Investigations of molluscicidal saponins from the Endod plant Phytolacca dodecandra

Triterpenoid and Saponin Rich Phytolacca dodecandra L'Herit (Endod): A Review on Its Phytochemistry and Pharmacological Properties

Phytolacca dodecandra L'Herit (Endod) is the most extensively studied plant among 35 known species in the genus Phytolacca (Family: Phytolaccaceae). The plant has been used as a viable treatment for various ailments, such as malaria, rabies, ascariasis, and skin disorders, in many parts of Africa. In Ethiopia, the dried and powdered Endod berries have been used for a long period of time as a detergent to clean clothes. Since the discovery of the molluscicidal activities of its berries more than five decades ago, P. dodecandra has been a research focus worldwide and several phytochemicals mainly of triterpenoids and saponins were reported. Additionally, various biological activities, including larvicidal, insecticidal, antibacterial, antifungal, and anti-inflammatory activities of its isolated compounds and crude extracts were investigated. Furthermore, some of the findings from pharmacological and phytochemical investigations were patented to be used in various medicinal formulations. The plant is still the subject of many investigations and hence, a thorough up-to-date review is required to provide comprehensive information needed for future exploitation of the plant. In this review, the phytochemical compositions and pharmacological activities are comprehensively addressed and discussed in details.

Molluscicidal effectiveness of Luo-Wei, a novel plant-derived molluscicide, against Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus

BACKGROUND

Control of snail intermediate hosts has been proved to be a fast and efficient approach for interrupting the transmission of schistosomiasis. Some plant extracts have shown obvious molluscicidal activity, and a new compound Luo-Wei, also named tea-seed distilled saponin (TDS), was developed based on the saponins extracted from Camellia oleifera seeds. We aimed to test the molluscicidal activity of 4% TDS against the intermediate host snails in China and Egypt, and evaluate its environmental safety to non-target organisms.

METHODS

In the laboratory, Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus were exposed to 4% TDS, and the median lethal concentration (LC₅₀) was estimated at 24, 48 and 72 h. In the field, snail mortalities were assessed 1, 2, 3 and 7 d post-immersion with 2.5 g/m³ 4% TDS and 1, 3, 7 and 15 d post-spraying with 5 g/m² 4% TDS. In addition, the acute toxicity of 4% TDS to Japanese quail (Coturnix japonica), zebrafish (Brachydanio rerio) and freshwater shrimp (Macrobrachium nipponense) was assessed by estimations of LC₅₀ or median lethal dose (LD₅₀).

RESULTS

In the laboratory, the LC₅₀ values of 4% TDS for O. hupensis were 0.701, 0.371 and 0.33 mg/L at 24, 48 and 72 h, respectively, and 4% TDS showed a 1.975 mg/L [corrected] 24 h LC₅₀ against B. alexandrina, and a 1.396 mg/L 24 h LC₅₀ against B. truncatus. Across all study regions, the pooled mortalities of O. hupensis were 72, 86, 94 and 98% at 1, 2, 3 and 7 d, following field immersion of 4% TDS at a dose of 2.5 g/m³, and were 69, 77, 85 and 88% at 1, 3, 7 and 15 d, following field spraying at 5 g/m², respectively. 4% TDS had moderate toxicity to Japanese quail (7 d LD₅₀ > 60 mg/kg) and to shrimp (96 h LC₅₀ = 6.28 mg/L; 95% CI: 3.53-11.2 mg/L), whereas its toxicity to zebrafish was high (96 h LC₅₀ = 0.15 mg/L; 95% CI: 0.14-0.17 mg/L).

CONCLUSIONS

4% TDS is active against O. hupensis, B. alexandrina and B. truncatus under laboratory and field conditions, and it may be a candidate molluscicide of plant origin.