetate (58) |
Hydrogen peroxide (H2O2), iodosobenzene (PhIO) catalyzed by porphyrin complexes (cytochrome P-450 models) |
25-Hydroxy-4α,14-dimethyl-5α-cholest-7,9-dien-3β-yl acetate (59), 25-hydroxy-4α,14-dimethyl-5α-cholest-8-ene3,7,11-trione (60), 4α,14-dimethyl-5α,7β-7,8-epoxychol-est-9-en-3-one (61), 8-hydroxy-4α,14-dimethyl-5α-cholest-9-ene-3,7-dione (62), 12α-hydroxy-4α,14-dimethyl-5α,7β-7,8-epoxycholest-9-en-3-one (63), 4α,14-dimethyl-5α,8α-8,9-epoxycholestan-3β-yl acetate (64), |
- None of the compounds tested had significant antifeedant effects for the insects M. persicae, R. padi and S. littoralis. - All were more effective post-ingestive toxicants on Spodoptera littoralis larvae than the natural (9, Fig.1), (64) was the most active |
[47] |
(2 and 9, Fig.1) |
Sodium periodate, ruthenium trichloride, tosyl chloride, pyridine / 70 ºC |
(31), 3-chloro-4α,14α-dimethyl-5α-cholest-8-ene (64) |
- They act as fungistatic reducing in vitro the conidia formation and germination of Verticillium dahlia, and Fusarium oxysporum fsp. melonis, and Penicillium expansum, - (64) more effective in inhibiting the growth of Penicillium syringae pv. tabaci and P. syringae pv. syringae, even being similar to the positive control (chloramphenicol). - (64) showed antibacterial activity on Erwinia amylovora but at a moderate level and significantly lower than the positive control |
[48] |
(9, Fig.1) |
m-CPBA + HCl TsCl + m-CPBA + HCl |
(44), 3-Tosyloxy-4,14-dimethyl-5-cholest-7,9-diene (65) |
- (65) able to protect tomato plants against Verticillium dahliae in a greenhouse, significantly reducing disease severity at 10 g/mL. (65) able to elicit H2O2 accumulation before and after fungal inoculation, and enhance peroxidase and polyphenol oxidase activities |
[49] |
(1 and 9, Fig.1) |
Sodium periodate, ruthenium trichloride, tosyl chloride, pyridine/70 ºC |
(31), (64) |
- Seeds of Nicotiana benthamiana treated with (31) and (64) and in the presence of P. syringae pv. tabaci did not harm germination and significantly reduced the diameter of the lesions in inoculated leaves, - (31) and (64) significantly reduced bacterial growth in plants, - Mock-inoculated leaves of plants that germinated in the presence of (31) and (64) showed enhanced ascorbate peroxidase and catalase activities. - Inoculated plants with P. syringae pv. tabaci previously treated with (31) and (64) made increase guaiacol peroxidase and polyphenol oxidase activities. |
[50] |
(1 and 9, Fig.1) |
Sodium periodate, ruthenium trichloride, tosyl chloride, pyridine/70 ºC |
(31), (64) |
Direct application of (31) and (64) on tomato seedlings significantly improved growth rate, leaf area, an increased content of chlorophylls, carotenoids, proline, and the activity of nitrate reductase, - (64) reduced leaf alteration indexes and the browning index of the vessels of tomato seedlings, induced by V. dahliae and Agrobacterium tumefaciens - pre-treatment with (31) and (64) reduced the diameter of lesions caused by the oncogenic strain C58 of A. tumefaciens , - (31) and (64) induced H2O2 accumulation and increased the activity of catalase, ascorbate peroxidase, and guaiacol peroxidase |
[51] |
ND: Not determined
Figure 4. Triterpene derivatives obtained from natural triterpenes isolated from E. officinarum latex. Compounds 66, 67 and 68 according to the structures presented in Figure 9 of Daoui et al. [52].
4. Extracts and Bee Products from
Origin
So far, the antimicrobial and insecticidal activities of triterpene derivatives from E. offcinarum latex have been greatly evaluated. Nevertheless, some works start to approach other attributes of E. officinarum extracts [2][33][53][54][2, 33, 53, 54] and bee products [55][56][55, 56]. In Morocco the Euphorbia honey is considered valuable but it has been scarcely studied, although the physico-chemical and palynological characteristics have already been reported [55][57][58][59][60][55, 57–60]. Generally, in the monofloral honey of Euphorbia origin, there is no specification of which species will be predominant, although three honey types of this genus can be produced (E. officinarum subsp. echinus, E. resinifera, and E. regis-jubae) [52][61][52,61]. Abderrahim et al. [62] demonstrated the antioxidant, synergistic antimicrobial and burn wound healing activities of monofloral honey of Euphorbia origin (the specification of the species is not provided) mixed with Allium sativum. Another beeproduct is propolis. The detailed chemical composition and antimicrobial activity of this natural product were evaluated by Chimshirova et al.[63] [63]. Fifteen compounds were isolated and identified, some of them being already reported as constituents of plants in the genus Euphorbia, such as the macrocyclic diterpenes and triterpenoids, and other groups of known compounds (e.g., coumarins, phenolic acids), and new ones (e.g., 29-norlanost-3-hydroxy-8-ene-7,11-dione). The ingol diterpenes found in propolis were those isomers characteristic of the E. resinifera latex. Such results may indicate the utilization of latex of E. resinifera by bees for making propolis, but also from E. officinarum, since obtusifoliol is generally present in the E. officinarum latex [56].
References