[1] Univ Yaounde I, Dept Organ Chem, Yaounde, Cameroon
[2] Yamagata Univ, Fac Agr, Tsuruoka, Yamagata, Japan
[3] Iwate Univ, United Grad Sch Agr Sci, Morioka, Iwate, Japan
[4] Tohoku Univ, Grad Sch Sci, Res & Analyt Ctr Giant Mol, Sendai, Miyagi, Japan
[5] Univ Yaounde I, Fac Med & Biomed Sci, Dept Med & Tradit Pharmacopoeia, Yaounde, Cameroon