Faculty of Science, Department of Plant Biology, University of Yaounde I, Yaounde, Cameroon.
Department of Organic Chemistry, Faculty of Science, University of Yaounde 1, Yaounde, Cameroon.
Biotechnol Appl Biochem. 2021 Aug;68(4):938-947. doi: 10.1002/bab.2017. Epub 2020 Sep 21.
Vernonia species (Asteraceae) are indigenous medicinal and food leaf vegetables commonly consumed in some African countries like Cameroon where they constitute a staple dish called "ndolé." Previous studies have demonstrated the nutritional importance of Vernonia, but there is little knowledge of their agronomic value and genetic potentials. Wide genetic variability in the genus has been established earlier through the study of its pollen. However, to the best of our understanding, no such study has been undertaken on the genetic variability of Vernonia with respect to its secondary metabolites. This study was therefore aimed at evaluating the genetic variability of Vernonia amygdalina (VAA and VALF) and V. calvoana (VCAB, VCAV, VCSB, and VCSV) morphotypes in 2016 based on secondary metabolite content and antimicrobial properties. This involved phytochemical analysis by HPLC/MS for the detection of alkaloids, flavonoids, phenols, and tannins in leaves from each of the six genotypes. Results showed that all tested genotypes are rich in phenols (18 analyzed), flavonoids, and tannins with, VAA richer in phenols (206.1 ± 3.12 µg/g of dry extract), followed by VCAV (197.9 ± 18.03 µg/g). The lowest level of flavonoid was found in VCSV (81.6 ± 7.21 µg/g), while the highest was from VCAB (132.8 ± 31.5 µg/g). VCSV (56.3 ± 4.08 µg/g) had the lowest level of tannins, while VCAB (97.8 ± 23.8 µg/g) had the highest levels. Assessment of antimicrobial activity of leaf extracts from the six genotypes was done by culture on Mueller Hinton (MH) agar and MH broth agar for bacteria and in Sabouraud dextrose agar and Sabouraud dextrose broth media for fungi, respectively. All morphotypes exhibited inhibitory activity on bacteria except VAA, with isoquercetin characteristic of VCSV. Chemotaxonomic analyses of Vernonia morphotypes highlighted the genetic diversity within species and variability of antimicrobial properties of ethanolic leaf extracts among morphotypes. These results provide baseline data in the valuation of genetic resources and the establishment of improvement programs.
马缨丹属（菊科）是原产于非洲国家的药用和食用叶菜，其中一些国家如喀麦隆将其作为一种主食，称为“ndolé”。先前的研究已经证明了马缨丹属的营养价值，但对其农业价值和遗传潜力的了解甚少。早些时候通过对花粉的研究已经确定了该属的广泛遗传多样性。然而，据我们所知，还没有针对马缨丹属次生代谢物的遗传多样性进行这样的研究。因此，本研究旨在 2016 年评估马缨丹属（VAA 和 VALF）和 V. calvoana（VCAB、VCAV、VCSB 和 VCSV）形态的遗传多样性，其依据是次生代谢物含量和抗菌特性。这涉及通过 HPLC/MS 进行植物化学分析，以检测来自 6 种基因型的叶片中的生物碱、类黄酮、酚类和单宁。结果表明，所有测试的基因型均富含酚类物质（分析了 18 种）、类黄酮和单宁，其中 VAA 中的酚类物质含量最丰富（206.1 ± 3.12 µg/g 干提取物），其次是 VCAV（197.9 ± 18.03 µg/g）。VCSV 中的类黄酮含量最低（81.6 ± 7.21 µg/g），而 VCAB 中的类黄酮含量最高（132.8 ± 31.5 µg/g）。VCSV 中的单宁含量最低（56.3 ± 4.08 µg/g），而 VCAB 中的单宁含量最高（97.8 ± 23.8 µg/g）。通过在 Mueller Hinton（MH）琼脂和 MH 肉汤琼脂上培养细菌以及在 Sabouraud dextrose 琼脂和 Sabouraud dextrose 肉汤培养基上培养真菌，分别评估了 6 种基因型叶片提取物的抗菌活性。除 VAA 外，所有形态都对细菌表现出抑制活性，VCSV 特征性的是异槲皮苷。马缨丹属形态的化学分类分析突出了种内遗传多样性以及形态间乙醇叶提取物抗菌特性的可变性。这些结果为遗传资源的评估和改良计划的建立提供了基础数据。
